¶A mental database and logic, used to represent ideas, associate one thing
with another and devise causal explanations.
¶Language, the gift of sharing ideas from the mental database with others.
UT's Professor Massimo Pigliucci's essay, Beyond Nature versus Nurture" from
TMP (The Philosopher's Magazine) Online, issue 19. Downloaded 8 August 2002
from http://www.philosophers.co.uk/issue19.htm.
see above
https://notes.utk.edu/bio/greenberg.nsf/aa8ec0ad132580fa85256cff00619f48/c13f4f93
546143f1852564420049e944?OpenDocument
How to estimate the amount of genetic determination:
1. hold the environment constant & look at changes across generations
2. hold genetics constant (clones, etc) and look at differences in different
environments
The variability of phenotypic expression can be succinctly represented as:
VT = VG + VE + VI
That is,
The total phenotypic variation =
variation attributable to genetics
+ variation attributable to environment
+ variation attributable to the interaction between the two (VG X VE )
Born With It? Author Suggests Yes
There is evidence that some universal human social behaviors and faculties are
innate, and presumably shaped in part by the genes. In "The Blank Slate," Dr.
Steven Pinker lists some behaviors of political consequence which he considers may
fall in this category.
Innate Social Behaviors
¶Primacy of family ties, making nepotism and inheritance appealing.
¶A propensity to share based on reciprocity where nonrelatives are
concerned (within the family, it is free).
¶A drive for dominance and a willingness to use violence to attain goals.
¶Ethnocentrism and other forms of group-against-group hostility.
¶Variation in intelligence (leading to inequalities) and in conscientiousness
and antisocial behavior (leading to punitive constraints).
¶Self-serving biases that deceive people into thinking they are freer, wiser
and more honest than they are.
¶A moral sense, biased toward kin and friends, and linked to ideas of purity,
beauty and rank.
Innate Abilities
¶An intuitive physics, used to keep track of the "oomph" of objects as they
fall, bounce or bend.
¶An intuitive biology, used to understand the living world by imputing an
essence to living things.
¶An intuitive engineering, used to make and understand tools.
¶An intuitive psychology, used to understand others by imputing to them a
mind with beliefs and desires.
¶A spatial sense and a dead reckoner tracking the body's motions.
¶A number sense, based on ability to register small numbers of things (1, 2
and 3) exactly and to estimate larger ones.
¶A sense of probability, used to estimate uncertain outcomes by tracking
how common one event is in relation to another.
¶An intuitive economics, used to exchange goods and calculate favors.
deficient sense of humour or a tin ear, must be the fault of bad parenting, bad
environment or other defects of culture or society.
Pinker believes that this bad idea infuses a whole cocktail of practical mistakes,
including utopian politics, madcap schemes of social engineering, optimistic
educational programmes and ludicrous views about gender. To oppose it he
mobilises the most modern of sciences, notably neuroscience, genetics, evolutionary
theory, and particularly evolutionary psychology.
The Blank Slate is brilliant in several dimensions. It is enjoyable, informative,
clear, humane and sensible. Pinker is well aware of the emotions and selfdeceptions that swirl around the science of human nature, and he parades a lurid
cast of villains from behaviourist B.F. Skinner to psychologist Jerome Kagan.
It is difficult to be morally sensitive while treading on people's dreams. But
Pinker manages it, while never compromising on the point that good morals and
politics need to acknowledge the truth about human beings as they are, rather than
how we might like them to be. Its political motto might be the remark E. O. Wilson
made about Karl Marx: "Wonderful theory. Wrong species."
All this is very sound. But is the breathless deference to the new sciences of the
mind and brain appropriate? Pinker writes rhetorically: "Every student of political
science is taught that political ideologies are based on theories of human nature.
Why must they be based on theories that are three hundred years out of date?" Yet
his chapter on conflict and violence explicitly relies almost entirely on Thomas
Hobbes, and his perceptive remarks on human greed and status come from political
economists Adam Smith and Thorstein Veblen. Pinker contrasts real science with
"armchair" theorising. But most theorising is done in armchairs, and such writers
were gifted observers of human nature long before they sat in theirs.
If we read carefully, the contributions of evolutionary theory, psychology or
neuroscience appear to be either little or controversial. For example, Pinker says
that there is an overwhelming consensus among experts that exposure to media
violence does not make children more violent. But I read the book immediately after
attending a conference on law and human nature which was told with equal
certainty of a consensus among experts on just the opposite. Evidently measuring
what the experts think is as hard as measuring anything else.
When it comes to evolution and psychology the matter is no different. Pinker is
unusually clear about the distinction between underlying evolutionary mechanisms
(selfish genes) and proximate psychological mechanisms (overt motivations, such as
lust or envy, altruism or malice). But politics and education need to assess the
degree of freedom evolution may leave to those mechanisms, as we seek to influence
them for the better. If we want to know about that, Hobbes or Leo Tolstoy may still
be better guides than the American Psychological Association.
September 17, 2002
Raging boffins
The nature v nurture debate has never been so fierce. Robin McKie and Vanessa
Thorpe report on the bitter row between two leading scientists
The Observer.
One is a boor, a scientific dinosaur and 'a hardline left-winger' whose ideas have
long since ceased to matter. The other is a 'wicked' individual whose ideas could
lead more children to be assaulted by abusive parents.
That is how two leading scientists have denounced each other over their claims
to know the causes of human aggression. Violence is in the air and, it appears, at its
roots.
In his book They F*** You Up British psychologist Oliver James argues family
influences are critical. Neuroscientist Steven Pinker says nothing matters more
than our genes. Both are openly abusive about each other's stance. Hence, the
accusation of one of Pinker's allies that James is 'fucked-up' while he has retorted in
turn that his opponent is telling lies.
Guardian Unlimited © Guardian Newspapers Limited 2002
from New Scientist
The Blank Slate: The modern denial of human nature
by Steven Pinker (£25 Allen Lane/ The Penguin Press)
reviewed by Simon Blackburn, professor of philosophy at the University of
Cambridge
http://www.newscientist.com/opinion/opbooks.jsp?id=ns235923
reviewed by H. Allen Orr in the New York eview of Books
http://www.nybooks.com/articles/16074
Steven Pinker challenges the notion that our experiences are all that shapes us.
Has he proved his case, asks Simon Blackburn
THE blank slate of Steven Pinker's title is the "white paper void of all
characters, without any ideas" to which philosopher John Locke compares the
original state of the mind, as it passively waits for experience to provide it with the
materials of thought and knowledge. Generalised beyond anything Locke intended,
the idea would be that the mind is empty of any powers or dispositions at all until
life's journey gets under way.
Gottfried Leibniz and David Hume, to mention but two, saw how hopeless this
idea was, since at the very least the mind or brain needs the capacity to make
something of whatever it is that experience affords us. But according to Pinker's
messianic book the idea lives on, often harnessed (inconsistently) with the romantic
view that the blank mind is inherently noble and that violence, aggression, even a
control their environment for the sole purpose of scientific or philosophical
investigation (or for any purpose, most would argue).
Unfortunately, this means that we are left with no sensible answer to a crucial
question. Our educational policies, for example, may be more or less fruitful
depending on the precise shape of human reaction norms. The same can be said for
policies concerned with curbing crime, or for a host of other fundamental and
difficult decisions we have to make in our societies. Regrettably, it should be clear
by now that this is where the line must be drawn and that the only honest answer a
philosopher or a scientist can give is 'I do not know'. There is of course a strong
temptation to keep guessing anyway. Sociologists, psychologists, and philosophers
of science have long pointed out that personal egos, social prestige, financial
rewards (personal or for research) all play into this tendency in a remarkably
complex fashion. The fact remains, however, that there are - and always will be some questions that science cannot answer (either at the moment, or in general). As
Richard Lewontin himself put it in a similar context: "I must say that the best
lesson our readers can learn is to give up the childish notion that everything that is
interesting about nature can be understood. ... It might be interesting to know how
cognition (whatever that is) arose and spread and changed, but we cannot know.
Tough luck."
Learning to live with this conclusion actually empowers the scientist, because by
not pretending to be omniscient she can enjoy the fruits of the most effective tool
humans have devised so far to understand the world around us. Ironically, this
leaves ample space to philosophers in crucial areas such as public policy and its
ethical consequences, since when science must be silent on a given subject matter
we are obliged to focus more on how the world ought to be rather than on how it
currently is.
Suggested reading
Not in Our Genes, R C Lewontin, S Rose & L J Kamin (Pantheon)
Phenotypic Plasticity: Beyond Nature and Nurture, M Pigliucci (Johns Hopkins
University Press)
On Human Nature, E O Wilson (Harvard University Press)
*Massimo Pigliucci (www.rationallyspeaking.org) is Associate Professor of Ecology
& Evolutionary Biology at the University of Tennessee. The following essay was
published in TMP (The Philosopher's Magazine) Online, issue 19. Downloaded 8
August 2002 from http://www.philosophers.co.uk/issue19.htm.
https://notes.utk.edu/bio/greenberg.nsf/9b4b43f8789f398785256419006803bd/ae1ad
66f5a60a9bf85256c30003a0c38?OpenDocument
READINGS ABOUT NATURE/NURTURE and HUMAN
POTENTIAL
http://www.observer.co.uk/focus/story/0,6903,796561,00.html
realise that if one changes either the genes or the environment, the resulting
behaviour can be dramatically different. The trick then, is not in partitioning causes
between nature and nurture, but in what is technically known as 'genotypeenvironment interactions', the way genes and environments interact dialectically to
generate an organism's appearance and behaviour. This dialectical relationship
produces different outcomes when genes or environments change, and the precise
shape of a reaction norm can only be found empirically.
The concept of reaction norms has dealt a fatal blow to a staple of
nature/nurture discussions throughout the last century: the much vaunted (or
criticised, depending on the author) measure of 'heritability' of a trait. When we
hear (or read in newspapers, textbooks, and even technical papers) that the
heritability of, say, intelligence (or homosexuality, or what have you) is 70% we tend
to conclude that that is a major reason to believe that genes have a lot to do with
determining the trait in question. Yet, biologists working on plants and animals
have shown over and again that heritability changes dramatically (sometimes
between 0 and 100%!) if one studies a different population of the same species, or
even the same population raised in a different environment. Furthermore, we now
understand that genetic influences do not imply rigid determinism: studies of
reaction norms in a variety of organisms have shown that the genes only set the
limits of what an organism can do, but that within such limits the degree of
'plasticity' of the organism - its ability to respond to different environmental
challenges - can be very high.
Perhaps one of the best examples of the true relationship between nature and
nurture is found in classic experiments performed by Cooper and Zubek in the late
1950s. They compared 'intelligence', as measured by the ability to avoid mistakes in
running through a maze, in two genetically distinct lines of rats. One line had been
selected for high performance in the maze ('bright' rats), the other for particularly
low performance ('dull' rats). When reared under a standard environment,
comparable to the one in which the selection process occurred, the two lines showed
a highly significant difference in their abilities (i.e., a high 'heritability' of the trait).
Cooper and Zubek, however, also reared individuals of the two lines in two other
environments: a situation in which the cage was entirely devoid of visual and tactile
stimuli ('poor' environment), and one in which the developing animals were exposed
to brightly coloured walls and toys ('enriched' environment). The results were
simply stunning: under the poor conditions, the bright rats performed as badly as
the dull ones, while under the enriched environment the dull rats did as well as the
bright ones (and the heritability of intelligence plummeted to zero in both cases)!
The inescapable conclusion is that maze-running ability in rats is very plastic, and
that different genes may lead to similar behaviours depending on environmental
conditions.
So, why is there still such an acrimonious debate among philosophers and
scientists about nature and nurture in humans? Because for both technical and
ethical reasons we simply cannot perform on ourselves the sort of clear-cut
experiments that Cooper and Zubek carried out on rats. Not only do humans have a
very long life span and encounter very complex environments during their typical
lifetime, but it is obviously unacceptable to experimentally breed human beings and
English philosophers, John Locke and Thomas Hobbes. Locke (1632-1704) was the
founder of the school known as empiricism, holding that knowledge can be gained
only through the use of the senses, as opposed to rationalism, according to which
the mind can derive knowledge solely on logical grounds. On the question of human
nature, Locke thought of the human mind as a tabula rasa (literally, a blank slate).
On it, experience writes and moulds the individual throughout her life. Innate
thoughts do not enter the picture, according to this view. Interestingly, Locke's
theory of human nature - like the ones espoused by biologists such as Gould and
Lewontin in modern times - was tightly coupled with his social theories. Locke
thought that people are born
essentially good and with equal rights, and that an ideal society should reflect
these fundamental assumptions.
Thomas Hobbes (1588-1679) espoused a different notion. In his books, and
particularly in the famous Leviathan he proposed that mechanical processes control
human actions, which are innately fearful and violent. Consequently, the only hope
for humans is to submit entirely to an organised state (and religious authority), so
to be forced to live in a reasonable way. This is not a far cry from the right-wing
politics implicitly or explicitly adopted by some social scientists involved in the
modern debate, such as Arthur Jensen, R J Herrnstein, and C Murray.
Of course, modern philosophers and scientists readily acknowledge that human
traits are in fact the result of both nature and nurture, but they are usually also
quick to add that one of these two components takes precedence. For example,
Gould, Lewontin and others think that the environment is the major determinant of
human nature. Their position could hardly be summarised more concisely than by
the title of one of Lewontin's books, Not in Our Genes. If the causes of intelligence,
aggression, or whatever other aspect of our behaviour are not in our genes, they
must surely be found in the environment. On the other side of the divide, Jensen,
Herrnstein, Murray, Wilson (albeit in a category of his own) and many others are
convinced that genetics and natural selection have shaped the physical as well as
mental characteristics of all living beings, including humans. When Murray
suggests (in the title of one of his articles) that 'IQ will put you in your place' he is
assuming that IQ is written in stone in the DNA of each one of us.
Interestingly from the point of view of the sociology of science, the modern
debate on nature/nurture has often been accompanied by unpleasantness, as in the
case of E O Wilson being treated to a shower of ice cold water during a conference
by somebody who disagreed with his opinions on sociobiology, and Gould being
characterised as someone "whose ideas are so confused as to be hardly worth
bothering with, but as one who should not be publicly criticised because he is at
least on our side against the creationists" by an esteemed British colleague. Clearly,
the emotional stakes are much higher than in your typical academic debate.
A solution to the nature/nurture problem has been at hand since the beginning
of the 20th century, with the introduction in evolutionary biology of the concept of
'reaction norm'. Simply put, a reaction norm is the set of all possible morphologies
and behaviours that a living organism with certain genes can exhibit whenever
exposed to a variety of environmental conditions. Biologists have quickly come to
become fearful after witnessing another monkey's fearful reaction, even on
videotape. However, they cannot be made to fear equally novel flowers by an
identical manipulation. Ridley tells us about these experiments to show that
learning is not arbitrary, but is somehow biased toward useful associations, and I
am retelling the story to make an additional point.
Arne Öhman and colleagues in Sweden have used Pavlovian conditioning to
demonstrate that people, too, can readily learn to fear snakes, but not flowers nor
even modern dangerous objects such as electrical sockets. They have, furthermore,
shown that this learning occurs even when brief exposures and "masking stimuli"
leave the experimental subjects unaware that there ever was a picture of a snake.
In this case, the origins of the fear are inaccessible to conscious knowledge, leaving
the phobics (and their analysts) free to fabricate their histories.
In Nature via Nurture, Matt Ridley makes the latest findings in developmental
genetics accessible to everyone, and best yet, he places the findings in a historical
and social context that makes sense.
Margo Wilson is an evolutionary psychologist at McMaster University.
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82ecab1e9385256c110013a7ce?OpenDocument
OPTIONAL READING, but sure to bring greater insight to your understanding of
biological determinism:
Beyond nature versus nurture
Massimo Pigliucci*
The debate on the relative importance of nature (genetics) and nurture
(environment) in determining human traits has been prolonged and often
acrimonious. Great minds have engaged in it over the last 300 years, including
philosophers John Locke and Thomas Hobbes, and scientists Stephen Gould,
Richard Lewontin, and Edward Wilson. The problem is that most of the debate has
proceeded on the basis of either a simplistically dichotomous view of the question, or
with a dearth of relevant empirical evidence. The controversy has in fact largely
been solved when it comes to plants and non-human animals. Unfortunately, most
philosophers are not aware of such progress, which has taken place within the
arcane discipline of evolutionary ecology. On the other hand, most scientists keep
focusing on the special case of humans which - while obviously the most interesting
- has demonstrated to be the most recalcitrant to empirical analysis and the most
open to philosophical inquiry.
While it is safe to say that humans have always investigated their own nature
and have certainly done so since the onset of Greek philosophy, modern positions on
the issue of nature/nurture may more or less clearly be traced to the works of two
penis. With reduced testicular hormone production, there will be little libido in
adulthood -- and presumably, not much desire to go to war, either.
So is KAL-I, not SRY, the real "culprit"? Or is the quest for simple, singular causes
bankrupt?
The "nature" that many pit against "nurture" is now a codeword for genetic
influence. But what exactly is that? Ridley notes that the word "gene" has at least
seven subtly distinct meanings. It was coined in 1909 from a Greek root referring to
birth, as a label for the "particles" of inheritance postulated earlier by Gregor
Mendel, but its chemical basis in DNA's double helix was not discovered until 1953,
and the human genome was not fully sequenced until 2001.
Today, both evolutionary theorists and those studying inherited disorders continue
to make productive use of something close to the original gene concept; the
molecular biology of the gene and its expression is simply not the focus of all work,
although it is very much the focus of some. Genes "merely" code for proteins, but
they are switched on and off by environmental events, as well as by other genes,
and those that serve the organism well proliferate in evolution. Ridley makes it
clear that we share genes and developmental processes with other species because
they continued to help the evolving Homo sapiens to survive and reproduce, but also
that the same genes may be co-opted for different functions in different species.
"Nurture" is code for environmental influence, which encompasses everything from
the chemical milieu within cells to social and cultural influences. And genes play
roles in all these influences. In explaining this, Nature via Nurture offers the
conceptual tools and the examples that readers need to help them move beyond
nature versus nurture, a false opposition that Ridley blames for multiple
misunderstandings: of the developmental process, of how the brain/mind really
works, and of why human cultures (and different species) can be so diverse in the
face of so much genetic commonality.
In educating us about these matters and about the history and social contexts of
ideas in the life sciences, Ridley also strives to allay fears of "genetic determinism."
Some popularizations indeed make our genes sound like puppet-masters, yet it is
obvious that the complexity of what makes us human has no point-by-point
correspondence with our mere 30,000 (or so) genes. It is no better, however, to infer
that human choices and actions have thus been liberated from human biology. (The
compelling phenomenology of deliberation and choice may fool us into thinking so,
but a great deal of clever psychological research has shown that we often have
surprisingly little conscious access to the sources of our preferences and actions.)
In my experience, this dualism, whereby genes are granted roles in our anatomy
and physiology, but not in our psychology and behaviour, is a more prevalent error
than "genetic determinism," which (as Ridley appreciates) has no real-world
adherents, notwithstanding the scare-mongering.
Another illustration of why nature and nurture are not opposites is provided by
studies of how monkeys come to fear snakes. Naive laboratory-raised monkeys
https://notes.utk.edu/bio/greenberg.nsf/e59872274575534a85256d2b003a7da9/00abe
40bd2db79be85256d2b0039c128?OpenDocument
http://www.globeandmail.com/servlet/ArticleNews/TPStory/LAC/20030517/BKNUR
T/TPScience/ [17 May 2003]
The Globe and Mail
A genetic truce
By MARGO WILSON
Saturday, May 17, 2003 - Page D7
Review of
Nature via Nurture: Genes, Experience, & What Makes Us Human
By Matt Ridley (Harper Collins, 326 pages, $36.95)
Here's a recent headline and subhead from a Toronto newspaper: "Are humans
hard-wired to behave aggressively? Y chromosome could be the culprit in war." Like
all of us, the British biologist and popular-science writer Matt Ridley has heard
such pseudo-explanatory claptrap too often, hence Nature via Nurture, his attempt
to explain why recent discoveries in the life sciences tell us as much about how
experience shapes us as about genetic influences.
Inheriting a Y chromosome from dad is, of course, what makes a child a boy rather
than a girl. But how? Ridley explains that the Y carries a gene (SRY) that switches
on another gene present in both sexes (SOX9), and that that's the end of SRY's role
in development. SOX9 turns on other genes, which turn on still others, which
regulate the production of hormones that masculinize the fetus's developing body
and brain. To call this developmental cascade "the culprit in war" would be absurd,
yet it sets the stage for the myriad ways in which experiences, including other
people's reactions to the child's maleness, continue to affect the behaviour of both
the boy and his genes.
Nature via Nurture is full of such information about how genes are turned on and
off in development, in learning and in response to stimuli both local and quite
indirect. It's not light reading, but Ridley is an engaging writer, with a track record
of biological books (Genome, The Red Queen) that are both popular and
scientifically accurate.
One way in which Ridley tells us how genes work is by explaining cases where they
don't. Men who lack a functional KAL-I gene, for example, cannot smell anything
and have small genitalia. (Mercifully, they are short of libido, too.) What their
missing KAL-I gene should have done was to produce a protein, anosmin, early in
fetal life. Anosmin causes certain cells to stick together, including migrating nerve
cell axons that would ordinarily stop and assemble olfactory bulbs, the brain areas
primarily responsible for the sense of smell. No KAL-I, no olfactory bulbs, and the
developmental disaster doesn't stop there: Other migrating axons which also
originate in the nose follow the same pathways, and under the influence of anosmin,
they ordinarily connect with cells that instruct the pituitary gland, at the base of
the brain, to produce the hormones responsible for differentiating the testes and
and enhancers that regulate these genes should also provide important insights into
how inherited and environmental factors affect brain and behavior.
Emphasizing the dynamic responsiveness of the genome over different time scales
not only provides a framework that includes both mechanistic and evolutionary
explanations of behavior at the molecular level, but may also attract more social
and behavioral scientists to the quest to understand the relationship between genes
and behavior. In the past, social and behavioral scientists might have dismissed
molecular studies of behavior in animal models by pointing to the greater
complexity of human behavior. Yet the examples offered here--pair bonding,
foraging, and care of offspring, each involving molecules known to also be present in
humans--illustrate complex behaviors performed over days and weeks or even a
lifetime. These behaviors have learned components and are performed in a social
context. The value of animal models can be further enhanced by applying genomics
to generate large-scale expression profiles of individuals with different genotypes
tested in different environments (9). In addition, the application of informatics
should enable new literature-based comparative analyses of behaviors across
different species (10).
Development of new tools marrying the vast literature on behavior with genomics
could also spark increasing involvement by social and behavioral scientists in
molecular genetic studies of behavior. This would be a welcome development indeed.
A complete explication will require the integration of diverse perspectives in
molecular biology, neuroscience, evolutionary biology, and the social sciences. Such
a collaboration, grounded in our rapidly increasing knowledge of the dynamic
genome, should help everyone get past the dilemma of nature versus nurture. Then
we can all focus on both the tremendous opportunities and the challenging ethical
concerns related to the study of genes and behavior.
References and Notes
1. Spanish proverb, cited in J. R. G. Turner, Biol. J. Linn. Soc. 29, 277 (1983).
2. A. Chakravarti, P. Little, Nature 421, 412 (2003) [Medline].
3. D. Ferster, Science 303, 1619 (2004).
4. T. R. Insel, L. J. Young, Nature Rev. Neurosci. 2, 129 (2001) [Medline].
5. K. A. Osborne et al., Science 277, 834 (1997).
6. Y. Ben-Shahar, A. Robichon, M. B. Sokolowski, G. E. Robinson, Science 296,
741 (2002).
7. D. Francis, J. Diorio, D. Liu, M. J. Meaney, Science 286, 1155 (1999).
8. I. C. Weaver, M. Szyf, M. J. Meaney, Endocr. Res. 28, 699 (2002) [Medline].
9. C. W. Whitfield, A.-M. Cziko, G. E. Robinson, Science 302, 296 (2003).
10. B. Schatz, Computer 35, 56 (2002).
11. I thank M. R. Berenbaum for the reference to the proverb, and Y. BenShahar, S. N. Beshers, N. E. Cantor, I. H. Carmen, D. F. Clayton, S. E. Fahrbach, T.
R. Insel, H. A. Lewin, M. Sen Sarma, M. B. Sokolowski, A. L. Toth, B. Schatz, and
L. Wraight for helpful discussions. Research from my laboratory cited here was
supported by NSF, NIH, and the Burroughs Wellcome Fund.
monogamous, whereas most other species of mammal are polygamous. Differences
in receptor distribution and behavior are associated with a microsatellite length
polymorphism in the promoter of the V1a receptor gene. Transgenic male mice with
a prairie vole version of this promoter respond to vasopressin by bonding with
females as if they were prairie voles. The V1a receptor gene demonstrates how
behavioral variation can be generated by inherited influences on gene expression.
The foraging gene (for), which encodes a guanosine 3',5'-monophosphate-dependent
protein kinase (PKG), causes inherited differences in behavior in natural
populations of the fruit fly Drosophila melanogaster (5). Allelic differences in for
expression result in two foraging variants: "Rover" flies have higher levels of for
mRNA and PKG activity and are more active food gatherers than "sitter" flies. An
ortholog of Drosophila for is involved in regulating food gathering in the honey bee
Apis mellifera. In this case, the effect occurs over a developmental, rather than an
evolutionary, time scale (6). The age-related transition by bees from hive work to
foraging is associated with an increase in for expression in the brain. Expression of
for in the bee brain also responds to the dynamic aspects of life in a bee colony, such
as when the need arises for some individuals to begin foraging earlier in life than
usual. For example, a spike in birthrate that results from favorable environmental
conditions in the spring yields a colony deficient in foragers; precocious foragers
show a premature increase in for brain expression. Likewise, treatment that
elevates PKG activity also causes precocious foraging. The for gene demonstrates
how behavioral variation can be generated by both inherited and social
(environmental) influences on the same gene, albeit in different species.
The steroid glucocorticoid hormone is an important component of the system that
coordinates behavioral responses to stress in vertebrates. Rats (Rattus norvegicus)
with a more active glucocorticoid receptor-encoding gene in their brains are more
tolerant of stress than individuals producing fewer receptors. These differences
explain variation in maternal care exhibited by different mother rats (7). Variation
in maternal care in rats is inherited; pups that receive the minimum care from their
mothers grow up to return the favor when they have their own offspring.
Apparently, pups experiencing indifferent care show profound changes in brain
gene activity, including decreased expression of the glucocorticoid receptor gene.
But these inherited differences in gene expression and behavior occur even in the
absence of DNA polymorphisms. In the case of the glucocorticoid receptor gene of
neglected rat pups, it is epigenetic modification of the DNA sequence through
methylation that is involved in their altered adult behavior (8). Hence,
environmental influences on behavior can cause epigenetic changes in the genome
that are inherited.
Any modern reformulation of nature-nurture questions concerning behavior
requires knowing which genes vary as a result of heredity and which genes respond
to environmental factors. A broad search for genes sensitive to both influences
might provide breakthroughs in the study of genes and behavior. These genes might
be pacemakers--evolutionarily labile and mechanistically important--and their
identification may lead to molecular pathways that are critical to the brain
machinery that modulates behavior. Identification and analysis of the promoters
When it comes to behavior, the nature-nurture controversy has not disappeared.
The public is leery of attributing behavioral influence to DNA rather than to the
environment and free will; worries abound over the ethical implications of biological
determinism. Many social and behavioral scientists are skeptical as well, either
because the concept of "DNA as destiny" does not jibe with their understanding of
the dynamic nature of behavior or because they consider human behavior to be
much more complex than that of animals studied from a genetic perspective. By
contrast, biologists have long accepted that genes, the environment, and
interactions between them affect behavioral variation. Traditionally, behavioral
variation has been partitioned using statistical analysis into genetic (G),
environmental (E), and G x E components, an approach that began long before the
advent of molecular biology. This retains the flavor of the nature-nurture
dichotomy, which influences how research in this field is interpreted. Fortunately,
we can now study genes in enough detail to move beyond the nature-nurture
debate. It is now clear that DNA is both inherited and environmentally responsive.
Behavior is orchestrated by an interplay between inherited and environmental
influences acting on the same substrate, the genome (see the figure). For behavior,
gene expression in the brain is the initial readout of the interaction between
hereditary and environmental information. Inherited influences ("nature") include
variations (polymorphisms) in DNA sequence transmitted from generation to
generation over an evolutionary time scale. DNA polymorphisms can affect protein
activity (sometimes via posttranslational mechanisms) and gene expression in the
brain: when, where, and how much of each protein is produced. The environment
("nurture") also influences gene expression in the brain during the lifetime of an
individual (2, 3). Environmental effects occur over developmental and physiological
time scales. Gene expression in the brain constitutes the first measurable indicator
of the interaction between the genome and the environment.
Until recently, this "first phenotype" was not easy to study. However, it is now
possible to investigate the relationship between gene expression and behavior in the
brains of animal models, thanks to new genomic techniques that make gene
expression analysis more sensitive, efficient, and comprehensive. As the following
three examples illustrate, we can finally begin to understand the interplay of
hereditary and environmental influences on genomic activity and individual
behavior. Each example deals with just one gene, but don't be misled. All behaviors
are influenced by the actions of many genes; the three highlighted here exert their
effects as part of gene networks that give rise to diverse pathways of physiological
activity.
The gene encoding the vasopressin V1a receptor plays a prominent part in the
social behavior of voles (4). The vasopressin system is dynamic in mammals, and
surges of this neuropeptide hormone occur in the brains of males after mating.
Inherited differences in the brain distribution of V1a receptors underlie striking
species differences in vole mating habits. The prairie vole (Microtus ochrogaster) is
Published fifty years after the discovery of the double helix of DNA, Nature via
Nurture chronicles a new revolution in our understanding of genes. Ridley recounts
the hundred years' war between the partisans of nature and nurture to explain how
this paradoxical creature, the human being, can be simultaneously free-willed and
motivated by instinct and culture. Nature via Nurture is an enthralling, up-to-theminute account of how genes build brains to absorb experiences.
Genome Genome: The Autobiography of a Species in 23 Chapters
In Genome, Matt Ridley examines in his inimitable style the mapping of the human
genome. He describes what the genome is, how it works, and examines how this
new knowledge will affect medicine, the pharmaceutical industry, business, politics
and our lives. Each chapter is devoted to one of the 23 human chromosomes, telling
the story of a particular gene on that chromosome and how it affects the individual
who bears it. Examining the most important scientific achievement since the
splitting of the atom, Genome makes a useful and entertaining contribution to
understanding who we humans are and where we are going.
The Origins of Virtue The Origins of Virtue: Human Instincts and the Evolution of
Cooperation
In The Origins of Virtue Matt Ridley applies an evolutionary perspective to
explaining the roots of trust, cooperation and virtue. He argues that humans have
cooperative instincts which evolved as part of our natural selfish behaviour; by
exchanging favours our ancestors were able to benefit themselves as well as others.
Ridley shows us how breakthroughs in computer programming, microbiology, and
economics give us new insights into how and why we relate to each other in the
ways we do.
The Red Queen The Red Queen : Sex and the Evolution of Human Nature
In the title of this book, Matt Ridley refers to the Red Queen from Lewis Carroll's
Through the Looking Glass, who has to keep running to stand still; he demonstrates
why sex has proved to be a successful evolutionary strategy for outwitting everevolving parasites and examines the key role played by sexual selection in human
evolution.
https://notes.utk.edu/bio/greenberg.nsf/e59872274575534a85256d2b003a7da9/a06ca
e6526fe9bc785256e8b005d7b5b?OpenDocument
archive website from
Science
Vol 304, Issue 5669, 397-399 , 16 April 2004
GENOMICS:
Beyond Nature and Nurture
Gene E. Robinson*
The horns of a dilemma are usually on the same bull (1).
something that is beyond the power of a man with a pencil. It's going to require
people who are good at systems dynamics. People who come out of business schools
are quite good at this kind of thing. It's going to come from some funny directions.
The economists are quite good at this kind of thing. The genome is going to turn out
to be quite like an economy. When you adjust interest rates you have some effects
here and other effects there, and then they have effects and they affect what affects
interest rates and so it all feeds back on itself. A lot of genomic phenomena are
going to turn out to be like that. So I do think that bioinformatics is the way a lot of
this is going. You only have to look inside a molecular biology lab these days and see
that they spend half their time comparing sequences on the Web with other
sequences, pulling out sequences that are similar, saying, "Oh my goodness, this
gene is like that one in fruit flies." But there's still going to be room for a lot of very
important wet biology in this, particularly when you get inside the brain, because
what's going to turn out is that the gross structure of the brain conceals immense
amounts of detail about which nerve cells are talking to which nerve cells, and the
genes are going to be the key to finding out what's going on there. These
alternatively spliced genes that seem to enable each nerve cell to have almost a
unique bar code on it that tells it who it needs to link up with when it gets to its
target. There's still room for some heroic biology in there.
http://www.thegreatdebate.org.uk/mattridley.html
Matt Ridley did research in zoology at Oxford before becoming a journalist. He
worked for The Economist for eight years and has been a columnist for the Sunday
Telegraph and Daily Telegraph since 1993. He is author of Nature Via Nurture
(2003), Genome (1999), The Origins of Virtue (1996) and The Red Queen : Sex and
the Evolution of Human Nature (1993). He is chairman of the International Centre
for Life, Newcastle upon Tyne's science park and visitor centre devoted to life
science.
Matt Ridley was on the panel at Determined to Survive? The Great Debate Freedom, Determinism and the Gene in June 2000.
Nature Via Nurture: Genes, Experience and What Makes Us Human
In February 2001 it was announced that the genome contains not 100,000 genes as
originally expected but only 30,000. This startling revision led some scientists to
conclude that there are simply not enough human genes to account for all the
different ways people behave: we must be made by nurture, not nature. Yet again
biology was to be stretched on the Procrustean bed of nature-nurture debate.
Acclaimed science writer Matt Ridley argues that the emerging truth is far more
interesting than this myth. Nurture depends on genes too, and genes need nurture.
Genes not only predetermine the broad structure of the brain, they also absorb
formative experiences, react to social cues and even run memory. They are
consequences as well as causes of the will.
same time as DNA falls into place. Suppose the base pairing mechanism of the
double helix had been discovered in the 1920s, which is not totally impossible. The
x-ray diffraction stuff wouldn't have been possible, but it's conceivable that a
chemist could have worked out what was going on in DNA without x-ray diffraction.
In the '20s, before computing, would we have even understood what we were looking
at? Possibly not. Would we have been able to imagine one day reading it, and
having the storage capacity to decode it? Or the other way of looking at it then is to
suppose that DNA happens on schedule and we invent machines for sequencing
DNA, but we haven't actually got computers by the '90s. How do we store the data?
Do we have a lot of clerks writing it down instead of computers? It is wonderful the
way the two branches of information technology, one called life and the other called
electronics, fall into place at the same time. I don't understand how that kind of
serendipity works in history, but it's an intriguing one.
In retrospect it became inevitable once we knew the genetic code and how it was
spelled out that one day we'd read the entire script of the human recipe. It's quite
surprising to think back to the mid-'80s and realize how controversial it was that
people suggested it. It was a tremendous distraction for biology from most
important tasks. It's far too expensive, and most of it is junk anyway. We shouldn't
read the whole thing, but should just do the interesting bits. The idea of the human
genome was a very controversial one. But a lot of people had faith that if you start
reading genes, the technology will catch up and get cheap enough so that you can
finish the job. And so it proved. Let's face it, the human genome project started in
about 1986 or '87, and between 1986 and 1998 it read maybe 10% of the genome.
And then it read 90% in the last year. I personally think that the trajectory would
have been much the same without Craig Venter's intervention. What would not
have happened is the publishing of a draft rough sequence in 2000. The key date
would have been the finishing of the golden, perfect sequence in 2003, which is just
happening as we're speaking. The trajectory to getting to that actually wasn't
changed by Venter's intervention, but in order for the human genome project to
announce a dead heat with Craig Venter's shotgun sequencing technique, we all
think of 2000 as being the year when it was finished. In fact, what was finished
then was a pretty messy draft that wasn't much use.
What's next? Lots of other genomes. It's going to be very important to get the
chimpanzee genome. The dog is going to be interesting, because then we can start to
look at the behavioral differences between breeds of dogs, and that'll pull out genes
to do with behavior. The mouse is obviously a key one for medical research. We've
already got the mouse genome. The rat comes soon. All the others like the rice
genome, which has just been finished. There's going to be scores and scores of
genomes sequenced. Then we can start talking about individual genomes, and Craig
Venter foresees the day when you or I can have our genome done for a thousand
dollars. I suspect there won't be much point in doing whole genome sequencing for
individuals, but there's going to be a huge significance in doing the interesting bits
once we start to work out what they are.
There's no question that the discovery moves in silicon now. In other words, a huge
amount of the significant stuff that we do next has to be both understood inside a
computer and modeled inside computers. The modeling of gene interactions is
certain number of repetitions or a lesser number—does the less active version of the
gene correlate with ending up a young adult who is antisocial and who's in trouble
with the law? No, it doesn't, in significant correlation. If you then break the data
down, though, into those who were abused in their childhood and those who weren't,
you find a very strong correlation with this gene. It turns out that if you have the
low-active version of this gene, and you had an abusive childhood, then you're going
to end up with an antisocial adult—not deterministically, but with a high
probability. That seems to me to be a terribly important study, because it shows
that when you parcel out the gene-environment interaction, you can find genes in
here that you wouldn't have found with the conventional gene-hunting techniques—
genes that correlate with behavior, but that react to the environment.
What are the social implications of finding this? Well, essentially there are none,
because we were against child abuse before we knew which genes were involved,
and we're against child abuse afterwards. It's possible that you can start to say to a
kid who has been abused and it's too late to intervene, "You are going to be all right,
because you don't have the particularly responsive version of the gene," or "You're
not going to be all right, and therefore we should start putting you on Ritalin or
Prozac to try and adjust your brain chemistry during your life." We're a long way
from that yet, but that's the kind of social implication you could pull out of it.
~~~
If you go back to before the first two months of 1953, and ask yourself what people
thought life was, you find nobody with anything like the right guess. Absolutely
nobody is talking in terms of a linear digital code, until the morning of the 28th of
February, 1953, when Jim Watson puts the base pairs together, and suddenly the
idea of spelling out an infinitely long, infinitely variable, but completely faithfully
reproducible code falls into place. You can say that Schrödinger used the term code
script at one point, but he talked much more about quantum mechanical ideas and
things like that. There were ideas that the secret of life was going to be some kind of
piece of chemistry, a piece of energy, or a piece of quantum mechanics. There were
all sorts of ideas out there, but nobody thought it would have anything to do with
linear digital information, like we use in books, strings of alphabetical letters. That
is why that is such an important moment, not because the thing was shaped like
two spirals—that's just aesthetically pleasing—but because the world changed on
that day. It took a long time for the world to realize it had changed, and Watson and
Crick got invited to give zero seminars in Cambridge during the next three years,
which is worth remembering, and there was nothing in the newspapers about it.
1953 was better known for many, many years as the year when Everest was
climbed, the Queen was crowned, the first issue of Playboy was printed, and all
these other tremendous anniversaries. But in retrospect we can see that it doesn't
really click with the population at large until O. J. Simpson and Monica Lewinsky
put DNA on the map in the '90s. It's forensic DNA, Alec Jeffries' discovery of DNA
fingerprinting, that really brings it home to people what we're talking about here,
which is a bar code, a message.
It's uncanny the way Turing and Shannon and all these people come together with
ideas of computability, digital information theory, and cybernetics at around the
things, you come up with these very strong results saying that variations of
personality within American society are caused by variations in genes. Variations in
intelligence within American society are caused mostly by genes, partly by family
environment. These results are fantastically robust now. They're not just from
Bouchard's study in Minnesota; there are also in the Virginia studies, the
Australian ones, the Dutch ones, and the Danish ones. There are big studies about
twins reared apart all over the world, and they're all coming to the same
conclusions, so it's no good wishing them away. But the people who don't like these
studies, and who wish them away, are actually allowing them to be more powerful
than they are, because they're essentially thinking that they're proving that genes
are important at the expense of environmental factors, and they're not. Often, the
stronger the environmental factor, the more genetic variation you're going to pick
up.
A good example is short sight. In a society where only half the people are literate,
the correlation between genes for short sight and short-sightedness is quite poor. In
a society where everybody's reading books as a child, the correlation gets much
better. So when the environmental factor, which is early reading, becomes stronger,
the genetic variability becomes stronger. So actually what these studies are picking
up is that the environment is good enough in American society to bring out the
genetic variation between people. On the whole you're holding it constant. You're
sending them to similar schools, giving them similar curriculums, and giving them
similar toys to play with and similar television stations to watch. So you're bound to
pick up the genetic differences. However, the twin studies have done a fantastic job
of proving heritability of things like personality in particular societies. Going from
that to finding out which genes are involved has proved immensely disappointing.
There's no question that this is a huge failure. A lot of people ten years ago would
have said it's now going to be comparatively easy to start walking down the genome,
hunting the actual genes involved in extroversion or neuroticism, and it just doesn't
work. Endless results show a small positive effect and then vanish, because it turns
out either that the effect is associated only with one population, or it just doesn't
replicate. Why is that? Is it because there are so many genes involved in these
things that you can't pick out the ones with very small effects? Most of them do
have very small effects. I don't think so; it's subtler than that. What's happening is
that you're getting gene-environment interactions that are under the radar of the
normal gene-hunting techniques.
A very nice example of this, which is still quite a controversial study, is Terrie
Moffitt's work on antisocial behavior and the mono-amine oxidase-A gene on the xchromosome, which is going to set the standard for how to understand the genes
involved in personality and behavior. I write about it in Nature via Nurture. She's
done a study of a cohort of New Zealanders in Dunedin who've been followed ever
since birth. All the kids in this town were followed every year of their life to see
what happened to them. It's about a thousand kids. If you take the 400 boys in the
sample who have all-white genetic ancestry up to the grandparent level—boys
because we're talking about a gene on the x-chromosome—and you look at their
mono-amine oxidase-A gene, and you look at whether it's the high-active or lowactive version—there are essentially two versions of this gene according to how
active they are, according to whether the promoter on the front of the gene has got a
flower, so after it sees a monkey reacting with extreme fear to this new thing called
a flower it should just as easily learn a fear of flowers. But it doesn't. It just learns
that some monkeys are crazy. So what's going on here is that there is clearly an
instinct for fear of snakes, and that's not surprising. Human beings have snake
phobia. It's the commonest of all the phobias, even though most of us hardly even
ever see a snake in our lives, but it requires an input from the environment. It
requires a nurture input to be triggered. We know this is happening in the
amygdala, and we're getting a bit of a handle on which cells are involved. We're not
yet down to the gene level, but I'd bet my bottom dollar there's going to be a little
pathway of genes in here that's mediating this process.
~~~
Judith Harris has made an immensely important contribution in that she has blown
the whistle on a huge mistake that's been made, which is to assume from the
correlation between parents and children that children are learning things from
parents. It turns out that once you control for heredity, through the use of behavior
genetics, twin studies and adoption studies, you find that in the development of
personality in particular—and that's quite a narrow point—children do very little
learning from their parents, but they do quite a lot of learning from their peers.
That seems to me a very important breakthrough. Judith Harris is building upon
the behavioral genetics studies, where people like Thomas Bouchard and others
with their studies of twins have made an immensely valuable contribution. But just
because they're proving that genes are important in things like personality doesn't
mean they're proving that environment is not important.
What it means is that they're proving that variations in family environment within
a particular society don't change personality. It's a bit like vitamin C. If you don't
get enough vitamin C it can cause a huge variation in your health, in this case
scurvy. But as long as you're getting enough vitamin C, having extra vitamin C
doesn't make you any healthier. And that's probably the way families are. You've
got to have a sufficient level of love, affection, interest and stimulation from a
family, but once you've got that, having extra doesn't change your development,
whereas genes do vary all across the spectrum, and can change your development
even in a constant environment. It's a bit like saying a kid with one toy in its entire
life is obviously massively worse off than a kid with ten toys, but a kid with ten toys
is not noticeably worse off than a kid with a hundred toys—or in my son's case, five
million toys, as far as I can make out.
There's a lot of people who want the twin studies to go away. They want them to
turn out to be methodologically flawed. They want to find that these twins knew
each other all along, or that somebody's faking the data—as indeed happened in the
case of Cyril Burt, as far as we can make out, although there are some people who
don't accept that. People who wish for that are going down the wrong alley. The
methodological criticisms have run out of room to be any use. For example, people
will say that you can't learn anything from comparing identical twins because
identical twins have shared a womb. The point is that a lot of the argument's
answered by the fact that you're also comparing non-identical twins reared apart, as
well as identical twins reared apart. And once you've got a decent database of these
of fairness in that. But there's an awful lot of people who've been trying to put an
end to the nature versus nurture debate, saying, "Come on. It's gene-environment
interaction, etc." But the one thing I'm absolutely sure of is that if you go and look
at the history of the nature-nurture debate—from Galton, through the 20th century,
through Lysenko, Skinner, Watson on one side of the fence, and Chomsky, and
people on the other side—you find that it's always very useful to pay attention to
what people are saying about their own theories. It's very misleading to pay
attention to what people are saying about each other's theories. On the whole,
people have been pushing each other into extreme positions that they don't occupy,
saying, "Look, I'm in the middle of the road. He's the guy who's on the verge. He's
the extremist."
What I find happens all the time in this debate is that you say that there are genes
involved in, let's say, sex differences, and people say, "Oh no, no, no. Sex differences
are social. They've done an experiment that shows that sex differences are socially
caused." And I say, yes, sure, sex differences are socially caused. I never said they
weren't. I just said there are genes involved too. Indeed, there are genes involved in
the social causation. That's the whole point. I don't actually know how sex
differences and behavior come about, and I don't think anyone does yet. But it's
pretty likely that what happens is a form of prepared learning, whereby there is an
instinct for boys to end up one way and girls to end up another. But the way that
instinct works is for boys to have an instinct to pick up from the world what boys do,
not to arrive in the world with a program in their head saying, "Pick up a stick and
go Pow! Pow! Pow! with it." It's "Ah, I like it when people go Pow! Pow! Pow! with
sticks. That fits with my perceived way I'm heading in the world." Or I don't,
according to which gender I am.
The classic and best experiment in this is Susan Mineka's work with a group of
monkeys in Madison in the '80s, where she set out to examine the ontogeny of an
instinct—in this care fear of snakes. Wild-born monkeys are afraid of snakes.
They're so scared of snakes that they will cower in the back of the cage screaming
rather than reach across a plastic model snake to get at a peanut when they're very
hungry. Captive-born monkeys are not afraid of snakes; they happily reach across
the model snake to get at a peanut. So what's going on here? That means that fear
of snakes must be learned. But how on earth do you learn fear of snakes? The
conventional classical conditioning wouldn't work very well, would it, because either
you have a bad experience with a snake to learn from, in which case you're dead, or
you don't have a bad experience, in which case you don't learn that snakes are
frightening. So how are you going to end up acquiring a fear of snakes? It seems an
absurd thing to acquire. She argues that what's happening is that there is a
program for fear of snakes, an instinct if you like, but that that instinct needs to be
socially triggered—in some sense triggered by a vicarious experience, by observing
another monkey having a fear of snakes. So she set up an experiment in which she
videotaped the wild-born monkey reacting with fear to a snake, and she then
showed this video to a captive-born monkey, which immediately acquired a fear of
snakes and was not then prepared to reach across even a model snake to get a
peanut. She now doctors the video, so that it has the same monkey reacting in the
same way in the background, but the bottom half of the screen now instead of
having a snake has a flower. Again, the captive-born monkey has never seen a
strengthened. In the future only one of them need fire and it will provoke a memory
of the other.
That process of changing the strength of synapses between nerve cells is mediated
by genes. It actually requires the switching on and off of genes in order to change
the synapses. These genes we now know, because of work on fruit flies, are called
the CREB genes. There are about 17 of them in that particular system, and they're
also in mammals and humans as well. They prove that memory and learning is a
genetic process. That doesn't mean that it's a hereditary process—of course not.
What we're talking about here is changing the expression of the genes in real life in
response to what is literally the formation of a new memory—a new experience, in
other words.
So the simple linear model of going from genes to behavior, which both the nature
people and the nurture people have subscribed to—the nurture people saying, that
model doesn't work, the nature people saying, that model does work—is wrong. It's
nothing as linear, as deterministic, or as frightening as nurture people would have
you believe, nor is it anything nearly as linear as the nature people would have you
believe. It's much more interesting than that. With these feedback loops, from
behavior back into the expression of genes, it means that the process of the creation
of human nature and the alteration of human nature throughout your life
intimately involves genes and experience at the same time. The more genes you
have, the more genetic programs you have, the more experience you can get into the
organism.
~~~
This doesn't fit into the wars between people on the nature side and the nurture
side very easily, and one of the things I've tried to do is to get away from the idea of
the nature-nurture debate being a simple pendulum from one side to the other. The
important point about this argument is that it's empirically driven. It starts with
molecular biology. It starts with Seymour Benzer and other people discovering the
genes involved in learning and memory; it starts with the discovery of real genes,
and what they're actually doing—the work of someone like Cathy Rankin, a
brilliant young scientist in Vancouver who has essentially observed in real time the
changes in the nematode as it learns a new experience. She's done so by getting the
genes to light up, literally. The cells that are expressing this process light up. She's
also finding that those who have had a social upbringing behave differently than
those with a solitary upbringing—in other words if they've been to school or been
brought up at home, if you like. These are worms, remember, nematode worms with
302 neurons. Total. Maximum. No brains. And yet you can see an effect of
developmental upbringing, social upbringing, etc., and it's these same synapses that
are involved in the process of learning and memory. Discoveries like that are
driving this new way of seeing the world, not theories. And to some extent the
theories have got to be a bit humble before the new data. That's my epistemological
position.
There's a possibility that you can adjust your theoretical thinking to this knowledge
and say it was what you were saying all along, and to some extent there's a degree
pedigree. Those two sense-changing alterations in the gene have happened in the
past 200,000 years. It was probably about 200,000 years ago they happened, and
they've elbowed aside all other versions of the gene. There's been a selective sweep
of these mutations through the species. So what we're looking at here is a gene that
was under very strong selective pressure around 200,000 years ago, which is around
the time that we think human beings first started using language in something like
the form that it is today. How that genetic change changes the wiring of the brain in
order to enable language learning I don't know, and nobody knows the answer. But
the point is the word enable there. Genes are enablers and not constrainers. People
tend to think about genes as being constraints on what human beings can do. In
fact, that's a very misleading way of looking at it. What's happened is that genetic
changes are necessary to enable kinds of learning, to enable kinds of nurture, and to
enable kinds of experience to get into the organism. In that sense genes are just as
important a part of the story of nurture as they are the story of nature. When you
start to see it that way, you can resolve the old nature-versus-nurture debate, and
you can instead start to talk about nature via nurture instead.
So one important point is that genes are designed to produce human behavior
through nurture. But there's another phenomenon going on too, which is equally
important and which again people in these kinds of debates over human nature
have missed. They couldn't have failed to miss it until recent molecular biology
made a difference. That is, behavior affects genes. It doesn't change the code of the
gene, and it doesn't change the encoded genome. Sure, you can change your encoded
genome by having a mutational accident, by flying in an airplane and having cosmic
rays damage your DNA. But what I'm talking about is changing the expression of
genes through things you do in your life. The encoded genome is a set of DNA. The
expressed genome is the RNA that's translated from it and then made into proteins.
That process of expressing the encoded genome is controlled by transcription factors
and all these other things that interact with the promoters, which turn the genes on
and off and turn the volume of the genes up and down like thermostat switches, or
whatever analogy you want to use. That process is itself at the mercy of the way we
behave because you can do things in your life that literally lead you to alter the
expression of genes.
Two quick examples of that to get the point across: One is stress. When you're under
stress, the physiological result is that cortisol increases in your body and has a lot of
effects. Cortisol is a transcription factor; it actually alters the expression of certain
genes. It does so largely in the immune system, which results in the suppression of
immune activity. It lowers your immunity, which is why when you're under stress
you're more likely to catch a cold. So here's an example in which something outside
you—whatever it is that causes stress, an argument or an exam—affects the
expression of your genes in your immune system. But a much more everyday
example is simply the process of learning and memory. Associative memory,
conditioning the association of one stimulus with another, is an immensely
important part of learning. That process involves the changing of the strength of
synapses between neurons in real time. As you form a long-term memory, you
change the shape and the size of the synapse, so that when two neurons that are
connected keep firing together—meaning that you're associating a particular smell
with a particular sight or something like that—then the connection gets
changes everything. We know that just because the first one or two glimpses inside
this box, the first lifting of the lid of the human genome, reveals to us enormous
insights into what's going on, and just from the first few genes we're looking at.
What I've set out to do, both in Genome and in Nature via Nurture is to try to put
these in historical context, because I think it is important not only to understand
how the old debates are going to be refracted through the new genomics, but also to
simply tell some of the stories that are coming out of the genomics labs and other
psychology and evolution labs that are using genetic information. The sheer
leverage that genomic science now has, compared with sciences that went before, is
very striking. What I mean by that is that with a small amount of effort you can get
really big results. You can get stuff that doesn't need statistics to prove that it's
significant in molecular biology in a way that you can't, necessarily, in brain
imaging or particle physics studies or something like that, which requires a lot more
effort to get a small amount of data.
The substance of what I'm interested in is that it's the genes that are related to
behavior, and how they work. The big insight is that genes are the agents of nurture
as well as nature. Experience is a huge part of a developing human brain, the
human mind, and a human organism. We need to develop in a social world and get
things in from the outside. It's enormously important to the development of human
nature. You can't describe human nature without it. But that process is itself
genetic, in the sense that there are genes in there designed to get the experience out
of the world and into the organism. In the human case you're going to have genes
that set up systems for learning that are not going to be present in other animals,
language being the classic example. Language is something that in every sense is a
genetic instinct. There's no question that human beings, unless they're unlucky and
have a genetic mutation, inherit a capacity for learning language. That capacity is
simply not inherited in anything like the same degree by a chimpanzee or a dolphin
or any other creature. But you don't inherit the language; you inherit the capacity
for learning the language from the environment.
That's a good example, because for the first time we've now got a gene, the FOXP2
gene on chromosome 7, which looks like it may be an important cog in that
machinery. It would be surprising, given it's the first gene that we've been able to
look at, if it was the most important cog, but it's certainly one of them. What
happens is that if that gene is broken you get, essentially, a human being with a
great difficulty in generalizing grammatical rules and in developing fluent speech.
You get a general language disorder. But what's interesting about that gene is that
although you might say, "Well, here's the language gene, and humans have got it
and nobody else has it," this is not so—it's present in mice; and chimpanzees,
orangutans and every other mammal has this gene. Indeed, it's a very highly
conserved gene with very little change over the past few million years.
So you might say, "How can it be important in language?" If you take Svante
Pääbo's work on it and you look at what's been going on in it, it appears that it's had
very little evolutionary change in it until you get to the human lineage. And then,
since the common ancestor of the chimpanzee there have been two amino acid
changes in the gene, which is as much in the whole of the rest of the mammalian
—JB
MATT RIDLEY'S 23 pairs of chromosomes, together with a doctorate form Oxford
University, equipped him for a career as a science journalist with The Economist
and the Daily Telegraph. His books include Nature Via Nurture: Genes, Experience,
and What Makes Us Human; Red Queen: Sex and the Evolution of Human Nature;
Genome: The Autobiography of a Species in 23 Chapters; Origins of Virtue: Human
Instincts and the Evolution of Cooperation; and editor of The Best American Science
Writing 2002.
He is chairman of the International Centre for Life, Newcastle-upon-Tyne’s science
park and visitor centre devoted to life science. He has ingeniously combined his
chromosomes with those of his wife, the neuroscientist Dr Anya Hurlbert, to
produce two entirely new human beings. His books have been shortlisted for six
literary awards. He has been a scientist, a journalist, and a national newspaper
columnist. He is also a visiting professor at Cold Spring Harbor Laboratory in New
York.
Matt Ridley presents his latest book: Nature Via Nurture
Human nature is indeed a combination of Darwin's universals, Galton's heredity,
James's instincts, De Vries's genes, Pavlov's reflexes, Watson's associations,
Kraepelin's history, Freud's formative experience, Boas's culture, Durkheim's
division of labor, Piaget's development, and Lorenz's imprinting. You can find all
these things going on in the human mind. No account of human nature would be
complete without them all .... But—and here is where I begin to tread new ground—
it is entirely misleading to place these phenomena on a spectrum from nature to
nurture, from genetic to environmental. Instead, to understand each and every one
of them, you need to understand genes. It is genes that allow the human mind to
learn, to remember, to imitate, to imprint, to absorb culture, and to express
instincts. Genes are not puppet masters or blueprints. Nor are they just the carriers
of heredity. They are active during life; they switch each other on and off; they
respond to the environment. They may direct the construction of the body and brain
in the womb, but then they set about dismantling and rebuilding what they have
made almost at once—in response to experience. They are both cause and
consequence of our actions. Somehow the adherents of the "nurture" side of the
argument have scared themselves silly at the power and inevitability of genes and
missed the greatest lesson of all: the genes are on their side.
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Beyond Edge: Matt Ridley's Home Page
THE GENOME CHANGES EVERYTHING
(MATT RIDLEY:) For the first time in four billion years a species on this planet has
read its own recipe, or is in the process of reading its own recipe. That seems to me
to be an epochal moment, because we're going to get depths of insight into the
nature of human nature that we never could have imagined, and that will dwarf
anything that philosophers and indeed scientists have managed to produce in the
last two millennia. That's not to denigrate what's gone before, but the genome
Ridley's survey of what is known about nature-nurture interactions is encyclopedic
and conveyed with insight and style. This is not an easy read, but fans of his earlier
book and readers looking for a challenging read will find this an engrossing study of
what makes us who we are.
http://www.edge.org/3rd_culture/ridley03/ridley_print.html
The substance of what I'm interested in is that it's the genes that are related to
behavior, and how they work. The big insight is that genes are the agents of nurture
as well as nature. Experience is a huge part of a developing human brain, the
human mind, and a human organism. We need to develop in a social world and get
things in from the outside. It's enormously important to the development of human
nature. You can't describe human nature without it. But that process is itself
genetic, in the sense that there are genes in there designed to get the experience out
of the world and into the organism. In the human case you're going to have genes
that set up systems for learning that are not going to be present in other animals,
language being the classic example. Language is something that in every sense is a
genetic instinct. There's no question that human beings, unless they're unlucky and
have a genetic mutation, inherit a capacity for learning language. That capacity is
simply not inherited in anything like the same degree by a chimpanzee or a dolphin
or any other creature. But you don't inherit the language; you inherit the capacity
for learning the language from the environment.
A Talk with Matt Ridley
THE GENOME CHANGES EVERYTHING:
Matt Ridley: EdgeVideo DSL+ | Modem
Introduction
"For the first time in four billion years," says Matt Ridley, "a species on this planet
has read its own recipe, or is in the process of reading its own recipe. That seems to
me to be an epochal moment, because we're going to get depths of insight into the
nature of human nature that we never could have imagined, and that will dwarf
anything that philosophers and indeed scientists have managed to produce in the
last two millennia."
Ridley is an original thinker with deep insights who is in the top ranks of people
writing about science. He also happens to be an English aristocrat who lives in
Newcastle-upon-Tyne in a stately home on beautiful grounds. He embodies the best
of that English tradition in that he uses his prestige, influence and his resources in
the interests of science. Such patronage, and I use the term in the good sense,
includes founding, and serving as chairman of the International Centre for Life,
Newcastle-upon-Tyne’s science park and visitor centre devoted to life science. The
centre is highly regarded for its serious research in genetics.
11. What do experiments on fruit flies reveal about the formation of memory, and
particularly its genetic component? Can genes be said to remember?
12. Ridley notes that in their extreme forms both naturism and nurturism have
proven attractive to totalitarian regimes. What examples does he cite? Why should
Nazis have favored a hereditarian view of human nature while communists
embraced an environmental one?
13. What role does Ridley believe genes play in human culture and language? Is
there such a thing as a 'culture gene,' and how might it operate? And how might the
development of culture have reshaped human physiology?
14. What 'morals' does Ridley derive from the nature-nurture debate? Do you agree
with his conclusions?
About the Author
Matt Ridley did research in zoology at Oxford before becoming a journalist. He has
been a science editor, Washington correspondent, and U.S. editor for The
Economist, and a columnist for the Sunday Telegraph and Daily Telegraph. He is
author of Genome (1999), The Origins of Virtue (1996) and The Red Queen: Sex and
the Evolution of Human Nature. He lives in England with his wife and two
children.
http://www.tleavesbooks.com/harper/hc05.htm
Matt Ridley, Nature Via Nurture
"Nature versus nurture" sums up in a nutshell one of the most contentious debates
in science: Are people's qualities determined by their genes (nature) or by their
environment (nurture)?
The debate has only grown louder since the human genome has been found to
comprise only 30,000 genes. Some scientists claim that we don't have enough genes
to account for all the existing human variations. Ridley, author of the bestseller
Genome, says that not only are nature and nurture not mutually exclusive, but that
"genes are designed to take their cue from nurture.
" Genes are not unchanging little bits of DNA: their expression varies throughout a
person's life, often in response to environmental stimuli. Babies are born with genes
hard-wired for sight, but if they are also born with cataracts, the genes turn
themselves off and the child will never acquire the ability to see properly. On the
other hand, stuttering used to be ascribed solely to environmental factors. Then
stuttering was found to be clearly linked to the Y chromosome, and evidence for
genetic miswiring of areas in the brain that manage language was uncovered. But
environment still plays a role: not everyone with the genetic disposition will grow
up to be a stutterer.
Topics for Discussion
1. Presiding over Nature via Nurture are the ideas and personalities of twelve
scientists, each of whom played a role in the nature/nurture debate. Did any
succeed in bridging the nature-nurture divide? Which of these thinkers remains
relevant to our understanding of human nature today?
2. How have our ideas about the differences between human beings and other
animals changed since Descartes? Given the evidence that animals -- or at least
certain apes -- make tools, wage war on their fellows, use some kind of language,
and enjoy 'recreational' sex -- what capabilities still seem exclusively human? And
considering that human beings may share as much as 98.76 percent of their genetic
material with chimpanzees, what other factors might explain the differences
between our species?
3. Discuss the 'blind watchmaker' argument of biological design. Contrast it with
Ridley's idea of a 'Genome Organising Device,' or GOD.
4. Recent experiments with rodents suggest that the substances vasopressin and
oxytocin -- or rather the receptors for those substances -- determine their ability to
form lasting pair bonds. What implications does Ridley think this has for our own
romantic proclivities?
5. Describe John Money's experiments in gender-assignment. Where else in this
book do we find accounts of scientific hubris and heartlessness?
6. Many of the thinkers Ridley discusses -- Francis Galton and B. F. Skinner
among them -- wrote about utopias. Is there something about the study of human
nature that predisposes one to plan perfect societies?
7. Even as we become more capable of saying which human traits are heritable,
says Ridley, the notion of heritability becomes more slippery. What does he mean by
this? Why does he claim that "the more equal we make society, the higher
heritability will be, and the more genes will matter"?
8. How would you summarize the evolution of scientific theories of schizophrenia?
Why is Ridley particularly critical of Freud's ideas?
9. According to Ridley, what roles do heredity and environment play in learning?
How do some genes change their behavior in response to information from the
outside world?
10. How does Ridley support his argument that nurture is sometimes less
reversible than genetic inheritance? Discuss the significance of Lorenz and
Gottleib's experiments with ducks, Barker's findings about the relation between
birth weight and heart disease, and studies that indicate a link between male
homosexuality and birth order.
this myth. Nurture depends on genes, too, and genes need nurture. Genes not only
predetermine the broad structure of the brain, they also absorb formative
experiences, react to social cues, and even run memory. They are consequences as
well as causes of the will.
Published fifty years after the discovery of the double helix of DNA, Nature via
Nurture chronicles a revolution in our understanding of genes. Ridley recounts the
hundred years' war between the partisans of nature and nurture to explain how this
paradoxical creature, the human being, can be simultaneously free-willed and
motivated by instinct and culture. Nature via Nurture is an enthralling,up-to-theminute account of how genes build brains to absorb experience.
http://www.harpercollins.com/author/authorExtra.aspx?authorID=14370&isbn13=9
780060006785&displayType=readingGuide
Reading Guide
* Nature Via Nurture
Introduction
In February 2001 a researcher announced that the human genome contained, not
100,000 genes as had been commonly supposed, but 30,000 -- less than twice as
many as a worm's. Many commentators concluded that this was simply too few
genes to account for the diversity of human behavior and that genetic inheritance -nature, if you will -- must be far less crucial to what we are than environmental
influences: nurture. Of course, this epochal discovery represented simply another
chapter of a debate that has been raging for over a hundred years, pitting
Darwinians against Freudians, hereditarians against environmentalists. To what
do we owe our characters, our talents and weaknesses: Nature or nurture?
In this timely, far-ranging, and lucidly written book, Matt Ridley arranges a truce
between those warring conceptual camps. Nature via Nurture demonstrates the
astonishing extent to which human beings are a joint production of heredity and
environment. It ushers readers into a world where genes are not puppet masters
pulling the strings of behavior, but are puppets at the mercy of behavior; where
instinct is not the opposite of learning; where environmental influences may be less
reversible than genetic ones, and where nature is designed for nurture. "The more
we lift the lid on the genome," writes Ridley, "The more vulnerable to experience
genes appear to be."
To make his point, Ridley ranges across disciplines from ethology to anthropology,
sexology to neurochemistry. He explores the role genes play in the sexual behavior
of humans, chimps, gorillas, and blissfully promiscuous bonobos, and the extent to
which environment shaped the evolution of the human brain. He assesses evidence
for the genetic bases of intelligence, body weight and religious fundamentalism and
the links between birth order and male homosexuality. He describes experiments
that unveil the neural mechanisms of love and learning. He offers lively précis of
the legacies of Darwin, Mendel, Freud, B. F. Skinner and Konrad Lorenz. The end
result is a book as provocative as it is informative, rich in research and implication.
In reaction to such fatalism, some have sought to redress the balance by
emphasizing the importance of environment and upbringing, but the role of genes in
determining what we become remains difficult to deny. In consequence, it has
become almost a cliche for many to say that nature and nurture are both important
and that neither should be over-emphasized at the expense of the other. But this
could easily be taken to mean that genes and environment are rivals, engaged in a
kind of struggle for control.
Ridley, in contrast, seeks to show that there is no competition between nature and
nurture. What we have instead is a complex interaction in which each influences
the other. Genes, or at least their expression, are modified by the environments in
which they find themselves.
Genes themselves are implacable little determinists, churning out utterly
predictable messages. But because of the way their promoters switch on and off in
response to external instruction, genes are very far from being fixed in their actions.
The line of argument followed here has much in common with Richard Dawkins's
The Extended Phenotype, as indeed Ridley acknowledges. The "selfish gene" notion
has been widely misunderstood but, as Ridley makes plain, it is an important
contribution to our understanding of ourselves.
Ridley draws on a wide range of recent research to illustrate his conclusions, which
are intended to be broadly reassuring. His message is: don't be frightened of genes.
They are enablers, not the arbiters of our fate. He compares them to computer
programs, which extend the range of functions that a computer can perform, to
make it more useful and flexible. And he finishes by drawing a number of morals for
society, even having a quick stab at the issue of free will. The solution to this
ancient riddle, he suggests, will come from recognizing that the chains of causation
that determine our actions are circular, not linear; effects can influence their own
causes.
Like other books by Ridley, this is a stimulating read providing plenty of ideas.
http://www.harpercollins.com/book/index.aspx?isbn=9780060006785
Harper Collins Promo
Following his highly praised and bestselling book Genome: The Autobiography of a
Species in 23 Chapters, Matt Ridley has written a brilliant and profound book about
the roots of human behavior. Nature via Nurture explores the complex and
endlessly intriguing question of what makes us who we are.
In February 2001 it was announced that the human genome contains not 100,000
genes, as originally postulated, but only 30,000. This startling revision led some
scientists to conclude that there are simply not enough human genes to account for
all the different ways people behave: we must be made by nurture, not nature. Yet
again biology was to be stretched on the Procrustean bed of the nature-nurture
debate. Matt Ridley argues that the emerging truth is far more interesting than
Matt Ridley Bio.............................................................................................................. 1
Book review by Anthony Campbell............................................................................... 1
Harper Collins Promo.................................................................................................... 2
Reading Guide * Nature Via Nurture ....................................................................... 3
About the Author........................................................................................................... 5
http://www.tleavesbooks.com/harper/hc05.htm ........................................................... 5
http://www.edge.org/3rd_culture/ridley03/ridley_print.html ...................................... 6
A Talk with Matt Ridley ............................................................................................... 6
http://www.thegreatdebate.org.uk/mattridley.html .................................................. 16
Beyond Nature and Nurture....................................................................................... 17
A genetic truce ............................................................................................................. 21
Beyond nature versus nurture.................................................................................... 23
READINGS ABOUT NATURE/NURTURE and HUMAN POTENTIAL ................. 26
The Blank Slate: The modern denial of human nature ............................................. 27
How to estimate the amount of genetic determination: ............................................ 30
http://www.harpercollins.com/author/index.aspx?authorid=14370
Matt Ridley Bio
Matt Ridley's books have been shortlisted for six literary awards, including the Los
Angeles Times Book Prize (for Genome: The Autobiography of a Species in 23
Chapters). His most recent book, The Agile Gene: How Nature Turns on Nurture,
won the award for the best science book published in 2003 from the National
Academies of Science. He has been a scientist, a journalist, and a national
newspaper columnist, and is the chairman of the International Centre for Life, in
Newcastle, England. Matt Ridley is also a visiting professor at Cold Spring Harbor
Laboratory in New York.
http://www.accampbell.uklinux.net/bookreviews/r/ridley-3.html
Matt Ridley
NATURE VIA NURTURE
Genes, experience and what makes us human
Book review by Anthony Campbell.
The review is licensed under a Creative Commons License.
The nature-nurture debate is an ancient one but it acquired a modern
interpretation when the science of genetics took off in the twentieth century.
Evidence from twin studies and other research suggested a fatalistic conclusion, a
kind of genetic determinism.
When genes were discovered, late in the second milennium of the Christian era,
they found a place already prepared for them at the table of philosophy. They were
the fates of ancient myth, the entrails of oracular prediction, the coincidences of
astrology. They were destiny and determination, the enemies of choice. They were
constraints on human freedom. They were the gods.