Alberta Zatta
9th July 2014
CHFSS – Introduction to Complexity
WHEN BIOLOGY MEETS COMPLEXITY
How Evolution Theory and Genetics are entering into a new Era
Element of Complexity in Evolution theory and Genetics:
As we try to define Complexity and Complex Systems what usually happens is that it is impossible
to find out a proper and unique definition, we rather find ourselves in front of more or less similar
lists of features which, combined together, give a general picture of the topic. Using those lists as
guidelines, it is possible to spot the presence of Complexity in many and unexpected fields. One of
them is for sure Biology, and in particular Evolution Theory and Genetics. The former is, in fact,
based on the interaction of multiple parts, such as organisms or genes, and what emerges from
their interaction is the changing in time of species. Moreover, one of the biggest issues about this
theory is centred on proving or confuting the presence of a central controller, meant as a guide
and causal principle of the entire evolution. Different tendencies have been developed during the
years, but in the most recent ones – those more closed to Complexity – this idea has been refused.
Another correspondence between this theory and the list of features of a Complex System could
be the non-linearity of evolution shown in recent studies by Gould and Eldrege1. They are
challenging the idea of straight adaptation and promoting the relevance of side-effects entering in
the world of possibilities and destroying the Darwinian principle “natura non facit saltus”. All these
latest developments have been supported by molecular biology and its interest in genetic code2. In
particular, the study of genes has underlined how it is not their number – they are, in fact, less
than what expected - ¸ but the relations among them that determine the emergence of what we
1
2
Melanie Mitchell, Complexity a guided tour, published by Oxford Press University,2009. Page 84.
Melanie Mitchell, Complexity a guided tour, published by Oxford Press University,2009. Page 87.
called traits or characteristics - supporting the presence of networks. All we thought to know
about genetics has been criticized by the discoveries and failures of the last decades – for example
Human Genome Project3 which by mapping the DNA showed that there are about 25,000 gens
and not 100,000 as expected – as to symbolize that maybe a change in paradigm is needed also in
Biology.
The object (brief historical digression – focus on the latest turning points) from Chapter 5 of
Introduction to Complexity by Melanie Mitchell
If we try to delineate the outline of the history of evolution theory it can be observed how it is not
a new subject in the landscape of science, it has, in fact, a long tradition of researchers and
discussions made upon it. The most famous and common approach began with Charles Darwin in
the 19th century who, challenging the Western conception of divine creation, turned the study of
the evolution of species into a real scientific subject. The main points of his enormous work are: all
species derive from a common ancestor; natural selection occurs when the number of births is
greater than existing resources; traits are passed through adaptive variations; evolutionary change
is constant and gradual. The major limit of Darwin’s theory was explained by using Gregor
Mendel’s study of pea plants. Darwinian results were not able to explain how traits are passed
from one generation to the next. The Austrian monk and physics teacher discovered some of these
rules which are still shared by modern-genetics and introduced the concepts of
dominant/recessive allele and the idea that alleles come from the parents. Anyhow, they moved
the direction of Evolution Theory towards another path: the Modern Synthesis. In fact, even if at
the beginning Mendel’s discoveries were considered the opposite of Darwinian results - because
they supported mutational theory more than natural selection - , after the introduction of
adequate statistics and mathematics it then turned out that the two were complementary thories
and from their union was born the Modern Synthesis represented by Fisher, Haldan and Wright.
3
Melanie Mitchell, Complexity a guided tour, published by Oxford Press University,2009. Page 87.
This new conceptual framework was based on the Darwinian principle that natural selection is the
ground of Evolution; moreover, the latter is a gradual process thorough natural selection with
small random variation which do not lead automatically to any improvement; macro scale
phenomena – as the emergence of a species - can be explained by the microscopic process of gene
variation.
Anyhow, the most interesting part in the history of Evolution theory from the point of view of
complexity began around 1960s and 1970s with Stephen Jay Gould and Niles Eldredge who
challenged the Modern Synthesis. Their starting point was the punctuated equilibria according to
which there are long periods with no change in the morphology of the organism followed by
condensed periods of large change which then lead to the emergence of a new species. This
principle broke down the Darwinian “gradualism”, and they also reshaped the relevance of natural
selection and the role of small gene variations by introducing two other mechanisms. The first one
is called historical contingency and it identifies all those random events – for example the falling of
a meteorite on earth - , of varied size, which concurred in the shape of the organism and can also
be called “tape of life”. This metaphor is, indeed, interesting because it shows how if we could
change the initial conditions we would see a completely different “movie” of Evolution; this
sensibility to initial condition prove its affinity with complexity. The second mechanism is called
biological constraint and it basically puts a limit on what natural selection can actually do. This
introduce the concept of side effect as an alternative to adaptations introducing discontinuity in
the evolution process
Example 1: The birth of conscience between continuity and discontinuity from “Quella volta che siamo
diventati umani” by Telmo Pievani
A good example of the joint work of the two principles biological constraint and historical
contingency is shown in the different studies about the birth of the mind and the subsequent
evolution of the Homo Sapiens. The initial question is, in fact, how it is possible that starting from
equal available structures, species could evolve capabilities so different form one another? In
particular, how can it be that our brain is so versatile if it could not transcend its initial adaptive
limits?
Darwin had already guessed an important principle: a structure can perform different
functions, or vice versa, a function can be performed by many structures. This innovative concept
were then developed in the course of the 20th century by E.Vrba, Niles Eldredge and Richar
Lewontin who changed the Darwinian pre-adaptation concept with the word exaptation. It means
that a character originated with a special function, or with no function at all, can then perform
processes different from what it was used to do. Our brain, so, would have developed areas not
used that then had been involved in the performance of functions not contemplated in the
original structure – such as play the piano or write a novel. The assignment of a function to a pre
adapted structure is called co-optation. This theory blends together so the biological continuity
and discontinuity due to historical contingency. The birth of our mind is the result of changes
happened in a short time frame after a long period of mutations’ absence – punctuated equilibria . In other words, a gradual biological change led our brain to develop different areas – which were
available already 150,000 years ago-, but they were cooptated to different function just 40,000
year ago in a discontinuous and sudden way.
This example shows how the development of the species is not linear, but on the contrary
from a small and random variation in the history of evolution we could have had very different
results and that from the interaction of various situations and occasions complex elements – as
our mind- can emerge. The graph of the evolution of our species cannot be represented by a single
line anymore, in fact, a multi branched shape would better convey the idea of the different path
that evolution could - and actually has – taken .
Example 2: Evo-Devo from Chapter 18 of “Introduction to Complexity” by Melanie Mitchell
We have just seen how complex dynamics are rooted in the history of our species, but not only,
they are also written inside our DNA being that also the study genetics is gradually entering
complexity. Some of the recent discoveries, in fact, show new and insightful characteristics of
genes. For example, they are not completely separated to one another and tend to overlap by
sharing DNA nucleotides; genes can move around, rearranging the structure of chromosomes
(“mobile genetics element”); a single gene can code for more than one protein – according to the
mapping of human genome we have, in fact, just about 25.000 genes - ; the complexity of living
organism derives from networks of genes, more than on a single one; and many others innovative
discoveries. All these new aspects of genetics gave birth to a new field of study called Evo-Devo,
the nickname of “evolutionary development biology”. It is basically focussed on three issues: 1)
what it is responsible for our complexity; 2) why, even if we share more than the 90% of our Dna
with other species, we are so different from them and 3) how, according to punctuated equilibria,
big changes happen in short period?. All these points can be synthetized by the word switch. It
gives, in fact, importance to the capability of genes of creating relation among them and switch
their position. This genetic regulatory networks allow numerous possibilities for gene expression
patterns. It was proved that even great differences in biological structure can, so, be explained by
the joint work of similar genes – such as the PAX6 gene responsible for eyes- shared by more
species, but arranged in different ways. It is, indeed, a matter of organization and it has been
proved by Edoardo Bonincelli the presence of gene-architects4 who organize the different function
for the gene-executers. The presence of a kind of hierarchy, as studied by Herbert Simon’s The
architecture of Complexity5, is itself one of the many signature of Complexity.
Consideration and Conclusions:
Just by scratching a litter bit the surface of biology it has been quite easy to comprehend how
it is ever more becoming a challenging topic. In fact, as for economics and social sciences, other
fields such as Evolution Theory and Genetics, are changing the way they look at reality. This
change causes many discussions among different tendencies, but at the same time is an
unmissable occasion to exploit the massive potential of these disciplines. Complexity, together
with other cutting edge theories, such as Chaos and the Science of Network, allows researchers to
discover connections and elements, that even though had always been under our eyes, could not
be detached under the previous gazes. As said by Neil Johnson, in his introductive chapter Two is
company, three is complexity, one could even know every single element of neurons, but if we
don’t understand how they interact our research would be useless. Even in this case we are in
front of a matter of lenses, or rather, of paradigm, and just by changing our focus we come up
with a completely different picture of reality.
I find particularly interesting see how the approach towards human beings and their history
has changed during the decades according to different theories and perspectives. It really made
me understand how complex we actually are, and I can just imagine the amount of amazing
breakthroughs that we are not able to see yet. Moreover, I was enchanted by the subtle dynamics
on which the phylogenies of our species is based: randomness, casualties, occasions and a litter bit
of fortune makes me wonder about our uniqueness. This new stage of Biology gives the right
4
http://www.rescogitans.it/main.php?articleid=311
Melanie Mitchell, Complexity a guided tour, published by Oxford Press University,2009. Page 109.
5
depth to our still mysterious laws and functioning and leads to its maximum one of the biggest
achievements of our species: our (unique) capability to question our own evolution.
Multiple choice
According to W.Brian Arthur’s Inductive Reasoning and Bounded Rationality, the El Farol Bar Problem:
a) use exogenous variables – such as weather or possible alternatives – to predict the attendance (false, all
the models used are simple autoregressive focal models, it means they use just past data about bar
attendance)
b) there is not a perfect model because once one discovers it, sooner or later will be copied by many other
cycle-detector predictors, who by following the model will weaken it and turned it imperfect. (true, for this
reason one of the greatest lesson from his model is that once we reach an optimal model or strategy we
have to change it and keep searching for the next possible one)
c) is diabolically complex because of the number of potential costumers (false, it is diabolically false due to
its counterintuitive nature)
d) has one perfect model which solves it and all use it. (evidently false, the theorem derived from this case
study is in fact that “there is not such a perfect model”.)