HUMAN EFFECTS UPON
EVOLUTIONARY PROCESSES IN
THE BIOSPHERE
John Cairns, Jr.
University Distinguished Professor of Environmental Biology Emeritus
Department of Biological Sciences
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061, U.S.A.
April 2011
. . . WHEN WE REGARD EVERY PRODUCTION OF NATURE AS ONE
WHICH HAS HAD A HISTORY; WHEN WE CONTEMPLATE EVERY COMPLEX
STRUCTURE AND INSTINCT AS THE SUMMING UP OF MANY CONTRIVANCES,
EACH USEFUL TO THE POSSESSOR. . . HOW FAR MORE INTERESTING, I SPEAK
FROM EXPERIENCE, WILL THE STUDY OF NATURAL HISTORY BECOME!
CHARLES DARWIN, On the Origin of Species, 1859
 Persuasive evidence indicates that the Biosphere is now experiencing a major biotic crisis.
 Even if humankind ceases severe stress on natural systems, the crisis will probably disrupt the
ecosystems that have survived so far.
 The present biota is one that humans understand. The new biota will probably be difficult to
understand in less than five to ten generations, and finding out about it will depend upon
scientific studies.
EXTINCTION IS A CONTINUAL PROCESS IN THE
BIOSPHERE; HOWEVER, AT GREAT INTERVALS, A MASS
EXTINCTION OCCURS AND NEW SPECIES REPLACE
MOST OF THE SPECIES THAT MADE UP THE DAMAGED
BIOSPHERE.
The sixth great extinction is now underway and if “business as usual” continues, the
Biosphere will go into disequilibrium again.
All life on Earth was not extinguished during the last five great extinctions, but many species
are gone forever.
The atmospheric and other conditions that will select species in the next Biosphere are
impossible to predict.
GLOBAL PROBLEMS CAN ONLY BE SUCCESSFULLY
SOLVED BY A CIVIL DISCOURSE ON AND A
COMMITMENT TO A COMMON GOAL BY ALL, OR A
SUBSTANTIAL MAJORITY OF, THE WORLD’S SOVEREIGN
NATIONS.
 A superb starting point would be to reduce atmospheric carbon dioxide by 35-40 parts per
million to increase Earth’s radiation to space by one half watt, if other greenhouse gases
remain at their present amounts.1
 Even this small amount will not be achieved rapidly. The tendency will be for some countries
to say “you first” to other countries.
 The usual claims will be voiced, i.e., reducing atmospheric carbon dioxide might have adverse
effects upon the economy.
 Humankind must decide if any of these objections override the survival of civilization.
NO SOVEREIGN NATION SHOULD ASSUME THAT
ITS NATIONAL VALUES ARE SUPERIOR TO THOSE OF
OTHER NATIONS  SUCH CLAIMS DO NOT LEAD TO A
PATH OF RESOLVING GLOBAL CRISES.
 Dramatizing the walking out of a United Nations conference because decisions are not
proceeding a certain way is not the course of action for reaching a consensus.
 If nations assume they can withdraw from any international conference at will, success will
be elusive.
 Any nation that permits harassment of scientists and their science for political reasons is
endangering its security.
THE REPEATED WARNINGS OF THE DIRE
CONSEQUENCES IF “BUSINESS AS USUAL” CONTINUES
HAVE ESSENTIALLY BEEN IGNORED.
 Illustrative examples are the warnings of the Union of Concerned Citizens2 and Millennium
Ecosystem Assessment,3 which resulted in the attacks on scientists and their science.4
 Science is based on observations of reality, which are usually communicated through
publication in peer-reviewed journals.
 Technology has created overexploitation of the Biosphere. Technology made abundant
resources available to one species, Homo sapiens.
 The result has been a short-term cornucopian era and long-term crises such as global climate
change, ecological overshoot, and vast numbers of humans still in poverty.
A PERPETUAL GROWTH MEME* IS NOT SUITED TO A
FINITE PLANET WITH FINITE RESOURCES.
 Some individuals are proponents of the availability of inexhaustible quantities of nearly all the
resources provided by nature.5
 If this assumption were correct, an ever growing human population would be possible.
 Exponential growth calculations of the human population show that even a growth rate of 1%
per year would not be sustainable.6
 Billions of people now living in poverty with poor nutrition, inadequate medical care, and
substandard housing would dispute the idea of inexhaustible resources.
 Neither available habitable space nor diminished renewable resources justify the perpetual
human population growth meme.
*A cultural unit, such as an idea, value, or pattern of behavior, that is passed from one person to another by non-genetic means.7.
RAPID SOCIAL EVOLUTION, WHICH FOCUSES ON
BEHAVIORAL OR CULTURAL TRAITS, SEEMS TO BE THE
ONLY HOPE FOR HUMANKIND TO RESOLVE THE
DANGEROUS GLOBAL CRISES IT NOW FACES.
 “. . . humanity is a deeply conflicted species. We are torn on the one hand between what
reason and moral judgment say we should do and what pure emotion and baser instincts
compel us to do, particularly in stressful circumstances.”7
 To avoid mass suffering and deaths in the 21st century, “What can I afford?” must be replaced
by “What can Earth afford?”
 Humankind must accept and abide by the universal laws of biology, chemistry, and physics.
 Humankind has developed a brain to cope with small-scale, personal/tribal crises but has
developed no global, community response to the eight interactive global crises.8
THE CAST (ALL FORMS OF LIFE) HAS BEEN ON
THE ECOLOGICAL STAGE OF EARTH’S EVOLUTIONARY
THEATER FOR APPROXIMATELY 3.5 BILLION YEARS.
 Practically all the actors (species) from earlier times are gone.
 Five major scene changes (great extinctions) have occurred, after which the cast (life forms)
changed dramatically.
 The play is “written” by the universal laws of biology, chemistry, and physics.
 One actor, Homo sapiens, has played a major, but a short, role in evolutionary time.
 Stress caused by human activities, if continued at present levels, will cause humankind to
become extinct and be replaced by a yet unknown species.
DELAYING THE ONSET OF A MAJOR
EXTINCTION OF SPECIES CAN PROBABLY BE
ACHIEVED BY NURTURING THE PRESENT
BIOSPHERE.
 Nurturing the Biosphere requires abiding by the universal laws of nature.
 Science is based on logic and empirical evidence, and the present assault on science and logic
will, if continued, result in catastrophes and human suffering.
 Science will flourish in an atmosphere of reason, logic, and civility.
 Throughout history, numerous attempts have been made to suppress science, but it has always
survived because the nations that nurture science have always benefited.
IF THE PRESENT BIOSPHERE COLLAPSES, THE MOST
FIT SPECIES INITIALLY WILL PROBABLY BE SMALL,
SHORT-LIVED, HIGHLY FERTILE ORGANISMS WITH
SUPERB DISPERSAL ABILITIES TO EXPAND INTO A
VARIETY OF HABITATS AND ABLE TO USE A WIDE
VARIETY OF RESOURCES.
These organisms may or may not be suitable as food for Homo sapiens.
Determining which species are edible will be a high risk undertaking.
They may compete with Homo sapiens for resources.
Global warming may increase the range of many diseases and carriers of disease.
THE RATE OF EXTINCTION OF SPECIES VARIES, AS
DOES THE REPLACEMENT RATE.
 If history is a useful guide, extinction is the norm over evolutionary time. Every 20 minutes,
another species is pushed to extinction (http:/www.conservation.org).
 Discussing the probability that Homo sapiens may become extinct is a taboo topic, but
avoiding discussion does not prevent extinction from occurring.
 If “business as usual” continues, the extinction of Homo sapiens will move from possible to
probable. This risk is well worth an informed discussion.
Acknowledgments: I am indebted to Darla Donald for transcribing the handwritten first draft of this Power Point and for preparing it for publication.
References
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http://www.grist.org/article/2010-12-21-a-conversation-with-billmckibben.
2Union of Concerned Scientists. 1992. World Scientists’ Warning to Humanity. Cambridge, MA.
3Millennium Ecosystem Assessment. 2005. Living Beyond Our Means: Natural Assets and Human Well-Being. Statement of the MA Board.
http://www.maweb.org/en/BoardStatement.aspx.
4Letter. 2010. Climate change and the integrity of science. Science 328(5979):689-690.
5Simon, J. 1998. The Ultimate Resource 2. Princeton University Press, Princeton, NJ.
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8Cairns, J., Jr. 2010. Threats to the biosphere: eight interactive global crises. Journal of Cosmology 8:1906-1915.