Currently, the human fossil record shows a correlation with climate patterns in Africa. About 5,000 to 10,000 years ago, the Earth's axis of tilt shifted (a process called precession), which changed the amount of rain that Africa received.
"It is not true that the Sahara Desert has been a permanent feature for millions of years," said Peter deMenocal, a professor at the Lamont-Doherty Earth Observatory at Columbia University. Africa oscillated between wet and dry every few thousand years, and each shift induced adaptation in the creatures that lived in the region.
About 3.35 million years ago, Ethiopia was forested and Lucy's species thrived with its ape-like features. The climate changed and the habitat switched to woodland, and then to the African savannah. Then, about 2.95 million years ago, it switched back to woodland. Unable to adapt, Lucy's species went extinct around this time after 900,000 years.
'Plastic' civilizations
About 2 million to 2.5 million years ago, an intense dry period led to the first migration of Homo erectus out of Africa into Southeast Asia, according to scientists.
About 5,000 years ago, with the creation of the Sahara Desert, humans migrated into the Nile Delta, creating an urban settlement, according to deMenocal.
"Civilizations and populations can be very plastic that way," said deMenocal. "Climate change alters ecological landscapes, creates unnatural selection pressures, and promotes genetic selection to fit the pressures."
A more visible effect of climate change on human morphology was the development of large nasal cavities in Neanderthals, the most recent relative of the modern human displayed at the Smithsonian.
"We used to think of environment as a backdrop, but now, with the development of environmental records, we are more in tune to the consequences of environmental dynamism," said deMenocal.
Scientists at the Smithsonian panel called for greater field exploration to create a larger record of our past. Gaps in the fossil record make it difficult to closely relate particular adaptations to climate change. Better climate modeling is also necessary, according to deMenocal.
The recent discovery of Australopithecus sediba, a new species of hominid from about 2 million years ago, in Malapa, South Africa, provides a new link that is yet to be correlated with past climate.
"All human species face questions about adaptation, long-term perspectives versus short-term gains," said Potts at the Smithsonian. "I'm hopeful because we are a species that's emerged from a long history of adaptation."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
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11 Comments
Add CommentCurrent hominid biological adaptations to the environment are far more likely to be in response to air conditioning than global warming.
Reply | Report Abuse | Link to thisThis is the first hominid species to experience life mostly from the confines of climate controlled environments, from home, auto and office. Not being exposed to global warming, there's little chance of significant biological adaptations occurring in response to increasing temperatures.
Must be too many fossils in the anthropology department, or too many journalists studying climatology.
383bigblock,
Reply | Report Abuse | Link to thisThere is a great deal of evidence indicating that some thing or things of great significance is/are happening to our world. Things that will materially affect our species such as: accelerating extinctions, increasing CO2 levels, changing weather patterns, unsustainable human population levels, etc.
None of these things are trivial. We are all affected. Considering and reporting on such things, as this article does, is intelligent behavior. It has survival value.
Trolling for places to repeat plutocratic propaganda (Global Warming "Kool-Aid") is not intelligent behavior. It is selfish behavior with no survival value for our planet.
John
But the really interesting feature of the explanation is that we really had learned in school to think of evolution taking place somehow on its own, sort of teleologically, until the last Ice Age. This new view makes much more sense.
Reply | Report Abuse | Link to thisThe pity is that so many Americans have subordinated their scientific objectivity to their politics. This is a fairly recent development since Kyoto, I believe-- and it is not a beneficial adaptation in terms of survival!
I've often thought we've been cheating natural selection.
Reply | Report Abuse | Link to thisAs you've said, we control our immediate surrounding to suit us, the way we live, and not adapting to it. Add that to over population from people that are not good parents, and do not raise their kids in the best way possible, only to repeat the same bad habits that natural selection would have erased, and we have a race that supports generations of people that do not contribute any sort of evolutionary advantage. After all, the species that don't pass on traits that help traverse the world around them, usually vanish, but with us, we are supporting their existence.
JohnSciNew - Actually, it's natural to expect to see your posting displayed after entering. However, if you're using MS IE as your browser you're not likely to see your comment posted, not matter how many times you hit the enter key. Not to go into web page buffer management issues, etc., but its best to return to the SciAm home page, then select the article again. This seems to be much less a problem if you're using the free Firefox browser from Mozilla.com, by the way.
Reply | Report Abuse | Link to thisagenthucky - Well put. Since we are collectively supporting increasingly detrimental behavior we are, as a species, increasing the risk of suffering unnatural deselection for it.
Reply | Report Abuse | Link to thisA much stronger and more immediate influence on human evolution is modern medicine. We are "correcting" seemingly minor problems to major, genetically transferred health issues, from nearsightedness (myopia) to diabetes, defective heart valves, and pheomelanin. We "correct" these problems and we pass on their the problem to our children. Not saying we shouldn't, just stating the obvious.
Reply | Report Abuse | Link to thisWhere you say"climate-changing masters of the planet," "climate-changing messers-up of the planet" would be more appropriate.
Reply | Report Abuse | Link to thisWhat is interesting to think about is what the human species will becomes in say 5000 years. When you consider how humans will incorporate genetic engineering and technology into the species, and well as a significant portion adapting to living "off planet", there are likely to be almost unrecognizable "humans" a few thousand years from now.
Reply | Report Abuse | Link to thisSisko - Alternatively, 5000 years from now humanity may have become a thin dusting of carbon on the Earth's surface for the preceding 4900 years. When you consider that our success has been derived from ever more rapidly consuming the resources of the one planet capable of sustaining advanced life forms, it's quite likely that we won't be around much longer. Only if humanity can adapt to living within the resources available can we expect to continue our rapid development. I seriously doubt that any significant portion of the human population can ever live "off planet" unless we can very quickly learn to live "on planet".
Reply | Report Abuse | Link to this70% of the mutations of the human DNA are deleterious, bad, reduce fitness and reduce intelligence. We have mapped over 4000 genetic defects so far and still finding more propagating in the human species. There is no evolution at all, never has been.
Reply | Report Abuse | Link to thisDNA is absolutely irrefutable PHYSICAL evidence of de-evolution with 100% no possibility towards more complexity or more fit to survive. Preserving what we have left of our genome is what we need to focus on, not perpetuation the medical industry with drugs that add to the degradation o the human genome's ability to have correct cell replication.
Evolution is a fraud, and is full of mystical human "magical thinking" emotion mental garbage faith and belief. There is no magic "evolution fairy" that fixes our genomes.
If you want to believe in evolution you are just delusional.
This is THE definition of evolution:
Evolution: "that theory which sees in the history of all things organic and inorganic a development from simplicity to complexity, a gradual advance from a simple or rudimentary condition to one that is more complex and of a higher character." Webster's Encyclopedic Dictionary of the English Language.
There is no advances towards more intelligent, more complex nor more fit to survive. Humans are heading for extinction by not taking care of their existing genomes from self destructive habits.
Wake up from you delusions and look at the facts.