CLUES FROM THE PAST: Our ancient ancestors can offer insight into our species' ability to survive and adapt over millions of years, scientists say.
Image: National Science Foundation
The plaster face cast of a large-nosed Neanderthal stares out into space. The extra cavities in his sinus helped trap air, which was subsequently humidified. There's nothing quite like having a warm pocket of air close to the brain to keep away the chill of the ice age, says Rick Potts, head of the Human Origins Program at the Smithsonian National Museum of Natural History.
The skulls of our closest ancestors tell the tale of human origins and the closeness of our evolutionary history to climate change, Potts said. The Smithsonian exhibit at the Hall of Human Origins, of which Potts is curator, explores the idea that defining evolutionary events like the discovery of fire or migration out of Africa could be direct results of a changing climate.
"Climate is certainly complex, and atmospheric carbon dioxide is higher that at any other time since the origin of our species," Potts said. "This is setting up for conditions that are equal to conditions our ancestors faced in terms of novelty. We want people to contemplate how well a species is equipped to deal with true novelty."
Fossils of hominids -- all two-legged species related to human beings -- document a history of human evolution from the ape-like Lucy (the first known Australopithecus afarensis) to the hand axe-carrying Homo erectus to the climate-changing masters of the planet that we are today. Now, at the outset of another climatic change triggered by human behavior, scientists say, the past can offer clues about our species' ability to survive and adapt over millions of years.
"People think, we're such a successful species, nothing can happen to us," said Potts. But, he pointed out, most of our ancestors sooner or later went extinct. Homo erectus, the forerunner of modern humans, lived for 1.5 million years, he said. Homo sapiens, by comparison, has been around for only 200,000 years. Yet even they decreased in population size to between 600 and 10,000 breeding pairs when hit with mega-droughts, heavy monsoonal rains and the eruption of a volcano near Sumatra about 70,000 years ago.
A growing body of work in paleoanthropology is showing that at least some of these evolutionary events occurred together with drastic and periodic changes in African and Eurasian climate.
"The idea that human evolutionary changes happen in response to static environments doesn't hold water anymore," Potts said.
Learning from a once-wet Africa
Studying past changes could provide clues about future evolutionary adaptations as humans address anthropogenic global warming, according to scientists who spoke on a panel about human evolution earlier this month at the Smithsonian. Researchers have named this epoch the Anthropocene, a period in geologic time when human activity has had an impact on the Earth's climate and ecosystem.
Earlier climate events were equally drastic, as recorded in layers of the Earth. Scientists correlate them with a sometimes sparse fossil record to draw correlations between climate and evolution.
They then create climate models similar to the ones used in global warming research. The crossover could make them more accurate at modeling future climate, said Andrew Cohen, a professor of geosciences, ecology and evolutionary biology at the University of Arizona.
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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.