HUMAN EVOLUTION

Monday, February 25, 2008

By Mira Oberman in Chicago | December 31, 2007

FOR more than 150 years, a debate has raged over the origins of modern humans.

The main body of scientific thought says modern humans migrated from Africa and then overwhelmed their more primitive European counterparts, the heavy-browed Neanderthals, or inter-bred with them.

But growing credence is being given to the theory that homo sapiens evolved from the Neanderthals, who mysteriously died out some 28,000 years ago.

A new study to be published on Wednesday in the early edition of the Proceedings of the National Academy of Sciences says evidence of huge climate change supports that theory.

Eugene Morin, an anthropology professor at Laval University in Quebec, argues that an extended period of harsh weather would have made Western Europe unwelcoming to new migrants at the time when the tools and cave drawings of modern humans began to appear.

He says it is much more likely that Neanderthals evolved as a result of these climate changes which drastically reduced the diversity and availability of animals to hunt.

"If the Neanderthals were already having trouble how would it have been possible for another population to survive?" he says.

"Even if they had a selective advantage they would still be facing the climatic conditions ... and would be competing with Neanderthals which would have been locally adapted."

Prof Morin examined the animal bones discovered at a rich archeological site in Saint-Cesaire, France and determined that the consumption of reindeer increased from 30 per cent to 87 per cent of the cave-dwellers' diet from about 40,000 to about 35,000 years ago.

And since a similar pattern was found in the bones of smaller mammals such as mice and voles, Prof Morin was able to conclude that a "relatively rapid" climatic change resulted in a drop-off in the region's bison and horse herds.

This climate change was as dramatic as the difference between the temperate forests near Montreal and the sparse Arctic region to the north, he explained.

With their survival tied to unstable reindeer herds subject to frequent crashes, the population density of Neanderthals in the region dropped dramatically, Prof Morin surmised.

This created a "population bottleneck" in which the genetic diversity of Neanderthals was dramatically reduced, allowing rare mutations to become fixed, Prof Morin concluded.

It's also possible that the harsh conditions forced the hunter-gathering Neanderthals to roam farther afield in search of food and to expand their social networks in order to protect themselves from hard times.

This may also have helped spread the genetic traits found in Cro-Magnons and the use of more complex tools and cave paintings.

"It still remains a mystery why all these changes occurred together, but I don't think they occurred as a result of a modern human migration," Prof Morin said.

"A lot of people have argued for a population increase (as modern humans expanded both numerically and spatially) and this study has shown that is not possible."
Is the Theory of Evolution Really a Matter of Faith?
By Leonard Steinhorn and Charles Steinhorn

Leonard Steinhorn is a Professor of Communication at American University, Author of The Greater Generation: In Defense of the Baby Boom Legacy, and a member of the HNN board. Charles Steinhorn is a Professor of Mathematics at Vassar College.

There are moments in history when wrongheadedness leads to interesting insights. Perhaps this is one of them.

Consider the Republican presidential candidates who said they didn’t “believe in evolution” at a debate earlier this year. They may have been onto something – but for all the wrong reasons.

The truth is, we don’t believe in evolution either. But we don’t have to, because we know it to be factually true. And that’s the nugget of insight that’s too often been missing from the public debate ever since Darwin first laid out his theory of evolution almost a century-and-a-half ago.

As a natural phenomenon based on scientific evidence, evolution is not a matter of belief or faith, any more than gravity or genetics, and to ask whether someone believes in it is a nonsensical question, much like asking if someone believes in subatomic particles.

Yet read the popular press and you’d think that the truth of evolution is based not on science or knowledge but on one’s personal worldview irrespective of evidence or proof, as if one’s approach to evolution should be no different from the act of believing in, say, immaculate conception or the existence of God.

Recently we conducted a newspaper database search of the phrase “believe in evolution” and found nearly a thousand citations from the last five years. Typical is a New York Times article that describes a married couple as “Christians who believe in evolution,” which suggests that scientific evidence and facts, like religion, can be true or false based on whether we believe in them or not.

The generous interpretation is that the press is simply lazy, preferring shorthand to a more accurate description, which might say that so-and-so “accepts (or doesn’t accept) the fact that evolution has occurred.” Stating it that way would acknowledge the fact of evolution and show that those who refuse to accept it are denying established evidence and proof.

Press reporting may also reflect a larger ignorance of science and specifically the meaning of “theory” as applied to natural phenomena. In science, “theory” has nothing to do with its popular usage as a notion or opinion, as when someone might offer a “theory as to why Bush went to war.”

Rather, a scientific theory offers a coherent and conceptual explanation for facts and evidence that have been observed and accumulated; it must be predictive and capable of testing by further scientific observation.

Thus the theory of evolution aims to make logical and rational sense of the facts of evolution, proposing mechanisms to explain how evolution occurs. Those who attack evolution as merely a “theory” misunderstand what a scientific theory is.

Compounding the problem is the he-said, she-said style of journalism so prevalent today, which leaves media vulnerable to a trap set by proponents of the latest attack on evolution, “intelligent design,” which is little more than an artifice devised to inject religion into the biology classroom.

Rather than portray “intelligent design” for what it is, a clever recycling of a centuries-old philosophical argument to "prove" the existence of God that has been dressed up as a scientific theory, the press reports it as an alternative to evolution and quotes advocates who complain about “viewpoint discrimination” against their cause.

This manufactured controversy will gain more media attention in 2008 with the release of Expelled: No Intelligence Allowed, a movie promoting “intelligent design” that stars actor Ben Stein, who claims it will chronicle how “freedom of inquiry in science is being suppressed.” Stein demonizes “Big Science” as an entrenched establishment that squashes dissent, claiming scientific credibility for “intelligent design” when in fact there is none.

Thus evolution simply becomes merely another “viewpoint” in the public debate, lending plausibility to the idea that it is a notion to be believed rather than a scientific fact to be known.

And that illustrates a larger problem that far transcends the evolution discussion. For years, many religious conservatives have tried to blur the line between their beliefs and objective truths. If belief masquerades as fact, and if the press allows them to coexist on an equal footing, then fact becomes just another opinion and belief gains credibility as an alternative. The media simply play along, reporting the controversy, as if no side has a greater claim to truth.

Nor is science the only field jeopardized by this blurring of belief and truth. It touches history and every other discipline dedicated to the pursuit of knowledge.

So when Republican presidential candidates say they don’t believe in evolution, bravo for them. If only they – and the media covering them – understood the real meaning of what they say.