Nothing but the tooth

When we see toothless actors on TV, we giggle and laugh, but when scientists come upon fossils of toothless humans, they get very formal and write a paper on it. This is exactly what scientists did in 2005 when they saw fossilized skull and jaws of a Homo erectus (that lived about 1.7 million years ago) that indicated it had serious chewing problems. Scientists are known to have strange reactions to what seem like normal occurrences such as losing one’s teeth.

Why should a human fossil showing really bad dental records matter to us? We are quite sure there were neither dentists nor persistent oral hygiene ads 1.7 million years ago. They did save on dental expenses but knowing how much of early human survival depended on being able to chew nature to pieces for their nourishment, we have to ask: how did early humans with no teeth survive at all?

Scientists characterize the terrible dental record as the “earliest and best-preserved case of severe masticatory impairment in the hominin fossil record.” Translation: among all the kinds of human fossil record even before Homo Sapiens, this individual lost all of its teeth except one and for a good portion of its lifetime, it was on a purely very soft diet.” The scientists became very curious whether he would have needed some help to find soft and easily chewable plants — something that was the exception in the Homo erectus diet. Or could he have just done it all alone?

In the latest issue of the Proceedings of the National Academy of Sciences (April 21, 2009), Jean-Jacques Hublin of the Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology wrote an article entitled The Prehistory of Compassion. He cited new evidence found in the current PNAS journal of pre-Neanderthals (500,000 years ago) whose skulls show deformities from birth but apparently, these individuals lived up to at least five years. Other pieces of evidence show extreme permanent injuries to limbs, including being deaf and blind, yet these individuals survived despite those injuries. Scientists could only infer that other humans might have helped them.

Other findings that Hublin cited extend to that of apes, our genetic cousins. Before these, evidence was only limited to helping other apes survive an injury when that injured member has already been incorporated in to the group before the mishap. He also mentioned documented cases of captive apes saving their drowning companion apes. We may, however, rise to a new level of understanding since he cited new findings — that of congenital cranial deformities in an ape fossil — one that lived to adulthood. This could mean that apes are capable of another level of altruism — one that extends even to a newborn with deformities. I also remember a program on the human story in the National Geographic channel where they found fossils of an adult human ancestor that showed that it suffered from a lingering debilitating bone disease. Anthropologists think he could not have survived through adulthood if others did not care for him.

The roots of evolutionary behavior can be quite a messy science. The pieces of evidence above are trying to find proof that indeed, helping the weak was a characteristic of our evolutionary ancestors and that it helped them survive. But “altruism” is a psychological, emotional response and the neurological peg for this does not fossilize. We can only infer like we did from how the toothless Homo erectus fellow fared given the overwhelming meaty requirement of his harsh existence. Hublin also admitted how indirect the evidence is for the evolutionary roots of behavior such as compassion. But those who know what science is really for need not be alarmed at this lack of definite explanations.

Last Saturday in Fully Booked in High St., we had a Café Scientifique on Understanding Darwin via video conferencing with Professor Steve Jones (geneticist and evolutionary biologist from University College London) and he was specifically asked: what is the evolutionary explanation for altruism? He cited some examples where cooperation without instant or direct rewards helped the survival of species but what was important was what he said in the end. He said that there need not be an evolutionary explanation for everything you see. He said it would always be the job of science to try and see if there are explanations but even if we do not find them, it does not mean that they are meaningless behavior. We humans feel good if we help each other out and whether or not our human ancestors did so to help them survive does not make our acts any more or less meaningful to our lives now.

So if your dentures survive a million years to be unearthed by tomorrow’s scientists, they would surely know that you figured out a way to get around teeth loss and still nourish yourself. If you also preserve your receipt, they will even know how much dentists have charged for this evolutionary advantage.

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