What if there were animals that were genetically close to modern humans, but startlingly different?
What if there were animals that looked very much like modern human animals and they were almost identical genetically, yet they differed from us in notable ways? Would their discovery shock and horrify people? Quite likely. Wouldn’t it also make many people start thinking deeply about the fact that modern humans themselves are animals? You’d hope so. Wouldn’t this discovery make us intensely curious about our own origins? Remains to be seen. What follows is a true story.
The evidence is overwhelming that large numbers of Neanderthals roamed Eurasia for 200,000 years. The evidence is also clear that Neanderthals differed from the modern humans in genetically small but socially and physiologically significant ways. This incredible story can be found in the October 2008 edition of National Geographic, in an article entitled “Last of the Neanderthals.” This article is a must-read article for anybody who wants to peer into the not-so-distant past in order to learn about his or her bipedal cousins. The article is filled with incredibly lifelike modeling of the Neanderthals. It is also filled with detailed information about Neanderthal physiology, as well as clues to Neanderthal lifestyle.
Neanderthals had large brains and enormous strength, but when the climate changed, modern humans appeared on the scene and the numbers of Neanderthals dwindled to zero about 28,000 years ago (carbon dating was applied to embers from Neanderthal fires). Neanderthals dominated Eurasia for 200,000 years. They settled from Spain to as far east as Siberia.
During that time, they poked their famously large and protruding noses into every corner of Europe, and beyond-south along the Mediterranean from the Strait of Gibraltar to Greece and Iraq, north to Russia, as far west as Britain, and almost to Mongolia in the East. Scientists estimate that even at the height of the Neanderthal occupation of Western Europe, their total number probably never exceeded 15,000. Yet they managed to endure, even when a cooling climate turned much of their territory into something like northern Scandinavia today — a frigid, the barren tundra, it’s bleak arise and broken by a few scraggly trees and just enough lichen to keep the reindeer happy.
From 45,000 years ago to 28,000 years ago Neanderthals and modern humans overlapped throughout Eurasia, the Neanderthals eventually dwindling to small pockets before their complete demise. Many people have wondered whether modern humans interbred with Neanderthals. That issue has been settled by Svante Paabo, who examined the DNA from an arm bone of the Neanderthal man. The answer is in the negative:
Paabo and his colleagues were able to extract it tiny 378-letter snippet of mitochondrial DNA (a kind of short genetic appendix to the main text in each cell) from the 40,000-year-old specimen. When they read out the letters of the code, they found that the specimen’s DNA differed from living humans to a degree suggesting that the Neanderthal and modern human lineages had begun to emerge long before the modern human migration out of Africa. Thus the two represent separate geographic and evolutionary branches splitting from a common ancestor.
As is typical for National Geographic, this article involves top-notch graphics to illustrate the well-written text. Those illustrations depict those long and low Neanderthal skulls which held brains which were actually a bit larger than those of modern humans. The Neanderthal bones clearly indicate that their “wide bodies conserved heat in cold climates, while a large cortical rib cage housed big lungs needed for high levels of activity. . . . [Their] sturdy, heavily muscled limb bones evolved in response to a demanding lifestyle [and] large muscles positioned to maximize leverage resulted in exceptional strength.”
It makes my head spin to imagine modern humans emerging from Africa into Eurasia only 45,000 years ago, only to suddenly encounter Neanderthals. If only I could be transported back in time to observe those interactions!
The two species were 99.5% genetically identical, but the differences (as described above) were notable. Consider further that while the modern human adult needs 2,200 calories per day to survive, the Neanderthal adult needed more than 4,000 calories per day. Perfect teeth from a recently discovered 42,000-year-old jawbone indicate that Neanderthals had a shorter childhood than modern humans, “and less time for brains to develop in the context of the social group.” Some Neanderthals had red hair. It is possible, though not certain, that they had the ability to speak. Lumps of pigment suggests that Neanderthals valued art.
The story ends 28,000 years ago in a cave on the island of Gibraltar, where scientists have now demonstrated that a small group of Neanderthals built a fire. “Their charcoal and stone tools are the last known signs of Neanderthal life.”
Speaking of evolution, the current issue of Scientific American is dedicated to the subject, in honor of Darwin’s 200th birthday. Lots of good reading! For example, one thing I didn’t know is that Darwin predicted that human ancestors likely came from Africa, despite the fact that during his lifetime the only known proto-human fossils were in Europe.
Svante Pääbo on Neanderthals, from Edge.org:
http://www.edge.org/3rd_culture/paabo09/paabo09_index.html#video