On January 9, 2013, PBS ran a wonderful documentary, Decoding Neanderthals, about Neanderthals, what we have recently discovered about them, and what it means to us as humans. There has been a lot of discussion about this topic spurred by both the 23andMe and the Geno2.0 tests that provide a percentage of Neanderthal to participants. Geno2.0 also provides a percentage of Denisovan.
Over 60,000 years ago, the first modern humans—people physically identical to us today—left their African homeland and entered Europe, then a bleak and inhospitable continent in the grip of the Ice Age. But when they arrived, they were not alone: the stocky, powerfully built Neanderthals had already been living there for hundreds of thousands of years. So what happened when the first modern humans encountered the Neanderthals? Did we make love or war? That question has tantalized generations of scholars and seized the popular imagination. Then, in 2010, a team led by geneticist Svante Paabo announced stunning news. Not only had they reconstructed much of the Neanderthal genome—an extraordinary technical feat that would have seemed impossible only a decade ago—but their analysis showed that “we” modern humans had interbred with Neanderthals, leaving a small but consistent signature of Neanderthal genes behind in everyone outside Africa today. In “Decoding Neanderthals,” NOVA explores the implications of this exciting discovery. In the traditional view, Neanderthals differed from “us” in behavior and capabilities as well as anatomy. But were they really mentally inferior, as inexpressive and clumsy as the cartoon caveman they inspired? NOVA explores a range of intriguing new evidence for Neanderthal self-expression and language, all pointing to the fact that we may have seriously underestimated our mysterious, long-vanished human cousins.
I’m going to share some of the highlights of the program, but this is in no way a spoiler, as the program contains lots of visual information that just can’t be conveyed by a review.
Chris Stringer from the Natural History Museum in London introduced us to the Neanderthals. It turns out that our perception of what a Neanderthal looks like is a result in large part of skeleton that was reconstructed improperly due to advanced arthritis, causing the individual to appear to walk hunched over, much like, well, our stereotypical view of a caveman. Just goes to show what bad PR can cause.
Neanderthal skeletons can be positively identified. Their facial structure is different than that of modern man, with an identifiable brow ridge and bones that push forward in the nose and mouth region, as compared to our flatter faces today.
Neanderthals lived a short life, most were dead by age 30. They were large and strong. They participated in up-close and personal hunting, using spears, which meant they had to come in close contact with their prey.
Neanderthals began living in Europe about 300,000 years ago, having exited from Africa. They evolved to fit the European, colder, climate. It had been thought up until recently that they lacked the brainpower of humans, had no spoken language, or the ability for such, no personal ornamentation, art or evidence of ritual or religion. These are the functions that make us uniquely human and separate us from the non-human world, and we fully believed that Neanderthals lacked these defining characteristics.
We have learned differently, much as a result of genetic discoveries that tell a different story of Neanderthals.
Homo sapiens left African about 40,000 years ago, and within 10,000 years, Neanderthals, who had spread throughout most of Europe and much of Asia were gone. The map below shows the locations where fossilized Neanderthal remains have been found.
The assumption has been made that Homo Sapiens were responsible for the Neanderthals demise, either by killing them off or providing too much competition for scarce resources, outnumbering them 10 to 1.
Svante Paabo, a Swedish geneticist now at the Max Planck Institute for Evolutionary Anthropology forever changed the genetic world, how we perceive Neanderthals, and paradoxically, how we think of ourselves.
Pääbo is known as one of the founders of paleogenetics, a discipline that uses the methods of genetics to study early humans and other ancient populations.
In August 2002, Paabo published findings about the “language gene”, FOXP2, which is lacking or damaged in some individuals with language disabilities. This research would prove critical, later, in the humanization of the Neanderthal.
In 2006, he announced a plan to reconstruct the entire genome of Neanderthals. In 2007, Pääbo was named one of TIME Magazine’s 100 most influential people of the year.
In February 2009, at the Annual Meeting of the American Association for the Advancement of Science (AAAS), it was announced that the Max Planck Institute for Evolutionary Anthropology had completed the first draft version of the Neanderthal genome. Over 3 billion base pairs were sequenced in collaboration with the 454 Life Sciences Corporation. This project, led by Pääbo, shed and will continue to shed new light on the recent evolutionary history of modern humans.
In March 2010, Pääbo and his coworkers published a report about the DNA analysis of a finger bone found in the Denisova Cave in Siberia; the results suggest that the bone belonged to an extinct member of the genus Homo that had not yet been recognized, the Denisova hominin.
In May 2010, Pääbo and his colleagues published a draft sequence of the Neanderthal genome in the journal Science. Below, a scientist at Max Plank extracting Neanderthal DNA.
Paabo shared in the program that many times during the Neanderthal sequencing project, he himself “despaired many times of being able to do it”, doubting that it could be done. It took a total of 4 years. The team found good candidates, 3 well-preserved female bone fragments from the Vindija Cave in Croatia.
Because of the age of the fragments, and because they had been in the ground for so long, much of the DNA recovered wasn’t Neanderthal, but that of bacterial organisms and fungus. The team developed a method to eliminate the bacteria, leaving only Neanderthal DNA. However, those genetic fragments still had to be reassembled, piece by piece, like a huge jigsaw puzzle with no picture on the box, into the Neanderthal genome.
Four long years later, the puzzle was finished. I hope the team had a very big celebratory party!
Ed Green, a scientist on Paabo’s team said that the first thing the scientists looked for was to determine whether or not Neanderthals had the FOXP2 gene for language, and if so, is it identical to the human version, or is it different. The answer was that it was identical to the language gene carried by Homo Sapiens, modern humans. This tells us not only that Neanderthals had the capabilities for language, but that this gene evolved in Africa, before Neanderthals left, 300,000 years ago.
The next question, of course, was whether or not modern humans carried any DNA that could be labeled as Neanderthal. In other words, the question of inter-species breeding arose. It was believed that this was impossible, because two different species cannot have fertile offspring. This was proven to be an inaccurate assumption relative to Neanderthal and Homo Sapiens.
Paabo’s team sequenced the DNA of 5 individuals from different parts of the world. They isolated parts of the Neanderthal DNA that were measurably different from that of modern humans. In other words, those sequences could be positively identified as Neanderthal. Compared against the DNA of the 5 contemporary individuals, only the person from Africa had none of the Neanderthal DNA.
Paabo didn’t believe the results, thought they might be an artifact of statistical error or the result of not enough data, so he had his team repeat the exercise with different people, again, and again, and again, and every time, the results came back the same. Neanderthals and humans inbred, and to the degree that there is Neanderthal DNA in every population on every continent outside of Africa today.
John Hawks, an anthropologist at the University of Wisconsin used jelly beans to illustrate Neanderthal DNA in worldwide populations today. It turns out that the Chinese have the least amount, with about 1% and the people of Tuscany have the most, with about 4%. So the mountainous areas of Europe and Italy were a hotbed of Neanderthal activity and human interbreeding.
This caused other experts to think again about the Neanderthals in what could be called a radical shift in perspective. All of a sudden, when we realized that they were part of us, they became more human to us. They could and probably did have speech, so they could and probably did other “human” things too.
Joao Zilhao, a paleolithic archaeologist at the University of Bristol, also a flintknapper, spent years reconstructing the process of making Neanderthal tools, what were once believed to be scraps of flint with sharp edges. He proved, among other things, that obtaining these “scraps” involved a complex process of very specific flintknapping strokes. This skill was far from the previously perceived unintelligent caveman, and furthermore, it likely required language instruction.
Another early technology, in use 250,000 years ago, involved a complex process to create a type of pitch to secure spearheads to spear shafts.
The Neanderthals began evolving before our very eyes.
Michael Walker, a professor of Zoology and Physical Anthropology at the University of Murcia, discovered indeed that Neanderthals likely did have ceremony and ritual, the hallmarks of religion, which involved the ability for complex thought and reasoning. Shells and bones, drilled or punched to be worn as ornaments have been identified, along with pigments believed to have been used as body paints.
We still do this today; look at the fans at any football game.
In addition, it appears that a burial may have been found in Spain, along with two panther paws. Michael mentioned them as a trophy, I thought more in terms of spiritual significance.
John Hawks discussed what the Neanderthal parts of our genome have done for humans. Many of the Neanderthal genes have no known purpose, but there is one significant exception. It’s somehow ironic that we may indeed have survived as a species in a foreign environment, colder Europe, thanks to inbreeding with the Neanderthals. Humans carry a very specific Neanderthal piece of DNA that is essential to the immune system’s ability to attack viruses and bacteria, the HLA or Human Leukocyte Antigen. Because individuals who carried HLA might well have survived when others didn’t, the HLA became naturally selected for, and therefore present in the descendant population, us, “saving lives to this day.’
As John said, we are just beginning to understand our debt to the Neanderthals. Not only that, we also are rethinking what extinction really meant. We have presumed that Neanderthals went extinct, or died out, because we could no longer find their remains in fossil evidence. Perhaps, as Mark Twain said “reports of my demise have been greatly exaggerated.”
Is the reason we could no longer find separate Neanderthals because they interbred and assimilated into the Homo Sapiens population who were probably the dominant species, outnumbering them ten to one? Was their extinction not a dying out at all, but an absorption? Perhaps that was simply the natural progression of things, or maybe they realized that their recipe for success, for long-term survival, was not to remain separate, but to become part of the larger population. In fact they do survive today in just that way, as a part of all of us outside of Africa.
Decoding Neanderthals is available to watch online at http://www.pbs.org/wgbh/nova/evolution/decoding-neanderthals.html