Neanderthals as living breathing people

What follows below is an audio version (with slides) of a presentation given at the Yale Medical School by science writer Carl Zimmer. His lecture starts with the discovery of the first recognized Neanderthal bones, and brings us up to modern times. The general theme of the talk is that those beings who have been recognized to be different have traditionally been characterized as barbaric and inferior. This theme holds true regarding Neanderthals, who have been traditionally characterized as brutish and uncivilized. Zimmer's talk includes numerous vivid reconstructed images, and the evidence on which they are based, suggesting that Neanderthals looked and acted quite human, indeed. The emerging truth is that Neanderthals were big-brained hominids who lived across great expanses of Europe from 200,000 to 20,000 years ago. They were prolific tool-users: For example, they made stone tools such as spear tips and bows and arrows; they cleaned hides and fashioned clothing. they lived in communities where they would have specialized areas for storing and preparing food. It appears that they left flowers at their burials sites. They made jewelry out of painted shells, suggesting that they were self aware.

The Red Headed Neanderthal from Carl Zimmer on Vimeo.

Starting at the 20 minute mark, Zimmer discusses the work of Svante Paabo of the Max Plank institute, which recently completed its analysis of DNA found in the bones of Neanderthals. Neanderthal skeletons that appeared to be hybrids provoked researchers to obtain an entire Neanderthal genome. Researchers then found that the Neanderthals have the same FoxP2 gene that we do, suggesting that they might have had language. The elephant in the room is that Neanderthals are no longer here and we are. But they are still living on in one sense, as Zimmer explains at the 41 minute mark. The Planke institute determined that between 1-4% of non-African DNA is Neanderthal. How's that for humanizing Neanderthals?

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Genomes, Souls, and Cousins

You may have heard the news. Humans and Neanderthals, apparently, had sex with each other at some time. Shocking, yes, I know. But the newish technology of sequencing genomes is turning up all sorts of fascinating (and potentially scandalous) data. In NatureNews Online you can read more about it.

The researchers arrived at that conclusion by studying genetic data from 1,983 individuals from 99 populations in Africa, Europe, Asia, Oceania and the Americas. Sarah Joyce, a doctoral student working with Long, analyzed 614 microsatellite positions, which are sections of the genome that can be used like fingerprints. She then created an evolutionary tree to explain the observed genetic variation in microsatellites. The best way to explain that variation was if there were two periods of interbreeding between humans and an archaic species, such as Homo neanderthalensis or H. heidelbergensis.

Speculation over Neanderthal/Human interaction has been ongoing for a long time. Some of the idiosyncrasies of the Basque language have even been hypothesized to have resulted from such interaction, as that region of Europe seems to have been the last place Neanderthal was known to live. That they shared space---and perhaps much more---with humans is, to say the least, and intriguing notion. [More . . . ]

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Your Neandertal Ancestors

Scientific convention used to be that modern humans came out of Africa and completely replaced Neandertals (also spelled "Neanderthals") without interbreeding (for example, see here). New evidence suggests that this hypothesis is incorrect, according to an article by Ann Gibbons called "Close Encounters of the Prehistoric Kind." The article appears in the May 7, 2010 edition of Science (available online only to subscribers). An international team has now completed the draft sequence of the Neandertal genome, which includes more than 3 billion nucleotides collected from the bones of three female Neandertals who lived in Croatia more than 38,000 years ago." The analysis described was astoundingly complex, and the consequences of this analysis are startling:

By comparing this composite Neandertal genome with the complete genomes of five living humans from different parts of the world, researchers found that both Europeans and Asians share 1% to 4% of their nuclear DNA with Neandertals. But Africans do not. This suggests that early modern humans interbred with Neandertals after moderns left Africa, but before they spread into Asia and Europe. The evidence showing interbreeding is "incontrovertible," says paleoanthropologist John Hawks of the University of Wisconsin, Madison, who was not involved in the work. "There's no other way you can explain this."

Therefore, many people living outside of Africa carry "a small but significant amount of DNA from these extinct humans." The consequences of this amazing finding are not lost on anyone:

In a sense, the Neandertals are then not altogether extinct, says lead author Svante Paabo, a paleogeneticist at the Max Planck Institute for evolutionary anthropology in Leipzig Germany, who is surprised to find out he was part Neanderthal. "They live on in some of us."

The Science article presents the following list of things we now know about Neanderthals:
  • The genomes of modern humans and Neanderthals are 99.84% identical.
  • The scientific data don't support interbreeding when scientists had most expected it (between 45,000 and 30,000 years ago in Europe).
  • Neanderthals coexisted with modern humans in Europe from 30,000 to 45,000 years ago, and perhaps in the Middle East as early as 80,000 years ago.
  • The amount of admixture is tiny, even among Europeans and Asians, but Neanderthals "are significantly more closely related to non-Africans than Africans on average.
  • The new data fits with the discovery of fossils and stone tools from Israel caves about 80,000 years ago (modern humans and Neanderthals both used these caves and had much in common--they used similar tool-kits and under the same animals). One Neandertal skeleton from the Middle East looked "less robust than Neanderthals in Asia and Europe.
  • Despite the ability to sequence some Neanderthal DNA, there is no possibility of cloning a Neanderthal.
  • "The isolated DNA was in pieces typically about 50 bases long, and there were many missing stretches. Further, despite the story one often hears in the mass media, DNA is not completely responsible for the appearance of an animal. "Chemical modifications to the genome, the way chromosomes arrange in the nucleus, and maternal components in the egg all play a role in translating a genetic blueprint into a viable individual." None of these are available with regard to Neanderthals. As soon as you substitute another oocyte (e.g., that of a modern human) for that of a Neandertal, you would change the resulting organism.
Despite the fact that there was some interbreeding, it did not happen much. This article quotes evolutionary geneticist Sarah Tishkoff, who asked "Was it a cultural barrier?" We are cousins with every living thing on planet Earth (including trees and see here), but many of us are both cousins and descendants of Neandertals. Therefore, for those of you who have had ancestors from anywhere outside of Africa (keeping in mind that all of us have ancestors from Africa), you are African and you are Neandertal. I'm planning on having a bit of fun the next time a bureaucratic form requires me to designate my "race."

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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 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.

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