Nov
26
2006

Neanderthals: kissing cousins or just a bunch of blabby relatives?

Neanderthalensis-Sapiens love child?: DNA sequencing may provide the answer. Photo courtesy of Mark Ryan's mother
Neanderthalensis-Sapiens love child?: DNA sequencing may provide the answer. Photo courtesy of Mark Ryan's mother

Did Neanderthals, the stocky, muscular human relatives that dominated Europe until 30,000 years ago, have the ability to communicate through language? And if so, did any of their chat sessions ever lead to dating and possibly mating with us, their not-so-distant cousins?

DNA extracted from the thigh bone of a caveman who lived 38,000 years ago in Croatia may supply scientists with the answers to these and other questions.

Two studies, one in Germany, the other in California, have reported new and exciting techniques for compiling the entire genome for Neanderthals, modern humans closest and most recent evolutionary link. Their research results, reported in the journals Nature and Science, respectively, convey they have demonstrated independently that it is now possible to recover the Neanderthal genome. Just a few years ago, the idea of doing this kind of sequencing was considered hopeless.

Dr. Svante Paabo who led one project at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany said that one million units of the estimated 3.2 billion units of Neanderthal DNA have already been mapped.

What has made this possible is a new DNA sequencing machine developed by a Branford, Connecticut company called 454 Life Sciences. The new sampler uses firefly light to sort through and catalogue vast amounts of fragmented DNA.

Dr. Paabo also shared some of his precious sample of Neanderthal DNA with Edward M. Rubin of the Joint Genome Institute in Walnut Creek, California. Using a different method, Rubin’s team identified 62,250 units of Neanderthal DNA.

Richard G. Klein, a Stanford University paleoanthropologist not involved in the studies, found the results “monumental.” He added that the full Neanderthal genome would resolve many longstanding questions about Neanderthals and their connection to modern humans, including physical and behavioral differences.

Of particular interest is whether Neanderthals could speak and had developed a language. The FOXP2 gene is thought to be one of the last evolving components leading to language development and has shown significant change since human-chimpanzee split occurred about six million years ago. If the Neanderthal genome is fully retrieved, and the FOXP2 gene more resembles the chimp version, then the thinking is that language development is less likely.

Dr. Paabo’s team has estimated the establishing Neanderthal population size to be about 3,000 individuals, while Dr. Rubin’s team reports that human and Neanderthal genomes are at least 99.5 percent identical. However, both research teams think it unlikely the two species interbred but the idea cannot be completely ruled out.

The extraction of readable DNA poses problems for scientists. The samples are often contaminated by bacterial DNA that attacked the remains when they were fresh or other human DNA left from curators or scientists handling the specimens.

On top of that, DNA begins to quickly degrade into short fragments after death making it tricky to locate a sample that has somehow survived. Dr. Paabo searched through museum collections all across Europe before finally finding one that satisfied his stringent criteria. It was a small bone from a cave in Croatia that had languished in a box of insignificant and relatively little-handled fossils. Only about 6 percent of the DNA present was Neanderthal, but with the new sequencing machine it should be more than enough to retrieve the specie’s gene sequence.

With 1 million units of Neanderthal DNA already mapped, Dr. Paabo estimates the rest should be completed in about two years.

SOURCES and MORE INFO:

BBC
454 Life Sciences Neanderthal info
Genome Research
Human Genome Project

Your Comments, Thoughts, Questions, Ideas

Gene's picture
Gene says:

Erik Trinkaus of Washington University in St. Louis has discovered a 40,000-year-old skull in Romania which seems to contain a mixture of human and Neanderthal features. He considers this to be evidence that the two subspecies did interbreed.

posted on Tue, 01/16/2007 - 12:43pm

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