Neanderthal DNA Sequencing (11/15/2006)

Work on the Neanderthal Genome Project is starting to bear fruit as two scientific papers are published in journals Nature and Science. So far a large portion of the Neanderthal DNA has been assembled. The Neanderthal, who became extinct 24,000 years ago may be our closest relative.

The project, recently announced hopes to answer questions that traditional archaeology has been unable to answer, such as what did they look like?, how smart were they?, did they use language? and of special importance, did they interbreed with humans?

The DNA information obtained comes in part from a Neanderthal thigh bone, and has allowed scientists to identify more than a million base pairs of Neanderthal DNA. Professor Edward Rubin with the Joint Genome Institute in Walnut Creek California, used cutting-edge DNA sequencing techniques to collect genetic material from a Neanderthal femur bone found in the Vindija Cave, Croatia. He is the head of one of the projects working on decoding the Neanderthal Genome. His paper was published in the journal Science.

Professor Rubin's team used a technique called metagenomics, where fragments of the Neanderthal DNA were incorporated into bacteria which then copied themselves. The method resulted in the recovery of 65,250 base pairs of Neanderthal DNA.

Meanwhile, Dr Svante Paabo, director of the Max Planck Institute for Evolutionary Anthropology, is also making headway. He is currently looking at a gene called FOXP2, which in humans may be responsible for our use of language. He is trying to determine if Neanderthals had the same gene.

Both teams agree that humans and Neanderthals split up genetically about 500,000 years ago, and evolved independently from that point. This fits with previous estimates from mtDNA analysis and archaeological data.

Dr. Paabo and his team also believe that Neanderthals came from a very small community of only 3,000 individuals. Current theories believe that humans may have gone through periods of rapid decreases in population size supported by anomalies found in the human genome.

Modern humans migrated to Europe about 40,000 years ago and within 10,000 years the Neanderthals virtually vanished from Europe. Some scientists believe that Neanderthals and Humans may have been at war, or at the very least were competing for the same resources. Others speculate that humans may have inadvertently killed them off through the spread of disease, for which Neanderthal may not have had antibodies to fight off.

More controversial is the possibility that Humans and Neanderthals interbred, opening the door for an intriguing possibility. Its possible that Neanderthals abducted human wives similar to the way Native American tribes would steal wives during raids on enemy camps. Because Neanderthals were bigger and possibly stronger than humans, because of the higher protein diet they at, it would have been difficult if not impossible for humans to take them back. Professor Paabo's analysis hints at a possible genetic contribution from modern humans into Neanderthals. If this is so, how compatible was the DNA?

Currently little is known about cross-breeding of different species. Our largest source of information comes from horses and donkeys. When a female horse and a male donkey successfully breed, the offspring is a called a Mule, and is unable to reproduce. Similarly when a male horse and a female donkey successfully breed, the offspring is called a Hinnie which is also unable to reproduce. The reason for this is that horses and mules don't have the same number of chromosomes, they have enough for a successful mating, but not enough to continue the genetic line.

Is it possible that the offspring of Neanderthals and Humans were sterile as well? This would be hard to prove, unless a hybrid human-neanderthal skeleton were too be found. Decoding the Neanderthal Genome is needed before a comparative analysis of their DNA and Human DNA, and even then would only prove that breeding MAY have been successful.

The Neanderthal Genome sequencing is expected to be completed in the next 2 years.

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