Brussels, 25 Jul 2006
A team of German and US researchers has announced plans to decipher the genetic coding of our closest relative, the Neanderthal, within the next two years. If successful, the research could shed light on the evolutionary history of man.
The Neanderthal (Homo neanderthalensis) was a species of the Homo genus that inhabited Europe and parts of western Asia as early as 350,000 years ago. Neanderthals disappeared from Europe 50,000 years ago, and from Asia 30,000 years ago.
The first Neanderthal fossil was discovered 150 years ago in the Neander Valley near Düsseldorf, Germany. Ever since that time, paleontologists and anthropologists have been striving to uncover the role of these stockily-built early humans in modern human evolution.
To find answers, scientists from Germany's Max Planck Institute for Evolutionary Anthropology, together with the US-based 454 Life Sciences Corporation, will sequence the three billion pairs that make up the Neanderthal genome and then compare it to already sequenced human and chimpanzee genomes.
But extracting and sequencing ancient DNA is easier said than done due to the fact that the fossils used are generally contaminated with genetic material from bacteria and people who have handled them. Professor Svante Paabo of the Max Planck Institute, who will lead the research, has made some headway in the field. Over the last twenty years he has been developing methods for demonstrating the authenticity of ancient DNA results, as well as technical solutions to the problems of working with short, chemically-modified DNA fragments.
In 1997, he pioneered the sequencing of the mitochondrial DNA (mtDNA), a small circle of DNA found in the cell's energy-producing mitochondria, from a Neanderthal fossil. Each mitochondrion contains multiple copies of mtDNA, so it tends to persist in fossils and bits can be retrieved by a technique called the polymerase chain reaction (PCR). While the research provided valuable information about the evolutionary history of the species, it comprised only about 0.001 per cent of the entire genome and was inherited exclusively through the female line. It therefore provided only limited insights into how the Neanderthal differed from modern humans.
The research will use a new system, which will allow it to go beyond the mtDNA method by individually amplifying a quarter of a million single DNA strands by PCR from small amounts of bone and sequencing them in less than four hours. Over the next two years, the Neanderthal sequencing team will determine about 60 billion bases from Neanderthal fossils in order to reconstruct a draft of the three billion bases that make up the genome of Neanderthals. The team will use samples from several Neanderthal individuals, including the specimen found in 1856 in Neander Valley, and a particularly well-preserved Neanderthal from Croatia.