A 38,000-year old bone has yielded the world’s first complete Neanderthal mitochondrial genome sequence, offering a tantalising glimpse at the genetic changes that separate humans from Neanderthals, which split some 600 millennia ago.
The mitochondrion – a structure often dubbed the cell’s powerhouse – contains a mere 16,565 DNA letters that code for 13 proteins, whereas the nucleus holds more than 3 billion letters that produce more than 20,000 proteins. If DNA were to the size of a standard soccer pitch, then mitochondrial DNA (mtDNA) would be equivalent to a small flowerbed.
For the time being therefore, the largely symbolic and technical breakthrough offers only limited insight into the evolution of humankind. “It’s kind of opening the window a crack,” says Tom Gilbert, an expert on ancient DNA at the University of Copenhagen, who was not involved in the sequencing project.
Yet the research, led by Richard Green and Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, will pave the way for the construction and analysis of the complete Neanderthal genome. A rough draft should be finished by the end of the year, Green told New Scientist.
No sex, please
This is not to say that such mtDNA sequences are of no use to scientists. Previous work on shorter stretches of Neanderthal mtDNA has dated their last common ancestor with humans to about 660,000 years ago, give or take 140,000 years.