Ancient mitochondria shed light on the Neanderthals

The Neanderthal population was quite small.

Wikström An international research team has succeeded in mapping the 38,000-year-old mitochondrial DNA of a Neanderthal. The research attempted to clarify the common genetic origins of the Neanderthals and modern humans.

Two members of the University of Helsinki faculty participated in the study: Mårten Wikström, a professor from the Institute of Biotechnology, and Liisa Laakkonen, a docent in the Neuroscience Centre.

Wikström says that the genes which include the mitochondria are inherited through mothers only, meaning that they are particularly well suited to researching hereditary connections.

“The genotype of Neanderthals deviates substantially from that of modern humans,” Wikström says. “The research results indicate that the species branched out from a common origin approximately 660,000 years ago. Neanderthals are, however, genetically closer to humans than chimpanzees are.”

The extinct population of our cousins also appears to have been especially small.

Heading up the research are Richard E. Greene and Svante Pääbo from the Max Planck Institute. For some time now, Pääbo has been developing methods to study ancient DNA.

All the researchers had at their disposal was 0.3 grams of bone which dated from an specimen found in Croatia in the 1980s.

“DNA is a chemical compound which easily disintegrates once it is discarded into nature, and for this reason extremely old strands of DNA are difficult to study,” Wikström explains. “New research methods made it possible to recover a DNA sequence from the bone samples in its original form.”

Mitochondrial genes only code 13 of the proteins found in humans, but these 13 are essential. The researchers from the University of Helsinki were asked to assist in the study because Wikström’s team specialises in exactly these proteins. The largest differences between humans and Neanderthals were found in the proteins that regulate cell respiration.

The study was published on 8 August in the esteemed journal, Cell.

Text: Kirsikka Mattila
Photo: Marika Mäklin

Translation: AAC Noodi Oy

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