Dating the last common ancestor of modern humans and neanderthals


Share post:

To discover why Neandertals are most closely related to people outside Africa, Harvard and Max Planck Institute scientists have estimated the date when Neandertals and modern Europeans last shared ancestors. The research, published in the journal PLoS Genetics, provides a historical context for the interbreeding. It suggests that it occurred when modern humans carrying Upper Paleolithic technologies encountered Neandertals as they expanded out of Africa.

Dating the last common ancestor of modern humans and neanderthals
Linkage disequilibrium patterns expected due to recent gene flow and ancient structure. (A) In the case of recent gene flow from Neandertals (NEA) into the ancestors of non-Africans (CEU) but not into the ancestors of Africans (YRI), we expect long range LD at sites where Neandertal has the derived allele, and this expectation of admixture generated LD is verified by computer simulation as shown in the right of the panel along with a fitted exponential decay curve. (B) In the case of ancient structure, we expect short range LD, reflecting the time since Neandertals and non-Africans derived from a shared ancestral population, and this expectation is also verified by simulation [Credit: PLoS doi:10.1371/journal.pgen.1002947.g001]

When the Neandertal genome was sequenced in 2010 it revealed that people outside Africa share slightly more genetic variants with Neandertals than Africans do. One scenario that could explain this observation is that modern humans mixed with Neandertals when they came out of Africa. An alternative, but more complex, scenario is that African populations ancestral to both Neandertals and modern humans remained subdivided over a few hundred thousand years and that those more related to Neandertals subsequently left Africa.

Dr. Sriram Sankararaman and colleagues measured the length of DNA pieces in the genomes of Europeans that are similar to Neandertals. Since recombination between chromosomes when egg and sperm cells are formed reduces the size of such pieces in each generation, the Neandertal-related pieces will be smaller the longer they have spent in the genomes of present-day people.

The team estimate that Neandertals and modern humans last exchanged genes between 37,000 and 86,000 years ago, well after modern humans appeared outside Africa but potentially before they started spreading across Eurasia. This suggests that Neandertals (or their close relatives) had children with the direct ancestors of present-day people outside Africa.

Source: Public Library of Science [October 04, 2012]



Related articles

Over 500 ancient artefacts unearthed in northeastern Iran

Over 500 ancient metal artefacts have recently been discovered during an archaeological excavation on the Bazgir Tappeh in...

Old bird, New World: Did the South American hoatzins originate in Europe?

The oldest fossil discoveries from France show that hoatzins once existed in Europe. Where did hoatzins come from?...

Earth-like planets are right next door

Using publicly available data from NASA's Kepler space telescope, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) have...

Puzzling 17th century grave of man buried face down discovered in Switzerland

In 2013 archaeologists discovered a cemetery in use as long ago as the early Middle Ages in the...

India’s ancient mammals survived multiple pressures

Most of the mammals that lived in India 200,000 years ago still roam the subcontinent today, in spite...

Feathered dinosaurs used tail plumage for courtship

A University of Alberta scientist has found that some dinosaurs could really shake a tail feather. Scott Persons...

Colliding stars explain enigmatic 17th century explosion

New observations made with APEX and other telescopes reveal that the star that European astronomers saw appear in...

Is this the face of Jack the Ripper?

On this day 123 years ago, Jack the Ripper claimed his first victim. But who was this serial...