The biggest expansion of man in prehistory?

DNA sequencing of 36 complete Y chromosomes has uncovered a previously unknown period when the human population expanded rapidly. This population explosion occurred 40 to 50 thousand years ago, between the first expansion of modern humans out of Africa 60 to 70 thousand years ago and the Neolithic expansions of people in several parts of the world starting 10 thousand years ago.

This is the first time researchers have used the information from large-scale DNA sequencing to create an accurate family tree of the Y chromosome, from which the inferences about human population history could be made. Since the Y chromosome is found only in men, its history and evolution are easy to study and interpret.

This study also highlights how information generated by other genetic studies, in this case by the company Complete Genomics, can be used to investigate human genetic archaeology. The lengths between the branches and the length of each branch on the Y chromosome family tree provide insights into the evolution of the human population. The closer the branches are, the more rapidly the population was expanding and separating, most likely into different geographic areas. The longer the branch length, the greater the time that group of people have been separated from the other groups.

"We have always considered the expansion of humans out of Africa as being the largest population expansion of modern humans, but our research questions this theory," says Ms Wei Wei, first author from the Wellcome Trust Sanger Institute and the West China University of Medical Sciences. "The out-of-Africa expansion, which happened approximately 60,000 years ago, was extremely large in geographical terms with humans spreading around the globe. Now we've found a second wave of expansion that is much larger in terms of human population growth and occurred over a very short period, somewhere between 40,000 to 50,000 years ago." [...] phys.org/

Actualización 03-11-12. Un nuevo análisis de ADN revela una explosión demográfica, antes desconocida, hace entre 40.000 y 50.000 años

La secuenciación del ADN de 36 cromosomas "Y" completos ha descubierto un período previamente desconocido, cuando la población humana se expandió rápidamente. Esta explosión demográfica se produjo hace entre 40.000 ó 50.000 años, entre la primera expansión de los humanos modernos fuera de África, ocurrida hace entre 60.000 y 70.000 años y la expansión de las gentes del Neolítico en varias partes del mundo a partir de hace 10.000 años...