Neolithic culture may have kept most men from mating

Studying the varying genetic diversity of different population groups is one method for piecing together the migration history of our species. Many analyses find a bottleneck in non-African populations dating back to around 50,000 to 100,000 years ago. This coincides neatly with the current estimate of the first wave of anatomically modern humans out of Africa. When humans first migrated out of Africa, they created a genetic bottleneck. Because a minority of people migrated, they took a minority of total human genetic diversity with them to the new colonies in Europe and Oceania.

What has not been noticed before, however, is a bottleneck of specifically male genetic diversity around 8,000 years ago. A recent paper in Genome Research suggests that, for every 17 female humans who reproduced at this time, only one male human managed to pass along his DNA. What's lacking is an obvious explanation for this pattern.

The analysis was based on data from 456 people from Africa, Europe, Siberia, Oceania, the Andes, and various regions across Asia. The researchers analyzed Y chromosome DNA, the genetic material passed down the male line, which can be used to glean information about historical male populations. They compared it to analyses of mitochondrial DNA, which is the genetic material passed from every mother to all her offspring, used to reconstruct information on historical female populations.