A study published in Nature Genetics last month has found that almost every man alive today can trace their ancestry back to a “genetic Adam” who lived approximately 239,000 years ago. This is 100,000 years later than suggested by previous studies, meaning humans are evolving at a much faster rate than originally thought.
Whole genome sequencing of 753 Icelandic males from 274 different patrilines was used to estimate the mutation rate of a male–specific Y chromosome sequence (MSY) based on two or more generations from the same patrilineal genealogy. Very little homologous recombination occurs in the MSY so variation occurs solely through mutation, a rate of 8.71 x mutations per position per year. These estimates, therefore, can be extrapolated to deduce the most recent common ancestor, the only man whose paternal line has continued to present day, referred to as “genetic Adam”.
“Genetic Adam” is the male counterpart to the “mitochondrial Eve”, who is thought to be the origin of all mitochondrial DNA in existence today. This study indicates that it is likely they lived in very similar time frames, as “Eve” is thought to have been alive 170,000 -180,000 years ago.
These findings could help to clarify dates of key evolutionary events such as human migration out of Africa. Other studies have also suggested that the rate of evolution is increasing, with 7% of genes having undergone recent evolution. This has led to the development of traits such as lactose tolerance resulting from the increasing consumption of milk through to adulthood, or the selection for individuals with sickle-cell trait which provides immunity to malaria in some African communities.