Recent Brain Evolution
According to new research by Bruce T. Lahn and Sarah Tishkoff, microcephalin and ASPM, two genes involved in determining the size of the human brain, have undergone substantial evolution in the last 60,000 years.
The researchers studied the worldwide distribution of the two genes’ alleles by decoding the DNA of the microcephalin and ASPM in many different populations.
With microcephalin, a new allele arose about 37,000 years ago, although it could have appeared as early as 60,000 or as late as 14,000 years ago. About 70% of people in most European and East Asian populations carry this allele of the gene, but it is much rarer in most sub-Saharan Africans.
With ASPM, a new allele emerged about 5,800 years ago (14,000 to 500 years ago). The allele has attained a frequency of about 50% in populations of the Middle East and Europe, is less common in East Asia, and is found at low frequency in some sub-Saharan Africa peoples.
The ASPM allele emerged about the same time as the spread of agriculture in the Middle East 10,000 years ago and the emergence of the civilizations of the Middle East some 5,000 years ago.
Dr Tishkoff said the statistical signature of selection on the two genes was “one of the strongest that I’ve seen.”
“Brain May Still Be Evolving, Studies Hint,” by Nicholas Wade