A year ago, Science published an article showing that the ASPM
and microcephalin genes continued to evolve even after the
emergence of Homo sapiens, being more prevalent in some
populations than in others. This finding raised many eyebrows
because the evolution of these genes is closely tied to increase
in brain size between lower primates and humans. Eyebrows have
been lowering over the past year. Two independent research
efforts have failed to find any relationship between ASPM
variants and performance on IQ tests. Today, the general feeling
is that it is time to move on to other things. This finding,
like so many others, seems to have been just a flash in the pan.
Yet some, like me, think otherwise. Two British researchers, Dan
Dediu and D. Robert Ladd have recently argued that the latest
ASPM and microcephalin variants are associated with populations
that speak non-tonal languages (PNAS "Linguistic tone is related
to the population frequency of the adaptive haplogroups of two
brain size genes, ASPM and Mi