Is Our Brain Too Big to Think Effectively?
Current Anthropology Volume 50, Number 2, April 2009
Konrad R. Fialkowski
"In their paper, “Archaic Human Admixture,” Garrigan and Kingan (2007) wrote,
In contrast to Xp21 and RRM2P4 examples, in which the putatively introgressed archaic lineages were found at relatively low frequencies, the MCPH1
D lineage occurs in nearly 70% of the sampled chromosomes. Lastly, the
D lineage is estimated to have introgressed into the anatomically
modern human genome approximately 37,000 years ago. … Could this be the
first example of adaptive hybridization in hominids?
However, the question arises of
what
was adaptive about this hybridization that shifted our genome back to
the allele of our evolutionary forefathers. The rapidity of
proliferation (70% in 37,000 years) implies that this particular allele
had led to an extremely high fitness in individuals.
At
the time of introgression, images had already been painted on the walls
of caves and burial ceremonies performed. Speech had been in use for
more than 100,000 years (Liberman 1991),
to the accompaniment of abstract thinking. Generally, similar to today,
reasoning and thinking were the primary faculties of individuals..."
Read the full paper.