Evolutionary theorist Gregory Cochran and anthropologist John Hawks claim to have found evidence of a huge increase in the rate of human evolution in the more recent period of human evolution of the last 40,000 years.

Hu­man ev­o­lu­tion has been speed­ing up tre­mend­ous­ly, a new study con­tends—so much, that the lat­est ev­o­lu­tion­ary changes seem to large­ly ec­lipse ear­l­ier ones that ac­com­pa­nied mod­ern man’s “ori­gin.”

Contrary to the common view that humans have changed little since out-of-Africa Cochran and Hawks think big changes have come since humans emerged as a distinct species.

“The or­i­gin of mod­ern hu­mans was a mi­nor event com­pared to more re­cent ev­o­lu­tion­ary chang­es,” wrote the au­thors of the re­search, in a pre­sent­a­tion slated for Fri­day in Phi­l­a­del­phia at the an­nu­al meet­ing of the Amer­i­can As­so­ci­a­tion of Phys­i­cal An­th­ro­po­l­o­g­ists.

Cochran and Hawks see a 2 orders of magnitude acceleration in human evolution in the last 40,000 years.

Hawks and Cochran an­a­lyzed mea­sure­ments of skulls from Eu­rope, Jor­dan, Nu­bia, South Af­ri­ca, and Chi­na in the past 10,000 years, a pe­ri­od known as the Hol­o­cene era. They al­so stud­ied Eu­ro­pean and West Asian skulls from the end of the Pleis­to­cene era, which lasted from two mil­lion years ago un­til the Hol­o­cene.

“A con­stel­la­tion of fea­tures” changed across the board, Hawks and Cochran wrote in their pres­en­ta­tion. “Hol­o­cene changes were si­m­i­lar in pat­tern and... faster than those at the archaic-mod­ern tran­si­tion,” the time when so-called mod­ern hu­mans ap­peared. But these changes “them­selves were rap­id com­pared to ear­li­er hom­i­nid ev­o­lu­tion.” Ho­mi­n­ids are a fam­i­ly of pri­mates that in­cludes hu­mans and their ex­tinct, more ape-like though up­right-walk­ing an­ces­tors and rel­a­tives.

Hawks and Cochran al­so ana­lyzed past ge­net­ic stud­ies to es­ti­mate the rate of prod­uction of genes that un­der­go pos­i­tive se­lec­tion—that is, genes that spread be­cause they are ben­e­fi­cial. “The rate of gene­ration of pos­i­tively se­lected genes has in­creased as much as a hun­dred­fold dur­ing the past 40,000 years,” they wrote.

Humans were already spread over large areas of land 40,000 years ago and were evolving to better fit their local environments. If human evolution has been rapid then different population groups likely possess important unique adaptations to local circumstances and the differences between groups are larger than politically correct people would like us to believe.

This reminds me of a recent paper in Nature Genetics that found a quarter of genes show different expression levels in Europeans and East Asians.

Ethnicity stems not just from differences in genetic sequence, but also from differences in the expression of genes shared by ethnic groups, according to a new study in Nature Genetics. The authors found that 25 percent of genes show different expression levels in Asian and European individuals, and single-nucleotide polymorphisms (SNPs) in regulatory elements likely account for many of these variations.

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To see if some of these polymorphisms could cause differences in gene expression levels, researchers led by Richard Spielman of the University of Pennsylvania in Philadelphia assayed gene expression differences between ethnic groups.

Spielman and his colleagues measured expression levels of more than 4,000 genes in lymphoblastoid cell lines derived from individuals from three different populations: Chinese, Japanese, and European. They found that gene expression levels from the Chinese and Japanese groups were largely the same, but that expression levels between the Asian groups and the European group differed significantly for more than 1,000 genes.

Local selective pressures produced so many differences.

Also see the March 2006 Plos Biology paper A Map of Recent Positive Selection in the Human Genome by Jonathan K. Pritchard and colleagues at the University of Chicago.

Cheaper DNA testing technologies are going to produce a huge flood of reports on human evolution and human differences.

March 2009 Update: This work has since become the basis for an excellent book by Cochran and Harpending entitled The 10,000 Year Explosion: How Civilization Accelerated Human Evolution.