Accelerating human evolution

The concept of the EEA, the Environment of Evolutionary Adaptedness, never made much sense. In its strong form it is based on the misunderstanding that we evolved during the Stone Age, and then we more or less stopped evolving.

World Science reports on a study by Greg Cochran and John Hawks,

The tra­di­tion­al pic­ture of hu­mans as a fi­n­ished prod­uct be­gan to erode in re­cent years, sci­en­t­ists said, with a crop of stud­ies sug­gesting our ev­o­lu­tion in­deed goes on. But the new­est in­vest­i­ga­tion goes fur­ther. It claims the pro­cess has ac­tu­al­ly ac­cel­er­at­ed.

It al­so down­plays the im­por­tance of a much-scru­ti­nized era around 200,000 years ago, when hu­mans con­sid­ered “ana­tom­i­cally mod­ern” first ap­pear in the fos­sil rec­ord. In the stu­dy, this ep­och e­merges as just part of a vast arc of ac­cel­e­rat­ing change.

“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. [...]

Hawks and Coch­ran said some of the most no­ta­ble phys­i­cal changes in hu­mans have been ones af­fect­ing the size of the brain case.

A “thing that should prob­a­bly wor­ry peo­ple is that brains have been get­ting smaller for 20,000 to 30,000 years,” said Coch­ran. But brain size and in­tel­li­gence aren’t tightly linked, he added. Also, growth in more ad­vanced brain ar­eas might have made up for the shrinkage, Coch­ran said; he spec­u­lated that an al­most break­neck ev­o­lu­tion of high­er fore­heads in some peo­ples may re­flect this. A study in the Jan. 14 Brit­ish Den­tal Jour­nal found such a trend vis­i­ble in Eng­land in just the past mil­len­ni­um, he noted, a mere eye­blink in ev­o­lu­tionary time.

Research pub­lished in the Sept. 9, 2005 is­sue of the re­search jour­nal Sci­ence by Lahn and col­leagues found that two genes linked to brain size are rap­idly evolv­ing in hu­mans.

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