3 ms·
There's no such "time scale", it all depends on the strength of the selection. Lactase persistence went from zero to ~100% in some populations in less than 3000
by bobcostas55 7y ago
There's no such "time scale", it all depends on the strength of the selection. Lactase persistence went from zero to ~100% in some populations in less than 3000 years.
- patrec 7y agoExactly -- Lactose tolerance is a common counter example to the strange notion that evolution in humans has somehow stopped either literally or practically (given supposedly glacial timescales).
- chrisweekly 7y agoYou're both right, of course. I was thinking in terms of evolutionary psychology and neuroanatomy -- areas where the timescales are "glacial" compared to the rise in lactose tolerance over a handful of generations.
- bobcostas55 7y agoThere's nothing inherently slow about selection on psychological traits. To give just one striking example, there is extremely rapid selection against intelligence in advanced societies going on right now, at a rate of about 0.25-0.3 standard deviations per century. US: https://www.pnas.org/content/suppl/2016/05/25/1523592113.DCSupplemental/pnas.1523592113.sapp.pdf https://www.pnas.org/content/suppl/2016/05/25/1523592113.DCS... (Table S11) Taiwan: https://www.sciencedirect.com/science/article/abs/pii/S0160289616303038 https://www.sciencedirect.com/science/article/abs/pii/S01602... Iceland: https://www.dropbox.com/s/9vq5t6urtu930xe/2017-kong.pdf https://www.dropbox.com/s/9vq5t6urtu930xe/2017-kong.pdf