Thread by @blog_supplement

Cranial capacity is normally distributed. Got 821 skulls from data of the early American phrenologist Morton. As noted before different measurement methods give somewhat different results but overall tend to be consistent. The data here is mean, when multiple measurements exist

The red lines on the right tail indicate the big-brained archaics & early sapiens, in order: Boskop: early African sapiens; Xujiayao-6: East Asian archaic; Amud-1: West Asian Neanderthal; Xuchang-1: East Asian archaics. The possibility that the east Asian archaics are actually

Denisovans has been proposed, though we don't know for sure. It shows that the biggest modern sizes were already attained by 100,000K years in some groups. In Morton's data the overall mean for sapiens is 1328 cc which is less than the average for Neanderthalis ~1500 cc. It has

been proposed that neanderthalis had better eyesight &correspondingly more acute visual processing & perception than sapiens. This might have accounted for some of that extra brain. At the other end, archaic Homo naledi had a mean volume of 500-550 cc, close to Australopithecus

^ that extreme left outlier should have been removed; Morton's notes indicate it was the skull of a pathological German female, probably with a pituitary dysfunction.