3 ms·
I see what you’re getting at, but wouldn’t the same pressure to reduce head size also inhibit the heads from getting big in the first place?
by BuyMyBitcoins 5y ago
I see what you’re getting at, but wouldn’t the same pressure to reduce head size also inhibit the heads from getting big in the first place?
- bpodgursky 5y agoExactly. And clearly there was pressure to downsize heads! But the tradeoff was that we lost brains, and until 40k years ago, that wasn't worth it. But with the advent of proto-civilization, the calculus changed...
- dredmorbius 5y agoThe fitness target isn't a stationary one. Larger heads might have been facilitated by a larger pelvic girdle (this seems to be the case in Neadnderthal skeletons AFAIU), which is an adaptation which would enable large (and possibly inefficient) brains, but at a cost for bipedal mobility, speed, and/or efficiency. Supposing a later competitor emerged with 1) smaller and 2) more effcicient brains as well as 3) narrower hips, then the previous advantage would become a (comparative) liability. It's a bit like Clayton Chistensen's Innovator's Dilemma: evolving yourself (or your species) into a corner. Advantageous for a while, but ultimately maladaptive, and hard to back out of. As with my other comments here, all but entirely conjecture.