[3chelon]

To be fair, aside from the preschool formatting of the article (one sentence per paragraph, a concerning recent BBC trend), the journalist didn't actually say anything incorrect.

But she did not answer the main question that was asked: why the human pelvis has not grown wider over the years? She said that there were two opposing forces, one for larger babies (they have more chance of survival), and the other was natural selection preventing them getting too large (by killing them both in childbirth).

Maybe I'm missing something, but neither of those answer the question of why the pelvis has not got larger.

All I can assume is that it is (a) an evolutionary trend of men to be attracted to younger and potentially, on average, slimmer and more healthy or fertile women, and (b) cultural, since there is evidence that in historic times and possibly also in less technologically advanced societies, larger hips are considered desirable (which makes total sense in a society with no access to modern medicine).

I'm sure some anthropologists will beat me up for these terrible generalisations, but in general, on average, it seems these forces may have an impact on pelvis size over generations?

[marchenko]

Men are indeed attracted to relatively wide-hipped women, but there is an upper limit on hip width. There is a biomechanical tradeoff between pelvic shape and locomotor efficiency. The width of the pelvis affects the energy needed for a bipedal gait, since it alters the shape of the largest bones of the lower skeleton and their associated musculature (compare the angle of the femur in men v women and imagine how it affects joint stress). So there's a three way evolutionary arms race between the needs of the large-brained infant, the need to successfully expel said infant, and the need to be able to walk and run efficiently and without musculoskeletal damage.

[Swizec]

> one sentence per paragraph, a concerning recent BBC trend

3 of your 5 paragraphs are a single sentence.

[3chelon]

Yes, deliberately, and not all of them. And my post contains far fewer sentences than the article.

[Swizec]

Funnily, those 3 paragraphs - because they were long sentences - were the easier to read on mobile. So there's one datapoint for ya.