Hip Hypothesis

bpod-mrc:

Women’s pelvises tend to be wider than those of men. It’s thought that this difference is due to the so-called ’obstetrical dilemma’ – the hypothesis that human females’ hips represent an evolutionary compromise between the need to deliver large-brained babies and the need to comfortably move around on two feet. And a new study shows just how far nature has apparently gone to accommodate this compromise. Scans of 275 human pelvises from people ranging in age from late foetus (far left) to more than 80 years (far right) reveal that male and female pelvis development is practically the same until puberty, at which point the female pelvis expands considerably until the ages of 25 to 30 – peak pregnancy years. After 40, however, the female pelvis once again narrows so that by old age it is more similar to that of the male and, presumably, more optimal for bipedal life.

Written by Ruth Williams

• Image courtesy of MorphoLab, Anthropological Institute and Museum, University of Zurich, Switzerland
• Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland
• Image copyright held by original authors
• Research published in PNAS, May 2016

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bone-of-contention:

anthropologymajorfox:

Heads up to people in bioanth, osteology, or any other field where learning all the finicky parts of the human skeleton comes in handy. There’s an awesome (and FREE) app called Essential Skeleton 4 that not only lets you look at everything from a variety of angles, but also quizzes you on them.

In no time you’ll be able to confidently point out the “pisiform articular surface of the right triquetral carpal”. Totally a fun ice breaker at parties. Also an easy way to not fail human skeletal biology this semester.

I have this app! It’s very useful. Honestly I didn’t expect this much out of a free app. I’ve paid for other anatomy-related apps that had far less content and detail.

Can you actually tell from just the skeleton if a woman has given birth or not? I’ve heard it both ways

dead-men-talking:

Funny you should ask – that’s what my master’s thesis is about!  

With what we have, no.  So far researchers have just focused on external “scars,” meaning extra bone growth or loss in areas associated with connective tissue and/or marks that are supposedly definite signs of pregnancy.  These have all been found to say nothing; they’ve been seen in males too.  Biggest problem I’ve seen so far is that we don’t actually know who has been pregnant and/or given birth in the skeletal collections that have been used.

I, however, have the huge fortune of being in a department with a large modern skeletal collection, for whom we have all of this information.  I don’t want to go into detail publicly since I haven’t defended my proposal for the department yet (don’t want anyone stealing my idea), but I’ll say I have a pretty good feeling I’ll be able to find something by comparing groups of females with each other.  If not, I’ll still be able to say that yet another method finds no difference, which is still entirely valid.

So stay tuned, because a year from now I might have an answer!