Dave Hone

So males won't have medullary bone.

Young females won't have them.

Females outside of the breeding season won't have it.

Females inside the breeding season, but maybe they've been really sick this year, don't have it, or they laid their eggs early and now they don't need it anymore, won't have it.

So occasionally, if you cut up a bone, which of course we try not to do that much,

you can get the signal of medullary bone and infer that you have a female in the breeding season.

But there's no, like, large bone structure differences.

Well, maybe there is, but we haven't seen it.

You look at things like kudu or black buck and all kinds of antelope or even most deer, and the males have horns or antlers and the females don't.

And then you look at something like Triceratops and all the Ceratopsians.

It's a big clade of, oh, it must be 40 species by now.

And every single one of them has the frill and has some kind of horn somewhere.

You don't have the hornless ones or the frill-less ones in the way that we do with a lot of these.

Pelvis differences works on humans and apes and maybe a couple of other mammals, but it's mostly not very good.

It's because we give birth to such a gigantic baby with a gigantic head compared to our sizes.

that women have different pelvises to men.

And then there's size differences.

Like, the skull is not as reliable as the pelvis.

It's not.

And then, again, you just need to look at, you know, humans are always slightly dodgy with this because of, you know, our evolutionary and cultural history.