Dave Hone

Yeah, but it already had a swim bladder that it was probably processing a minimal amount of oxygen through, and the swim bladder evolved for a certainly different function.

Yeah, but again, you've got stuff that's not a million miles away from that.

You have things like frogfish.

Yeah.

which are fully marine, but kind of clamber through seaweed and stuff.

And they've got pseudo-functional limbs.

Again, it's that Tiktaalik is not a weirdly derived frogfish, but it's not like it's a fish that suddenly came on land or a fish that suddenly evolved legs.

There was already that selective pressure that was pushing it into a new opportunity, which gave it an

and then on and on and on, and that's what keeps going.

But it also brings up another thing, going back to dinosaurs and the behavior stuff, which, again, I think has been a problem, is the functionality thing and how there's always been, I think, this big perception of

single traits having single functions which isn't how a huge amount of biology works for some yeah like eyes are used for seeing they don't really do anything else um but i think there's a lot of again it comes down to a lot of the sexual selection stuff but things like horns on triceratops that's probably quite good for fighting off predators but it's also quite good for fighting other

triceratops and then things like elephants dig with their tusks as well as fight other elephants as well as fight lions as well as stripping the bark off trees so you've got to be very careful about how you think of functionality in two different ways one way is what possible things could that thing do and what possible things could have been the main selective pressure before so you think about elephant tusks as i say they do all these different things but when an elephant's just got

The tiniest little nubs, like the first elephant whose teeth are growing the wrong way and have pushed out of its jaw and now it's got a couple of little spikes.

It can't really dig a hole with them.

It's certainly not digging for water.

They're probably not great against a predator because you'd basically have to get on your knees to try and lean over and try and stab it a bit.

But you can show off to the girls and you can immediately fight another elephant who's head-to-head the same height as you and you've got a massive advantage.

So evolutionarily, they probably started as some kind of sexually selected feature.

But now, functionally, they are probably compromised by the fact that having the best fighting tusks, but also having the tusks that are best at digging up water to keep you alive during a drought, is putting selective pressure on that.

And those are... Although sexual selection appears in both ends, those are two different things.