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Fishy breath and sexy evolution

Let’s talk about the evolution of fish to amphibians. I got to thinking, let’s just isolate one factor – change in breathing from gills to lungs, from underwater breathing to air breathing. If you have some kind of half-way stage, then I’d say you have a survival of the fittest problem. According to evolutionary theory, as I understand it, the first amphibians and their immediate predecessors would have no land or air based predators. So at the halfway stage, Mr Fish-amphibian is water-based but somewhat restricted to surface or near surface environments. That rather restricts his movement and range. If I was a fish predator, that means that I don’t need to waste energy chasing regular fish, who can go to the surface, or evade me to the deeps, all I need to do is feast on those critters at the surface who can’t escape in 3D, only in 2 dimensions – easy meat. Or, if our half fish-half amphibian friend was a predator, he has a distinct disadvantage, because he is limited only to the near-surface area. Evading him is easy, advantage to fish who can swim deep to avoid being lunch – one hungry surface-tied predator. Either way, I don’t think that the survival of the fittest test is passed, natural selection leads to extinction of the ‘half-and-half’ creature.
Kind of reminds me of my biology teacher back in the day at Spalding Grammar School. Mr Searle by name, surly (and crude) by nature. I have never forgotten his lesson on the evolution of sexual intercourse. It went like this. Amphibians come fully out on to land. Problem is that Mrs reptile’s eggs dried out in the sun. So she put a calcium shell round them to stop them drying out. ‘That’s no good’ says Mr Reptile, ‘my sperm are going to need ruddy pneumatic drills to get in there!’ So Mr and Mrs Reptile go into deep thought mode over this vexing problem, and then a big grin spreads over Mr Reptile’s face. ‘I know’ he says, ‘Let’s have a bit of leg-over’.
And that was it.
I kid you not.
And it probably succinctly encapsulates all of the problems with the development of sexual intercourse in evolutionary theory.
I sure hope the teaching of evolution in biology has improved at Spalding Grammar School since my day.
Oh, wait, I’m not sure I do hope that……