The subject of sex can be challenging to write about, but when it’s in the news it can’t be avoided. We shall endeavor to maintain our customary high standards throughout this post.
The topic is sometimes raised by creationists, who assert that sex couldn’t have evolved. The first time we ran across that argument was at the Jack Chick website — see Jack Chick: Sex Is Evolution’s Nightmare. Then the same line was echoed by Answers in Genesis (AIG). Our post about that one was Answers in Genesis: Sex Didn’t Evolve. Here’s a quote from the AIG article:
Sexual reproduction is only possible when both sexes have fully functional reproductive organs at the same time. … How is it then possible that such different and complex organs, which fit one another in every morphological and physiological detail, could have evolved suddenly?
Now we’ve found an article at PhysOrg that, ah … touches on the subject: Sex? It all started 385 million years ago (w/ Video). As that title suggests, there’s a video you can watch if you click over to their article. Your Curmudgeon hasn’t seen it, so proceed at your own risk. Anyway, here are some excerpts from the article, with a bit of bold font added for emphasis:
It may not have been love as we know it, but around 385 million years ago, our very distant ancestors — armoured fish called placoderms — developed the art of intercourse. So suggest a team of evolutionary scientists, who point to the fossil of a placoderm species blessed with the name of Microbrachius dicki.
There’s some information about them at Wikipedia: Microbrachius, which briefly mentions the latest findings, but we’ll stay with PhysOrg. Let’s read on:
Measuring about eight centimetres (four inches) in length, M. dicki lived in habitats in modern-day Scotland — where the first specimen was found in 1888 — and in Estonia and China. Placoderms have previously been found to be the most primitive jawed animal — the earliest known vertebrate forerunner of humans.
Then it gets interesting:
But they now have an even more honoured place in the book of life.
Oh dear, here it comes:
Microbrachius is the first known species to copulate in order to carry out internal fertilisation, according to a paper published on Sunday in the journal Nature.
Here’s a link to that paper: Copulation in antiarch placoderms and the origin of gnathostome internal fertilization. PhysOrg continues:
Male fish had bony, L-shaped genital limbs called claspers which transferred sperm into the female, a more effective way of reproduction compared to spawning in the water, the study says. The females, for their part, developed small, paired bones with which they locked the male organs in place in order to copulate.
Egad, this is terribly graphic! Here’s more:
“‘Microbrachius’ means little arms, but scientists have been baffled for centuries by what these bony paired arms were actually there for,” said John Long, a professor of palaeontology at Flinders University in Adelaide, Australia. “We’ve solved this great mystery because they were there for mating, so that the male could position his claspers into the female genital area.”
Ah, the mystery has been solved. Moving along:
Covered with thick, bony plates covering the head and trunk, placoderms ruled the world’s oceans, rivers and lakes for around 70 million years. They were then were wiped out around 360 million years ago in a mysterious mass extinction.
Well, they had a good long run. Another excerpt:
The critters handed on features such as jaws, teeth and paired limbs that are seen today in reptiles, birds and mammals, including humans. If the new study is right, the “claspers,” over hundreds of millions of years, evolved into the penis.
There’s more in the PhysOrg article. They actually describe how the, ah, deed was done. We’ll let you discover that for yourself. It’s going to be interesting to see what the creationists say about this — other than I ain’t no kin to no placoderm! Maybe they won’t say anything at all.
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