The Dawn of the Deed: The Prehistoric Origins of Sex
John A. Long
University of Chicago Press, 2012
Where did sex as we know it come from? As paleontologist John A. Long explains, it popped up, so to speak, in the placoderms, armored fish of 380 million years ago. Long traces the topic from his discovery of odd little structures on an Australian fossil he named Materpisces (mother fish). Sex emerged as a way to more reliably pass along genes, and eventually to bond in some species, as opposed to the original vertebrate strategy of dumping sperm and egg into the water and swimming off to do something else. It's a bit odd that copulation developed in fishes whose bony plating could only have complicated matters. I wondered how my favorite prehistoric creature, the orca-sized Dunkleosteus terrelli, managed the feat while carrying a half-ton of armor. Long explains that, as the pladoderms developed modified fin rays into organs called claspers (still seen in modern skates and rays), they became long enough to get around the armor problem. It still wasn't easy: claspers have often been seemingly painful things for females to endure, and the claspers in at least some placoderms only pointed toward the tail. This means sex was done in a position where the female was essentially being shoved into the seafloor. Long continues his readable (if sometimes a bit technically worded) account through the problems of dinosaur sex (some people wondered what would happen to your blood pressure if you're having sex with your head several stories above the action) to such modern oddities as the penis of the Argentine duck, which is longer than its body. This is, above all else, a scientific detective story, as Long and his collegues go through painstaking field work and fossil cleaning punctuated by "Eureka" moments and ending with Long explaining fossil fish sex to the Queen of England (she listened politely). Readers with an interest in evolutionary biology will like this book very much, as will people who read it just for some conversation-stopping tidbits to toss out at cocktail parties. An excellent book all around.