The Dawn of the Deed: The Prehistoric Origins of Sexby John A. Long
We all know about the birds and the bees, but what about the ancient placoderm fishes and the dinosaurs? The history of sex is as old as life itselfand as complicated and mysterious. And despite centuries of study there is always more to know. In 2008, paleontologist John A. Long and a team of researchers revealed their discovery of a placoderm fish fossil,
We all know about the birds and the bees, but what about the ancient placoderm fishes and the dinosaurs? The history of sex is as old as life itselfand as complicated and mysterious. And despite centuries of study there is always more to know. In 2008, paleontologist John A. Long and a team of researchers revealed their discovery of a placoderm fish fossil, known as “the mother fish,” which at 380 million years old revealed the oldest vertebrate embryothe earliest known example of internal fertilization. As Long explains, this find led to the reexamination of countless fish fossils and the discovery of previously undetected embryos. As a result, placoderms are now considered to be the first species to have had intimate sexual reproduction or sex as we know itsort of.
Inspired by this incredible find, Long began a quest to uncover the paleontological and evolutionary history of copulation and insemination. In The Dawn of the Deed, he takes readers on an entertaining and lively tour through the sex lives of ancient fish and exposes the unusual mating habits of arthropods, tortoises, and even a well-endowed (16.5 inches!) Argentine Duck. Long discusses these significant discoveries alongside what we know about reproductive biology and evolutionary theory, using the fossil record to provide a provocative account of prehistoric sex. The Dawn of the Deed also explores fascinating revelations about animal reproduction, from homosexual penguins to monogamous seahorses to the difficulties of dinosaur romance and how sexual organs in ancient shark-like fishes actually relate to our own sexual anatomy.
The Dawn of the Deed is Long’s own story of what it’s like to be a part of a discovery that rewrites evolutionary history as well as an absolutely rollicking guide to sex throughout the ages in the animal kingdom. It’s natural history with a naughty wink.
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THE DAWN OF THE DEEDThe Prehistoric Origins of Sex
By JOHN A. LONG
The University of Chicago PressCopyright © 2012 The University of Chicago
All right reserved.
Chapter OneThe Machismo of the Argentine Duck
Time is a substance from which I am made. Time is a river which carries me along, but I am a river; it is a tiger that devours me, but I am a tiger; it is a fire that consumes me, but I am the fire.
Jorge Luis Borges (Argentine poet and essayist, 1899–1986)
The male Argentine duck (Oxyura vittata) sports a penis as long as its entire body. The longest one measured was 1.3 feet long (42.5 centimeters) on an average-sized duck. It was discovered by a team of zoologists led by Dr Kevin McCracken of the Institute of Arctic Biology and the Department of Biology and Wildlife in Alaska.
The corkscrew-shaped penis of this duck is the largest known, relative to an animal's body size, in the entire vertebrate world. Even the mighty blue whale, spanning 100 feet (30 meters) in length with a penis extending 8 feet (2.5 meters) outside its body, doesn't come close to this little duck in overall body size comparison. (Of course, one must bear in mind the obvious difficulties involved in attempting to take measurements of an erect blue whale penis, or 'dork'. They only come out during the intensely emotional time of mating, and there are few brave enough to saddle up next to one with tape measure in hand whilst the male is desperately trying to implant his dork into the vagina of his massive mate. Needless to say these figures are only estimations from nearby observers.)
For your general interest, and we really should get this important fact out of the way at the start of the book, the human male penis ranges between 5.1 and 5.9 inches (13 and 15 centimeters) in length (for 95 per cent of all males measured), with the largest human penis size ever officially recorded being 13.5 inches (34.3 centimeters) long by 6.2 inches (15.7 centimeters) in circumference. The honor of taking this particular measurement fell to the famous American obstetrician and gynaecological researcher Dr Robert Latau Dickinson (and yes, I do acknowledge a certain irony in his surname). Dickinson (1861–1950) was not only a prolific medical scientist and surgeon but an enthusiastic public health educator, as well as a talented author and artist. He drew, painted and made sculptures of the sometimes remarkable things he saw on his travels. Many of his works were published and some are preserved in the Library of Congress in Washington DC. His big claim to fame, though, is that he was the first surgeon to introduce many of the standard gynaecological practices which are nowadays routine, such as tying off the umbilical cord of newborn babies before severing the cord after childbirth. He was also one of the first medical researchers to obtain detailed sexual histories of his patients, often using his artistic talents to make accurate drawings of many of his patients' genitalia. In his lifetime he recorded some 5200 individual case histories, so he was clearly the top expert on genital size and shape variation for his day. His measurement of the largest known human penis was taken around 1900 (owner unknown), so we can rest assured it did not involve any surgical augmentation such as might occur today.
Humans, in fact, hold the record for penis size amongst our anthropoid cousins, the great apes. The male gorilla has an erect penis size of only 1.5 inches (4 centimeters) and an orang-utan is only slightly larger, but the chimpanzee's tackle is about twice that size. To be 'hung like a gorilla' would be considered a grave insult indeed in some parts of Africa.
Early research on ape genitals revealed remarkable variation in their testicle size and sperm counts. Not surprisingly this relates to their frequency of copulation and thus also relates directly to their social hierarchies. Professor Roger Short from Melbourne University in Australia published pioneering work in this field back in 1977, showing that although a chimpanzee is one quarter the weight of a gorilla, its testes are four times heavier. Female chimps often mate with more than one male during their oestrus (time of peak fertility) whereas gorillas do not, so the chimps have a premium on larger sperm production to ensure mating success. Such seminal observations form a fundamental rule of nature and have since been observed in birds and other mammals, as we will discuss later in the book.
So back to our well-hung little Latino duck. Why would a duck, of all creatures, need to have evolved the longest male genital organ of any backboned creature? The scientist who announced the extended size of the Argentine duck's penis in 2001, Dr Kevin McCracken, did so mainly because the previously longest Argentine duck penis ever measured was only around 8 inches (20 centimeters), so finding another that was almost 7 inches (17.7 centimeters) longer when gravity extended it downwards was indeed an unexpected surprise. The authors of the paper speculated that perhaps it is somewhat like the peacock's tail, whereby males might try to impress females with their elaborate plumage allowing females to assess the better mates. In a similar way, the female Argentine duck might select males with larger penises as part of a display of mating prowess. The sexual selection process identified by Charles Darwin might have driven the males to extreme lengths, so to speak.
Very little is actually known about Argentine duck sex. Can the males put it all the way in without harming the female? Probably not, even though these ducks are reported to be boisterous and promiscuous. The shaft of the Argentine duck penis is in fact covered with spines while only the tip is soft and brush-like. This tip may serve another function, perhaps working with the spines like a bottlebrush to scrape out sperm from a previous male, thus ensuring the mating male with the most appropriately bottlebrush-shaped penis wins the evolutionary competition to inseminate the female and pass on his genes.
All of sexual selection can be summarized simply by the notion of quantity versus quality. The males, having virtually unlimited quantities of sperm, want to inseminate as many females as possible to spread their genes far and wide, whereas the females, with a limited number of eggs in many cases, just want the best quality sperm they can get.
Unlike the external mammalian penis sported by Homo sapiens, the duck penis is formed from an extrusion of soft tissue from the inside of its bottom, which comes out when aroused through a combined anal and genital opening called the cloaca (from Latin, meaning 'sewer'). The penis is made erect through filling with lymph fluid rather than blood, which is the usual way to engorge a mammalian penis. Duck penises have another interesting ability: they can literally explode out of the duck's body.
In 2009 Patricia Brennan and colleagues Chris Clark and Richard Prum, all from Yale University, published a paper in a prestigious scientific journal exploring this explosive discovery. Their research concerned the male Muscovy duck (Cairina moschata), commonly bred at duck farms for their tasty meat, and the speed of their penis eversion (the coming out or unraveling of the enormous corkscrew-shaped penis). The first step was to study how professional 'duck fluffers' collect semen for artificial insemination. The drakes are aroused by introducing a female duck during the breeding season, and as the male mounts the female his cloacal region begins to swell indicating his readiness to copulate. The duck fluffer then whips the drake off the female and quickly touches the aroused male cloaca whilst holding up a specially made corkscrew-shaped glass jar to catch the penis exploding out of its body and ejaculating as it fully extends. In the lab the researchers measured this phenomenon and found that the entire 8-inch (20-centimeter) duck penis would extend from inside the cloaca to outside and fully erect in just 0.348 seconds. (Next time you are barreling down the highway at 75 miles per hour, just think you are going as fast as a Muscovy duck can erect his penis.)
The Muscovy duck experiment highlights one of the fundamental differences between mammal and bird penises and begs the question: did the mammalian penis evolve separately from that of ducks and other animals? Most zoologists today would argue that it did. More importantly, it also raises the questions of when, where and why the practice of mating by copulation first evolved? If you think about it, the idea that a male of some primitive archaic creature one day decided to put a part of his anatomy inside a rather delicate region of the female, then decided it felt funky enough to ejaculate his sperm, is pretty odd. The evolution of intimate sex through copulation thus poses a lot of interesting scientific questions both behavioral and physiological, and also from the point of view of evolutionary success.
In order to explore these questions we have two main sources of information. Firstly, we have observations from the living world of animals about how and why they mate, and about their relative levels of success, or 'fitness', as biologists like to call that success. Secondly, we have the fossil record of the past life of the planet, which usually tells its stories through scientific interpretation of ancient bones, plants and impressions – graphically, for example, in the two fossilized sharks from Montana dated at around 330 million years old, showing the female biting the large overhanging head spine of the male in readiness for mating.
Had anyone proposed to me ten years ago that I would become an expert on the origins of intimate sex, my reaction would have been one of laughter and denial. Yet my team of colleagues and I have now published a series of papers attesting to the extraordinary discoveries we have made over the past 25 years. These discoveries have revealed not just the origins of sexual intimacy by copulation in our distant ancestors but also the intricate structure of the world's first male vertebrate copulatory organs. The implications of these discoveries in understanding our own evolution are indeed significant, but the most intriguing part of the work is showing in particular how the male sexual organ has evolved through the ages, as revealed through a series of quite unusual fossil finds.
To explain this story we've had to do some truly strange things, like direct the world's first paleo-porn movie and give lucid talks about copulation to museum board members.
The first discovery in this complicated series of finds goes back to 1983 when I was still a paleontology student working on my doctorate at Monash University in Melbourne. I had become fascinated by the ancient armor-plated behemoths called 'placoderms', meaning 'plated skin' and named after the thick bony plates that covered their head and trunk regions. At the time on hand at the university I had some excellent fossil specimens of whole fishes, many represented by parts never before shown in the group of placoderms called 'phyllolepids' – meaning 'leaf scale', as their skin plates were thin and broad, indicating they were a rather flattened fish something like an armored sole. Anatomical features such as jaw parts and the tail region were able to be studied for the first time in this enigmatic group. The material represented a new genus which I named Austrophyllolepis. Prior to that discovery only one genus of the group had been known, Phyllolepis, and it was mainly represented by northern hemisphere sites, in particular from Scotland, East Greenland, North America, Russia and Europe. Thus the name I chose for the new group, Austrophyllolepis, meaning southern Phyllopis.
Although I suspected at the time that parts of the Austrophyllolepis pelvic fin I was studying could relate to reproduction, I lacked the statistical proof to take it any further (having only a few good specimens). Then, in August 1986, I led an expedition to the now famous Gogo fossil sites in the north of Western Australia, and the first big discoveries that would impact on the origin of vertebrate reproduction were made.
In those days, as an eager 29-year-old just a few years out of university, I was keen to prove myself in the cut-throat world of paleontology. Usually one does that by mounting a major expedition to some remote and often dangerous part of the world in the hope of finding something clearly big and important, along the lines of Howard Carter finding Tutankhamen's tomb or Arthur Evans' discovery of the Minoan civilization on Crete. But when my big chance at fossil renown came along on that at times ill-fated expedition, I would not fully know the secret of one of my discoveries for at least another 20 years.
Gogo Station is near the small inland town of Fitzroy Crossing in the Kimberley region, about four days drive north of Perth. The typical grassy paddocks are surrounded by spectacular jagged limestone ranges, adorned with bottle-shaped boab trees and scraggly bohemias. Now a vast cattle station nearly 60 miles (100 kilometers) across, it was here, 380 million years ago, that myriad bizarre life forms once teemed through an equatorial algal reef. There were masses of primeval fishes, corals, sponges and shells, ancient coiled squid-like animals called goniatites, and schools of bizarre shrimp with peculiar bivalved carapaces – as opposed to today's shrimp which have a series of segments like onion rings. Today the well-preserved remains mainly of fishes and crustaceans at Gogo are encased in rounded limestone concretions (or nodules) littering the valley floors.
The first scientific expeditions to this site were run jointly by the Natural History Museum of London, the Western Australian Museum and Hunterian Museum of Glasgow in 1963 and 1967, then the Australian Museum and the Bureau of Mineral Resources briefly explored there again in the early 1970s.
It took me and my team of volunteers almost a whole week on that first expedition in 1986 before we even started finding anything worth collecting. About one in a thousand nodules contain a fossil fish, and once split open they need to be glued together again for examination back in the laboratory. Our approach was to hit the nodules with a small sledge hammer to see if any fossils were inside them, but soon enough we found that most nodules were barren. Scientists can suffer the same highs and lows of emotion as any self-doubting artist or writer, and at one stage dismal thoughts ran through my brain that the whole trip would be a complete failure because earlier expeditions to the site had cleaned up all the good fossils. Add to that the numerous breakdowns of my hastily purchased off-road vehicle, the two occasions when we were stranded without radio contact, and the time two of us had to walk 10 miles (15 kilometers) through the desert to reach the highway and then get a lift into town for mechanical assistance (I recall we were followed by a starving dingo, who probably thought we would ultimately provide him with some nourishment, at least), and for a while there it wasn't looking good.
After a week or so of hard, back-breaking work in the hot Kimberley sun, however, we eventually stumbled upon areas of Gogo nodules that hadn't been searched thoroughly in the earlier trips. I recall the great excitement of those early days when we began to find superb new specimens and each day added unusual and potentially new species to our haul. By the end of the trip we had bagged a great number of good specimens that included more than a 150 fish and many crustaceans, but most importantly the Gogo fossil fishes we found were very special due to their unique preservation. Most fossil fishes this old (around 380 million years) are two dimensional, crushed flat between sheets of shale. But the Gogo fish skeletons were enclosed in their three-dimensional entirety within the limestone concretion, which would allow us to 'prepare' the bones out of the rock with a weak acid solution. This method slowly and gently dissolves the limestone away, leaving the delicate bones poking out in perfect form, just as the remains of your Friday night snapper dinner might sit on a plate after you've eaten the flesh. As the bones are exposed they are hardened with plastic-based glue and then re-immersed in the acid bath until all the rock is gone and just the bones are left. Then the bony parts are reassembled to make a perfect 3-D skeleton. In some cases, we have the whole fish skeleton embedded within two slabs of acrylic or epoxy resin which, when the rock covering the fish is dissolved away, reveals the delicate bones poking out from an articulated skeleton.
Excerpted from THE DAWN OF THE DEED by JOHN A. LONG Copyright © 2012 by The University of Chicago. Excerpted by permission of The University of Chicago Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Meet the Author
John A. Long is vice president of research and collections at the Natural History Museum of Los Angeles County. His other books include, most recently, Frozen in Time: Prehistoric Life of Antarctica and The Rise of Fishes.
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If you're curious about the origins of sex & the "apparatus" thereof-this is a must read! the style of writing is intelligent & humorous(yes,a paleontology book thats definitly NOT dry & dusty as many others on this subject)garanteed to have you hooked till the very last chapter.kudos to Mr. Long for showing how from ancient armored fish(placoderms) might have done "it" up to our closest releatives-the randy chimpanzees-this is the sexyist fossil book of the year!!