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Promiscuity: An Evolutionary History of Sperm Competition

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"Promiscuity" is about sex. Well, I suppose that much is obvious. And sex always makes for great reading. We are all obsessed and entertained by it. Still, this book took me by surprise. It is not your typical book about sex: offering cheap thrills or mundane, overdigested sociopsychological chatter. It is a unique guided tour of the bizarre world of reproduction throughout the animal kingdom. It is also a glimpse into the odd world of evolutionary biologists, in this case those who spend their lives contemplating the meaning behind all of the bizarre variations on sex in the animal world. Apparently, these highly respected academic scholars go to work each day to figure out such things as why some fruitflies make sperm that are 20 times longer than their bodies and why others produce seminal fluids that are toxic to their mates, why some marine flatworms have dozens of penises, why certain slugs have a penis that is longer than their body and that occassionally become so horrifically tangled about their mate that they must be chewed off, why dunglfies sometimes drown their mates in wet dung, why females of one species of catfish fertilize their eggs by drinking sperm, and why deep-sea anglerfish males bite their mates and never let go. The list goes on and on, preparing me with remarkable ammunition for the next dinner party.

Yet this stranger-than-fiction book is not merely a collection of Ripley's sex tales. It is a well-organized treatise of cutting edge science that masterfully instructs the reader as to the common evolutionary threads that define the underlying nature of sex. The reader is left, for example, with an abundant understanding of why sex between men and women is more about conflict than cooperation, which personally clarified much in my life. The first paragraph of the book reads in part, "Status for the Mediterranean male is all-important, and tradition dictates that a man who fails during a hunting expedition can expect his wife to be unfaithful. In parts of Italy it is widely believed that a man must shoot a honey buzzard each year if his wife is to remain faithful. So strong is this belief, and so powerful a motivating force is the idea of female fidelity, that even after they have emigrated to the United States many Italian men return home each year to shoot a honey buzzard. It is not a little ironic that in order to fulfil this ritual a man usually leaves his wife behind. Moreover, in some instances it is the wife who actually encourages him to go!" The remainder of the pages are as engaging as this first one. I recommend this book to anyone that ever has had or ever hopes to have sex.

If you want to be grossed out, amused and steeped in leading scholarship all at the same time, this may be your book. In a fun, concise and well structured book, Birkhead gives us an up-to-date account of sperm competition in animals. The examples used are wide-ranging, from bed bugs to people, and never fail to raise an eyebrow. A Doay sheep female copulated 163 times in five hours and a man eating sushi once learned that the wiggly things in his tongue owed their thanks to a squid spermatophore. Beyond these exemplars of bizarre, though, this book contains cogent arguments for the place of sperm competition. It kindly sandbags the sensational claims of Baker and Bellis (in their Human Sperm Competition), giving us a fairer treatment in its place, both with respect to humans (where sperm competition has been of relatively little recent importance, evidenced by the relatively small testes and poor sperm quality of males) and numerous other taxa. The section on female benefits to multi-male mating is also worth noting. Evidence is amassed for female benefits in obtaining sufficient sperm, resources and improving the genetic quality of their offspring (e.g. through pairing her genes with a good MHC complement). These last ideas on genetic benefits will continue to inspire new research, just as other ideas in the book should too (accessory glands such as the prostate may have originated in the evolutionary battle of the sexes). It could be stated that the book overstates the case for sexual conflict, when benign agreements have been reached; after all, it wouldn't pay over evolutionary time for the faithful California mouse or swan to employ cruel mechanisms at expense to a partner. Yet this book is worth the strange questions and looks you'll get on the bus when people see its cover and look over your should while reading it (just as happened to my yesterday).

This is a very interesting book on evolution (actually it is one of my favorites). In spite of the seriousness of the subject, this book also provides large quantities of amusing data which can even be used on a relaxed pub conversation. If you ever thought about the significance of sexual behavior in nature, the advantages of each type of behavior (monogamy x polygamy) and some other not-so-common issues (i.e. sperm shape and size, testicle size, ejaculatory volume etc) this is the book for you. I had a lot of fun reading it and even a few laughs.

This is an important and valuable book for anyone interested in evolutionary biology. It exposes the competition not only between males but between males and females for control over reproduction, particularly after coitus occurs. Securing a reproductive opportunity is not the prize. The prize is fertilizing the egg, and many species have evolves ways of controlling when and by whom that happens.

Birkhead is a careful scientist with competent writing skills. His review, including some of his own research, illustrates once again themes found pretty much in all evolutionary areas, including some bizarre adaptations which should delight those interested in biological curiosities. Still, I am skeptical that the casual reader is really going to enjoy this book.

Survival in the face of disease has long been identified as the likely driver for the origin of sex. There is evidence it plays a role in sexual selection, so that, for example, the length of a swallow's tail seems to correlate with resistance to pathogens. More interesting, is that a female may actually be able to choose sexual partners on the basis of whose genotype will be most different from her own, increasing the odds that the diversity of her offspring will permit some survival in the face of new mutations of viral and bacterial attackers or parasites. Sperm selection can not only occur via choice of mate, but when there are multiple inseminators, by selection of sperm (more research needs to be done to confirm this). Supporting studies have been done on mice as well as fruit flies.

We may take for granted that there is a "large" egg, and a small, mobile sperm, but Birkhead provides theoretical reasons why sex would evolve this way, as contrasted to two equal size gametes fusing.

i hesitate to write a review of this book because it might appear 'pervy' just to comment ;) but in all fairness, this book is worth reading for anyone interested in science, biology, sex, or ourselves :) ..anyone who enjoys this book would also probably enjoy the weekly publication: NewScientist :)

If you ever wondered about such glorious subjects as...okay, it's a book about sex, but the scholarly parts of sex normally only pondered by zoologists, not the boxing ring style blow-by-blow accounts you might read in novels. I'll tell you, my fellow Amazonians, if ever you want to feel stupid in what you thought you knew about the wonderful world of sex, read-this-book. And if ever you want to be amazed to death about the wonderful world of sex, read-this-book. And if you never EVER want to eat sushi again, read-this-book!

Did you know there are many species out there that have multiple schmeckles? No, it's true! A schmeckle here, a schmeckle there, a schmeckle everywhere! And did you know that some species die during copulation? And here I always thought nuns were just trying to scare us about that! Or that threesomes, foursome, heck hundredsomes are perfectly natural among many members of the phylum Chordata? Of which we and 97% of all life-forms are a part, folks! And how about the fact that in nature when studied in its entirety it is more common for males to raise the offspring than it is females? Okay, I don't think this book said that, but it's the sort of fact it would have had if it had included it. (Did you follow that?)

Seriously, ladies and non-ladies, this book is great! It studies reproduction as carried out by virtually every species known to exist. It elevates the mind to consider sex as evolution's largest tool, and it has a vigorous full tilt go at sex as a scholarly topic rather than the fodder for humor or arousal it often is. (None of you are turned on or laughing, are you? I should hope not!) Overall Promiscuity: An Evolutionary History of Sperm Competition does for biology what Schoolhouse Rock did for mathematics and other really, really dull stuff. I mean it makes an otherwise universally boring subject like sex fun!