Promiscuity: An Evolutionary History of Sperm Competition

by Tim Birkhead

Males are promiscuous and ferociously competitive. Females--both human and of other species--are naturally monogamous. That at least is what the study of sexual behavior after Darwin assumed, perhaps because it was written by men. Only in recent years has this version of events been challenged. Females, it has become clear, are remarkably promiscuous and have evolved an astonishing array of strategies, employed both before and after copulation, to determine exactly who will father their offspring. Tim Birkhead reveals a wonderful world in which males and females vie with each other as they strive to maximize their reproductive success. Both sexes have evolved staggeringly sophisticated ways to get what they want--often at the expense of the other. He introduces us to fish whose first encounter locks them together for life in a perpetual sexual embrace; hermaphrodites who "joust" with their reproductive organs, each trying to inseminate the other without being inseminated; and tiny flies whose seminal fluid is so toxic that it not only destroys the sperm of rival males but eventually kills the female. He explores the long and tortuous road leading to our current state of knowledge, from Aristotle's observations on chickens, to the first successful artificial insemination in the seventeenth century, to today's ingenious molecular markers for assigning paternity. And he shows how much human behavior--from the wife-sharing habits of Inuit hunters to Charlie Chaplin's paternity case--is influenced by sperm competition. Lucidly written and lavishly illustrated, with a wealth of fascinating detail and vivid examples, Promiscuity is the ultimate guide to the battle of the sexes.

Genres: Science, Biology, Nonfiction, Evolution, Nature, Psychology, Sexuality

292 pages, Paperback

First published May 2, 2000

About the author

Tim Birkhead is an award-winning author and one of the world’s leading bird biologists. He is the coauthor of Ten Thousand Birds: Ornithology since Darwin (Princeton) and the author of The Wonderful Mr. Willughby: The First True Ornithologist, The Most Perfect Thing: The Inside (and Outside) of a Bird’s Egg, and Bird Sense: What It’s Like to Be a Bird, among other books. He is a Fellow of the Royal Society and professor emeritus of zoology at the University of Sheffield.

Reviews

[Yennifer · Rating 4 out of 5]

For people who enjoyed the BBC's Planet Earth and other animal-focused documentaries, this book is for you. I learned surprising and fascinating pieces of information about animals and their mating patterns – including sperm competition.

I did, however, take issues with a few concepts and passages in the book. The author, Tim Birkhead, seemed to dislike feminist based on his word choice when mentioning them in Promiscuity.

The first time in which he mentions feminists is in chapter 1.

Female academics interested in sexual selection on opposite sides of the Atlantic differed in their approach to the gender bias in behavioural ecology. Without doubt, the most radical feminists were (and still are) North Americans. By contrast, those in Europe adopted a much more subtle, and ultimately probably a more persuasive, strategy in their efforts to change the way (male) biologists thought about reproduction. Moreover, it is important to recognize that amending the gender bias has not ben an entirely female perogative; several male behaviour ecologists have actively promoted the female perspective. It is unfortunate, therefore, that these include several who continue to be, until recently at least, targets of North American feminist criticism. (Birkhead, 20)

This statement, while seeming to protect male biologists and ecologists, makes some broad (and frankly irksome) generalizations. Merely because certain feminists in North American are considered here as “radical” or criticize those who, according to Birkhead, do not deserve this treatment, does not mean every feminist interested in this topic should be labeled as an extremist. However, I have not read articles by these women, and so that is merely a guess. Upon first reading, I decided that perhaps I had misinterpreted his word choice here, and read on.

Unfortunately, the issue with feminists was again brought into focus in chapter 7.

Almost from the beginning, feminists interested in sexual selection ranted and gnashed their teeth in frustration at its androcentric bias, but until recently to no avail. (Birkhead, 195)

Birkhead describes them as “ranting”. This does not portray feminists as have an eloquent or articulate disposition at all. According to the author, feminists are also prone to “gnashing” their teeth. This imagery seems to reflect a kind of ineloquent, animalistic people.

According to Birkhead, female researchers have been attempting to “force” men to see things through their lens. The use of the word “force” is, inherently, aggressive, and does not give a peaceable visage to feminists, nor to female biologists.

There has undoubtedly been a battle between female and male researchers to force biologists to consider the female perspective, and many with an interest in feminism may feel that, while they may not have won, there has been considerable progress.

If the person reading this book is a feminist, they might notice that in chapter 7, Birkhead lists reasons as to why a human woman might have extra-pair sex.

There are two broad possibilities. Females may trade sex for resources: money, food, a house, parental care or fertility. Alternatively, or in addition, females may engage in extra-pair copulations in order to improve the genetic quality of their offspring. (Birkhead, 199)

Nowhere in this passage does Birkhead consider that females (women) may have sex merely because they enjoy it. However, I would concede to his omission of this piece of information had he not later mentioned males (men) having sex for their own enjoyment.

First, in humans it is usually males that seek out females. Second, males use prostitutes for sexual gratification, not to increase their chances of paternity.

While I do not pretend to have the knowledge to contest these facts, I would be curious to see which studies Birkhead referred to to determine that it is mostly men that “seek out” women.

The most prominent issue with the text is at the end of chapter 7, when Birkhead uses the mating systems of various species of animals to study human beings. While I find animals to be revealing about certain behaviours in people, I believe this kind of comparison should be done lightly. The risk here is seeming racist or insulting a people.

The passage in question concerns the Inuit people. Birkhead talks about pairs of couples exchanging partners, and creating more family ties through their offspring.

But, if having additional family was so crucial, why didn't the Inuit exchange their spouses more widely? What was so special about reciprocating pairs of couples? The answer to this question has come not from the study of people but from research on the co-operative polyandrous mating system in birds. (Birkhead, 218)

I find the particular lead-in to at the end of that passage to be deplorable. To devalue cultural norms based on marriages and relationships to the mating patterns of birds? I don't feel as diplomatic towards this use of language as I do to the previous issues. I believe that perhaps these Inuit customs are a bit more complex, and would require actual discussion between an interviewer and an Inuit person to be understood—not through unrelated animals.

[Kathleen · Rating 3 out of 5]

A friend gave me this book as a joke when I graduated from WSU with my bachelor's in zoology. It actually turned out to be a good book. The author certainly makes potentially dry material interesting and often very funny. This book reviews the history of sexual selection and the understandings of fertilization and sperm competition in a way that actually keeps a person interested. If you are planning on reading this book, the only warning I have is that it is a bit deep in some areas, so it takes a while to read. Very good book for the science minded.

[Rebecca · Rating 3 out of 5]

I read this in college and it was a bit too in depth at times and I felt like I was studying for a genetics test or something. It was interesting, though.

[Noelle Al-musaifry · Rating 4 out of 5]

This book is hilarious and informative. The pictures are fascinating and disgusting. If you care about evolution, population biology, or sex-linked traits, you should read this book.

[Samy Rose · Rating 5 out of 5]

It really is a science book. Heavy duty reading. Fascinating but if I leave it for very long, I forget the stuff and start over. I may never finish it. But it's great. Heavy, though.

[Shashank · Rating 5 out of 5]

Wonderful account of never ending sexual tales of various animals.. I understand now that it's ok for female animals to copulate with several males as it, in most cases, enhances their reproductive strategy or offsprings.

[Makomai · Rating 3 out of 5]

"Ancora da studente, a Bristol, Parker era stato incoraggiato a studiare il comportamento del tafano giallo dall’importante entomologo Howard Hinton. Com’era fatto comune per gli studenti migliori di quei tempi cosi’ eccitanti, Parker venne convinto a proseguire il proprio lavoro per la laurea, sempre sotto la supervisione di Hinton. Una volta trascorso un anno di studio ateleologico, Parker si rese conto che se avesse voluto ottenere un qualsiasi risultato significativo avrebbe dovuto porre delle domande specifiche. Dopo aver passato diversi mesi con il naso a pochi centimetri da piccole zolle di sterco di vacca, osservando l’intensa competizione tra i maschi di tafano per le femmine, Parker penso’ che il problema verso cui si sarebbe dovuto rivolgere era la selezione sessuale, e specificamente la competizione tra maschi. Lo scenario era questo: una femmina di tafano arriva al mucchietto di sterco pronta per copulare ed e’ poi quasi immediatamente in grado di rilasciare le proprie uova sulla superficie dell’escremento. Non deve attendere a lungo: non appena arrivata, subito viene acchiappata da un maschio che istantaneamente copula con lei. Prima che lui abbia finito, un maschio piu’ grosso afferra i due, allontana il primo maschio dalla femmina, se ne libera e copula a sua volta. La faccenda si ripete incessantemente sotto gli occhi di Parker, ora dopo ora, giorno dopo giorno, su ogni mucchietto di sterco fresco."

Questa e’ la scienza: piena di merda, ripetitiva e soprattutto indeterminata tanto sul risultato (anche incertum an) quanto sulla direzione.

Questi sono i veri eroi.

[Bastian Greshake Tzovaras · Rating 5 out of 5]

As far as I can tell that's a pretty good summary on sperm competition, even if it's over 10 years old and thus lacks the findings done since then (e.g. polyandry in humans is more frequent than stated in the book). But if you want a general introduction that isn't exactly the usual textbook format you'll have fun with it.

I really enjoyed Birkhead's puns and how he played with language to create an interesting reading. He also gives tons of references to primary research literature, so if you want to dive into the specifics of a sub-topic you can easily do so.

The only thing that bugged me: For many examples only the generic species names (or even only of groups) are given, so there's no easy way to figure out which species show the described traits.

[Val Cuellar · Rating 5 out of 5]

Excelente libro para interesados en la biología, genética y epigenética de diferentes especies de animales, el lenguaje llega a ser un poco tedioso pero la mayoría está escrito como un libro de divulgación.

[Zack · Rating 4 out of 5]

Interesting if this is what you're into. Animals, not humans though.