Why is Sex Fun?: The Evolution of Human Sexuality (Science Masters) (Paperback)

Diamond's theme is that human sexuality is not just different from that of the other animals, but almost drastically so. Reproductive strategies range from 'r' [sow 'em and forget 'em] through 'K' [no sacrifice is too great] with humans almost the ultimate K practitioners. Evolutionary pressures on a creature that wasn't a good predator but fine prey led us down a path resulting in a massive investment in raising offspring.

What are the implications of our version of sexual techniques? Human beings have evolved in a way that natural sexual signals have been buried out of sight. It's called concealed ovulation and methods of pinpointing when a woman was likely to conceive weren't developed until this century. Fish, birds, and other mammals [particularly baboons] exhibit colours, engage in ceremonial displays or have other visible indications that the time is right! But humans keep it a big secret. Is there a valid reason?

And when a sexual coupling has generated a foetus, we put more time, energy and resources to its birthing and upbringing than nearly any other animal. Almost from the instant of conception the foetus and the mother are at war over resource allocation. Mum and babe each want the calcium, iron and other factors required by the one for survival and the other for growth. All this is pretty draining on Mum, who still has a life to lead while carrying that powerful parasite in her womb.

And where's Hubby during all this? That is a major part of Diamond's account of human sex relations. Males invest minimal resources in producing offspring and in most mammal species, decamp after coupling. Human males, however, form part of the renowned 'nuclear family'. In the chapter "What Are Men Good For?" Diamond shows how and why human males are bonded to mates in a way few other species exhibit. One major aspect of this bond, of course, is the nearly constant availability of a sexual partner [NOT 'object']. From that derives that since human women can conceal their ovulation so well, he'd better stick around to ensure any other offspring are indeed his. Since she is receptive all the time and can conceive at some indeterminate time, he'd better be there at the right time. That this situation doesn't always keep males in line is exemplified by the study showing that up to 20 per cent of British babies were conceived by someone other than the purportive parent.

Diamond goes to some effort to make human males more captive to their familial role than they might wish. As stated, the minimal expenditure of some sperm to occupy a mate for a year or so isn't always enough to foster a strong sense of responsibility in men. However, Diamond's proposed solution is one of the most astonishing ideas submitted by anyone yet. He suggests that hormonal treatments for men, inducing lactation and giving men the chance to learn the meaning of nurturing. How much more 'politically correct' can one be? One hopes this chapter was written because of Marie adopting a Lysistratian role, witholding favours until Diamond acceded to her demand for its inclusion. That, or some life- threatening gesture are the only acceptable reasons for a man of Diamond's qualifications trying to reverse the whole course of evolution and make humans even more unique among the animals than they already are. There are enough feminists out there trying to reverse the status evolution has given us. Diamond's suggestion nearly invalidates an otherwise captivating and informative book. [stephen a. haines - Ottawa, Canada]

Why does Professor Diamond repeatedly characterise the reader as a unimaginative dolt? Each question in the book is introduced like this:
1. The author makes an observation about human sexuality
2. He imagines the book's reader giving an simple-minded reply.
3. The Professor explains why the question is more complex than you, the reader, had thought.
4. Now, the answer.

After a while this device started to wear on me. Why does he assume that people who read his books are unable to think for themselves? Does he really believe that all (most?) of his readers will have the same knee-jerk reaction to the questions he poses? The worst example is the question of concealed ovulation; the text asks why this would evolve when it leads to inefficiently permanent receptivity. In answer to this question the author has the reader exclaim "Obviously because it's fun!" after which he takes a whole page to explain why "having fun" isn't a valid evolutionary explaination. Excuse me, Professor Diamond, I'm reading a book entitled "Why is sex fun?" and seventy pages in you don't credit me the intelligence of wanting an answer.

I'm certain that ignorant objections really were made while the Professor was preparing his manuscript, but it would have been nice if he could have found a way to address them without talking down to the readership. (Maybe a dialogue with a comedy simpleton in a dunce's cap?)

This book tries to trace the evolutionary causes of modern biology and behaviour. Some scientists believe that this is more like a "Just So" story than a scientific reconstruction (because there's no direct evidence for the process - just an outcome). Personally, I think that the most plausible "Just So" story has a valid place in the science masters series, but you might not.