Given the popularity of current lifestyles involving swapping and polyamory, and the amount of cheating on one's significant other that is supposedly going on, many commentators on the sexual scene have come to wonder whether monogamy has had its day. There have been books like "Monogamy" by Adam Phillips and "The Myth of Monogamy" by David Barash and Judith Lipton, as well as a number of discussions of monogamy on websites such as "Pandalous." Last, and definitely least, is "Sex at Dawn" by Christopher Ryan and Calcilda Jetha. Whoever are the writers or writer of "Sex At Dusk," the book is a masterful rebuttal of "Sex at Dawn." You would never know this from some of the hit and run reviewers on Amazon, who claim it is either a conservative screed or the work of someone sexually uptight. It is neither, and my guess is that some of these reviewers got bogged down at the beginning of "Sex at Dusk" or just do not want to know the facts of life. It is true that the writing in "Sex at Dusk" is sometimes clumsy, especially in the early going, while Ryan and Jetha's book is stylistically very good. But smooth words are not necessarily true words.There have been a number of trenchant positive reviews of this book in "Psychology Today" and "The Chronicle of Higher Education" as well as on Amazon. But there is more of value that can be said. It may seem at first that "Sex at Dusk" is merely a paragraph by paragraph refutation of "Sex at Dawn." But it is really a very educational book about how genetic evolution works (something Ryan and Jeptha do not seem to understand), and especially how it has worked in the development of modern humans.The thesis of "Sex at Dawn" is that monogamy has never been the natural way of life for human beings, whether prehistorical or modern. Rather it came into being with the advent of agriculture (and property) about 10,000 years ago. Before that time, our forager ancestors lived in small groups which passed their time in a sexual free-for-all where no one cared who fathered whom (and who was related to whom - a recipe for incest) and children were raised by the group. In this regard humans were like bonobos, the great apes Ryan an Jetha claim to be the closest to us, at least in their sexual practices. Their view is that both male and female humans are sluts. In other words, both males and females have basically the same attitude toward sex; they want as much as possible with as many people as possible. If this sounds silly, it is. They seem to successfully plead their case by cherry picking quotations from biologists and anthropologists (they are neither). "Sex at Dusk" gives you the rest of what these biologists and anthropologists have to say, and the end result is a complete refutation of "Sex at Dawn." It becomes obvious after awhile that Ryan an Jetha misrepresent the views of practically everyone they quote. This is what happens when you have an agenda and do not let anything get in the way of it.We should not be fooled by the state of sexuality in the Western world today. Widespread recreational sex (sex engaged in purely for pleasure) is a rather recent innovation in the world. Well-placed men may have engaged in it in the past, but it is not clear women did until recently. What changed? The advent of the condom in the first half of the twentieth century and the pill in the second half. However, I believe that men will always be more interested in recreational sex than women. The reason, as made clear in "Sex at Dusk," is that only men are sluts. To put it less crudely, men are simple creatures when it comes to having sex, but women often have ulterior motives for having sex. The main reason for this difference is that men and women are physically different when it comes to their contributions in producing children. Men have a lot of sperm and like to spread it around. Women have few eggs and need to make the most of them, or their genes will not be passed down. And since women, at least until recently, were much more indispensable than men for raising children, it was important for them to have men to help out in both protection and obtaining food. Pair bonding with a suitable male was a great boon in this regard. Men will care for children they believe are their own, so they are naturally concerned with paternity. "Sex at Dusk" makes it very clear that that all great ape males are concerned with paternity. And humans did not wait until the development of agriculture to start pair-bonding. The forager communities that Ryan and Jetha mis-describe are no different in this respect. The idea that early human communities raised children in common has no basis in fact, at least if forager communities are the model. As for the great apes, males will sometimes kill the children of females they mate with if they do not think these children are their own. And higher ranking females will sometimes take children away from lower ranking ones and then let them starve.While Ryan and Jetha would like you to believe that early human communities were sexual paradises, and many modern forager communities as well, the truth is exactly the opposite, According to the researchers cited in "Sex at Dusk," sex in forager societies is generally "nasty, brutish, and short" to adapt Thomas Hobbes' famous description of humans in a state of nature. This is especially true of sex for women, but in some cases even for men. In the case of women, sex is often traded for food, especially meat. It may sound a little odd, but after reading about all the forager communities mentioned in "Sex at Dusk" one can only conclude that for most of them sex is a serious business. Does this mean that they never enjoy it? Obviously not. But sex had consequences and those consequences were necessary for the future existence of a community in conditions where the majority of children died young. Furthermore, sex had special consequences for women who got pregnant and would need help surviving to term and being able to raise their children successfully. We live at a time, at least in developed nations, when most sex does not have consequences, unless it is to spread STDs, the latter being another argument for monogamy. Actually, the lack of the usual consequences is slowly eating away at the population of many industrialized nations today.A particularly humorous claim of Ryan and Jetha is that the noises some females make during sex are an attempt to advertise their readiness for other males. The section of "Sex at Dusk" which deals with this is a complete take down. While it is true that chimp and bonobo females sometimes make noises during sex, it turns out that these noises are directly correlated with the rank of the male in the troop, and in some cases with whether any high ranking females are around. As to humans, in most of the forager societies that have been described, sex is generally carried out in a secretive way, and noise is discouraged. Ryan and Jetha have a very peculiar view of humans. Maybe they think we are a like tigers. The female tiger will roar out in the jungle when she is in heat in order to attract males. What else can the female tiger do? Tigers live solitary lives and this is the only way they can get together to reproduce. On a more serious note, a university study has found that most of the "moaning" of women during sex is done to speed up their partner's climax and especially to boost his self esteem - and not to attract other males.Given the different sexual imperatives of men and women it would be surprising if men and women wanted the same things out of sex. And we have to remember that these imperatives are built into our genes. Men would like to have as much sex with as many people as possible. According to "Sex at Dusk" it appears that the authors of "Sex at Dawn" have the hidden purpose of convincing women to want just what men want. This is an age of equality between the sexes, but why should women want to ape men?Pair-bonding, or what we usually call monogamy in humans, is as old as humanity. (And there are great apes that have a version of it.) The fact that people in relationships sometimes stray does not prove that monogamy is outmoded or a kind of straightjacket. It is actually a very successful way of dealing with the world, and thus even those who are attracted to many people have good reasons for confining their sex acts to a particular person. Besides being a dishonestly written book, "Sex at Dawn" embodies the worst side of modernism, which latter seems intent on the social atomization of people and the depersonalizing of their activities, even such intimate activities as sex. As such its preaching is dangerous to the fabric of society and to the quality of human life. On the other hand, "Sex at Dusk" has no message or agenda. It gives you all the facts and lets you judge these matters for yourself. Anyone reading it will learn a lot about humans and those animals most closely related to humans. It is truly an educational experience, and I might add that it corrected some misconceptions I had. It may well do the same for you.