Australian evolutionary biologist Rob Brooks’s book Sex, Genes & Rock ‘n’ Roll: How evolution has shaped the modern world has been released. It’s a good read - accessible and amusing. The books ranges between more serious issues such as obesity, population control and infanticide to the more light-hearted, the exploration of rock ‘n’ roll that the book title foreshadows. It is a book I’ll be adding to my list of recommendations for those who ask why evolution is relevant today.

I think it is fair to describe Brooks as an optimist when it comes to population. He shares the common view among biologists that resource scarcity and peak oil will be troublesome (an issue that I am relatively optimistic about - as most economists seem to be) but he finds hope that population growth may be curtailed. His logic lies in the idea of sexual conflict, which occurs because men and women do not have the same interests when it comes to mating. Women must invest in pregnancy, childbirth (which risks death) and breastfeeding, so have a higher incentive to invest in the child than the father, who only needs to give a couple of minutes of his services.

By considering sexual conflict, Brooks adds a dimension that is often missing from discussions of population. As power shifts in a relationship to the female, an expected result will be a reduction in fertility. If you wish to cut fertility, educate women and increase their power. However, I’m less optimistic than Brooks as I’m not convinced that the fertility decline will be permanent. and don’t consider increasing population to be a one way path to success in the long-term (despite the increase in ideas that comes with more people).

As I read the chapters that addressed sexual conflict, I realised that I should have written a few of my posts on Bryan Caplan’s Selfish Reasons to Have More Kids differently. Brooks alerted me to more dimensions of sexual conflict than I had considered at the time. In particular, the asymmetric investment of men and women makes statements that men and women want the same number of children seem even less plausible.

As a libertarian leaning economist, the chapter on obesity was the one that most directly confronted my biases. Brooks’s argument is that humans have evolved to varying degrees to the high carbohydrate diet of the modern world. As populations transition from their old diet high in protein, fat and complex carbohydrates, the risk of obesity increases. Populations with the shortest exposure to modern agriculture and grains are the most vulnerable. Once you add in the subsidies given to many grain and sugar producers and the higher prices of protein and fresh fruit and vegetables, this combination directs the human diet in the wrong direction.

The solution proposed by Brooks is to consider subsidising protein and vegetables, and taxing simple carbohydrates such as sugar. At the least, we should remove the perverse subsidies that we offer many farmers. Although I am always supportive of removing subsidies, I’m naturally wary of any story involving taxes or subsidies to shift human behaviour. However, I want to explore this issue in some depth, so will come back to it in a later post.

The rock ‘n’ roll story contained in the book is one that seems obvious, but at the same time, is a story that so many resist. Why are rock stars predominantly male? What is the evolutionary rationale for their actions when it seems to increase their death rate by so much? When you look at Brian Jones of the Rolling Stones, dead at 27 but with four children to four different mothers (and I’ve seen higher estimates of his reproductive output), the evolutionary explanation seems clear. Evolution is not just about survival - it is largely about sex. And if you want to read a book about sex, Brooks’s book is as fun to read as any.