I didn't know that evolutionary biology even existed as a discipline; now I am absolutely intrigued. Here are some examples of how it informs modern thinking (these are gleaned from the ABC interview and other interesting material on Brooks' website):
- Statistically, the world's richest people are more likely to have male babies. This may mirror the evolutionary reality that if a female animal is having a bad year or is unhealthy, they are more likely to have female offspring. During the 1960s in China, there was a famine - and a huge increase in the number of female births.
- Many diseases have a genetic basis. Natural selection has not eliminated the genes responsible because few of our ancestors lived long enough to suffer from most cancers or from dementia. Also, some genes that improve our fitness in early life come at a cost later on. For example, a gene called ApoE-ε4, elevates intelligence in early adulthood but it increases the risk of developing Alzheimer's by 5 to 20 times the normal risk. The new field of Darwinian medicine is showing how many common human maladies are a consequence of the inefficient way natural selection worked on our ancestors.
- A study by Face Research Lab has found that women in poor health are more likely to have a preference for masculine facial features. Brooks and some collaborators hypothesised that this could be because in poorer countries where health is more likely to be poor, there is also likely to be greater inequality between the richest and the poorest households. It may follow that women prefer the most masculine men where household income and security depends more on male aggression and status. Upon testing this theory, Brooks and co found that income inequality (the Gini index, often used by economists) is a better predictor of variation among countries in preferences for masculinised faces. He also showed that homicide rate is a promising correlate of preferences – with countries where homicide rate is high also preferring more masculinised faces.
- Evolutionary theory also predicts that a catastrophe is looming in the next decade, as 20 to 30 million more boys than girls come of age in China and India. In many animal species, when males overabound, they often compete so fiercely to court, win and even coerce the few available females into mating that everybody suffers. The same is true when the supply of men on the marriage market exceeds the demand from females.
