Biologically, sex is an investment. To procreate requires time, energy, and resources. The reward is strong and healthy offspring with a new, better, combination of genes.
It was Darwin who first suggested that animals take care in selecting their mates. However, the scarcity of eggs compared to the abundance of sperm, coupled with the time and energy needed for an embryo to develop, creates a biological inequality. Consequently, females tend to have agency and be the selective sex, while males compete to secure a mate for reproduction.
A new paper, published in Science, suggests that Darwin dismissed this due to his patriarchal views. He downplayed female variation, placing emphasis on male variation, sexual ornamentation, and male dominance hierarchies. Interestingly, he focused on male variation as a driver of sexual selection, despite this inherently meaning females have agency in choosing between the variations within potential mates.
Sexual selection, the process by which members on one biologial sex choose who to mate with, is multifaceted. Animals consider a vast number of factors including sound, smell, and appearance while making this choice. Females have been shown to select for traits that don’t necessarily benefit the male’s ability to survive. This is perhaps illustrated most vividly by the male peacock, whose tail appears to offer no benefit in life beyond attraction of a mate, actively hindering them in flight and predator evasion. Importantly, for some species, sexual selection is driven by males, but it remains driven by investment of time or energy. In pipefish, where the males carry fertilised eggs until hatching, females compete for male attraction.
Research in the years since Darwin’s theories were published has revealed that the process of sexual selection is far more complex than he suggested. Arguably, this could be attributed to the lack of scientific knowledge of the time. However, there’s evidence Darwin understood strategy and variation beyond his writing, but that perhaps he felt uncomfortable writing about such things. He would certainly have observed behaviours by female dogs and cats having litters with multiple males, and female birds choosing multiple males to fertilise one – or more – eggs in the reproductive tract.
What can be said is that it was unavoidable for Darwin’s work to be unaffected by the patriarchal and sexist culture he lived in. In his private letters, he referred to women as ‘inferior intellectually’, noting that female chit-chat was ‘good for one’s health – but a terrible loss of time’. In a time where genetics were almost entirely misunderstood, there were gaps in Darwin’s understanding of sexual selection. Had he had more knowledge of genetics, perhaps he, along with many great scientists of the time, wouldn’t have married his first cousin.
While Darwin’s private writing highlights his sexism, and his public works show his conclusions were likely influenced by misogynistic views, it’s important to note that he wrote the foundation of modern evolutionary biology. Ultimately, Darwin paved the way for scientists of our time to understand sexual selection.
