Although one of Darwin's central ideas was that males adapt and compete for the attention of females due to the fact that females have the power over mate choice, a new study by researchers at McMaster University claims that this is not true. The claims stem from an examination of male and female fruit flies that indicates that females do not have specific sexual preferences, conflicting with the 150 years of evolutionary theory surrounding mating choice.
"Darwin's female-choice theory has become the foundation for explaining the presence of exaggerated secondary sexual traits in many males, such as the peacock's tail feathers," said Rama Singh, one of the study's authors, in a press release.
"It has also led to a cottage industry based on the idea that female choice is based on the genetic quality of the males, known as the 'good gene hypothesis,'" added Singh. "Sexually exaggerated traits are said to be male advertisements to females of their good genes, when in fact they may simply be a means of making the male more visible to females or intimidating other males."
The team proposes that the Victorian values of Darwin's time could have seeped into his scientific thinking and given females more power in sexual negotiations than they actually have. For example, a female "choosing" a bigger male over a smaller one may be under coercion or threat, or due to the fact that the bigger male has eliminated all competition.
The team examined this question using a garden fruit fly, Drosophila, and sexually aroused a female with a male (large size or small size). Afterwards, they removed the male and offered two new males: one large or one small. The results showed that the aroused females showed no specific preference for bigger males and exhibited mating patterns that were random, pointing to the idea that once aroused, females have no mate preference.
Singh believes that in the realm of mate choice, there is no such thing as pure male charm - all male maneuvers can be perceived as somewhat influenced by direct or indirect coercion or physical threat. These actions are lumped into the category of the "male sex drive," which he believes acts as a compliment to Darwin's idea of "female choice."
Of course, when it comes to humans, Singh believes that sexual behaviors are not hard wired and completely uncontrollable - we act under the assumption that we can control and moderate it through rules governed by social interactions and the idea that our brain has control over our body.
The findings were published in the Dec. 11 issue of PLOS One.
