A new study has revealed that male brains are wired in such a way that they suppress the ability to locate food in order to instead focus on finding a mate.
Douglas Portman, an associate professor in the Department of Biomedical Genetics and Center for Neural Development and Disease at the University of Rochester and lead author of the study, said that while they know that human behavior is influenced by numerous factors, including cultural and social norms, these findings point to basic biological mechanisms that may not only help explain some differences in behavior between males and females, but why different sexes may be more susceptible to certain neurological disorders.
The findings were made in experiments involving C. elegans, a microscopic roundworm that has long been used by researchers to understand fundamental mechanisms in biology. Many of the discoveries made using C. elegans apply throughout the animal kingdom and this research has led to a broader understanding of human biology. In fact, three Nobel Prizes in medicine and chemistry have been awarded for discoveries involving C. elegans.
The study focuses on the activity of a single pair of neurons found in C. elegans – called AWA – that control smell. Smell, along with taste and touch, are critical sensory factors that dictate how C. elegans understands and navigates its environment, including finding food, avoiding danger, and locating a mate.
There are two sexes of C. elegans, males and hermaphrodites. Though the hermaphrodites are able to self-fertilize, they are also mating partners for males, and are considered to be modified females.
It has been previously observed that males and hermaphrodites act differently when exposed to food. If placed at a food source, the hermaphrodites tend to stay there. Males, however, will leave food source and “wander” – scientist believe they do this because they are in search of a mate.
The Rochester researchers discovered that the sensory mechanisms – called chemoreceptors – of the AWA neurons were regulated by the sexual identity of these cells, which, in turn, controls the expression of a receptor called ODR-10. These receptors bind to a chemical scent that is given off by food and other substances.
In hermaphrodites, more of the ODR-10 receptors are produced, making the worms more sensitive – and thereby attracted – to the presence of food. In males, fewer of these receptors are active, essentially suppressing their ability – and perhaps desire – to find food. However, when males were deprived of food, they produced dramatically higher levels of this receptor, allowing them to temporarily focus on finding food.
The researchers found that the normal worms left their food source and eventually made their way to the center of the dish where they mated with the hermaphrodites. The genetically engineered males were less successful at finding a mate, presumably because they were more interested in feeding. By examining the genetic profile of the resulting offspring, the scientists observed that the normal males out-produced the genetically engineered males by 10 to one.
The study was published in the journal Current Biology.
