When male and female fruit flies age, their brains become desexualized. Age-related changes take place in both sexes, but the male brain becomes feminized to a larger extent than the female brain becomes masculinized. This is the conclusion of a study performed by a research group at Linköping University. [1]

Figure 1. That aging neutralizes sex differences in the brain

Figure 1 shows it is a well-known fact that weaker individuals cannot afford to “invest” in sexual behaviors to the same extent as their healthier conspecifics. However, it is not clear if aging, which weakens individuals, also leads to a reduced investment in sexual activities. You might think that for individuals close to the end of their lives, going “all in” on reproduction, in order to pass on their genes before it is too late, would be best. Sexual behaviors are directed from the brain, and to find out what happens to sex differences in this tissue when fruit flies age, the researchers have investigated how genes expressed to different degrees in young males and females change over time. [2]

The fact that females change less with age than males is presumably the result that the connection between investment in sexual traits and reproductive success is not as strong in females as it is in males. While a male fruit fly, in order to reproduce, must compete with other males to quickly find females and encourage them to mate through an intricate and demanding dance performance, a female only needs to decide how much energy she has available for reproduction. Aging implies that there are reduced amounts of resources available to invest in reproduction and other activities for both sexes, but stiff competition among men means that the cost of further investment is greater for them than for women.

The results of the study are reminiscent of those obtained by the group in a previous investigation. In that study, sex differences in gene expression were compared between male and female flies of high and low genetic quality. Similar to how aging reduces sex differences, the previous study showed that reduced gene quality makes gene expression more similar in male and female flies, and again it was the males that changed their gene expression more than the females. [3]

References:

1. https://phys.org/news/2022-08-aging-neutralizes-sex-differences-brain.html
2. https://mixpoint.in/plants-animals-molecular-computational-biology/2022/08/new-study-shows-that-aging-neutralizes-sex-differences-in-the-brain/
3. https://trending-town.com/a-new-study-shows-that-aging-neutralizes-sex-differences-in-the-brain/

Cite this article:

Thanusri swetha J (2022), That aging neutralizes sex differences in the brain, AnaTechMaz, pp.83