Masculinity is toxic not only in a figurative sense. At least in fruit flies. This conclusion was reached by researchers from the University of California at Berkeley, according to phys.org.
In humans and other species with XY sex chromosomes, females often live longer than males. Repetitive sequences in the genome may be one explanation. They are inherent in both males and females, however, scientists suspect, a large number of repeats on the Y-chromosome can create a "toxic effect" that shortens the life of males.
To test this hypothesis, the researchers studied the fruit fly species Drosophila miranda. Males of this species have twice as many repetitive DNA as females and a much shorter lifespan. It was found that in the cells of young male flies, DNA is stored tightly packed, and repeating sections are disabled. However, when the male flies begin to age, the DNA unwinds, freeing up more repeating regions. These "meaningless" repetitive regions can be toxic, because when activated, they tend to move around the genome and fit into random places, disrupting the work of genes.
The results also support the hypothesis that repetitive stretches of DNA are associated with the physiological manifestations of aging. Previous studies in fruit flies have shown that when repetitive areas become active, for example, they impair memory.
All of this could explain why species with XY sex chromosomes, including humans, have females live longer than males.
The research results are published in the journal PLOS Genetics.