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posted by Fnord666 on Thursday March 05 2020, @03:59PM   Printer-friendly
from the genetics-go-figure dept.

Arthur T Knackerbracket has found the following story:

According to popular theory, men live shorter lives than women because they take bigger risks, have more dangerous jobs, drink and smoke more, and are poor at seeking advice from doctors.

But research by scientists at UNSW Sydney suggests the real reason may be less related to human behaviour and more to do with the type of sex chromosomes we share with most animal species.

In a study published today in Biology Letters, researchers from UNSW Science's School of Biological, Earth and Environmental Sciences analysed all available academic literature on sex chromosomes and lifespan—and they tried to establish whether there was a pattern of one sex outliving the other that was repeated across the animal kingdom.

Specifically, they wanted to test the 'unguarded X hypothesis' which suggests that the Y chromosome in heterogametic sexes—those with XY (male) sex chromosomes rather than XX (female) sex chromosomes—is less able to protect an individual from harmful genes expressed on the X chromosome. The hypothesis suggests that, as the Y chromosome is smaller than the X chromosome, and in some cases absent, it is unable to 'hide' an X chromosome that carries harmful mutations, which may later expose the individual to health threats.

Conversely, there is no such problem in a pair of homogametic chromosomes (XX), where a healthy X chromosome can stand in for another X that has deleterious genes to ensure those harmful genes aren't expressed, thus maximising the length of life for the organism.

First author on the paper and Ph.D. student Zoe Xirocostas says that after examining the lifespan data available on a wide range of animal species, it appears that the unguarded X hypothesis stacks up. This is the first time that scientists have tested the hypothesis across the board in animal taxonomy; previously it was tested only within a few groups of animals.

Zoe A. Xirocostas et al. The sex with the reduced sex chromosome dies earlier: a comparison across the tree of life, Biology Letters (2020). DOI: 10.1098/rsbl.2019.0867

-- submitted from IRC


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  • (Score: 0) by Anonymous Coward on Thursday March 05 2020, @07:04PM

    by Anonymous Coward on Thursday March 05 2020, @07:04PM (#967039)

    Assume they are correct and show in a million other species with 'guarded X's that the males live as long, and in a million other species beyond that with 'unguarded X', they live shorter - both relative to females. That still doesn't prove, in any way whatsoever, that the scenario for humans is the same. Human physiology may share some useful characteristics with more simple organisms all the way down to at least mice. But human behavior and intelligence is completely unlike any other species. This makes a cross-species comparison of something that's going to be heavily influenced by behavior quite meaningless.

    I'd argue the same is also true even for the species in general. For instance Black Widows are named such for the fact that females have a habit of cannibalizing their partner after sex. In other species, such as mantises, sometimes the female doesn't even wait for the act to finish before chowing down. Needless to say, there's going to be some bias in longevity in these and many other species for reasons that have little to nothing to do with their genetics relative to their behavior.