Mother's Curse: Why Females Live Longer Than Males

Why do females usually live longer than males? Science may have the answer, dubbed the "Mother's Curse" hypothesis:

The loophole lies in the mitochondria, the energy-generating parts of our cells. The mitochondria have their own DNA, separate from the DNA that resides in the nucleus of the cell that we usually think of when we think of the genome. In almost all species, the mitochondria DNA is passed down solely from mother to child, without input from dad.

This direct line of inheritance may allow harmful mutations to accumulate, according to a new study detailed today (Aug. 2) in the journal Current Biology. Ordinarily, natural selection helps keep harmful mutations to a minimum by ensuring they're not passed down to offspring. But if a mitochondrial DNA mutation is dangerous only to males and doesn't harm females, there's nothing to stop mom from passing it to her daughters and sons.

"If a mitochondrial mutation pops up that is benign in females, or a mutation pops up that is beneficial to females, this mutation will slip through the gates of natural selection and go through to the next generation," said study researcher Damian Dowling, an evolutionary biologist at Monash Univeristy in Australia.

The result: a load of mutations that don't harm females, but add up to a shorter life span for males.

Link (Image: Shutterstock)

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@afghan: Yes, even controlling for accidental death, male lifespans are still shorter on average; failing to control for that would make any study on senescence useless. However, I was given to understand that it was due to higher average testosterone levels in men, since castration practically eliminates the life expectancy gap. Castration could hardly eliminate harmful mitochondrial mutations though, which leads me to be skeptical about this theory.
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Neat theory but there are two thoughts I've got:

1. It seems hard to believe that such a huge difference in expected lifetime would come from a single-purpose energy-producing organelle.

2. After removing all the deaths attributable to young male stupidity (driving too fast, motorcycles, just about everything after that happens after "hey, watch this", leading lives of violence, etc.) are the expected lifetimes _still_ different between men and women who make it past 30?
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What about mutations that are beneficial to males but not females? They don't support the theory so we'll just ignore them.
I hope taxpayers weren't footing the bill for this "research".
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