Narrator: This is Science Today. For the first time, a team of researchers at the University of California , Riverside has determined statistically that fish have menopause and that it's not affected by evolution. Biologist David Reznick, who
led the study, says their research of guppies in Trinidad may have implications for humans.
Reznick: For animals in general, what it says is that menopause may not be in any way a product of natural selection. In the case of humans, it's been argued at great length that human menopause is something that's been shaped by evolution and that in fact, it's an adaptive feature of our life cycle – that women live well beyond their capacity to reproduce because of what's been referred to as a ‘Grandmother Effect'.
Narrator: That's the evolutionary concept that grandmothers enhance the ability
of their daughters to reproduce and affect the survival of their grandchildren.
Reznick: Our data argue that menopause may just be a by-product of how the animal's put together and the earlier life history of the animals. And so, in the
case of a guppy, the only reason for them to live beyond the end of their ability to reproduce is because different parts of the body age at different rates.
Narrator: For Science Today, I'm Larissa Branin.