Menopause may be a factor in longevity in five species of whales, including killer whales, in which this biological phenomenon occurs, suggests a study published this Wednesday in the scientific journal Nature.
Women, five species of whales – beluga whale, narwhal, pilot whale, killer whale and false killer whale – and chimpanzees from a particular community in Uganda are the only known mammals to go through menopause, and a study led by scientists from the University of Exeter, UK, concludes, that females of these whale species live approximately 40 years longer than females of other species of similar size.
Researchers speculate that some species of toothed whales (a group of species distinct from baleen whales) have evolved so that females live longer and help younger generations survive without competing with daughters or granddaughters for reproductive partners.
The increase in life expectancy may be due to “transitional advantages, the help that older females can provide to younger members of the family,” and the reason for not extending reproductive life is to avoid competition with daughters, explained one of the study authors. investigation, Samuel Ellis.
In most cases, females outlive males of their own species, and in the case of killer whales, females can live up to 80 years, but usually die around 40, according to the study.
For researcher Darren Croft from the University of Exeter, “it is quite surprising that among more than 5,000 species of mammals, this characteristic (onset of menopause) is observed in only a few species.”
The study’s findings suggest that the evolution of menopause in odontocetes bears “striking similarities” to the evolution of menopause in humans: lifespan increases without simultaneously extending the reproductive period.
“This is the same pattern of life history that we have seen in humans. It is absolutely amazing that we can make such comparisons with a group of animals that are so different” and from which we are separated by 90 million years of evolution, the researcher added.
In the case of the five species of toothed whales studied, they all exhibited an “unusual social structure”, a kind of matriarchy in which females remain in close contact with their children and grandchildren, which helps improve the family’s chances of survival.
Menopause, the study suggests, occurs when a species benefits, and despite the differences between whales and humans, their convergent evolution opens up new perspectives for understanding the evolution of menopause in general, according to the researchers.
Author: Lusa This morning Post
Source: CM Jornal
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