Scientists have recently uncovered why female killer whales experience menopause. Even if menopause was characterized by biologists as being a mystery, they might have eventually figured it out. This particular species of whales reach menopause, just like women do. The explanation may have its cornerstone in the mixture of cooperation and conflict which appears between younger and older female killer whales.
- Scientists reveal the reasons why female killer whales are bound to reach menopause.
- The older whales enter a competition with their daughters and their newborn calves are more likely to die.
- Killer whales, pilot whales and humans are the only known species to experience menopause.
The new study was published on January 12 in the Current Biology magazine. Apparently, killer whales represent one of the three species which experience menopause. The other two are humans and pilot whales. Experts have always wondered why these three species evolved to experience such extended periods of their lives unable to reproduce.
In the case of killer whales, they start reproducing around the age of 15 and stop having babies when they reach the age of 30 or 40. Nevertheless, they may live for even more than a hundred years. A group of scientists conducted by Darren Croft, a behavioral ecologist at the University of Exeter, tried to find more answers which could help them finalize the study about female killer whales and the reason they experience menopause.
Since the 1970s, in the Pacific Northwest, scientists have continuously gathered information concerning the deaths and the births of killer whales which live in family groups. Researchers revealed an important idea. When older killer whales reproduce at the same time as their daughters who live within the same group, the babies of older whales are more likely to die during their first 15 years of life.
Nevertheless, if older whales had more babies in the absence of their reproducing daughters, their calves managed to survive. Croft argued that this is not about the fact that older mothers are not able to take care of their babies as well as young mothers usually do. The main reason is that the older ones are more likely to lose if they enter the competition with their daughters and their calves may die.
The game may focus on food because older female whales are thought to be more likely to share their fish with others members of the family. Females always mate with males from other groups and then get back to their family group. Thus, when a new whale is born, their father is not around, and some individuals are determined to live in groups where their relatedness is quite decreased.
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