The study, led by Dr. Sam Ellis and his team at the University of Exeter, has found that the evolution of menopause in toothed whales is similar to that in humans. In both cases, females have extended their lifespan without increasing their reproductive lifespan, leading to a longer post-reproductive phase where females can focus on raising their children and grandchildren, ensuring their survival and well-being.
Menopause in Toothed Whales and Humans
The researchers examined the reproductive patterns and lifespan of toothed whales, such as killer whales and narwhals, and compared them to humans. They found that like humans, female toothed whales experience menopause, where they stop reproducing long before the end of their lifespan. This extended post-reproductive phase allows them to focus on supporting their offspring and grandoffspring, which can greatly improve the survival and well-being of their family members.
The study suggests that the evolution of menopause in both toothed whales and humans is likely driven by the benefits of older females being able to provide care and support to their younger family members, rather than continuing to reproduce themselves. This “grandmother hypothesis” explains how the extended lifespan and post-reproductive phase in these species can be advantageous for the survival of the family group as a whole.