Female orcas live longer primarily due to a combination of the benefits older females provide to their groups and the costs associated with reproductive competition between mothers and daughters.
Here's a breakdown:
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The Grandmother Effect: Older, post-reproductive female orcas, often called "grandmothers," play a crucial role in the survival of their family groups. They possess accumulated knowledge of the environment, particularly regarding salmon migration routes and foraging strategies. This knowledge significantly improves the hunting success and overall well-being of their offspring and grand-offspring.
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Reduced Reproductive Competition: As female orcas age and eventually go through menopause, they cease competing with their daughters for reproductive opportunities. This reduction in competition benefits the younger generation, allowing them to reproduce more successfully and contributing to the overall fitness of the pod. If older females continued to reproduce, it could negatively impact the survival rates of their daughters' offspring.
In summary, the extended lifespan of female orcas, especially after menopause, is an evolutionary adaptation that enhances the survival and reproductive success of their family groups through knowledge sharing and reduced competition.
