Title: Post-Menopausal Female Killer Whales Shield Sons from Aggressive Encounters, Study Finds
Introduction:
New research conducted by scientists at the University of Exeter has revealed that post-menopausal female killer whales protect their sons from injuries sustained during fights with other whales. The study, which examined tooth-rake marks on male and female whales, suggests that the protective effect is limited to sons and hints at the evolutionary advantages of menopause in certain species.
Background:
Only six species, including humans and five types of toothed whales, are known to experience menopause. Female killer whales, for instance, live up to 90 years in the wild, with an average of 22 years post-menopause. The reasons behind this prolonged non-reproductive stage have long intrigued scientists, and previous studies have shed light on the benefits of post-menopause in killer whale populations.
Findings and Methodology:
The research, based on an analysis of nearly 7,000 photographs of southern resident killer whales off the Pacific coast of North America, revealed that males with post-menopausal mothers showed fewer signs of aggressive encounters. The protective effect was observed once mothers had stopped breeding and did not extend to daughters. Tooth-rake marks on the skin of killer whales can only be inflicted by other whales and can indicate significant injuries.
Researchers combined the photographs with population-tracking data to draw their conclusions. It remains unclear exactly how mothers protect their sons, but conflicts typically involve rivalry over mates. The experienced female mothers may use their knowledge of other social groups to help their sons navigate risky interactions or involve themselves directly in conflicts.
Significance and Implications:
The similarities between humans and killer whales in terms of the role played by older females in society are intriguing. Just as in humans, it appears that older female whales utilize their knowledge and experience to benefit their society by finding food and resolving conflicts. From an evolutionary standpoint, it makes sense for whale mothers to focus their efforts on their sons, as males can breed with multiple females and have more potential to pass on their mother’s genes.
Conclusion:
This study provides valuable insights into the adaptive nature of menopause in killer whales. By protecting their adult sons from aggressive encounters, post-menopausal female killer whales contribute to the survival and reproductive success of their offspring. The findings highlight the vital role played by older female whales in the social dynamics and welfare of their species.
The study, titled “Post-Reproductive Killer Whale Grandmothers Improve the Survival of their Grandoffspring,” was published in Current Biology.
Disclaimer: The information provided in this article is based on the research findings and statements made by the scientists involved.