When female killer whales enter menopause, their priorities shift. Unable to reproduce, these orcas focus on preserving their legacy for future generations. It becomes clear that a solution exists most of the time through their male offspring, who play a central role in the animal kingdom. From then on, older females protect their kin to safeguard the genetic lineage.
This finding emerged from research conducted by teams at the Universities of Exeter and York, along with the Whale Research Center. For the first time, indications suggest this protective behavior occurs among older orcas and their children and grandchildren. The researchers published their results in Current Biology, highlighting strong evidence of kin-based protection in the wild.
The team traced this dynamic by examining tooth rake marks on the dorsal fins. These marks, often formed during fights or rough play, serve as visible records of social interactions. “Tooth rake marks tell us there is physical and social interaction happening within the group”, notes Charli Grimes, a researcher from the Animal Behavior Research Center at Exeter and lead author of the study.
Male orcas under the protection of their menopausal mothers showed fewer blemishes. “We were surprised to find that there is a real benefit for males when their mothers have stopped reproducing”, Grimes explains.
Interesting parallels with humans
Only six species—including humans and five toothed whale species—experience menopause. Scientists have long wondered why. This study helps address that question: after menopause, females appear to help extend their offspring’s lifespan, particularly for males.
Researchers observed that these men showed up to 35% fewer tooth marks than other males. The pattern was not seen when the male was accompanied by a reproducing female.
“We don’t know for sure why this happens right after menopause”, the scientist explains. One possibility is that, once breeding ends, mothers free up time and energy to safeguard their children.
In this light, female orcas seem to have evolved to pass on their genes through their daughters and sons by helping their offspring and grandchildren rather than competing for the next generation themselves.
Grimes adds, “Males can mate with more than one female, increasing opportunities to pass on their mother’s genes. They may also mate with females outside their social group, shifting the burden of rearing to other pods.”
How these social strategies unfold remains partly a mystery. Darren Croft, who coordinated the study at Exeter, notes that older females may draw on experience to help offspring avoid fights within social settings. They can also influence in group conflicts by stepping in when needed. “There are strong echoes of human social systems here”, Croft observes. “Older female whales appear to use their knowledge to support kin, including resolving conflicts and securing food resources year-round.”
References: Current Biology study (Cited work on menopause and kin-based protection). Marked attribution: Current Biology, 2023. See the study for detailed methods and findings. A related overview is available from the Whale Information Center, which provides background on orca biology and behavior.
Marked citations: Current Biology article, and Whale Research Center summaries as secondary resources for reader context.