Whales reveal how menopause shapes evolution and family bonds

Whales are the ocean’s giants, captivating us with their size and mystery. But did you know some female whales live for decades after they’ve stopped having babies? This unique stage of life is known as menopause, and besides humans, only a handful of ocean-dwelling mammals experience it.

But, why would an animal stop reproducing during its healthiest years? It’s a puzzle even for scientists. Most animals keep having babies until they physically can’t anymore. This makes menopause an evolutionary head-scratcher.

A recent study from University of Exeter explains why this unusual adaptation might have emerged.

The longevity of whale

There are a few whales that go through menopause: short-finned pilot whales, false killer whales, killer whales (also known as orcas), narwhals, and beluga whales. The females of these species are built to last.

They outlive most other similar-sized whales and even their male counterparts by a significant margin. For example, female orcas can reach their eighties. This extended lifespan wouldn’t be possible without menopause.

These whale grandmothers use their extra years to support their extended families. They become expert food finders, sharing their catch during tough times. They lead their pods with their extensive knowledge of migration routes and feeding grounds.

Menopause gives whales an edge

“The most obvious way for a female to do this is to breed for the entire lifespan – and this is what happens in almost all animal species,” said lead author Dr. Sam Ellis, from the University of Exeter.

“There are more than 5,000 mammal species, and only six are known to go through menopause. So the question is: how and why did menopause evolve? Our study provides some of the answers to this fascinating puzzle.”

“The process of evolution favors traits and behaviours by which an animal passes its genes to future generations,” noted Ellis.

Insights from whale menopause

The whale research reinforces this exciting idea: Menopause didn’t evolve to cut short female lives but to extend them in a way that benefits the whole family.

“The evolution of menopause and a long post-reproductive life could only happen in very specific circumstances,” said Professor Darren Croft, executive director at the Center for Whale Research.

“Firstly, a species must have a social structure in which females spend their lives in close contact with their offspring and grand-offspring. Secondly, the females must have an opportunity to help in ways that improve the survival chances of their family.”

Imagine a whale mother who keeps having calves late in life. Her children will compete with her grandchildren for food and resources. This puts a strain on the whole family’s success. But with menopause, whale grandmothers can shift their focus from having their own babies to helping those babies survive and thrive.

Implications for humans

Amazingly, even though humans and whales look nothing alike, we’ve followed a remarkably similar path when it comes to menopause. Both human and whale grandmothers play vital roles in raising and guiding the next generations.

It seems this special social structure is what opened the door for menopause to evolve —across two drastically different branches of the animal kingdom.

There’s still so much we don’t know about menopause, but this study brings us closer to understanding its purpose and origins. It’s a reminder that evolution often finds surprisingly smart ways to maximize an organism’s success.

Perhaps the next time you see a pod of whales, you’ll picture the powerful grandmothers among them, leading their families across generations.

The study was published in the journal Nature.

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