Menopause ‘may explain why some female whales live decades longer than others’

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Menopause might explain why some female whale species resembling belugas and narwhals live round 40 years longer than others, scientists have stated.

Apart from people, whales are the one mammals that undergo menopause.

This pure organic course of is thought to exist in simply 5 species of toothed whale: short-finned pilot whales, false killer whales, killer whales, narwhals and beluga whales.

The researchers stated the findings, revealed within the journal Nature, recommend that menopause might have advanced to allow these whales to outlive lengthy sufficient to develop into grandmothers – to allow them to care for their households by sharing meals or “babysitting”.

Being post-menopausal additionally means these species can have lengthy lives with out competing with their daughters or granddaughters for mates, scientists say.

Professor Darren Croft, of the University of Exeter and government director on the Centre for Whale Research, stated: “The evolution of menopause and a long post-reproductive life could only happen in very specific circumstances.

“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.

“For example, female toothed whales are known to share food and use their knowledge to guide the group to find food when it is in short supply.”

The researchers analysed information from scientific literature to assemble the life historical past of 32 whale species.

The crew stated “male menopause” didn’t evolve in the identical means as a result of male whales usually are not in the identical social group as their kids or grandchildren.

Professor Croft stated: “So they (male whales) don’t actually have the opportunity to be able to provide help that late in life to their close kin, so evolution just favoured them to continue to reproduce until the end of life.”

But this additionally means females typically outlive the males of their very own species.

For instance, the researchers stated, female killer whales can live into their 80s, whereas males are sometimes useless by 40.

They stated that regardless of being separated by 90 million years of evolution, whales and people have “remarkably similar life histories which have evolved independently”.

Prof Croft stated earlier work on killer whale populations has proven the life expertise of post-reproductive females “is really crucial in dealing with environmental challenges in times of hardship”.

He stated: “We see just the same patterns in human societies – in hunter-gatherer societies – in times of drought, or in during times of social conflict, where people would turn to the elders of their community who would have had the experience (and) the knowledge.

“I think it is important to draw that parallel between humans and cetaceans in terms of the role that these older matriarchs in the case of tooth whales, or grandmothers in the case of human societies, are playing.”

Lead creator Dr Sam Ellis, from the University of Exeter, added: “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 research was funded by the Leverhulme Trust and the Natural Environment Research Council (NERC).