Killer whales experience menopause – just like humans

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Just like humans, killer whales experience menopause – and the rare evolutionary trait improves their offspring's chances of survival, according to experts.

Killer whales are one of only three species able to continue living long after they have stopped reproducing. This allows mothers to spend the rest of their life looking after their offspring.

Scientists are investigating why the animals evolved this trait. Researchers, from Exeter University and York University, have secured funding from the Natural Environment Research Council (NERC) to analyse a dataset of more than 550 killer whales recorded over 30 years.

The dataset, compiled by the Centre for Whale Research in the US, contains birth and death dates as well as details of the genetic and social relationships in two populations of killer whales, which share their menopausal trait with only humans and pilot whales.

"Our main aim is to understand why these killer whales have a menopause strategy that's so similar to humans. Female killer whales stop reproducing in their 30s or 40s but live until they are 90," said Dr Darren Croft of Exeter University, a lead investigator on the study.

The researchers believe the reasons for the menopause in killer whales lie in their unusual social structure.

Written By: Mark Riley Cardwell
continue to source article at theguardian.com

10 COMMENTS

  1. They can live 90 years. That is astounding. I wonder if there are studies that include info about longevity in captivity vs. in the wild. (I’ll get back to you)… I think that this really underscores the cons of keeping these magnificent animals in a tank for their entire lives. There may be pros, but….

    • In reply to #1 by crookedshoes:

      They can live 90 years. That is astounding. I wonder if there are studies that include info about longevity in captivity vs. in the wild. (I’ll get back to you)… I think that this really underscores the cons of keeping these magnificent animals in a tank for their entire lives. There may be pr…

      Average age of death for females in the wild (what I’ve calculated from data on the Northern and Southern Residents found in the Pacific Northwest) averages a little over 40 years, not counting for those who died before their first year (usually sex isn’t known at that age, anyway). I haven’t adjusted for living individuals, though.

      The oldest living females in captivity right now are in their late-40s – one at Sea World, one at Miami Seaquarium. Corky, at Sea World, is thought to have been born in 1964. If you take average age at death from the time orcas were first kept in captivity, the number is pretty low – a lot died after just a few years. People often factor in stillbirths or neonate deaths among orcas in captivity, which aren’t often observed in the wild, and don’t factor in individuals who are still living. I’m sure the overall number is still lower than it is in the wild, though.

      Another consideration is that most orcas in captivity generally have a genetic history tied to Icelandic pods. Two are from the Pacific Northwest, and some born in captivity have mixed heritage. A couple of them have a transient for a grandfather. Earlier captures drew from populations in the Pacific Northwest. I’m not sure if that would affect calculations.

      This article generally focuses on matrilineal groups found among the Northern and Southern residents and up into Alaska. Among transients (recently renamed to Bigg’s killer whales), which are found in the same areas as the residents, older offspring tend to disperse from their mothers, depending on group size. Transients hunt marine mammals and keep their groups small, generally under 5 individuals. Males are sometimes solitary – no solitary females have been observed yet.

      I’ve been told by someone who studies orcas in New Zealand that their group affiliations are more fluid. Affiliation between orcas doesn’t necessarily mean relation.

      • In reply to #4 by Kim Probable:
        >

        This article generally focuses on matrilineal groups found among the Northern and Southern residents and up into Alaska. Among transients (recently renamed to Bigg’s killer whales), which are found in the same areas as the residents, older offspring tend to disperse from their mothers, depending on group size. Transients hunt marine mammals and keep their groups small, generally under 5 individuals. Males are sometimes solitary – no solitary females have been observed yet.

        Orcas come in specialist cultural groups, each with its own lifestyle.

        The US west coast southern residents, round up and whack fish to stun them and then pick them off, while the transient Orcas hunt seals. Larger growing Orcas hunt whales.
        There are three different hunting cultures in the Antarctic, which avoids competition between different groups of Orcas. Some Antarctic Orcas hunt penguins. Others hunt seals. New Zealand Orcas catch sting-rays.

        Orcas through these specialisms, seem to have been in the process of speciation for hundreds of thousands of years.

        An observation was even made of an Orca attacking a Great White Shark and eating its liver.

  2. Many years ago an old lady friend of mine was overdue, driving back from abroad. (before mobile phones). I contacted the police thinking she may have been in an accident. The cops had no record of any matching accidents, but they also asked if this overdue person was on any medication. I said she was on HRT, The cops (not knowing what they were) asked what would happen if she did not take them. Without thinking I said “She gets a bit ratty”.

    HRT – Hormone replacement therapy. (my contribution to medical science!)

  3. Do Elephants get menopause ? The matriarch is the obvious leader of the group because she usually holds more of the memories of the furthest distances travelled, and skilled knowledge that she has built up – only with many decades experience – this knowledge is invaluable to her family unit even if her body is not as reproductive and perhaps because reproduction has stopped she will continue to help her genes survive by caring for her kids and grandkids, probably a key reason that helped humans become more complex and successful family units.

  4. “Male and female offspring continue to live with their mothers for the duration of their mothers’ life, with males returning to their mothers’ sides after mating with females in other family groups.”

    “In a previous study, published in the journal Science last year, the researchers showed adult males have a 14-fold increase in mortality risk the year after their mother dies.”

    These are clearly deeply conscious and emotional beings.
    Its simply sick to think of confining them in to pools for our entertainment.

    • Terra and Kim,
      First, Kim, that was some great info, thanks. Second, Terra, I couldn’t agree more. Then when one of them harms a human, the news goes haywire and everyone shakes their head and wonders “what went wrong?” well, I could tell them what went wrong, but I do not think that they’d want to hear it.

      @ everyone on that other thread, why don’t we all break into Sea World and spray paint all over their property epithets about how we hate their profiting on a fellow mammal, then when the crime gets tracked to us, we can cry that the punishment is not fair even before the punishment is actually handed down! Once again, the message is the correct one, the method is illegal.

      In reply to #8 by Terra Watt:

      “Male and female offspring continue to live with their mothers for the duration of their mothers’ life, with males returning to their mothers’ sides after mating with females in other family groups.”

      “In a previous study, published in the journal Science last year, the researchers showed adult male…

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