Globicephala-macrorhynchus

MATRIARCHAL SOCIETY - THE WISDOM OF MENOPAUSE ORCAS HELP SURVIVE THE YOUNGER

Classic life-history theory predicts that menopause should not occur because there should be no selection for survival after the cessation of reproduction. Yet, human females routinely live 30 years after they have stopped reproducing. Only two other species— orcas (Orcinus orcaand short-finned pilot whales (Globicephala macrorhynchus) — have comparable postreproductive lifespans. In theory, menopause can evolve via inclusive fitness benefits, but the mechanisms by which postreproductive females help their kin remain enigmatic. 
however, a study about orca behavior, published in Current Biology, suggests that older females provide valuable information for the survival of the group.
According to the study’s authors, female orca, who are mothers between 12 and 40 years can get to fulfill 90. But, What is the evolutionary point of living so long without being able to reproduce? Until now it was known that the longevity of mothers increases the chances of survival of their sons.
According to the authors, females led their groups especially in times of shortage of salmon. Information on how and where to find fish, it can be vital for survive.
The wisdom they bring older females “may help explain why female orca and women continue to live long after they have ceased to reproduce,” said Brent, who lead the study

  • Photo:  A postreproductively aged female, J16, leads her adult son and two adult daughters. credit: Dave Ellifrit, Center for Whale Research.
  • Reference: Brent et al. 2015. Ecological Knowledge, Leadership, and the Evolution of Menopause in Killer Whales. Cell

PILOT WHALES AKA THE CHEETAHS OF THE DEEP SEA.

Marine animals that undertake breath-hold dives to access underwater niches must balance their access to two vital, but spatially separated resources: oxygen at the surface and food at depth and thus, Short-finned pilot whale use the same, highly specialised hunting strategy that cheetahs use, scientists report in a recently study. They say it gives the lie to our perception that deep sea whales are slow, energy-saving creatures. No other whale has been recorded to swim nearly as fast at depth.

Were tagged and studied 23 short-finned pilot whales (Globicephala macrorhynchus) living off the coast of the Canary Islands, one of only three places in the world that these whales permanently reside.

During the day, they look lazy the surface, often in social groups. That led scientists to previously think the whales only hunt at night. But the tags demonstrate the whales also hunt during the day. And when they do, they dive deep, and they dive fast. Tags showed the whales take just 15 minutes to dive to depths of 800m to 1,000m (0.6 mile), and more.

Mammals and Menopause
  • Human females spend about one third of their lifetimes in a post-menopausal state. (x,x). Even without the benefits of modern medicine, a study of women in India during the 1880’s found that women of a menopausal age lived an average additional 15 years. (x)

  • While other animals may go into a reproductive decline, or even perimenopause (literally the time “around menopause”), they generally die soon afterwards.

    • Example. Rhesus macaques: average life span- 25 yrs; evidence for menopause onset (in captivity) - ~35 yrs. (x)

    Chimpanzees and elephants were once thought to be potentially menopausal mammals, but both have shown evidence for remaining fertile even in old age! (x, x, x

    When looking at the reproductive strategies in the animal kingdom, the 'have as many offspring as possible’ looks like a common method… so what kind of evolutionary advantage would there be to these three species having long lived, but nonreproductive, females? That’s where the Grandmother Hypothesis comes in. 

    • The Grandmother Hypothesis: When grandmothers help feed and care for their grandchildren after weaning, their daughters are able to produce more children in a shorter period of time. 

    Of course there are also resource based (multiple generations cannot reproduce successfully in same group with limited resources) and social group (avoidance of inbreeding when offspring remain in social group) based hypotheses which could also contribute to selection for menopause in these species. (x, x, x)

    Could other animals experience menopause? Possibly. Due to sample collection, analysis difficulties, and individual variation, there is still a lot scientists don’t know about when it comes to menopause. We’ll just have to keep an eye on this still developing area of reproductive biology!

    This was a tricky one, but you guys did a great job!
    Points (for at least 2/3 correct) go out to oosik, koryos, sapiens-sapiens, gaypretzels, solointhesand, corvidheart, hyaenabee, and alphacaeli.

    Bonus points to koryos, carriemp, pistol-pony-showdown, sapiens-sapiens, justaquickquestion, wolf-eyedwanderer, mongrelmutt, gaypretzels, solointhesand, ktsaurusr3x, corvidheart, and hyaenabee!

    Check out the mess of sources (and open access articles!) below the cut.

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    Okay, before anyone says anything, yes I am aware that these pictures do not show the full reality of cetacean captivity. However, I was looking through my 2009 San Diego photo album and ran across pictures like these. Keep in mind, when I took these pictures I was a pro-cap. I saw nothing wrong with these. Yes, I wanted them to have bigger tanks, but I was mostly elated to be seeing these whales again in person (the last time I went was 4 years prior). I was so moved by these just now that I needed to share.

    First picture: one of the pilot whales after a show. Can anyone ID them?
    Second picture: Ulises waiting for Believe to start.

    **You do not have permission to use these images elsewhere without my approval.**