No, this isn’t how it works

Beluga whales and narwhals go through the menopause – taking the total number of species known to experience this to five.

Along with humans, killer whales and short-finned pilot whales were the only others previously known to experience the ‘change’ with most species being able to continue to reproduce until they die.

The study used data from the dead whales of 16 species and found dormant ovaries in older beluga and narwhal females.

The researchers believe they go through the menopause to prevent resources being taken away from their other children and grandchildren, but stay alive to help protect the younger pod members.

Nothing evolutionary like the menopause (or, to remain with female sexual oddities like tits, the female orgasm in humans and so on) is because “taking care of younger pod members” or anything like it. It’s always, but always, because the population is descended from those who carried the genes for those things, menopause, tits and so on. Those attributes led to more children surviving to have children, thus the genes spread.

It might well be that the post-menopausal whales do those things, that they’re beneficial to the survival of their genes down the generations, but it’s still not because nor in order to. It just happened than then the environment sorted through whether it led to that greater long term progeny production.

12 thoughts on “No, this isn’t how it works”

  1. It’s dismaying to see that it’s the scientists quoted who appear to think that this menopause is deliberate.

    Any variation, whether in behaviour (hibernation, climbing trees) or any other characteristic (size, diet, disease resistance) is a by product of random mutation.

    Randomness means that evolution can’t be meaningful. It just happens.

    Scientists used to think that only a few species slept. It turns out they all do. I suspect something similar will happen to studies of the menopause.

  2. “It’s always, but always, because the population is descended from those who carried the genes for those things, menopause, tits and so on.”

    [genes that trigger behaviour X] cause [Behaviour X] causes [increased survival/reproduction] causes [genes to spread] causes [all organisms have genes that trigger behaviour X].

    Haven’t you ever played the “Why?” game with a 5-year-old? There’s always more than one “Why”. Why do those attributes lead to more children surviving to have children?

    “Randomness means that evolution can’t be meaningful. It just happens.”

    Sigh.

  3. Isn’t the reason most species don’t have menopause is that few individuals survive to experience it?

  4. Human children take a decade (or two!) to become self supporting, so there is strong gene-survival benefit in the parents and grandparents surviving reproduction/birth for said decades, to provide nurture to kin.

    But older you are, more environmental damge, so less chance of undamaged offspring late in life. Hence gene survival benefit in removal of old-age reproduction reducing competion with same genes in younger generations.

    It’s all just numbers: game theory. Richard Dawkins (despite his later aberrations) explains this perfectly in “The Selfish Gene”.
    I suspect the OT was just sloppy talk “X because of Y” simply as short hand for the “mathematical outcome of Y in game theory of X”. No meaning, just numbers.

    And yes, menopause, like cancer, is largely a failure of age and hence affects only apex predators in “rich” societies, i.e. those where you don’t get eaten or starve much earlier.

  5. @NiV… ‘Why do those attributes lead to more children surviving to have children?’

    Darwin explained that. Organisms best adapted to their environment are more successful in reproduction.

    Example. As Central London’s buildings, originally gleaming white Portland stone, got grimier from soot, light coloured moths were more easily spotted by birds and so got eaten. Darker coloured moths not so much, so more dark moths survived to have children and the dark moth population grew whereas the light coloured moth population did not and died out.

    Then Mankind intervened and restored those sooty buildings to their gleaming former white selves.

    Guess what? Less dark moths stood out less and got eaten less. Moths with gene mutations making them much lighter colour survived most to have more kids…. you know the rest.

  6. Bloke in Costa Rica

    Several writers on evolution, Dawkins and Dennett among them, have noted this rhetorical inversion of cause and effect. At its most egregious it falls under the rubric of what are pejoratively termed “Just-So Stories”. As long as you realise you are using a shorthand when you say something like, “adaptation X is for behaviour/characteristic Y” then little harm done. But you have to remember that the “for” in that sentence has no teleological significance. I think the temptation to see purpose or directedness in evolution (and the natural world beyond) lies behind the curious persistence of nonsenses like group selection.

  7. “Darwin explained that. Organisms best adapted to their environment are more successful in reproduction.”

    Yes. I know. My point was that Tim was objecting to the common teleological mode of explanation on the grounds that evolutionary adaptations are “always, but always, because the population is descended from those who carried the genes for those things”. But the reason the population is descended from those who carried the genes for those things is that they do things like “prevent[ing] resources being taken away from their other children and grandchildren, but stay[ing] alive to help protect the younger pod members”. The teleology is the useful, novel, interesting part of the explanation.

    Tim was nit-picking, and I was nit-picking his nit-picking. Teleological “intentional design” explanations – so long as they’re not taken too literally – are an easier way to describe what’s going on, and not incorrect. They just miss out the steps in the chain everyone ought to already know.

    If you believe brains are made of neurons following the deterministic laws of physics, then *all* talk of agency and intention is figurative. But it’s how we simplify the world.

  8. Just a little unsure about how those who stop producing children pass that characteristic on. Through their non-children?

  9. @rhoda

    They have the genetic trait from conception, it is only expressed later in life, by which time they have already passed in on to their children. If not having more children improved survival of the child you already have the the trait is passed on when the child has children.

  10. “Just a little unsure about how those who stop producing children pass that characteristic on. Through their non-children?”

    Through their children’s children – and indeed, everyone else in their family sharing the same gene that, as grandmothers and great aunts, that they devote their later years to raising and supporting. And through the children they have just before menopause, who have a better chance of survival through not sharing resources and attention with sickly younger siblings. When the gain in number of descendants from giving older children more resources exceeds the gain from having more children, it makes sense to stop having children.

    It could also be a trade-off between having more children and an increasing risk of dying in childbirth, and not being around to support the children you have. Or it could be something else entirely.

  11. Coming at this from the other end, if professional women delay childbirth,will this eventually push the age of menopause up by favouring late menopause females?

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