Let’s talk about sex, baby. Well, sort of, reproduction really but hopefully I caught your attention. Menopause. Probably something most people don’t want to think a lot about, but biologically it is actually really interesting… at least I think so.
Let’s think about it a bit, what is menopause? Well essentially it is just a female living on for many years after losing her ability to reproduce. It doesn’t sound like much, but from a biological perspective the entire purpose of any organism is to pass its genetic material on to the next generation, so once an individual loses its ability to do that, their existence becomes unnecessary. If a female can’t produce and raise offspring is survival really worth it? So it isn’t really surprising that very few species have long female survival periods after stopping reproduction, yet a few species do. Humans, of course, is the obvious one, but it also occurs in killer whales, possibly in elephants, and… you guessed it – short-finned pilot whales, the star of the Tenerife show!
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| Adult and juvenile pilot whale |
Since I’ve told you menopause is actually biologically unusual, you may wonder why it happens at all. It may help you to know that both killer whales and short-finned pilot whales exist in what are known as matrilines, or matriarchal societies. Here, female offspring will stay with their mother throughout their life, with in turn their female offspring remaining, forming a group of closely related females. Males tend to leave the group, at least partly, in order to reproduce with females they aren’t related to. Female short-finned pilot whales will not reproduce after the age of 40, yet they can live to around 65 years old, so there must be a good reason for sticking around for another quarter of a century!
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| Juvenile pilot whale surfaces to breathe |
Granny, Grandma, Nanny, whatever you call her, everyone loves their Grandmother right? But think about how much knowledge she has, how many years of life experience she can pass on to her children and her children’s children. I’m sure if you think about it you’ve learned something from your Grandmother, even if it’s just the secret family recipe for the world’s best apple pie! Just as in humans, older female short-finned pilot whales hold a wealth of information which can help their offspring to survive and reproduce successfully. So even though she may no longer be producing more of her own offspring, her years of knowledge are ensuring that her genetic material that’s already out there is getting the best possible chance of surviving in to another generation. Let’s hear it for Granny pilot whale!
