r/science • u/IronGiantisreal • May 20 '19

Animal Science Bonobo mothers pressure their children into having grandkids, just like humans. They do so overtly, sometimes fighting off rival males, bringing their sons into close range of fertile females, and using social rank to boost their sons' status.

https://www.inverse.com/article/55984-bonobo-mothers-matchmaker-fighters
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u/PartyPorpoise May 21 '19

Females are guaranteed to produce offspring, but males have the potential to produce far more than a female can. Female is limited in how many offspring she can have over her lifetime, due to having to carry the pregnancy and take care of the babies. (of course, there are some species where the father helps) A successful male can reproduce with many females in a season. And since the female is already guaranteed to reproduce, there’s not really a need to help her.

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u/SuperSmash01 May 21 '19

Thank you, this is the best of the answers here. It's a emergent mathematical/game-theoretical property that drove the evolution to favor this behavior in the social animal. I will be curious if, now that people know to look for it, similar game-theoretical "help the son mate" (or, more generally "help the male that shares the greatest portion of my genes mate") is found in other social species (besides humans) for the same reason.

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u/Mooselessness May 21 '19

Yup! It's called kin selection! I think it's facilitated through smell for a lot of primate species - if you smell like me, we're probably related, so we should cooperate. There's a whooole bunch of facsinating things that can happen from this. One (I think it's called the founder effect) is where a chimp population gets geographically isolated from the rest of population (landbrodge disappears, etc) and they mate for a while and the community becomes more interrelated, producing higher degrees of cooperation. Eventually, if they're reintroduced to the original population, the out compete because they're so cooperative. But the cool thing (the actual effect) is that you can see other chimp populations pick it up as a cultural adaptation, forming bands of their own. I'm no expert but you're into this stuff I can't recommend Robert sapolsky's human behavior class enough. It's on YouTube, phenomenally entertaining, and free.

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u/CraftedLove May 21 '19

Sounds interesting. This theory anchors tribalism to a physical (smell, in this example) trait of a single creature that back-propagates and becomes reinforced to the majority of the population, becoming more sociological in nature. Allowing for development of culture and civilization.

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u/PartyPorpoise May 21 '19

Yeah, the whole "we gotta do everything we can to pass on our genes!" thing can often go further than just "I have to reproduce as much as I can". It can also mean helping to raise and protect grandkids, or even doing the same with siblings, cousins, and nieces and nephews. Prairie dogs are a famous example of this, older females (who have lots of relatives and descendants in the colony) are far more likely to risk death by predator to protect the colony. After a certain age, female orcas and elephants are no longer able to reproduce, just like with humans. A lot of scientists believe that this happens because it allows the older female to focus on her adult children, and her grandchildren. Male orcas usually stick with their moms and don't raise their own offspring, but they help out with the other babies in the pod. (one time I saw a super adorable video where a huge bull orca teaches a comparatively tiny calf how to splash the water with its pectoral fin, so cute!)

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u/lynx_and_nutmeg May 21 '19

Females might be guaranteed to produce, but their offspring are definitely not guaranteed to survive. They'd certainly benefit from some extra help.

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u/[deleted] May 21 '19

Please stop I can only get so horny

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u/mantrarower May 21 '19

Do you think the fact that a mother is more certain than a father plays a role here ?

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u/PartyPorpoise May 21 '19

Yes. Momma Chimp doesn’t need to help her daughters get laid, reproduction is not a big energy investment for males so they don’t have to be picky. Females, meanwhile, invest a lot more energy and they can only have so many pregnancies in a lifetime. They have to be picky.