Different litters

Chou Toshio

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This is a simple topic but one surprisingly ungoogle-able.

Anyone think of how novel it is how humans raise siblings?

It's much more common in the animal kingdom for siblings to literally try to kill each other than for parents to simultaneously raise offspring from different age litters.

So what animals do raise offspring of different litters/ages simultaneously? This is a surprisingly complex behavior.

Orcas?
Apes?
Are there others that even really do it besides humans?
Maybe colony animals, but that's not really the parents doing it?

Thoughts? Is multiple litter rearing surprisingly an incredible phenomenon? Or nothing special about our species?
 
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Cresselia~~

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Humans are probably the only species that keep an offspring for so long.
That's probably why siblings from different litters are kept together.

Edit: Interesting. I didn't find anything from google neither.
 

Kink

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Our offspring remain young and developing far longer than other animals, especially chimps. Our larger social brains require far more time in order to be fully developed. A baby chimp for example will spend the first year of its life desperately clinging onto its mother and the two are inseparable. Given the birth rates of such baby chimps, the mother's attention can only be on a single baby at a time. Even if its baby dies a mother will sometimes carry it around instinctually for several days/weeks before finally letting go.

This differs vastly; humans and their babies have developed a far less "aggresssively" developmental relationship, slowing down the potential social development of the "animal" (human in this case), and giving far more time for mothers to produce additional offspring despite their initial children still being in instinctual danger from the world. Sociologically, in combination with our evolutionary traits, siblings provide an opportunity for a child to engage in more aspects of their immediate world. The capability of food surpluses and social development has encouraged siblings to take a cultural and evolutionary form in our lives.

- King UU expert on the world
 
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Brambane

protect the wetlands
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Intentional siblicide (so not baby mantises eating each other because they are there) is actually pretty rare outside of avians. The reason why it is so common in birds is because, if resources are readily available, the cost to produce and incubate an egg is low enough to justify producing an extra egg in case something were to happen to the first one. Siblicide then occurs when the first chick is healthy and proceeds to kill its sibling to eliminate its competition. There are some birds which perform this behavior obligately and those which perform it only when resources are scarce, perhaps initiated by prolonged feelings of hunger or some other environmental cue.

Reptiles don't truly display siblicide because they are precocial and usually disperse after hatching. If kept together for one reason or another, some species may cannibalize but there is no preference for or against siblings in such a scenario. This is also true for most fish and amphibians. One exception to this being intrauterine cannibalism, where sharks, other fish and one salamander afaik will consume their less developed siblings.

Some mammals do care for multiple sets of offspring, but there is a notable time gap in development between them. The older offspring are usually weaned by the time the next generation is born, which is no coincidence. Milk is costly to produce for the female, and feeding two sets of offspring would either make it so the younger set doesn't get enough food or the female expends too much energy to maintain milk production. The parents may continue to "raise" older offspring in the sense of offering protection and shelter, but at this point they are sufficient enough to feed for themselves. In large social groups, typically female offspring will also stick around to help raise their siblings after reaching sexual maturity while the males disperse.

There are examples of siblings helping out one another and next season's siblings. Earwig nymphs will take care of each other and share food with siblings, especially if the mother is not present to provide care. One of the most remarkable examples is in corvids, american crows. Whereas many parents will chase away their offspring once they are sulf-sufficient so they don't compete with them for resources, crows will often stick around with their parents after becoming self-sufficient, sometimes even for years. They will assist their parents in raising future clutches. More interestingly, they will often leave their parents for the non-breeding season and return during nesting to help care for the young.
 
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Chou Toshio

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Our offspring remain young and developing far longer than other animals, especially chimps. Our larger social brains require far more time in order to be fully developed. A baby chimp for example will spend the first year of its life desperately clinging onto its mother and the two are inseparable. Given the birth rates of such baby chimps, the mother's attention can only be on a single baby at a time. Even if its baby dies a mother will sometimes carry it around instinctually for several days/weeks before finally letting go.

This differs vastly; humans and their babies have developed a far less "aggresssively" developmental relationship, slowing down the potential social development of the "animal" (human in this case), and giving far more time for mothers to produce additional offspring despite their initial children still being in instinctual danger from the world. Sociologically, in combination with our evolutionary traits, siblings provide an opportunity for a child to engage in more aspects of their immediate world. The capability of food surpluses and social development has encouraged siblings to take a cultural and evolutionary form in our lives.

- King UU expert on the world
I knew that chimps develop way faster than humans, but do chimp mothers wait until the baby is an independent adult before having new babies?
 

dwarfstar

mindless philosopher
Putting aside the obvious category of eusocial animals (bees, wasps, ants, termites, and naked mole rats), another group of animals (or set of groups, really) where we see generational overlap like that is in social spiders. There's a mode of social organization that's evolved independently in Stegodyphus sp. and several other genera in multiple families where a large number of adult females and multiple generations of their offspring (male and female) will all cohabit in a single colossal web and share whatever food they catch with the rest of the group. Older juveniles will help to feed not only any of their own siblings who are too young to kill prey for themselves, but sometimes unrelated spiderlings as well. There doesn't seem to be any fitness disadvantage involved in giving some of their food to other spiders, related or otherwise, and baby spiders who receive this kind of care have been shown to grow faster and end up healthier than conspecifics raised in isolation under laboratory conditions.
 

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