These experiments are about trying to explain what you mean by "cooperate". Your points feel right, but even if they're true they aren't very helpful in actually explaining behavior. For example, your explanation seems to directly apply to adoption, but most people don't choose to adopt despite the enormous number of orphans in the world. Why not?

> These experiments are about trying to explain what you mean by "cooperate".

It's not clear to me what you mean by this.

In the example of the experiment in the example cooperate means the snow is cleared faster.

In my example cooperate means raise the young together.

> but most people don't choose to adopt

Because our biology drives us to want to have our own offspring. It seems obvious that if our biology drove us to want to raise other people's offspring we wouldn't be having this conversation. Although this has been an extraordinarily successful strategy for dogs and cats.

> Because our biology drives us to want to have our own offspring.

But just a few minutes ago you said our biology drives us to "cooperate to raise the young." Do you see how this topic might deserve some more study? Basically, my only issue with your comment is "The end."

You explain why but not how. Is it a spandrel from some other evolutionary trait that eventually became something important? Is it a process of higher-order brain functions that we have? Is there an alternative method that brought this about (stuck in a proverbial room with only a fruit basket and no way out)?

More descendants, too. :-)

More dependants, too. :-)