Why can't kindness and greed both be inborn? It's not an either/or thing. Obviously both traits can have benefits depending on the context.
^^^^^ CB: My thought on this is that greed refers to wealth which is a learned concept. We aren't born with any instinct regarding wealth. Our attitudes to weatlh are entirely learned. "Kindness" is better termed inclination to live in cooperation with other people, This is amenable to a certain amount of instinct, though learned as well.
As far as benefits, greed or cooperation could benefit an individual in a given context, in the sense of their surviving and having offspring. The study in the post argues that predominance of cooperation was an adaptive advantage for the _species_ in the long historical context in which we came to dominate the ecological niche we were competing with some other species for, cooperation, sociality, language and culture ( which are highly social activities) were advantages over species which were less social. Two heads are better than one is the idea; better for the two, for both, than for the one by him/herself.
^^^^^^^
Also, I think the equation of kindness and sociability is dubious. Armies are social, but they aren't very kind. Also you can in theory derive a social order from individuals who are absolutely selfish, as that Hobbes guy did.
^^^^^^ CB: Sure.That's kind of popularizing. However, they didn't have armies back then. They were being very kind. Having war would have been maladaptive for the earliest humans, since wars involve killing your own species members.
^^^^^
We also have no way of really knowing how social our immediate ancestors were...
^^^^^ CB: It sort of like we know what is happening tens of thousands of light years away. or billions of years ago , or quarks, or quantum mechanics - Scientific study and inferences by paleoanthropology that are astonishing but possible. Read some paleoanthro.l