[Diamond]

An evolutionarily-derived morality would promote the survival of the group (society) and hence its members

Why should I care what's good for society, or for the group? Where did this force, this law, to always seek the survival of the species come from? Where does this moral rule positing the good of the group come from? If you appeal to the good of society, you are already appealing to a prior moral rule that is in place and you need a further justification for that moral rule. Saying that it evolved begs the question.

Cordially,

[bluepistolero]

Yes, take for example all of the patricides, matricides, infanticides, suicides, and what have you. If survival of the group, let alone the species, was some mindless aim, where does it all come from? It cannot all be bad hair days and that time of the month.

bluepistolero

[Junior]

Why should I care what's good for society, or for the group?

Because without the group your chances of survival go way down. As an individual, you are not the fastest or strongest critter in the environment and would be short work for some mediocre predator if you don't starve first. As part of the group, though, you can have help fighting off the predators or hunting for food.

The proto-people with the greatest sense of cooperation were able to survive and pass their genes on. Those lacking this sense were slowly weeded from the genepool.