Where does this "morality" come from?
evolutionary forces. Do you understand the concept of group evolution? Let me explain it.
IE, say you have 3 groups of 10 people, all living together isolated from the other groups.
in the first group, all 10 are murderers. Wicked murderers. Wretches, all of them. They arn't going to get along very well, because they don't look after their own kind.
the second group, are indifferent to eachother. They meet to mate, that's all. Otherwise they ignore eachother.
The third group, cooperates and helps eachother, and works together to achieve their goals.
Now, which group, from a natural selection standpoint, would be most successful? The third group, obviously. The first group will destroy itself, the second group is no better than if they were not a group, the third group works together and the sum is greater than the parts.
So, people organize themselves into tribes, groups, governments, ideologies, etc... and natural selection acts not just on the individual but also on the tribe or government or ideology.
( when you get to larger groups, it's mostly ideologies doing the evolving, actually. IE, an ideology or moral system that works better towards social cohesion will be selected for, because the individuals in the group like it better and would rather live under that ideology than some other. )
If society has "evolved" why are our morals pretty much the same as they were three thousand years ago?
I completely disagree that our morals are pretty much the same as they were three thousand years ago, but then again, I suppose I am talking to someone who quotes morality from leviticus.
Let me give you a list of changes in morality between Leviticus and now:
1) Nobody sacrifices bulls to God anymore.
2) Nobody cares if you shave your beard.
3) Women are not to be bought and sold, they have the same rights as a man. Women are people just like you.
4) Eating shellfish and pork is not considered immoral, because we know that pork and shellfish arn't dangerous to eat if you cook them properly.
5) It's OK to be Gay.
an incomplete list, of course.
Like you pointed out regardless of if you call it social cohesion or morality it is the same. The old if it walks like a duck and talks like a duck...
But people are going to have disagreements about what morality is or about what should or should not be legal and IMO a democratic government of laws is a better way to resolve this than a couple thousand year old book.