It is precisely because of these ideas that I have trouble seeing how morality is rational with God excluded. If what you describe is true (in terms of an evolved morality and altruism) then it would agree with reason to impede upon those who I do not regard as "my own."
That's precisely it. Even with the huge population growth of humanity, we still retain the impulse toward altruism and helping out our fellow humans. It is a type of misfiring, I'll give an example. We often witness moths circle a flame and eventually fly into it, it seems an irrationally suicidal impulse so why would natural selection favor it? The reason why is that for millions of years, moths evolved to use the moon to navigate the planet in semi-circular patterns. Before man there was no flame except for the relatively rare occurrences where nature would produce a lightening strike, or the sun would shine down uninterrupted on a parched field, etc.. Humanity came along and produced purposeful fires nightly and then went on to create artificial light. The moth still has that navigation system honed over millions of years to use the brightest object in the sky (the moon), so when seeing a flame, or artificial light, they navigate it in circular patterns until they eventually run right into it. They're not attempting suicide, just mistaking the flame for the moon. The same misfiring seems to be happening with the morality of humanity, our urge to altruism is a kind of misfiring of that same selected system to look out for other tribe members, even though most of humanity are no longer other members that could share our genes. As misfirings go, this seems to be a pleasant one...
After all, it is evident that man is reaching a state, due to resource consumption and overpopulation, where the earth is not able to sustain us. It would only make sense to decide who is "mine" and in a sense disregard those who do not fall into this criteria.
The process of evolved morality I described isn't at an intellectual level, but a deeper emotional one...
I would like to share an example from a piece of literature I'm currently reading. In the book, Crime and Punishment, the main character (Raskolnikov) decides to commit the murder of a pawnbroker. This pawnbroker is old, decrepit, and a generally malevolent old hag in general (takes advantage of the misfortune of others) . She is neither a productive member of society, or well liked by anyone (and thus would be un-missed in Raskolnikov's reasoning). The reason he murders her is because of her substantial wealth, which he seizes and plans to use for the betterment of the productive members of society who have fallen into misfortune (including himself). Was Raskolnikov wrong in doing this? I would say yes, though his intentions could be considered noble (in a twisted sort of way), due to the sanctity of life declared by the Ten Commandments. But in the absence of God, I don't see how this would be in a sense wrong. After all, his actions would help many who needed it. Would the benevolence outweigh the malevolence? From an evolutionary viewpoint, I think so.
I was just speaking about this concept with my son. If a healthy person walks into a hospital and there are ten people that would be saved if we sacrificed the one healthy individual and gave his organs to the ten dying patients, would that be moral? I'm glad we've decided it is not, an individual's rights to his own body trump the need of the many. No one would like to walk around in such a cannibalistic society where whatever you have can be taken based on another's need.
I'm sure you get the concept I conveyed about how most anyone can pick and choose the moral parts of the bible from the immoral ones, or god's moral actions from his immoral actions. How would we be able to do this unless our morality came from a source outside of those things? That's the million dollar question for you...