Should the Possibility that Morality Stems from Evolution Even Be Considered? Hmmmm.
I have allways wondered whether evolution might be a good explanation as to why, (some) humans are endowed with a conscience.
For example: humans who felt an instincual revulsion to murder, lived in more stable tribes, this in turn resulted in propagation of DNA. Conversely humans who lacked this revulsion to murder, lived in unstable tribes ultimately resulting such that DNA would not get passed along. (I have no evidence for this, its just a hypothesis).
What i cannot explain is why a trait for 'not stealing' would have evolutionary advantage. That said I'm not so sure our conscience endows us with a revulsion to theft. Perhaps aversion to theft is learned rather that acquired, so a sociologucal factor rather than a biological factor.
@Brillig explained (quite well) why we evolutionarily evolved to kill humans outside our group (soilders for instance) but why we dont kill within the group (a random on the street for instance). He states
Humans have developed a myriad of instincts through evolution that promote social bonds on various levels, such as family, city, and country. — Brillig
Where i would disagree with this explanation is that cities and countries are very recent phenomenon (on an evolutionary timescale). While we are constantly evolving, an insufficient length of time has passed, during which to evolve in respect to these new sociological inventions. For the sake of enhancing your argument, when one tribe (or family) encountered another tribe (or family), their were many risks, diesease transmition or insufficient food/water for both tribes to coexist. Thus the tribe that could kill the other had an evolutionary advantage. When more tribes start killing each other it adds an additional risk factor when tribes encounter each other. The ability to kill outside of your tribe/family became a necessity for surrvival, while within the tribe/family there remain all the evolutionary factors for why not to kill. In essence within groups killing reduces surrvival, but between multiple groups killing increases chance of survival.
This is however a side note your question, my real problem with an evolutionary explanation would be that it describes how humans act and have acted. What an evolutionary explanation cannot tell us, is why we aught to act a certain way (note Humes is aught distinction). Additionally by my estimation evolution lacks a definitive value on which to ground morality or ethics, unless one counts surrvival to be a sufficient value. I find such a foundational value to be very dubious because it fails to distinguish whose survival is important, mine? Yours? Everyones?