Yes, but even in a group it would be possible for human rationality to decide "f*** everyone else, I'm taking what I want because I need it now, even if I have to kill for it" especially if their own survival conflicted with the needs of the group. This has happened at times. Christian morality though will not allow this (even though it can be ignored if one wishes) since it answers to something (or someone) higher than our own egos.