“Aye, science clearly shows that there is an evolved genetic basis to morality. That being 90% psycho monkey pack predator and 10% bee is a very effective combination. There is no absolute morality in that. Higher, intentional morality, rationalism, enlightened self interest and ‘true’ altruism beyond it, to the other, any other, strangers, the species, comes with headspace, privilege, in some; noblesse does oblige, and storms. Which must have been selected for unless it too is a spandrel. Rationality demands co-operation to equity; equality of outcome. Universal kindness. Science proves it. That being co-operative works, from each according to their ability, to each according to their needs. It’s easily quantifiable. Empirical. Scientific.”
This is a good example of the inability of science to address most key aspects of morality. Humans are not monkey-bee hybrids; that is merely a metaphor. The genetics and reproductive patterns of eusocial insects are quite different from that found in mammals, though mole rats have a somewhat similar social system. Human ethics depend strongly on ideas, which have a strongly non-genetic component of transmission. Ideas easily jump from individual to individual, can get mutated and recombined in all sorts of ways, and do not require any clear ancestral idea but can come essentially out of the blue. This also means that, unlike with genes, ideas are very difficult to trace back without historical records.
What evolved, genetic basis is there for morality? Of course, many moral choices are likely to have some effect on one’s chances of passing on genes. But there are all sorts of possible advantages and disadvantages of any particular action. Either more cooperative or more selfish approaches can give an advantage under particular situations. “This could provide an evolutionary advantage under certain circumstances” describes practically anything, and as such, actually explains practically nothing, just like “that’s the way some sort of unspecified designer wanted to design it”. Kin selection is invoked to explain tribe members taking sides in a dispute with more genetic precision than their language defines and to explain someone risking their life to help a stranger. What human traits are genetic versus learned versus individual innovation? Humans are both practically (small litter size, long developmental period, don’t do well in captivity, complex) and ethically terrible subjects for genetics experiments. Even the relatively simple traits popularly billed as Mendelian in general biology like attached earlobes, handedness, or tasting PTC are rarely reliably documented genetically. Given the ease of human genomic sequencing, it’s not hard to come up with genetic variants that correlate with some trait, but there’s so much DNA that mere chance will produce several correlates. And there is the possibility of spandrels. If a particular moral choice is not a direct product of selection, but merely reflects a capacity that has been generated by the evolutionary process, then the choice might conceivably have no possible evolutionary advantage and still be a byproduct of evolution.
The claim above also illustrates confusing description with prescription. “Here is a possible explanation of how that moral belief could arise evolutionarily.” That might even be specific enough to be possible to investigate and come up with some evidence, though in reality such ideas are rarely amenable to rigorous testing. But that is worthless with regard to my deciding what I should do. If someone disagrees with me, should I try to figure out what their point is and seek to explain the issue, or should I resort to insults and dismiss them? The fact that I can think of possible evolutionary influences that could favor one or the other does nothing to assist with choosing which to do, though it might make a handy excuse if I know I’m picking a bad option. Hume and Kant pointed out the logical failing of a supposedly purely empirical and rational approach to ethics. “This is the way things are” cannot tell us what is the way things ought to be. “Rationality demands co-operation to equity; equality of outcome. Universal kindness. Science proves it. That being co-operative works, from each according to their ability, to each according to their needs. It’s easily quantifiable. Empirical. Scientific.” “We hold these truths to be self-evident…” These are merely fancy ways of saying “Smart people will of course agree with me about what is right and wrong”. In reality, in modern (“Enlightenment” onward) Western culture, these moral systems are generally “I have picked the parts of Christian ethics that I like and dismissed those I don’t.” Being co-operative works. So does being treacherous. The tragedy of the commons applies to many situations. To each according to their ability to grab stuff, from each according to what each is compelled to give is the actual practice of both communism and unbridled capitalism. “Look out for #1” is generally quite effective as a short-term strategy. Of course, it is bad for everyone else, and likely to do more poorly in the long run than a more cooperative approach, but evolutionary self-interest is not overly concerned with either of those. Besides, why shouldn’t I say “I don’t care if this is in my evolutionary self-interest or not, it’s what I want to do?”
Of course, it is true that good morals are generally good for you. They tend to involve delayed gratification and an increased advantage for the total group rather than maximized individual advantage, but your whole group crashing tends to be bad for your individual success. But overall, following good ethical principles probably will be in your best interest. So it is not at all surprising that plausible evolutionary explanations can be found. But again, the existence of a possible evolutionary explanation neither proves that it is correct nor gives philosophical compulsion to actually follow that principle.
Another way to illustrate the problem here is to try making similar claims about another natural law, such as gravity. Gravity tells us that masses will tend to move together, given the opportunity. Therefore, I should drop a heavy rock on your foot. (Don’t worry, in reality I wouldn’t want to damage the rock.)