If a person, derives his world from his senses, and acts as he instinctively would, no science need be involved - he is acting as he is programmed to. I think morality is much the same, it is a society, deriving its collective world from the senses of all its individuals, and acts as it instinctively would. As a society, deriving the world from our tongues, our stomachs, and our hearts, we have decided confining pigs and cows to dirty prisons, kidnapping their children and forcefully impregnating the adult females, and killing the healthy adult animals, is fine, because it will fill our stomachs and delight our noses and tongues. On the other hand, some of us deriving the world from the empathy in our hearts, because some of us see the similarity between the cognition of elephants and our own, conclude elephant poaching is murder. Some others, who live closely with elephants and rely on their farms to not be invaded by elephants, who rely on their crops to fill their stomachs, see killing elephants as a justifiable act comparable to killing cows and pigs.
Morality is relative, and it is a derived from our experiences with the world. Even if our senses are fooling us, morality is right according to our point of view, and that's all that need to ever matter. No science need be involved, and there is no need to couch it in reason.
You like elephants, I like elephants. We both eat beef. Poachers and farmers who live next to elephants rely on crops for food and see elephants as a source of income. They're closer and can attack the elephants before we can stop them. We have money to fund non-profit organisations to hire veterinarians to treat the elephants before they die and to hire rangers to shoot at the poachers and farmers who attack elephants for their own family's benefit. That's just how it is.