Earth's evolution contains ethical principles To elaborate further, consider the difference between the size, shape and location of physical things versus their colour. It would have conferred a reproductive advantage on our ancestors to develop faculties of sense that gave them fairly accurate impressions of the size, shape and location of physical things in their immediate environment. Why? Because if you make systematic errors in judgement about those things, then you'll be killed by those physical objects quite rapidly. Your reproductive career will be over before it began.
That account is vindicatory of the impressions of the size, location and shape of things (at least in our immediate environment). That is to say, such an evolutionary account explains why our sight and touch will be fairly accurate in what they tell us about the size, shape and location of things immediately around us.
But now consider colour. Although seeing things as coloured would aid in us being able to perceive their size, shape and location, it wouldn't matter what particular colours things are. What would matter is just that we perceive them to have some colour and that we perceive contrasts. Specific colours would not particularly mater. And thus, an evolutionary account of the development of our faculty of sight would give us reason to think that the actual colour of things in reality may not very reliably match the colours we perceive things to have.....in fact, parsimony would favour us concluding that in reality nothing has any colour at all and that colours are projections of our mind that enable our faculty of sight to work, but are not features of the things we perceive by means of them.
So that's a debunking account of colour: given an evolutionary account of our development, it is more reasonable to suppose colour is not a feature of reality but a projection of our mind.
Thus thought our sight gives us the impression there are coloured, sized, located and shaped things, it is acutally only the size, location and shape that we have reason to think are real features of teh mind-independent objects, not colour.
The impression there are moral principles and moral values is akin to the visual impression of a coloured world. It conferred an advantage on our ancestors to get the impression things were coloured, but not because things are actually coloured, but because that way they could get the impression of the actual size, shape and location of things (features things really have). And likewise, getting the impression there are moral principles conferred an advantage because it encouraged behaviour that was adaptive, rather than because there were actual moral pricniples there to be perceived and whose misperception would kill one.