Individuals are not stable things, they are fleeting. Chromosomes too are shuffled into oblivion, like hands of cards soon after they are dealt. But … - Richard Dawkins

It would be deeply depressing if the only way children could get moral values was from religion. Either from scripture, and God knows we don't want them to get it from scripture, I mean, just look at scripture. Or, from being afraid of God, being intimidated by God. Anybody who is good for only those two reasons is not really being good at all. Why not teach children things like the Golden Rule, do as you would be done by, how would you like it if other children did that to you, so why do you do it to them... I think it's depressing that anybody should suggest that you actually need God in order to be moral. I would hope that our morals come from a better source than that, and therefore they are genuinely moral rather than based on outmoded scripture, or based on fear.

I can think of no moral objection to eating human road kills except for the ones that you mentioned like 'what would the relatives think about it?' and 'would the person themselves have wanted it to happen?', but I do worry a bit about slippery slopes; possibly a little bit more than you do. There are barriers that we have set up in our minds and certainly the barrier between Homo sapiens and any other species is an artificial barrier in the sense that its a kind of 'accident' that the evolutionary intermediates happen to be extinct. Never the less it exists and natural barriers that are there can be useful for preventing slippery slopes and therefore I think I can see an objection to breaching such a barrier because you are then in a weaker position to stop people going further. Another example might be suppose you take the argument in favour of abortion up until the baby was one year old, if a baby was one year old and turned out to have some horrible incurable disease that meant it was going to die in agony in later life, what about infanticide? Strictly morally I can see no objection to that at all, I would be in favour of infanticide but I think i would worry about/I think I would wish at least to give consideration to the person who says 'where does it end?'

Don't ask God to cure cancer & world poverty. He's too busy finding you a parking space & fixing the weather for your barbecue.