Was ritual sacrifice good for the survival of the Spartans or any other culture in the long run? How many prosperous societies today practice ritual sacrifice?
However, there is no instinct that we have garnered from either culture's supposed "failure" - only knowledge of what the others before us have gone through to augment our knowledge and decision making processes now. I would argue that the human species stopped playing according to the "survival of the fittest" model long ago - ever since we put doctors/healers into practice to prolong the lives of those with genetic deficiencies allowing them to opportunity to survive and procreate (mind you, I am not saying this is "wrong" by any means - there is no right/wrong to be had there). Besides, even the idea of their having "failed" for those specific reasons is entirely moot. You'd never pin down their reasons for "not making the cut" to any one thing. I'd have you also realize that there are a fair number of apparently functioning cultures in present day that are far younger at the moment than some of the others who did practice ritual sacrifice in the past (the Mayans, for example).
And I'm not at all arguing that I think ritual sacrifice is "good" - not at all. I'm simply pointing out that "murder = bad" is not a valid equation for all humans. There may not even be instinctual governance of any kind on the murder of other human beings. Those in your immediate social circle? Certainly - because you came to care about them and trust them through experience. But a limit on the murder of those who threaten you? Historically? Not so much.
Ultimately this means that we are able to utilize our knowledge, experience and intellect in general to overcome our instinctual limits of even what is "right" vs. "wrong", beneficial vs. detrimental. We always have been - and those would all be examples of humans choosing "good" for themselves. More succinct examples:
1. A human woman likes men of a certain "type" - it could be argued that her instinctual desires for a male with good genes to procreate with are at work. However, she meets an amazing deaf man in a wheelchair who is nowhere near her "type" physically, but is emotionally and intellectually spot-on with what she's looking for, and she marries him. Choice for "good" made by the individual, despite any claims of what is
supposedly "good" being made otherwise (through societal pressures, physical instincts, etc.)
2. A farmer raises livestock for years on end, building a massive farming empire, he's wealthy and life is "good". But over time he sees the effects his farms have on the environment, and on the animals - more and more of them in closer and closer quarters. Eventually he switches gears to become an avid force against large-scale farming operations like the one he had for years. The "good" changed through experience and gathering of knowledge. A decision was made as to what was the greater good.
So, if we have some sort of external force informing us that things are either good or bad from the start, then how do we end up in situations where our mind is changed? Where we have to make a choice as to what we feel is "good" for ourselves? Why would there be choice in the equation at all?