Surivial of the Fittest?

"You know that survival of the fittest idea as the kind of overarching of idea for life, beneath which everything else bows down. And even extending into spheres like economics or political philosophies  as a kind of final truth of egotism."
"Yeah, what about it?"
"It doesn't really work, does it."
"Why not?"
"Because if it was the over-ruling idea of life, then for the higher animals anyway life wouldn't get very far, or rather it wouldn't get going in the first place."
"Why's that?"
"Isn't it obvious - think about babies, in the wild they're all more or less totally helpless if left to their own, and so wouldn't survive if not for the self-sacrifices of the fittest, the adults. So self-sacrifice is a far higher principle for life than any kind of egotism, within which notion life would quickly die out with the pure selfishness of the self-serving individual. Though of course the self-serving individual wouldn't exist in the first place without the self-sacrifice of its parent or parents to bring through its long period of basic helplessness. And it's no good talking about this as being about species rather than individuals, because what kind of egotism is it that sacrifices itself for the good of the species? That's the opposite of egotism. And so all-in-all self-sacrifice is obviously enough a far higher principle for life."
"I'll have to think about it."