I am not a biologist, and don't have much technical knowledge of biology. That being said, having observed the real world, it seems that, at least for mammals, human beings seem to "care" more about their offspring than other mammals might. One reason, of course, is the fact that human babies/children require more assistance than other mammal babies.

Imagine, however, that at any given point in time, we can summarize the resources that a mammal needs as $X$. A fraction of that $X$, call it $x=F/X$ goes towards the children. This could be for human beings, the fraction of income devoted each period to the child, for lions the fraction of meat given to cubs etc. If a species gives $x=0$, then trivially, the species dies out. If a species gives out $x=1$, the species might still die out because it can only donate resources for one period, and the infant may not be able to fend for itself next period.
If one were to plot this $x$ over time across species, it would necessarily decrease, as the infants become autonomous eventually.

Is there any empirical work that correlates such a measure of "devotion of resources" to long-term survival of the species? In other words, are those species that survive long term best able to calibrate this $x$ to an optimal one to maximize survivability?

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    $\begingroup$ Arguably, 100% of any animal's resources go to offspring or are intended to go to offspring (sometimes you get eaten too soon), it's just a matter of how exactly those resources are allocated to different phases of the offspring's life. A female mammal is going to give a lot more post-birth resources than most other animals, but it doesn't seem quite fair to discount the effort put into eggs by other females, even if no post-natal care is given. Many species give every ounce of energy they have left to make as many eggs as possible and die immediately after. $\endgroup$
    – Bryan Krause
    Nov 2 '21 at 14:08
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    $\begingroup$ And, certainly, animals spend some of their own resources running, climbing, or flying about, so that doesn't go directly to offspring, but it's still an indirect cost of preparing to reproduce. Even males that don't seem to put as much direct resources into offspring put resources into competition with other males, locating mates, etc, which are all resources dedicated to ensuring their next generation. $\endgroup$
    – Bryan Krause
    Nov 2 '21 at 14:11
  • $\begingroup$ Yes you are right @BryanKrause . I thought of this after watching videos of say, lions eating before their cubs, when both were hungry. But this makes sense according to what you say, as the lion's survival is more crucial to the propagation of the next generation than say, any particular cub's. $\endgroup$
    – ChinG
    Nov 2 '21 at 15:23
  • $\begingroup$ @BryanKrause - The first thing I thought of when I read this was a male (mountain goat/whatever antelope) headbutting so many other males that it dies before they do (more energy expenditure and less time for nutrition), but gets to sire more offspring. It's not just about food allocation. $\endgroup$ Nov 3 '21 at 0:27

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