Sapiens also talks about how humanism is completely made up. Who says a human deserves rights? Why should humans not own other humans? Because we built up a moral system on made up beliefs, largely religious in origin.
And that is good. Otherwise why protect weak humans? Why not just behave more "naturally", like animals?
That's fundamentally why we can do it and animals can't. If humans were unable to store or save, billions of people would die off rapidly. As a species we'd largely stop being so generous & kind with each other. Famines would be common (again). We'd never be able to successfully support such an immense population scale. Operating by a year to year razors edge, is incredibly risky and difficult. Inevitably the mistakes will hammer you. Instead of 10 steps forward and 9 steps backwards (leading to quite slow net population growth), today we're able to make 10 steps forward and maybe 1-2 backwards, leading to immense success overall (whether we're talking about % that make it to old age, or % that survive infancy).
If other animals could store their productivity (including surplus productivity) for 50%-100% of their life span (or more), much less widely distribute/trade it for further self-benefit, it seems like it would lead to fascinating consequences over many generations of evolution.