If you want to eat, it helps to be able to crack what nuts you can find. If you are finding nuts and trying to crack them, it’s best when you have the right tool.
Some capuchin monkeys can crack nuts easily because their forebears left them the right tools.
A medium-sized Long Island hermit crab looking to upgrade their home has the best chance of finding a larger castoff shell that has been vacated, but a very large crab is going to have a harder time finding an upgrade, as there are fewer oversized shells in the average vacancy chain. In related news, hyena daughters born to high-ranking mothers are getting early access to fresh meat.
Scientists studying these phenomena are asking questions. They are hopeful that a better understanding of the mechanisms of inequality may be useful when it comes to fostering change. Humans, after all, are vastly more cooperative than other species, one scientist observes, and cooperation is an asset that can work in any number of directions, depending on intent.