Throughout this entire process, finite energy budgets
fundamentally cause the aforementioned trade-offs.
If energy were unlimited, organisms could in principle start reproducing
soon after birth (i.e. no trade-off between growth and
reproduction) and preserve themselves indefinitely (i.e. perfect maintenance).
But throughout the entirety of biological evolution, energy has never been free and abundant,
it has always been costly and scarce. Therefore, all organisms
must spend it strategically, in a way that best maximizes fitness.