The Evolutionary Trade-off of Living
Every organism follows a life strategy that pits survival against reproduction. You cannot have it all, so life evolves to balance the energy spent growing up versus the effort used to raise offspring.
Nature forces every creature to make a budget for its limited energy. A mouse invests heavily in rapid reproduction to outpace predators, while an elephant focuses on longevity and massive parental investment. This theory explains why species develop such different lifespans and physical traits based on their environment. It essentially views your entire life cycle as a calculated strategy for passing on genes.
Source: Life history theory