Part 11/13:
Similarly, in animal models like rats, dominance and submission can be observed through play. Studies reveal that rats understand the importance of fairness: the dominant rat must sometimes allow the subordinate a chance to win, or else the play ceases. This indicates an innate sense of fairness or "proto-morality," which is embedded deep in mammalian biology.
Summary: A Biological and Psychological Tapestry
In sum, human sex differences are shaped by a complex interplay of evolutionary pressures, biological wiring, and social learning. From physical strength and size to neuroendocrine adaptations for caregiving or competition, these differences influence behaviors, vulnerabilities, and social roles.