Hominid evolution is generally characterized by these animals becoming more gracile. Humans are impressively physically weak compared to their primate cousins.
Concomitant with hominin descent came more cohesive sociality, which included greater regularity of cooperative behaviors, notably tribal defense (a necessity in the face of augmented group conflict). Technology also afforded the ability to survive in the face of a hostile environment as well as fortifying tribes with advancing weaponry.
Humans became more gracile and their bones weaker as they adopted agriculture and settled down to a more sedentary lifestyle. Ingenuity and loss of strength represents a complex life-history trade-off, especially with sociality stirred in.