If we look across many, many different species of animals, not just us primates, but also including other mammals, birds, even marsupials like kangaroos and wombats, it turns out that there's a relationship between how long a childhood a species has and how big their brains are compared to their bodies and how smart and flexible they are.
Daca ne uitam la multe, multe specii diferite de animale, nu doar primate ca noi, ci si mamifere, pasari, chiar si marsupiale, ca de exemplu cangurii si ursul australian rezulta ca exista o legatura intre durata copilariei a fiecarei specii si cat de mare este creierul in comparatie cu corpul lor si cat de inteligenti si flexibili sunt.