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.
Ja pavērojam dažādas dzīvnieku sugas, ne vien primātus, bet arī citus zīdītājus, putnus un pat somaiņus, piemēram, ķengurus un vombatus, izrādās, ka pastāv sakarība starp sugas bērnības ilgumu un smadzeņu lielumu attiecībā pret ķermeņa masu, un to, cik tie ir gudri un elastīgi.