News Animals Sumatran orangutans start crafting their engineering skills as infants The baby primates start early on nest-building techniques — a craft that takes years to hone Orangutans devote years of practice to nest building, an essential skill for life in the treetops. Sumatran orangutans start learning the skill at as young as 6 months old, a new study finds. ROMEO GACAD/AFP via Getty Images Share this:EmailFacebookTwitterPinterestPocketRedditPrint By Elizabeth Anne Brown May 17, 2024 at 9:30 am At six months old, human infants are still working on sitting up by themselves.