Within a year of birth, boys and girls also prefer different toys. Boys prefer cars, trucks, balls and guns. Girls prefer dolls and tea sets. Although evolution has clearly not had the opportunity to mould a preference for tea sets, there is evidence from another species which suggests that human infants might be predisposed to prefer toys that have particular adaptive significance to their sex. Several years ago, Melissa Hines, of City University in London, and Gerianne Alexander, of Texas A&M University, gave some vervet monkeys a selection of toys, including rag dolls, pans, balls and trucks. Male monkeys spent more time with the trucks and balls. Females played for longer with the dolls.
Obviously, cultural stereotyping is an improbable explanation for this. Nor could male monkeys have evolved a preference for fire engines. The theory put forward to explain what happened — and the similar innate preferences of human children — is that the toys preferred by young females are objects that offer opportunities for expressing nurturing behaviour, something that will be useful to them later in life. Young males, whether simian or human, prefer toys that can be used actively or propelled in space, and which afford greater opportunities for rough play. —The mismeasure of woman (The Economist)