A three-year study of 128 mammal species, including humans, found that longer pregnancies and longer suckling times produce bigger brains in babies, possibly leading to a higher IQ.
The study suggests that women who breastfeed their babies for up to three years following nine-month pregnancies have a long period of dependency because it is required to support the growth of 1,300cc brains, the journal Proceedings of the National Academy of Sciences reports.
But animals such as fallow deer, which have roughly the same body weight as humans, are pregnant for just seven months with a suckling period of up to six months.
This results in 220cc brains, six times smaller than human brains, according to the media.
Robert Barton, anthropologist from Britain’s Durham University, said: “We have discovered that brain growth in babies is linked to the amount of time and energy mothers invest in their child.”
“There is a strong relationship between specific issues in the way a mother invests in producing her offspring and a link between growth of the foetus and length of gestation.”
The scientists focused on brain and body size, maternal investment and life history variables in mammals such as gorillas and whales.