The benefits of breastfeeding are under the spotlight again as research out today shows brain growth in babies is linked to the length of time mums breastfeed.
Scientists at Queen’s University Belfast and Durham University have concluded that the longer the pregnancy and breastfeeding period in mammals, the bigger a baby’s brain grows.
The study of 128 mammal species, including humans, shows that brain growth is determined by the duration of pregnancy and how long they suckle.
The researchers say the findings reinforce the suggestion breast is best for brain development and add further weight to the World Health Organisation’s advice of six months’ exclusive breastfeeding followed by breastfeeding up to the age of two or beyond supplemented with solid foods.
The study, published in the Proceedings of the National Academy of Sciences, helps to explain why humans who suckle their babies for up to three years in addition to their nine-month pregnancies, have such a long period of dependency as this is necessary to support the growth of our enormous 1300cc brains.
In comparison, species such as fallow deer, which are the same body weight as humans, are only pregnant for seven months with a suckling period of six months, resulting in brains of 220cc — six times smaller than ours.
The anthropologists from Queen’s and Durham’s Evolutionary Anthropology Research Group analysed statistical evidence on brain and body size, maternal investment, and life history variables in mammals, including gorillas, elephants and whales.
They found that brain size relative to body size was most closely linked to maternal investment — the amount of time a mother spends carrying her offspring in pregnancy and how long she continues to breastfeed.
Co-author of the investigation, Dr Isabella Capellini from Queen’s, said: “Our study shows that the slower pace of life and increased lifespan in species with larger brains are a consequence of the greater costs of growing large brains more than the benefits for reduced mortality.
“The findings help us understand the implications of evolutionary changes at different stages, before and after birth, but we now need to do more research to pinpoint exactly how changes to the pre- and postnatal growth phases affect the structure of the brain.”