Adults who were breastfed as babies tend to have higher intelligence, spend longer at school, and earn more income, regardless of their family's social class. These results come from a new study out of Brazil that followed 6,000 individuals, beginning in their infancy, over the course of three decades. 

About 3,500 of the study's participants, who are now 30-year-old adults, recently sat down to take a standard intelligence test. When researchers compared their scores with other data collected during the last 30 years, they found a positive correlation between having been breastfed and succeeding in life. 

Leader of the study, Dr. Bernardo Lessa Horta, said from the Federal University of Pelotas, Brazil:

"Our study provides the first evidence that prolonged breastfeeding not only increases intelligence until at least the age of 30 years, but also has an impact both at an individual and societal level by improving educational attainment and earning ability."

While the study cannot account for all possible causes of school success — perhaps mothers who breastfed were also better tutors to their children — it does rule out family income as an explanation for success or failure. The reason, say researchers, is that at the time of the study, all Brazilian families breastfed their children, unlike in countries like Britain and the US where formula was thought healthier than mother's milk.

It's likely that breast milk helps the brain develop during the formative months of infancy, when the child begins taking in the world for the first time. In her Big Think interview, nutritionist and real foods advocate Nina Planck discusses the scientific turnaround concerning breast milk and how society has benefited form it:

"Breast milk is also very important to the growing child because it not only provides complete nutrition and provides a number of antibodies and really enhances immunity in multiple ways, but it develops and matures the digestive tract and the immune system. So it has effects ... it affects the whole developing child. Two of the three systems, which are immature at birth, immunity and digestion, are greatly enhanced by breast milk."

Read more at The Guardian.