Breast-feeding babies changes their lives for the better. Bernardo Horta published an unusual study in Lancet Global Health. Unusual in that he looks at adults rather than children and teenagers.
He found those who had been breast-fed for more than a year compared to those breast fed for less than a month had a 3.76 points higher IQ than the later. They had attended school for 0.91 years longer and their income was 15% higher than those nursed for less than a month.
There is no doubt that there is no better nutrition for an infant than human milk. But probably what is most important is the human contact and bonding which takes place.