From a Reuters article of the same title on MSNBC.com:

Breastfeeding's calming effects seem to be long-lasting.

Years after being weaned, breastfed children cope better with stressful situations like their parents' divorce than their bottle-fed peers, researchers said on Thursday...

Breast milk is full of nutrients, hormones, enzymes, growth factors and antibodies that are passed from mother to child.

Research has shown breast-feeding reduces infections, respiratory illness and diarrhea in the child and cuts the risk of post-birth bleeding in the mother.

In an observation study published in the journal Archives of Disease in Childhood, Montgomery and his team studied how breast- and bottle-fed 10-year-olds coped with the stress of their parents' marital problems.

The children were among 9,000 youngsters who had been monitored from birth for a major British study. Their teachers were asked to rate their anxiety level on a scale of 0 to 50.

There was a higher level of stress in all the children but the breastfed youngsters coped better.