Recruiting another life-form to babysit

Henry must have more bacteria in his gut than he knows what to do with. This piece in the NY Times discusses breast milk sugars that give infants a "protective coat" in their guts. Those science guys are learning that parts of breast milk that cannot be digested by babies, and previously thought to be extraneous?, are actually serving a purpose!

"Dr. German sees milk as “an astonishing product of evolution,” one which has been vigorously shaped by natural selection because it is so critical to the survival of both mother and child. “Everything in milk costs the mother — she is literally dissolving her own tissues to make it,” he said. From the infant’s perspective, it is born into a world full of hostile microbes, with an untrained immune system and lacking the caustic stomach acid which in adults kills most bacteria. Any element in milk that protects the infant will be heavily favored by natural selection.

“We were astonished that milk had so much material that the infant couldn’t digest,” Dr. German said. “Finding that it selectively stimulates the growth of specific bacteria, which are in turn protective of the infant, let us see the genius of the strategy — mothers are recruiting another life-form to baby-sit their baby.”"