Nitya Jain & W Allan Walker Nature Reviews Gastroenterology & Hepatology
Evolutionary development of the mammary gland has driven mammalian survival.
Human milk has a choice of 200 – 250 unique oligosaccharides which form its third largest solid component. These oligosaccharides are partially or not digested by the infant and provide a carbon source for the intestinal flora of Bifobacterium Infantis. Genomic sequence of this strain has revealed 700 unique genes and selective pressures for evolution may be expected to continue.
German J B, 2008, Dept. Nutrition University of California, Davis
Also see Pediatric Research 2015 January Vol. 77 (1) p. 220 Walker WA and Lyengar RS (Open access Harvard Medical School)