It’s hard to understate the importance of your mom. Mother’s milk instills lifelong flavor preferences and populates your microbiome with bacterial life that defines you as an adult. The maternal stuff of life also gives your body its first defenses against the onslaught of childhood infections. When infants don’t receive those immunological protections, and instead drink formula made with tainted water (an incredibly common problem in the developing world), it can have lethal consequences.
The other problem: Not all milk is created equal. "Human breast milk is very different from cow or goat milk," Elizabeth Maga, an animal scientist at University of California-Davis, says. "Human babies need different type of nourishment than animals." (Indeed, as J. Bruce German, a food chemist and milk expert also at the University of California-Davis, says, "It’s even difficult to extrapolate some of the benefits of human milk from one mother to another.")
In other words, even when human breast milk isn’t available, we probably won’t be bringing back the days of wet-nursing babies on non-human bovine or caprine surrogates any time soon—as the Greek god Zeus was said to have done as a baby or as 19th century Catholic nuns in Italy and France did with abandoned children. At least, on regular goats and cows. There may be some better options, soon, because Maga and her colleagues have successfully added human genes for some of the enzymes and proteins found in breast milk to domesticated mammals.The transgenic dairy goats can make milk with up to about 60% of the lysozyme and lactoferrin found in mother’s milk, which means a longer shelf life (these chemicals kill pathogenic bacteria) and also a faster cheese-ripening process (they kill off the milk’s beneficial bacteria sooner). So far, though, neither babies nor researchers have actually tried the modified milk, but baby pigs have. In a recent study on the toddler equivalent in pigs, Maga says, "We found that pigs can resist infection by E. coli, so we’re using them as a model to treat and prevent childhood diarrhea."
Since 1989, the dawn of the transgenic barnyard, when a Scottish research created Dolly, the first transgenic mammal that produced a blood-clotting hemophilia drug, scientists have created cows that can resist udder infections and cows that can produce milk designed to ward off the ill effects of chemical warfare. Drugs derived from transgenic goat’s milk and, more recently, genetically modified carrot cells have both been approved by the U.S. Food and Drug Administration, but opposition to genetically modified food, like the AquAdvantage salmon, probably means food from these animals won’t make it into the mouths of hungry Americans any time soon (though a lot of genetically modified food does.)
Still, there’s a chance that a modified milk could serve an important humanitarian function in places where children die from simple, treatable ailments. "Our goats are not going to cure diarrhea everywhere, but it could make things better," Maga says. "It shouldn’t be written off just because it’s genetically engineered."