Why can animals foster different species with their breastmilk but humans only really do well with human breastmilk?

Question

Why can animals foster different species with their breastmilk but humans only really do well with human breastmilk?

In: Biology

Answer 1

Before the invention of baby formula human infants were commonly fostered on goat’s milk and sheep’s milk, and it was not unheard of for them to be fostered on cows milk or even horse milk. Basically all domesticated animals that we harvest milk from have been used to feed human infants. But they do best on their own species milk (as most species do) and when that was not possible with the mother for one reason or another a wet-nurse was fairly easy to hire and in modernity we have formula that can be purchased.