It’s really weird that we just drink the milk that cows make for their babies, right? Why do we do that?

Because they didn’t put up much of a fight, according to TED-Ed. A recent lesson from Jonathan J. O’Sullivan on the science of milk says cows were the easiest mammals to domesticate out of the milk-producers we could have used, and the fat content of their milk is similar to what human mothers make.

Read: Signs You Are Lactose Intolerant

We are practically addicted to milk from the moment we leave the womb, and for good reason. TED-Ed explains that “since it has all of the vital nutrients for development and growth — proteins, carbohydrates, fats, vitamins and minerals, and water — milk is the only thing a baby even needs to ingest for the first six months of life.”

That jibes with what the World Health Organization recommends for breastfeeding mothers: giving the baby breastmilk exclusively for six months, then starting to add other foods.

But as we get older, we move to different species of milk. It doesn’t even have to be from a female — according to TED-Ed, certain male goats and cats can also make milk. They do it in the same way females do: cells absorb all the good stuff that makes milk and then “synthesize tiny droplets of fat” that combine and are eventually secreted. They just may not make the same volume as their female counterparts. Male dayak fruit bats lactate but Boston University notes that they produced very little milk, especially when compared to females of their kind.

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But most of the world sticks to the mainstream milk producers. The Food and Agriculture Organization of the United Nations breaks down milk consumption around the world, showing that 85 percent of it comes from cattle, with buffalo, goats, sheep and camels making up most of the remainder.

See also:

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