Is animal milk healthy?

It is unnatural for humans to drink milk.

Question: Is animal milk healthy?
Position‹4 of 4: It doesn't matter, we shouldn't drink milk regardless.
Argument‹2 of 3›: It is unnatural for humans to drink milk.

Other mammals do not drink milk past childhood, and it's unnatural that we do.

The argument

The argument turns on what milk is for. Milk is produced by mammals to feed their young; it is the mechanism that carries an infant through the period before it can eat what adults of its species eat. That is why no species of animal drinks milk after infancy naturally. Once young mammals grow up they stop drinking it and — the other half of the same arrangement — the mothers stop producing it. Weaning is not a habit that happens to fall away but the completion of the process milk exists to serve. Human adults who drink milk depart from that arrangement in two ways at once. The first is a matter of timing: they go on consuming milk long after the stage of life it was made for. The second is that the milk is taken from another species altogether. Either departure would be a break with the natural order on its own; together they describe something that occurs nowhere else among mammals. The biology bears this out rather than contradicting it. Only a genetic mutation, which much of the world's population does not possess, allows us to drink cow's milk at all. That distribution is telling: if drinking milk into adulthood were simply the human condition, the capacity to do it would not be the exception carried by some populations and absent in others. And the substance itself is calibrated for a different animal. Cow's milk is meant for infant cows, which have largely different digestive systems and nutritional needs than humans do. Whatever it contains was assembled for a calf. Taken together, the case does not depend on establishing that milk is unhealthy. Even if the health question were settled favourably, it would remain unnatural for humans to drink it, and on this view that is reason enough not to.

Premises

[P1]No species naturally consumes milk after infancy, and milk is biologically intended to nourish the young of the species that produces it. [P2] Cow's milk is specifically suited to the digestive systems and nutritional needs of infant cows, not adult humans, and only a genetic mutation absent in much of the world's population allows humans to digest it. [C] Therefore, regardless of health claims, humans should not drink animal milk because doing so is unnatural.

Counter-arguments

-Many humans have evolved to drink cow’s milk, and evolution is a natural process. -It doesn’t matter if it is natural or not, drinking milk can still be beneficial to humans.

Rejecting the premises

[Rejecting P1] The premise appeals to nature, which does not establish what is good — cooking, clothing, spectacles and antibiotics all fail the same test — and the factual claim is loose, since adult mammals will drink milk where it is available. [Rejecting P2] Lactase persistence is an evolved adaptation that arose independently in several populations rather than a defect, and evolution is itself a natural process, so the mutation tells against the premise rather than for it; the digestive difference concerns lactose tolerance specifically, not a general unsuitability. [Rejecting C] Even granting that the practice is unnatural, that is a claim about origin rather than effect — the question asks whether milk is healthy, which naturalness does not answer.

Framing

Something that does not occur in nature is unnatural and wrong.