So, great news! All mammal milk (including that of humans) is modified, nutrient dense sweat!
Monotremes (like the echidna and platypus) do not have specialized nipples but instead have patches of skin that ‘sweat’ milk to keep their eggs moisturized, and then to feed their young, which lap it off of their uh…skin.
Paleontologists think that this feature probably evolved from either non-mammalian synapsids or early mammals keeping their eggs nice and supple (instead of the hard-shelled eggs of birds) and eventually the childes just…. started….licking it, and I guess it helped them out nutritionally.
Therians (Mammals that have nipples; placentals and marsupials) have glands/nipples specifically for the purposes of nursing their young with this funky modified sweat we call milk, but yeah. It’s sweat. It’s funky nutritious sweat.
queerlybeloveds 