primary: only get once from animal ex, meat, blood, hid, furs, sinew, etc.
secondary: can repeatedly get from the animal ex, milk, wool \[og sheep were hairy not wooly\], horse power \[pull ploughs, carts and so on\], dung, etc.
most likely domesticated for secondary ex, dogs domesticated 20 000 - 30 000 ya upper Paleolithic for hunting, guarding and sled pulling