Guest above. Nits are the eggs of lice. When monkeys or apes are grooming one another,they are ridding each other of body insects such as fleas and lice and their eggs. Thus nit-picking. They also are removing flakes of salt and dead skin.

Obviously a human nit-picker is one who indulges in criticizing the most trivial,miniscule and least important of another's mistakes. Which has nothing to do with weaving. Maybe.

rr