Why do we have baby teeth?

Humans get two sets of teeth because the jaw grows substantially between infancy and adulthood. Baby (deciduous) teeth begin forming before birth and start to erupt around six months of age. The 20 baby teeth are smaller to fit the small jaw and serve as spacers, keeping room for the 32 adult teeth developing in the bone beneath them. As permanent teeth grow, they gradually dissolve the roots of the baby teeth above, causing them to loosen and fall out, usually between ages 6 and 12. If a baby tooth is lost too early, the neighbouring teeth can drift into the gap and cause crowding later.