This article brought a strange conundrum to mind. If Paleolithic man was in Australia 40,000 years ago, why were the aboriginal people still living in the Stone Age when the first Europeans arrived? There were advanced cultures in the Americas by 100 B.C.E., whose ancestors had arrived by 12,000 to 15,000 years ago.

Norbert Edwards
Buffalo, N.Y.

Why modern civilizations appeared where they did remains unclear. Aboriginal cultures were every bit as complex as those elsewhere and adapted to an incredibly harsh environment .—B. Bower