The Anasazi did manage to construct in stone the largest and tallest buildings erected in North America until the Chicago steel girder skyscrapers of the 1880s.

All recognized famous inventors had capable predecessors and successors and made their improvements at a time when society was capable of using their product.

Forced to choose between limiting population or trying to increase food production, we chose the latter and ended up with starvation, warfare, and tyranny.

Throughout history, adultery has had few rivals as a cause of murder and human misery. The reason we tend to resemble our mates is that many of us are looking for someone who reminds us of our parent or sibling of the opposite sex, who in turn resembles us.

Technology causes problems as well as solves problems. Nobody has figured out a way to ensure that, as of tomorrow, technology won't create problems. Technology simply means increased power, which is why we have the global problems we face today.

Although native Africans domesticated some plants in the Sahel and in Ethiopia and in tropical West Africa, they acquired valuable domestic animals only later, from the north.

History followed different courses for different peoples because of differences among peoples' environments, not because of biological differences among peoples themselves