[fella]

Reading the accounts of the European explorers of the Americas show that the native tribes were in a constant state of war with each other. The Inca had just overpowered their neighbors to consolidate their empire and were embarked on a civil war. The Aztec were constantly raiding for human sacrifice. The North Americans were engaged in numerous inter tribal wars. It’s no wonder they didn’t have time to invent the wheel.

[Harmless Teddy Bear]

And European nations were also in a constant state of war with each other at that time. The only time there was peace in Europe was when they were under the heel of Rome and even then there were uprisings, civil wars and of course, invasions of and from other countries.

No wonder they didn't have time to come up with the concept of zero.

[Boogieman]

It was much the same for all prehistoric societies. Even the ones that didn’t engage in human sacrifice like the Aztecs still practiced constant war, slavery, mass rape of female captives, and often cannibalism.

[blam]

" It’s no wonder they didn’t have time to invent the wheel."

They had no draft animals.

The massive Inca sacrifices were about protein supply. Those sacrificed 'victims' carcasses was parcelled out and eaten.

All explained in this book: