How come city states first developed in Eurasia and America within a couple of thousand years of each other?

Question

The earliest evidence of people in the American continents dates to 13,000 years ago. About 10,000 years later they started building cities. There's no evidence they had contact with other humans until the last thousand or so years.

They were presumably hunter gatherers who spread from the Eurasian and African continents. 13,000 years ago all humans were hunter gatherers.

Yet 9 to 11 thousand years later groups of humans that had no contact with other humans started independently building cities in Mesopotamia, North Africa, China, Pakistan and the Americas.

If the human species has been around for tens of thousands of years, why did cities first develop at roughly the same time in so many different places in the world?

Answer 1

the simple answer is "surplus"

cities are only possible when some people in the group are freed from food production/procurement... if you cant afford to have members of the community in full-time positions (religious, government, etc) then you cant have cities...

agriculture allowed people to have more food than was necessary to sustain the community, so it was unnecessary to have every single member of the group participate in food production...  

although hunter-gatherers were capable of hunting more food than they could eat, it was difficult to store things like meat and berries for long periods of time... once agriculture developed, grains could be stored as a surplus and people could become full-time specialists in things other than food gathering...

Answer 2

Humans in America almost certainly predate that, as the Clovis culture wasn't the first. There's some evidence that there were three previous population waves, Australoid, Ainu and European. They probably weren't as isolated as we think, as nicotine and cocaine have been found in Egyptian mummies, and one 12th century Hindu goddess statue is holding an ear of corn. There's some evidence the Chinese had contact with the Americas.

The history of city building probably goes back ten thousand years or more, it's just that a lot of prime stone age city sites are now under 100m of water. Also, if they weren't built of fired bricks or stone, they won't leave much trace. the Trypillian culture in Europe had pretty big cities(7,000 years ago), but they built with wood, so they didn't leave much trace behind.

Since the ice age ended, we've had an unusually stable climate compared to what came before. This has probably caused the explosion of civilizations after the stone age.

Answer 3

Perhaps you're on to something and you've marked a key aspect of human evolution.

Perhaps not.

Answer 4

Probably because you can't build a city, until you develop farming (A storable food source for more than a few seasons)!

Nomadic hunter/gatherers, or seafaring vessels, could have easily contributed to the spread of this "new" idea, called farming, and it gradually caught on, as many animals of prey for humans, were scarce, if not extinct, at the end of the last Ice Age!

Answer 5

Actually, theres archaeological evidence that people have been living in America for well over 20 thousand years.  Many with DNA links back to Europe and Greece.  Do your homework.