The path of civilisation

For most of history, waterborne transport was easier and quicker than movement overland.

Scale was highest in the vicinity of waterways, where people were more mobile and could get in touch with each other more easily.

The first civilisations or city-level eigenmodes ("civilisation" = "city-based society") emerged along rivers. These included the Nile valley (Egypt), the Tigris-Euphrates basin (ancient Iraq or Mesopotamia), the Indus valley (or Harappan civilisation) and the Yellow River (China).

Early state formation was along rivers, where mobility, i.e. scale, tended to be higher

As the technology of water transport improved, the cutting edge of civilisation shifted from rivers towards seas, notably the Mediterranean...

The 'middle sea'--a relatively benign, tideless sea--facilitated societal intercourse and was the focus for the next stage of civilisation

...and then from seas towards oceans...

Improvements in navigation took trade and interaction to the next higher level, favouring those regions bordering the Atlantic ocean

This logic was interrupted by the development of railways, highways and air transport, all of which diminished the advantage of societies bordering on water.

As technology continues to develop and humans build a space-going civilisation, the advantage will shift again towards those regions where it is easiest and cheapest to launch rockets into orbit. These are the equatorial regions where the boost from the earth's rotation is biggest.

As humanity moves into space, scale will be highest along the equator, where launching rockets is easiest, and the centre of civilisation will move once again, towards this belt

That civilisation is most advanced where scale or interactivity is greatest means that, if there are other intelligent races beyond this planet, then they are most likely to be found in the vicinity of galactic cores, where stars are closest. I have stated before that I think humans are probably alone in the universe but, on the basis of this historical theory, I would urge SETI researchers, if they are going to look for extraterrestrial life, to concentrate their attentions where worlds are densest.