.....Trade was also a boon for human interaction.....
And still is.
My background is in trade. We still use most of the instruments and law that although refined, have been in existance for a very very long time.
In marine insurance there is the law of common responsibility that dates frome time immemorial. If a vessel get is trouble and it is necessary to jettison cargo to save the ship, all with cargo on the vessel ,or there insurers,share the loss.
The banking world although much refined still uses letters of credit to allow distant banks to settle accounts of their local merchants.
I read a book on the history of gold ( actually listen to it on CD) and learned that the domestication of the camel was a major technical development. The camel initially came into use hauling salt to the African Gold Coast and returning with gold. The salt and gold traded at some times ounce for ounce.
Prior to the camel, the transport was by bullock cart. The camel was 2 or 3 times faster extending the days journey to 20 or 30 miles instead of 10. The time invested in the trip was substantially reduced. The camels also took less water and feed and in addition to speed offered lower maintenance and operational cost.
"The salt and gold traded at some times ounce for ounce."
I've read that too.