[quote]much like the idea that Africans willingly sold other Africans into slavery[/quote]

Not according to the rapid white supremacists in the Nigerian government.

http://www.theguardian.com/world/2009/nov/18/africans-apologise-slave-trade

You've only proven my point, with no incentive to develop the very helpful wheel any further, they would not have. Thus the long term material impact of colonialism.