The tidy African national boundaries

I was wondering why African nations have such tidy boundaries.. where is the trace of nature?

(See the boundaries between

Italy & France, Switzerland, Austria

China & Pakistan, India, Nepal)

Then I found this

http://en.wikipedia.org/wiki/Economy_of_Africa#Borders

In the Scramble for Africa, national boundaries in sub-Saharan Africa were established by Europeans using latitude and longitude rather than natural borders. This separated population centres from their supplies of food and natural resources. The artificial borders of modern African states cut across cultural, tribal, linguistic and religious boundaries, creating ethnic and religious cleavages which impede national unity and induce internal violence.

Is this still sort of natural? since the tidy borders are mostly within Sahara.. -__-