Thanks for this comment. Humans certainly are predisposed to equality, but it might better be termed as "reciprocity".

You may have read a very famous book by Jared Diamond called "Guns, Germs and Steel" which won the '98 Pulitzer in nonfiction. A lot of these conversations about wealth and equality (and why they are not equal among different sets of society, or among countries) are addressed in the book. This is definitely a life-changing read worth looking into.

Because you might be really (really) busy, I also recommend a short article that sumarizes a lot of the themes in an interesting way: http://www.umass.edu/preferen/gintis/SocJusticeRes.pdf Cheers - Jamison