Finish: River out of Eden

Yesterday, I finished reading River out of Eden. It is easier to read than God Delusion or Selfish Gene. Is it because I have been preparing myself by reading the hard stuffs before?

Some interesting ideas from the book:

- if you and your spouse do not share a common ancestor, that means you and your spouse belong to different family trees whose have different root but somehow evolved similarly so that the current generation can copulate and give birth to a child. Impossible.