I liked their conclusion:
Wall Street Journal said:...So by these various biological measures, are humans a pair-bonding or a tournament species? Neither. Across populations, men are roughly 10% taller and 20% heavier than women, need 20% more calories and live 6% shorter—more sexually dimorphic than monogamous species, less than polygamous species. Moreover, compared with, say, monogamous gibbons, human males have bigger testes and higher sperm counts…but pale in comparison to polygamous chimps. Measure after measure, it's the same.
It turns out that we aren't monogamous or polygamous by nature. As everyone from poets to divorce attorneys can attest, we are by nature a profoundly confused species—somewhere in between. http://online.wsj.com/news/articles/SB10001424052702304104504579374872476645630