Love and arranged marriage

In the wake of yesterday's review of a paper on heritable variance in trait preferences realized in romantic partners I couldn't help but be intrigued by this new study out of PLoS ONE, Evolutionary History of Hunter-Gatherer Marriage Practices. It's actually a pretty thin piece of work in all honesty from what I can tell. They wanted to query ancestral ranges of marriage patterns by mapping the cultural variation in customs onto a phylogenetic tree. To generate that tree they took mtDNA sequences, which to me seems kind of old school. Using the cultural patterns present in living hunter-gatherer groups they presumed they could infer the ancestral state. So combining these two sources of data they generated this: