In Nature Ecology & Evolution this week, an international research team presents the results of genomic and other analyses that suggest Theobroma cacao — the plant used to make chocolate — was domesticated earlier and in a different region than currently believed. While existing archeological evidence indicates that cacao was domesticated 3,900 years ago in Central America, the scientists identified the plant in three independent lines of evidence — cacao starch grains, residues of the T. cacao-specific alkaloid theobromine, and ancient DNA — in artifacts from a site in Ecuador that dates back 5,300 years. "To our knowledge, these findings constitute the earliest evidence of T. cacao use in the Americas and the first unequivocal archaeological example of its pre-Columbian use in South America," the authors write.
And in Nature Genetics, investigators from Amgen subsidiary Decode Genetics and collaborators report the discovery of new osteoarthritis-associated genetic variants through a meta-analysis of samples from Iceland and the UK Biobank. Among the findings are 16 novel loci — 12 for hip osteoarthritis and 4 for knee osteoarthritis — two of which are rare or low-frequency missense variants. The researchers also discover that a large fraction of the osteoarthritis risk variants associate with height, with the risk alleles associating with either increased or decreased height, "suggesting that these associations disturb pathways that affect the growth and differentiation of bone and cartilage in ways that affect height both positively and negatively." GenomeWeb has more on this, here.