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Science Studies Examine Archaic Admixture in West Africans, Variant Linked to Cannabis Dependence Risk

By studying the genomes of modern-day West Africans and two species of archaic humans, scientists from the University of California, Los Angeles, have discovered evidence of interbreeding between the ancestors of West Africans and an unidentified group of archaic humans. As reported in Science Advances, the researchers compared the genomes of four populations of West Africans with those of Neanderthals and Denisovans, two species known to have bred with early humans. They document introgression in the present-day populations from an archaic population that likely diverged before the split of modern humans and the ancestors of Neanderthals and Denisovans. "The signals of introgression in the West African populations that we have analyzed raise questions regarding the identity of the archaic hominin and its interactions with the modern human populations in Africa," the authors write. Further genomic analysis will be required to gain a detailed understanding of archaic introgression and its role in adapting to diverse environmental conditions, they add. GenomeWeb has more on this, here.

A genetic variant common in European populations may predispose adolescent women to cannabis dependence, according to an animal study appearing in Science Advances. Weill Cornell Medicine scientists and collaborators focused on genetic variation in the enzyme fatty acid amide hydrolase (FAAH), which regulates endocannabinoid molecules. In avoidance experiments, the team found that young female mice with a particular FAAH variant showed a preference for a chamber where they had previously received injections of THC, the psychoactive ingredient in marijuana. In comparison, both female mice lacking the variant and adolescent male mice avoided the chamber. In studies where mice were given cocaine instead of THC, all animals showed a preference for the treatment chamber. "These findings suggest that this endocannabinoid genetic variant is a contributing factor for increased susceptibility to cannabis dependence in adolescent females," the study's authors write.