Disease-causing viruses engage their hosts in ongoing arms races: positive selection for antiviral genes increases host fitness and survival, and viruses in turn select for mutations that counteract the antiviral host factors. Studying such adaptive mutations can provide insights into the distant history of host-virus interactions. A study of antiviral gene sequences in African monkeys suggests that lentiviruses closely related to HIV have infected primates in Africa as far back as 16 million years.
The hippocampus in the brain’s temporal lobe is responsible for more than just long-term memory. Researchers have for the first time demonstrated that it is also involved in quick and successful conflict resolution.