Horse domestication changed the course of human history, and the starting point seems to be at least 5,500 years ago with the Botai people, who lived in what is now northern Kazakhstan. Scientists found evidence of mare milk in nine ancient cooking vessels from the area, as well as damage in 15 horse jaws from bits or bridles, suggesting that the Botai had horse farms. Their findings appear in the March 5 Science. —David Biello


Cocktails of antiviral drugs can suppress the AIDS virus and provide a boost to the immune system's T cells, which are depleted by HIV. In some patients who take the cocktail, however, the T cell count remains low, making them vulnerable to opportunistic infections. In a small, early-stage clinical trial, French researchers found that interleukin-7, a growth factor, increased the number of active T cells, suggesting that intermittent shots of the compound could keep an HIV-infected immune system working. The findings appear in the March 16 Journal of Clinical Investigation. —Philip Yam


Ice cores not only contain evidence of past atmospheric conditions, but they also may hold clues about astronomical events. In an Antarctic ice core, researchers in Japan discovered spikes in the concentration of nitrate ions. The spikes coincide with two stellar explosions in the 11th century: one in 1006 and the other in 1054, which created the Crab nebula. Gamma rays from these supernovae could have boosted atmospheric levels of nitrogen oxides that got trapped as nitrate ions in air bubbles in the ice cores. —John Matson