the evolution of social behavior was studied through an artificial selection experiment on female house mice. researchers found that some females defended their pups more aggressively than others, and that about 60% of the variation in this behavior was due to genetic differences. through selective breeding, females from the selected line were bred to produce more aggressive offspring, while control line females were bred randomly. after eight generations, selected females defended their pups significantly more aggressively, spending on average 15 seconds attacking intruders, compared to 3.77 seconds for control females. the brains of selected mice showed altered expression of genes, including neurotensin. these results show that social behavior evolves through the same mechanisms as other traits. the study demonstrates that maternal defense of pups can evolve in response to artificial selection. the graph shows the relative aggression of the selected line compared to the control line, calculated as the average attack duration divided by the control line's average attack duration. this study highlights the role of genetics in shaping social behavior and provides evidence that social traits can be influenced by selective pressures. the research was conducted by stephen gammie and colleagues, and published in 2006 and 2007. the study is part of a broader evolutionary analysis of social behavior, contributing to our understanding of how social traits are inherited and modified over generations.the evolution of social behavior was studied through an artificial selection experiment on female house mice. researchers found that some females defended their pups more aggressively than others, and that about 60% of the variation in this behavior was due to genetic differences. through selective breeding, females from the selected line were bred to produce more aggressive offspring, while control line females were bred randomly. after eight generations, selected females defended their pups significantly more aggressively, spending on average 15 seconds attacking intruders, compared to 3.77 seconds for control females. the brains of selected mice showed altered expression of genes, including neurotensin. these results show that social behavior evolves through the same mechanisms as other traits. the study demonstrates that maternal defense of pups can evolve in response to artificial selection. the graph shows the relative aggression of the selected line compared to the control line, calculated as the average attack duration divided by the control line's average attack duration. this study highlights the role of genetics in shaping social behavior and provides evidence that social traits can be influenced by selective pressures. the research was conducted by stephen gammie and colleagues, and published in 2006 and 2007. the study is part of a broader evolutionary analysis of social behavior, contributing to our understanding of how social traits are inherited and modified over generations.