The issue focused on question of responsibility for evolution The researchers conducted three experiments on 54 mice and 46 rats to investigate whether exposure to artificial rewards led to stronger aggression or depression in mice or rats exposed to rewards from strobe lights and bottle treats. All mice received regular rewards from routine hunting activities as well as everyday rewards like fruit and vegetables. By measuring daily intake of sucrose and glucose and comparing these levels with animals exposed to artificial rewards, they showed that mice exposed to artificial rewards showed stronger aggression than mice exposed to everyday