Testosterone influences sex drive and sexual acts, searching for mates, territorial behavior such as urine marking, and aggression between males. Testosterone may also affect confidence and the role of the experience of fear in some dogs. Removing the testicles removes the primary source of testosterone in the body, resulting in changes in sex drive, hormone-related behaviors, and hormone-related health concerns. Neutering will result in a reduction in sexual behaviors, seeking mating opportunities, and urine marking. Some of these sexual behaviors can be dangerous, resulting in fights between dogs, roaming and being injured by cars, fences, poisons, and other threats, and neutering will decrease these risks. There is conflicting evidence at this time, but it is possible that neutering males before puberty may correlate with increased aggression directed toward strangers and strange dogs. Neutering was historically considered a crucial part of therapy for all dogs displaying unwanted aggression.