Nervousness, excitement, anger, and territorialness are the most popular stimuli for animal aggressiveness.

courage; aggressiveness;

a feeling and it shows aggressiveness

Evan Frank Mottram Durbin has written:

'Personal aggressiveness and war' -- subject(s): War, Aggressiveness

Weight training does not cause aggressiveness, however many weight lifters who are unsatisfied with the results end up turning to steroids.

Steroids CAN cause aggressiveness, health problems and even sexual disfunction.

However the men who use steroids will deny that.