premise: howling is a kind of sound sent2: sound can be used for communication by animals sent3: animals usually keep away from danger or problems sent4: warning can be used to indicate danger or problems sent5: a wolf is a kind of animal sent6: a warning is used to warn animals sent7: warning is a kind of communication sent8: establishing a territory requires keeping other animals away.
hypothesis: earth's tilt on its rotating axis causes the amout of daylight to change