“Man is the only creature endowed with the power of laughter.”
You are wrong if you think that people are single from animals who can laugh.
check "laughing rooster" in youtube :D :D :D :D :D
apes are ancestor of human being.
"Apes Giggle Like Humans"
<a href="http://www.youtube.com/watch?v=SnbKzDkZktQ">http://www.youtube.com/watch?v=SnbKzDkZktQ</a>