Then God created the dog, and told him, "You will hold vigilance over
the dwellings of Man, to whom you will be his greatest companion.  You
will eat his table scraps and live for 25 years.   And the dog
responded, "Lord, to live 25 years as a dog is too much.  Please, no
more than 10 years." And it was so.

God then created the monkey, and told him, "You are Monkey.  You shall
swing from tree to tree, acting like an idiot.  You will be funny, and
you shall live for 20 years."  And the monkey responded, "Lord, to live
20 years as the clown of the world is too much.  Please, Lord, give me
no more than 10 years and it was so.

Finally, God created Man and told him, "You are Man, the only rational
being that walks the earth.  You will use your intelligence to have
mastery over the creatures of the world.  You will dominate the earth
and live for 20 years."  And the man responded, "Lord, to be man for
only 20 years is too little.  Please, Lord, give me the 30 years the
mule refused, the 15 years the dog refused, and the ten years the monkey
rejected."  And it was so. So God made Man to live 20 years as a man,
then marry and live 30 years like a mule working and carrying heavy
loads on his back.  Then, he is to have children and live 15 years as a
dog, guarding his house and eating the leftovers after they empty the
pantry; then, in his old age, to live 10 years as a monkey, acting like
a clown to amuse his grandchildren.