Re: how many animals other than humans have lips?

	This is a very challenging question since it really asks for the 
definition of a lip.  While my dictionary was completely unhelpful, my 
histology text was much more informative.  
	The human lip is a zone of transition between the outer thick layer of 
skin (epidermis) on the chin and the mucous bathed epithelium of the mouth.  
This zone of change is called the vermillion (red) zone.  This area is red 
because the skin is very thin and in close juxtaposition with blood 
vessels.  In addition, this zone is special in that it does not possess 
hair follicles (thank God!) nor sweat glands.  However, the text noted that 
sebaceous glands, usually associated with hair follicles, have occasionally 
been found in lips despite the absence of the latter.
	The lip is one of the more sensitive part of your skin.  This is 
probably why people kiss lips to lips.  We use our lips to feel how hot a 
cup of coffee is or how cold an ice cube is.  One amazing test that we did 
in my high school physics class isto sense kinetic energy with your lips.  
To do this, just stretch a piece of rubber band between your two hands as 
far as you can and bring the piece to your lips.  You will feel heat on the 
elastic band.  While we witnessed the change of potential to kinetic 
energy, I was more amazed that my lip could detect heat that my hand coul 
not!
	The lip is truly an amazing piece of anatomy.  The answer to your 
clever question is that the vermillion zone is unique to humans.  If one 
defines a lip as that zone, then no other animals besides human possess 
lips!  
	Alas to dog and cat lovers! When you think you are kissed by them, you 
really are muzzled.  The jowls of these animals abruptly change from their 
hairy skin to the mouth epithelium, without transition zone.

Reference : Color Atlas of Histology,1990, J.N. Gardner, editor. Williams 
and Wilkins, Baltimore.