The photo displayed is linked to a FaceBook posting which I recently received. As I sometimes do (although probably not as frequently as I ought to) I searched a bit further to learn more about this strange term deuterostome.
There were two surprising things I learned, the first being that there is nothing at all rare about deuterostomes. Almost all of us humans and other mammals are the same even if we've never heard the term before.
The other surprising thing is that while the sign above might be amusing it is based on a complete misunderstanding of the process of development which we go through. We deuterstomes do not start out as "assholes," but rather as a hollow ball which at some point develops a single hole which is the anus, followed by a second hole which is the other end of the digestive track: the mouth. The fact that the anus develops first and the mouth second is what distinguishes a deuterstome from its opposite counterpart called a protostome.
So the correct interpretation of the facts is that we develop assholes first followed by our mouths, not that we "are" simply assholes to start with. Of course, if you still wish to stick to the illogic expressed in the sign, writing this blog would likely mark me as an exceptionally arrested deuterostome!