Beer festival symbolism

i was invited to a beer festival by some friends early this year and upon seeing the commemorative glasses for the 33rd annual cambridge (england) beer festival i had to get one.

below are pictures of this obviously masonic design.
the small text not picked up by the camera reads 'natural selection' and opposite to it reads 'charles darwin'.
I thought you may be interested to see yet another example (among a deluge) of the influence freemasonry has on our lives at every level.

i have a neck injury that prevents me typing much more, but i leave it up to your discearnment to identify the symbolism and its meaning.

http://img321.imageshack.us/img321/8696/234156ai6.jpg
http://img451.imageshack.us/img451/7435/234222jq7.jpg
http://img168.imageshack.us/img168/9638/234301qm8.jpg
http://img168.imageshack.us/img168/1223/234336oa4.jpg
http://img168.imageshack.us/img168/1223/234336oa4.jpg