Happy birthday Origin of Species!

Today marks the 150th anniversary of the publication of one of the most important books in the history of mankind. On the Origin of Species set out Darwin's incredibly simple idea that explained so much about life on Earth, and that forced humanity to see itself for what it is: just one small branch in the great tree of life. Happy birthday Origin of Species!

[And for any pedants out there, I know that the above image does not come from Origin.]