Lizardworld

I am not speaking of randomness, but of the central principle of all history-contingency. A historical explanation does not rest on direct deductions from laws of nature, but on an unpredictable sequence of antecedent states, where any major change in any step of the sequence would have altered the final result. This final result is therefore dependent, or contingent, upon everything that came before-the unerasable and determining signature of history....Replay the tape a million times from a Burgess beginning, and I doubt that anything like Homo sapiens would ever evolve again.
(Stephen Jay Gould, Wonderful Life)


With Dr Who looking at the old monsters Silurians again in "The Hungry Earth"; I've taken the late Stephen Jay Gould's idea of "contingency" (most represented in his book "Wonderful Life") - that if life's tape was replayed, there are so many unpredictable factors, that nothing would quite be the same. Instead of humans, we might have homo reptilia!

Lizardworld
 
The contingent facts of history
Seem set in stone, a progression
A ladder in time for all to see
Upward motion, this impression.
 
But rewind the tape, play again
See how the die is now thrown
There may be life, but not men
Chance can certainty dethrone
 
Now lizardworld may emerge
Reptile bipeds walk the earth
Mammals wiped out in purge
Different intelligence rebirth
 
It is a truly wonderful life
Time splits upon luck's knife.