So, according to this Velikovsky the reason for the neolithic revolution
would be cataclysms? In which sense?
What has to do "mass extinction" with agriculture? 

Sorry but I'm not sure I understand what you mean.

>>Cataclysm. See Velikovsky's "Worlds in Collision"; J. McCanney shows 
>>that collision isn't needed, as a gravity wave from a close approach 
>>combined with the flood is enough to cause mass extinction.

>>Willoiam