Mass extinction of animals that had been food could have made agriculture necessary, as it was for these: 
http://www.independent.co.uk/life-style/house-and-home/gardening/chelsea-exhibit-reveals-a-hatred-of-horticulture-1981135.html
and http://www.thunderbolts.info/home.htm
or it could have been the wrong kind of immigrants.

William






Emiliano Bussolo wrote:
> 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
>>>       
>
>
>