>> The factor in question was the careful use of 'pastoralism' with   
   >> domesticated animals to retard the desert.   
   >   
   >I read it but it does not say exactly what they did to achieve this?   
   >Seasonal movement and selective grazing might reduce the problem but it   
   >does not remove the problem.   
      
   That is the problem with science news accounts, they might not ask the same   
   question of the research material as we might want.   
      
   Here is another account that has more detail along the lines of your   
   question:   
      
   https://phys.org/news/2018-10-humans-onset-sahara-years.html   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)