Homo sapiens is a small-group social animal that physically seems to be limited to personal relationships with a few individuals.   Nonetheless humanity is struggling to deal with societies of billions as  human technologies now pose existential threats tied to those numbers.  In The Human Swarm Mark Moffett presents an intriguing overview of the biological roots and cultural evolution of this now-critical situation.” 

—Paul R. Ehrlich, Bing Professor of Population Studies at Stanford and author of The Population Bomb and Human Natures