http://www.williamcalvin.com/bk2/bk2ch1.htm
http://www.williamcalvin.com/bk2/bk2ch4.htm
http://www.sciencedaily.com/releases/2013/06/130626142710.htm
http://what-if.xkcd.com/44/
http://ecodevoevo.blogspot.com/2009/10/prehistory-of-throwing-things.html
http://williamcalvin.com/1980s/1983JTheoretBiol.htm
http://www.williamcalvin.com/1990s/1993Unitary.htm
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571064/
http://www.bbc.com/news/science-environment-23061016
http://cashp.columbian.gwu.edu/neil-t-roach-evolution-throwing