"Other researchers have suggested that fresh milk provided a more pure fluid alternative to contaminated water sources in arid environments" http://www.npr.org

"Other researchers have suggested that fresh milk provided a more pure fluid alternative to contaminated water sources in arid environments" http://www.npr.org/blogs/thesalt/2012/12/27/168144785/an-evolutionary-whodunit-how-did-humans-develop-lactose-tolerance http://www.npr.org/blogs/thesalt/2012/12/27/168144785/an-evo... "Milk is uncontaminated by parasites, unlike stream water, making it a safer drink." http://darwinstudents.blogspot.com/2009/02/evolution-of-lactose-tolerance.html http://darwinstudents.blogspot.com/2009/02/evolution-of-lact...