View full lesson: http://ed.ted.com/lessons/the-science-of-milk-jonathan-j-o-sullivan The milk industry produces in excess of 840 million tons of products each year. Why do humans drink so much milk? And given that all mammals lactate, why do we favor certain types of milk over others? Jonathan J. O’Sullivan describes how milk is made. Lesson by Jonathan J. O'Sullivan, animation by TED-Ed.