For hunter-gatherers living 10,000 years ago, domesticating plants and animals created a surplus of food that led to stability and advancement of technology and culture. But now as the world’s population blasts past 7.4 billion, land and water use has become constrained. Now we have factory farming, huge land & resource use  and  climate change. Kurzgesagt, in another excellent video, examines the cons (and pros) of meat and dairy consumption.