Alexis Madrigal of The Atlantic argues that dairy breeding is the perfect lens through which to further the study of genetics. Meticulous breeding records and centralized genetic information has been kept on a number of bulls since the 1960s and there is a small and easily measurable number of traits to follow such as milk production, protein in the milk, and udder quality.

One reason for the change in breeding emphasis is that our cows already produce tremendous amounts of milk relative to their forbears. In 1942, when my father was born, the average dairy cow produced less than 5,000 pounds of milk in its lifetime. Now, the average cow produces over 21,000 pounds of milk. At the same time, the number of dairy cows has decreased from a high of 25 million around the end of World War II to fewer than nine million today. This is an indisputable environmental win as fewer cows create less methane, a potent greenhouse gas, and require less land.

While we may worry about the use of antibiotics to stimulate animal growth or the use of hormones to increase milk production by up to 25 percent, most of the increase in the pounds of milk an animal puts out over the pastoral days of yore come from the genetic changes that we've wrought within these animals. It doesn't matter how the cow is raised -- in an idyllic pasture or a feedlot -- either way, the animal of 2012 is not the animal of 1940 or 1980 or even 2000. A group of USDA and University of Minnesota scientists calculated that 22 percent of the genome of Holstein cattle has been altered by human selection over the last 40 years.

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