Bison Purity

Bison at Prairie State Park, MDC

When humans first arrived in North America, bison roamed much of what is now the United States, upwards of sixty million of them by some estimates.  By the end of the nineteenth century there were only around 400.  This was a result of hunting pressures to feed settlers and the building of the railroads and the value attached to their hides and eventually even their bones.

Conservation efforts since the turn of the century have restored herds into some of their native range as well as some bison being raised on farms and ranches.  DNA studies now show that few of the restored bison herds are "pure." Over the last 200 years, most bison mated with a cow along the way.  Bison have their needs, you know, and cattle were much more available.

A recent article in the Wall Street Journal* (of all places!) called attention to the fact that the herds of bison are being culled of members which show the contamination of their genes with cattle genes.  Those impure bison are sold to become steaks and burgers in an attempt to promulgate pure bison. With improving DNA techniques however, we may well find that there is a little bit of cow in every bison.

The quest for pure bison stock has led to a great deal of tail pulling.  After a calf is put in a restraining pen, special pliers are used to grab a bunch of tail hairs to study its DNA.  Since their hairs are firmly attached, this startles (to put it mildly) the 300 pound calf and puts the puller at risk from the pullee.  Rapid extraction and retreating is the preferred technique as "the bison will start pooping and their tail acts as a manure spreader."

So the decision of what to do with the impure herds remains.  A purist would eliminate any "genetically tainted" members of the herd.  Another school of thought voiced by ecologist Rurik List is that "If they look like a bison, behave like a bison and live in the historical range, let's keep them."

The problem with this search for purity is that the gene pool is being drastically diminished by killing and eating bison with miniscule amounts of cattle DNA.  The smaller the pool of animals left to interbreed, the less protection there is from disease and genetic errors along the way.

What if advanced DNA techniques show that there are no "pure" strains left?  Somewhere we have to draw a line between the ideal and the practical.  Sometimes perfect becomes the enemy of good.

* Wondering If That's A Genuine Bison?  Try Pulling Its Tail, Wall Street Journal, November 26, 2011.