The Need For Genetic Diversity In All Species

When I read and wrote about Bill Best's book, "Kentucky Heritage Seeds Growing, Eating, Saving", I learned a great deal and was also reminded of a basic principal I learned many years ago.  That principal is the fact that we need as much genetic diversity in all species,plants, animals, vegetables, as we can get.  As gene pools narrow, the tendency for minor genetic problems becomes intensified and the more narrow a gene pool gets the more likely it becomes that a specific species will become extinct.  Seed savers, zoo keepers, and farmers all work all around the world to keep as many species as possible with a broad, diverse genetic base.  This quote from the website "The Teacher Friendly Guide To The Evolution Of Maize" puts it nicely into a nutshell:  

"Genetic diversity is important because it helps maintain the health of a population, by including alleles that may be valuable in resisting diseases, pests and other stresses. ... If the environment changes, a population that has a higher variability of alleles will be better able to evolve to adapt to the new environment."

Bill Best talks in his book about how seed companies, agricultural companies, and others, have weakened and harmed many different types of vegetables by breeding for long shelf life, mechanical harvestability, and other traits.  What he says is that they have created nice, round, thick skinned tomatoes with a shelf life of a week or more but those tomatoes have no flavor and also tend to lose specific combinations of nutrients which are important to both animals and people.  In my life, I have also seen problems arise from the fact that breeders of horses, Thoroughbreds and Standardbreds specifically, bred for speed with little concentration on breeding for other traits.  As a result, high numbers of both breeds have a tendency to be mean and aggressive.  I have actually known several Thoroughbred stallions who had successful careers as race horses and were nearly too mean to be handled on the farm and in the breeding shed.  

I knew several blind individuals in my young days and had a girlfriend who was blind and owned a Seeing Eye Dog from the wonderful, non-profit, Seeing Eye.  The Seeing Eye is the first and definitely the best of the organizations which breed and place guide dogs.  They invented that effort and have always been the organization which their imitators fail to equal.  But The Seeing Eye, for several years, sought to breed a specific type of German Shepherd which was medium in size, highly intelligent, and very docile in disposition.  Over time, they found they were breeding far too many dogs with significant health problems  such as hip dysplasia.  They were actually forced to seriously alter the gene pool in the dogs they had been breeding with too narrow a gene pool.  They brought in other dogs, diversified the gene pool, and created a much better dog which was not exactly what they had originally sought.  

Dalmation dogs, which were bred for years to produce their famous spots now have a tendency to breed deaf dogs.  Nearly all short faced dog breeds such as pugs, bull dogs, and a few other breeds have a very high rate of breathing and tooth structure problems.  Humans, when we seek to play God with our plants and animals have consistently made matters worse.  Now, in this age of genetic alteration, we are headed into a period when we are likely to further damage many species of plants and animals and even to create problems in humans if we allow scientists to go beyond the range of common sense. 

There is also a concept called hybrid vigor which has been used for hundreds of years by farmers and other breeders of plants and animals to produce better plants and animals.  It is described in this manner: 

Hybrid vigor is the increase in certain characteristics like growth rate, size, fertility, yield etc. of a particular hybrid organism over its parents. Hybrid vigor is also known by some other names, including heterosis and inbreeding enhancement.

 Hybrid vigor is what we need in both plants and animals. It can also come in handy in humans.  As we diversify any gene base, we make the resultant offspring better.  We create plants with flavor, texture, productivity, and other qualities which are highly effective for the world at large.  When we breed cattle, hogs, sheep, and other food animals with diverse gene pools, they have better feed conversion rates, better taste, better body structure, and better reproductive rates.  As a civilization, we are facing a scientific and ethical nightmare if we allow too much narrowing of the gene pools in plants and animals.  We must work as individuals and societies to protect the diversity of all these populations and species.  Our increased knowledge of genetics has placed us at the edge of a scientific precipice and we must not allow ourselves to fall over the edge.  

Roughly twenty years ago, my wife was a patient at the National Institutes of Health in Bethesda, Maryland, for several years during the time when the human genome research was in its infancy.  We would travel to NIH about two or three times a year and stay for up to five days.  During this time, we met patients, researchers, and medical staff from all over the world who were involved in cutting edge research much of which has contributed to the ongoing problem of destroying diversity in gene pools.  It was a highly educational experience.  We learned a great deal there.  But over time, I have realized that all this research has become a classic double edged sword and we must use it wisely.