Conservation efforts: backtracking along evolution, or still more randomness?

 “In the long history of humankind (and animal kind, too) those who learned to collaborate and improvise most effectively have prevailed.” –Darwin

               Evolution, which has occurred naturally for over 440 million years, is now being taken into the hands of a single species and changing the balance of biodiversity here on Earth. In efforts to reverse damage to biodiversity and extinction humans have taken it into their own hands to breed endangered species in order to keep the distinct species alive. However the fact that we are in the position where a concerted effort to preserve species is necessary has already thrown off the balance of randomness in evolution. Examples of our attempts to restore biodiversity include the regrowth of the bison population and the introduction of the bovine DNA into the species. These series of events are casting into question the role of the human species in the fate and randomness of Earth.

The history of evolution on Earth has a cycle of millions of years of growth and progress punctuated by mass extinctions. There have been five mass extinctions recorded in the Earth’s fossil record, all following a similar pattern of a large-scale disturbance, the disappearance of biodiversity, and then the period of recovery that takes anywhere from 25 to 100 million years. Within this recovery period the majority of redeveloped biodiversity results in new creatures. The first extinction in our fossil record happened 440 million years ago in the late Ordovician period and resulted in the extinction of 85% of marine species as an apparent result of drastic climate change. The second occurred 365 million years ago in the late Devonian period. This time, 70% of all species (primarily fish and marine invertebrates) died out, the cause again believed to be climate change. 245 million years ago the third and largest extinction wiped out 95% of all marine species and over 75% of vertebrates. While it has been more difficult for scientists to pinpoint a primary cause for this extinction and it could potentially be a combination of several factors, climate change remains the most important factor. The fourth great extinction occurred in the late Triassic period 208 million years ago and resulted in the extinction of roughly half of all species and making way for the evolution of the dinosaurs. Climate change, an increase in rainfall specifically, is believed to be the stressor of change. The fifth and most well-known extinction took place 65 million years ago between the Cretaceous and the Tertiary periods. Caused by a massive volcanic explosion or meteorite that disrupted the earth’s eco system, half of all species became extinct including dinosaurs, making room for our ancestors.

            Many scientists are now speculating that we are in a sixth extinction, one that is for the first time caused by a single species: humans. 10,000 years ago the human population on Earth was approximately 1 million; we now number over 6.6 billion. The inordinate human use of resources and life is causing the loss of almost 30,000 species per year, a significantly faster rate than preceded past mass extinctions. It is being suggested that this sixth mass extinction could be of an even greater magnitude than the third mass extinction and is approaching perhaps 1,000 times more quickly than any have before. Darwin saw this general trend of large populations domination smaller ones; on page 174 of On The Origin of Species he writes, “…the struggle for the production of new and modified descendants, will mainly lie between the larger groups, which are all trying to increase in number. One large group will slowly conquer another large group, reduce its numbers, and thus lessen its chance of further variation and improvement.” And humans, clearly, are not only one of the large groups but the largest, and only growing in numbers.

            There are a myriad of examples of species being pushed to extinction by humans through either direct or indirect threats, as most people know. I want to focus on the American bison and herd growth from the brink of extinction. In the 1800s European settlers in America were pushing further and further West and through the great prairies that were home to the 30 to 60 million bison. While Native Americans had traditionally been hunting the wild bison, in the 1970s mass slaughters by the settlers left the bison on the brink of extinction. By the early 1890s there were only a little over 1,000 left. Bison parts were used for various purposes including use of skins, but food and sport were the primary reasons for the mass hunts. As the continental railroad was being built settlers would ride the trains shooting the bison for sport. Buffalo meat is more nutritious than beef; it is lower in fat and cholesterol and higher in iron.

            While bison population numbers have grown and are now near 500,000 thanks to conservation efforts, these are not pure bison; the still essentially pure bison herds live in small, protected areas such as Yellowstone National Park and Wind Cave National Park. All other bison show evidence of cattle genes. Before about 10 years ago there was no concern about bovine DNA within bison herds as it was forgotten that cattle and bison were left to graze freely with each other. About 1-12% of today’s bison DNA is in fact bovine DNA, leaving pure bison herds with numbers of perhaps 15-20,000 head. Some people have proposed slaughtering all bison that are not pure in an effort to keep the bison as a distinct and pure species, and others question whether or not these hybrids should be classified into a species of their own. The issue at hand is keeping a sufficient bison population without reducing the gene pool.

            While there have, as I have described, been natural mass extinctions, the problem at hand is the unnatural and human induced extinction of mass numbers of species. I have been thinking a great deal about humans and their role in the randomness of the universe. We think of ourselves as the pinnacle of evolution, and yet we seem to be its demise. Does this have to be the case? Do human efforts to combat extinction count as the randomness of evolution because species that can best work together evolve and dominate? In other words, are our efforts to reverse the extinctions that we have caused another random piece of the universe, or are they a more calculated backtrack towards the original randomness of the species?

 According to the introduction of the bovine DNA into bison and the fact that it went for so long unnoticed, I will argue that our actions maintain randomness, for we can never get back to the original, exact place in evolution of the species before we pushed it to the brink of extinction. Everything is always changing- that’s what evolution is. So as time marches on, conservation and protection efforts will too, as will the species. Will the species, with our help, arrive at the same place it would have had it evolved naturally? Most likely not, but it could happen, just as the sugar glider and flying squirrel look the same and yet the sugar glider is actually a marsupial, most closely related to the kangaroo. Very unlikely that they should look so much alike, and yet through the randomness of evolution, it happened. I don’t know what the Earth will look like in 1 million or even 1,000 years or if everything will have been driven to extinction; I do however believe that even though humans are manipulating species population around the world on a large scale, that randomness is still and will continue to be random.

Works Cited