RESEARCH:: Celebrating Darwin

Evolution Every Day
By Dr. Robert S. Feranec, Dr. Jason R. Cryan, and Dr. Jeremy J. Kirchman

One hundred and fifty years ago, Charles Darwin published On the Origin of Species by Means of Natural Selection. Darwin did not invent the idea of evolution within this book; in fact, many other scientists and natural historians had already discovered evidence (like fossils) that evolution had occurred. However, these earlier workers did not understand how evolution occurred. Darwin’s great contributions were to (1) synthesize the previous (and somewhat nebulous) ideas of evolution into a more cohesive theory of how all species are related through common ancestry, and perhaps more importantly (2) propose a mechanism, the process of natural selection, by which species diverge from one another. In On the Origin..., Darwin outlined natural selection as the strongest force driving the evolution of species. Since its publication, evolution by natural selection has withstood continuous scientific testing, and is now widely regarded as one of the most important processes driving evolution.

As evolutionary biologists and museum scientists, we study and discuss evolution almost every day. Because of our training and experience we are able to see how evolution affects our daily lives. Although it may not occur to many nonscientists, evolution is all around us, affecting our lives every single day.

Each year, many of us get vaccine shots for the influenza virus. If we are vaccinated one year against the flu, why do we have to get vaccinated the next year? The answer is, simply, because of evolution. The flu virus reproduces very quickly, accumulating genetic mutations rapidly, leading to many slightly different strains of the flu. This year’s flu vaccine makes us immune to some strains, but the mutations in other strains make these strains different enough that our vaccine-induced immunity is ineffective against them. These resistant strains quickly spread and reproduce, and will become next year’s dominant flu strain. So, the flu vaccine that you get this year will not work next year, because evolution by natural selection will have produced new flu strains that require new vaccines.
If you own a dog or cat, your pet is a product of human-directed evolution. Breeders chose desirable traits of individual animals and bred them to pass along those specific characteristics to the next generation. In dachshunds, for example, breeders chose small individuals that had long thin bodies, and bred them with other individuals that were small and had long, thin bodies. Comparing the diversity of dogs today to the original dog species of a few thousand years ago, it’s obvious that the dog population has evolved as a result of this selection.

Just as dog breeders selected dachshunds to be small, thin, and long, farmers have selectively bred their agricultural crops and animal products to produce much of the food that we eat. For example, based on current eating preferences, farmers have bred chickens and turkeys to have more white meat by selecting individual birds with larger breast muscles. Today these birds are so big and disproportioned that it is difficult or impossible for them to fly or, sometimes, even walk! We’ve done the same with plants. Think seedless watermelons, oranges, and grapes. Orville Redenbacher, whether he recognized it or not, was an agent of evolutionary change: in producing popping corn seed, he bred individual corn plants together that produced only large popped kernels. Thus, the selective breeding of individuals to enhance certain traits (like these consumer-favored ones) is a kind of evolution that scientists call artificial selection.

From vaccines and antibiotics to our pets and most of the foods we eat, evolution affects us every day. We believe that everyone should have a solid understanding of evolution, and that evolution needs to be taught in schools at every level. The New York State Museum has a long tradition of studying and teaching evolution, and in the next few essays you will read about how three museum scientists study different aspects of evolution and why this research is important.

In On the Origin of Species…, Darwin explained that evolution is the logical outcome of a process that he called natural selection, which he described as having four basic postulates:

1. Individuals within populations are variable for certain traits;
2. At least some of this variation is passed from parent to offspring;
3. Every generation, some individuals are more successful at surviving and reproducing than others. This differential survival and reproduction is often tied directly to the variation among individuals in that population; and
4. As individuals with favorable traits out-reproduce other members of the population, the population will become dominated by individuals with favorable traits.

Darwin’s logic is clear. If there is some naturally occurring variation within a population that can be passed from parent to offspring, and if individuals experience differential success at mating and reproduction, then some traits will be passed along to the following generations with higher frequency than others. This is how Darwin envisioned evolution: individuals with a heritable advantage are better able to survive and reproduce (that is, they are ‘naturally selected’) and will therefore pass along their advantageous traits to their offspring. The frequency of those advantageous traits will be greater in the next generation, and in this way, populations will change ever so slightly from one generation to the next: evolution by natural selection.