Understanding Evolution

Evolution is simple, but often misunderstood.

First, a quick note about religion. Creationists have become a loud voice in social media and elsewhere. So much so, that some Christians assume their own denomination opposes evolution, even if it does not. “..of Americans in the 12 largest Christian denominations, 89.6% belong to churches that support evolution education”1 and yet some members of those faiths aren’t aware of this. Perhaps it’s because church leaders who support evolution don’t realize it’s unclear, and don’t think to inform their congregations about their views on science. Of course everyone has their personal view on the topic, but if the views of your church concern you and you have questions, talk to your minister. You may be surprised.

What is evolution? It is a natural consequence when organisms live in an environment. Individuals who do best at coping with their environment are more apt to reproduce, making the genes of those best at surviving more common. There is no goal to evolution. An individual may die before reproducing, due to poor adaptation or just chance, but statistically those who are better at surviving and reproducing will be more apt to pass on their genes. Over short periods of time, this can cause subtle changes in the population. Over extremely long periods of time, it can cause the entire variety of life we see on earth.

Long eared puppyPeople understand a dog breeder can breed hounds with long ears, until they get puppies with even longer ears. This is evolution through artificial selection, not unlike evolution through natural selection. But some people have more trouble picturing the evolutionary transition between species. One stumbling block is our conception of time. As an individual, we’re lucky if we live 100 years. So trying to comprehend over 3,000,000,000 years of evolution on our planet boggles the mind. Over that amount of time, organisms can develop massive changes, far more than a puppy with really long ears.

Another stumbling block is our concept of a species. As human language developed, we named organisms in our environment, particularly species there were helpful or harmful. When early man spoke of a bear, or an apple, he wanted his family to know what he meant. Each particular species seemed unchanging to them, and in many ways it still does to us. But upon further study, we find that populations flow and change, and defining a species is somewhat arbitrary. Some people believe evolution takes place only within a kind, not between different kinds–but the flow of genes is continuous. There’s no exact point where one kind ends and another begins, through time, or even in current populations.

In the June 2008 Scientific American article “What Is A Species?” 2 Carl Zimmer talks about how populations of gray wolves and red wolves have been collectively classified as one, two, three or more species. Some wolves are also interbreeding with coyotes, bringing their genes into the wolf population, as well. Using Latin taxonomic names like “Canis lupus” may make it seem species identification is set in stone, but even today, naming a particular population is still largely a matter of language and convenience. With the wolves, it became an issue because “endangered species” are protected under our laws. We’re just trying to define the species, so we can follow our own laws. Nature doesn’t recognize these species boundaries, they are artificial.

Manatee image from Kyle Kyle McBurnie, SD Expeditions http://sdexpeditions.com/

Manatee image by Kyle McBurnie,
SD Expeditions http://sdexpeditions.com/

Whether or not those wolves have evolved into different species, you may be thinking they are still all dogs, all one kind (not unlike our puppy with long ears). Perhaps it’s harder to see, for example, how manatees and elephants have a common ancestor. But is it really that hard? Their are toenails on a manatee’s flipper that look like the toenails of an elephant, and other morphological similarities. Their common ancestor probably looked something like the hippopotamus, which is semi-aquatic, although hippos are in a different genetic line.

But we don’t have to rely just on morphology, the fossil record, and speculation to determine how closely different species are related. Today we have the tools to map DNA. We use DNA evidence to solve crimes, to determine who fathered a baby, and to determine how closely different species are related. The more genes are shared, between individuals or between populations, the more closely they are related. All of the life on our planet is interwoven in this way, a diverse and wonderful mosaic.

1. National Center for Science Education: What do Christians REALLY Believe about Evolution?
2. What Is A Species?