Evolution is a scientific theory; it explains much of what we observe in the living world. Atomic theory explains observations in chemistry. Gravity explains observations of the cosmos and movements of earth-bound objects. Theories are grand ideas which illuminate and elucidate what we see around us: life, the universe, all that.
Many refuse to see the beauty and truth of evolution, and a common ingredient among adherents of intelligent design, baraminology or other supernatural explanations is a poor appreciation of the diversity of life. This lack of appreciation is understandable. The modern world frees us from worrying which plants are edible, what kind of wood burns best or which insects are truly a threat, so it is easy to become oblivious to the huge variety of plants, trees, insects and life around us.
No naturalist doubts for a moment that life is a grand tableau of evolutionary lineages changing and diversifying. Doubt comes from not realizing how grand the tableau. We can all tell a pine tree from an oak, but if your curiosity stops there, can you be expected to understand the evolution of flowering plants?
Fortunately, it is not necessary to know every pine tree or moth in order to appreciate life's diversity. Knowing the basic parameters -- about a dozen pines occur naturally in our region a thousand or more moths -- is adequate, or at least a good start. An understanding of biodiversity fosters stewardship and wisdom.
Just as gravity explains Earth's trajectory around the Sun, evolution explains the diversity of life. To appreciate evolution, you must first appreciate what needs to be explained, and that is biodiversity. Plants, fungi, microorganisms, mammals, spiders, birds, insects; evolution explains them all.
Intelligent design and other flavors of creationism explain nothing. They push diversity into the unknowable and render planetary history and the tableau of life an incoherent mess. That is unacceptable. Evolution has no competing theories because nothing else comes close to explaining as much about life as evolutionary theory does.
I have decided a running theme of this blog should be the diversity around us. Southern Appalachian forests are a good classroom for learning what evolution explains. Our mountain's age corresponds to the earliest emergence of terrestrial life, plant and animal, so local natural history encompasses events like the origin of flowering plants, insect flight, mammals, birds and the rise and fall of dinosaurs. Much can be learned from the patterns of diversity around us.