Speciation and variation – Evidence of common descent

As predicted by evolutionary theory, populations evolve in response to their surroundings. In any ecosystem there are finite opportunities to make a living. Organisms either have the genetic tools to take advantage of those opportunities or they do not. House sparrows arrived in North America from Europe in 1800s. Since then, genetic variation within the…

Human Chromosome 2 – Evidence of Common Descent

Since the mid-1800s, biologists have generally shared the belief that all living things descended from a single common ancestor. Based on fossil evidence and comparative anatomy, Charles Darwin proposed that humans and great apes, which including chimpanzees, gorillas, and orangutans, share a common ancestor that lived several million years ago. More recent research has propped…

Artificial Selection – Evidence of Common Descent

Artificial selection is not direct evidence of evolution, but it is indirect evidence, a process that helps us to understand natural selection. Humans have been artificially selecting and domesticating animals and plants for many thousands of years. In effect, domestication is a long-term, practical experiment that clearly demonstrates that species can actually change dramatically by breeding…