What is Evolution?

In biology, evolution is defined as any change in the heritable traits within a population across generations. These heritable traits include physical characteristics and instinctive behaviors. Evolution helps us understand how life diversified into various forms and how modern creatures continue to adapt.

All healthy living things reproduce by duplicating DNA and passing it to future generations. DNA contains coded information for growth and function. In simple organisms like amoebas, reproduction involves copying DNA and splitting, but errors (DNA mutations) can occur, leading to variations in offspring, such as an extra-long arm. If these modified traits are passed on, evolution has occurred.

In more complex creatures like badgers, reproduction involves two parents. A sperm cell (half DNA) from the father combines with an egg cell (half DNA) from the mother, creating a new organism with a unique combination of traits from both parents. New traits can also arise from DNA mutations. If these traits are passed to the next generation, evolution has occurred.

Small evolutionary changes accumulate over multiple generations, leading to dramatic differences. For example, all dog breeds evolved from an ancestral group of gray wolves through human-guided selection. Overwhelming evidence from genetics, chemistry, paleontology, and mathematics suggests that all living things share a common ancestor. Simple reproduction with variation over billions of years is responsible for life's diversity.

While evolution might seem random, it is not. In the mid-18th century, Charles Darwin and Alfred Russel Wallace discovered natural selection, a force capable of guiding random evolution to produce order and complex functions. Natural selection, to be discussed in the next video, provides the 'breeder' for evolution beyond human intervention.

Biological evolution is defined as any change in heritable traits within a population across generations. Living things reproduce imperfectly, leading to small variations that accumulate over time to create dramatic differences in body form and function. Evidence strongly indicates that all life on Earth is related, making all living organisms, including humans, turkeys, and pumpkins, part of a single extended family.