Natural Selection - Why It Matters

What Was Important About Darwin's Discovery?

Darwin showed HOW evolution works in his famous book, The Origin of Species. After many years of sailing around the world as a passenger on the ship, The Beagle, Darwin had collected numerous specimens of sea and island life and had made many observations of plants and animals in their natural environment.

He documented the relationships between the environment and the structures and functions of plants and animals that gave them the ability to survive and thrive in such environments. He realized that each species had its own "niche" in the environment, which is a combination of the role, function, and place of an organism in the environment. His train of thought went like this:

animals survive when they are adapted to the niche in which they live
animals are adapted because they have special anatomy and function that fits the niche
the niche then specifies what it takes for an animal to survive in that particular niche

Thus, the niche exerts a selection pressure. Only animals that are adapted to the niche can survive.

But, you may say, how can complex animals and plants evolve from mere random chance events? Nothing as complicated as humans could arise by accident or chance.

But is evolution really random? Is the influence of niches and their selection force really random? If the selection forces of niches dictate what it takes to survive in the niche, that is hardly random. Not all possibilities are equally likely. The chance for any organism to fill a niche is not 50:50.

For some animals and plants, there is 0 likelihood that they can survive in a particular niche. Cows can't live in the ocean. For other types of organisms that have the right combination of genes, the chances can be much higher, even 100% chance of being adapted to that niche. Porpoises can live in the ocean.

If several organisms can survive in the same niche, then competition becomes a factor and one or more species may be forced out of the niche by competition. None of this is random. For more on the evidence for the Theory of Evolution, click here.

Why Scientists Think Natural Selection is So Important

For scientists, evolution is a unifying principle that is consistent with all biological knowledge.

Natural selection is the only possible mechanism, based on observable evidence, that can explain how the environment can determine which species can survive and evolve and which cannot. Life is precious and fragile. Adapt or die. Anything that we humans do to the environment can change natural selection forces and thus create the risk of driving species into extinction.