Question

1. Describe how evolution can arise via natural selection.

Answer 1

Evolution just means "change over time." If you have ever been to a natural history museum, you will have seen a sequence of fossils showing the change over millions of years, for example, in humans, birds, whales, or any other species.

Natural selection is the process through which this change occurs. It is the driving force of evolution. All organisms are born with small variation (mutations). But nature selects which ones get to reproduce (mainly by killing all the others).

It's a beautifully simple process. If an organism's random variation helps it survive (by finding food and not becoming it) and find a mate, those genes will be statistically favoured and will spread through the population over the generations, helping its descendents do the same.

Natural selection is a powerful constructive force because the environment acts as a filter, persistently selecting those minute variations in one direction. For example, if the climate changes and it becomes colder, those incapable of dealing with the lower temperatures will die and not get a chance to reproduce. Any change, in any gene, that results in a trait that has even a tiny statistical advantage will be favoured. Repeat this millions and millions of times in a population and over many many generations you will see the organisms adaptto the new climate. And when populations are split and adapt to different environments, you get new species forming.

This is evolution by natural selection.