 What is extinction, and how does a species become extinct? To extinguish something it means to stop it from existing, like blowing out a candle flame. When a plant or animal species that once lived stops existing entirely, we say that that species has become extinct. Why do certain species of plants and animals sometimes become extinct? According to the theory of evolution, individuals of the same species show a range of variations. Some individuals have characteristics that are better suited to their environment, making them more likely to survive and reproduce, whilst others are less well adapted. These less well adapted individuals may eventually fail to reproduce and eventually their genes are removed from the population. If an entire species fails to adapt to changes in its environment or compete with other organisms for resources and its birth rate is lower than its death rate, then it will become extinct. It may surprise you to know that over 99% of all species that have ever lived are now extinct. Typically, most organisms become extinct within 10 million years of their first appearance. Although some species have survived without much change for much longer than this, these long surviving organisms are sometimes called living fossils. The African Ardvark and the Himalayan Red Panda are two examples of such living fossils, as both have remained genetically unchanged for millions of years. From time to time, an event takes place on Earth which causes a mass extinction. These mass extinctions are identified by a significant and often devastating change in the number and variety of organisms alive at one time. The most famous mass extinction, called the KT extinction event, occurred about 65 million years ago and involved the extinction of the dinosaurs. The most devastating extinction event happened 251 million years ago and completely eradicated 96% of all known species. This was probably due to a comet or asteroid impact. Today, many species are becoming extinct at an alarming rate. This is of great concern to biologists and ecologists. It is currently estimated that 50% of all living species will be extinct by the year 2100. But what can we do to slow down or halt the spiral of extinction? Stopping habitat destruction is a key starting point as well as becoming greener, lowering our carbon footprint and using sustainable products. We may be able to affect this and it's up to all of us to play our part.