Over time, certain features of an animal species can change in order to help the animals survive in their environment. This process is called evolution. It occurs because, when animals are born, they inherit their traits from their parents. Animals with certain traits are more likely to survive and reproduce, so these traits are passed down to their offspring. Over many generations, these traits spread through the whole species.
WHAT ARE GENES?
Every animal has DNA (a long string of genes) in its cells. Genes are pieces of information about that animal’s features. For example, humans may have one gene for brown eyes, and another gene for curly hair.
When an animal is born, roughly half of its genes come from its mother, and half come from its father. This is called inheritance, and it is why we often have features in common with our parents. For example, if your father is very tall, and you are very tall, you have inherited your height from your father.
NATURAL SELECTION AND EVOLUTION
Some genes may mean that one animal is better suited to its environment than another animal. For example, an animal with a gene for long legs may be able to run faster, making them more likely to escape predators. This is an ‘advantageous gene’, as it means that that animal is more likely to survive, and therefore more likely to reproduce. Their offspring will then inherit the gene for long legs.
However, an animal with a gene for short legs is more likely to be killed by predators, so will not reproduce, and their genes will not be passed down. This is called ‘natural selection’, or ‘survival of the fittest’.
Over many generations, these advantageous genes become more common, and eventually spread throughout the whole species. This means the traits of that species change in order to increase their chances of survival. This process is called evolution.
IS EVOLUTION STILL HAPPENING TODAY?
Evolution is a very slow process, but it can still be seen in many species today.
For example, in Mozambique’s Gorongosa National Park, elephants have started to be born without tusks. Normally, this is very rare – only 4 in every 100 elephants are born tuskless.
However, during Mozambique’s civil war, many elephants were killed so that their tusks could be sold in order to pay for weapons. This meant that elephants without tusks were less likely to be killed. They survived the war, reproduced, and passed their genes onto their offspring. 1 in 3 elephants born in Gorongosa National Park since the end of the war have been tuskless.
This is an example of the elephant species evolving in order to survive poaching.