“If humans evolved from monkeys, why do they still exist?” asked one of the children at my daughter’s school. It’s a great question about the theory of evolution and how there came to be so many different types of creatures on Earth.
There are many different forms of life on Earth – from bacteria and fungi, to plants and animals.
Evolution is a theory that explains how there came to be so many different types of living thing on Earth. It describes the gradual changes that happen when creatures reproduce in combination with changes to the places in which they live.
Millions of years ago, the first living creature was something very small and simple. We call it our ‘common ancestor’ because it is from this creature that all the living things on Earth have been created, through reproduction and natural selection.
Reproduction is the biological way to make babies. For humans, two parents are needed and, if an egg from a mother is fertilised by a sperm from a father, then an embryo can develop and grow into a baby. The baby will be similar to its parents but not exactly the same as either of them. This is because it gets some DNA from each parent – it is a mixture of both of them. (I explained about DNA in my post: how does a seed know what to grow into?)
Over many cycles of reproduction, DNA differences can lead to the creation of new species, especially if a change in the environment makes those differences important for survival. This is called ‘natural selection’ and this video explains more about how that can work.
So, what about humans and monkeys?
Humans have evolved over millions of years, as have monkeys and apes. We share a common ancestor and our DNA codes are very similar but humans didn’t evolve from monkeys. Instead, we evolved alongside them and other animals. To find out more about how this happened, check out the BBC Bitesize pages on human evolution.
And try this fun game to see how similar human DNA is to that of other living creatures – you might be surprised by some of the answers!