Have we stopped evolving?
Everyone who lives today comes from one woman named Eve. She lived in East Africa 200,000 years ago.
There are no big differences in the genetic material between people from different countries. There are larger differences between different chimpanzees. Since we are so similar, some people wonder if we have stopped developing.
Menneskets evolusjon med et menneske med smarttelefon
Some traits are favoured
Evolution is a term for changes and development that happen over time. For human evolution to take place, more people must be born than those who stay alive.
Humans must be different from each other, and the differences have to be passed on to their babies. Some traits are better for surviving in their surroundings. People with these traits have a better chance of growing up and having babies.
Prosessen av hvordan en solsikke blomstrer
New traits
We get new traits in three different ways.
Mutation
Babies grow from cells holding genetic material from both a woman and a man. In these cells the genes are copied. Sometimes errors occur when genes are copied. These errors are called mutations.
Gene flow
When groups of people live apart for many years, they develop differently. If they come together again and start sharing genes, new traits are made. This is called gene flow.
Reproduction
A baby gets genetic material from both parents. Humans are a young species, and we grow more slowly in number than other animals. Because of this, we don’t get so many new traits in the population. Your genetic material is almost the same as mine. We look different, but still, we have close genetic ties.
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Environment and natural selection
The environment also plays a big part in our development. Traits that make our chance for survival bigger are those that are passed on to us. If a person has traits that make them survive better and have more children than others, this person’s genes are more likely to continue to the next generation.
Naturalist Charles Darwin called it the «survival of the fittest». This means that you need traits that society needs. Exactly which traits those are will change from time to time. So it is getting a bit complicated since both culture, science and technology change our society and people need to fit in.
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Charles Darwin illustrasjon
From Eve to Lucy
Our human-like forefathers were completely dependent on their surroundings. Lucy was a fossil woman who lived 3.2 million years ago. She looked a bit like an ape with a large jaw, long arms and fur. But she walked on two legs. She lived in trees, but the trees were disappearing and Lucy had to spend more time on the ground. Eggs found near her show that she was storing food.
Climate change forced our forefathers to leave the woods. They had to walk under the burning sun to survive. Bare skin and the ability to sweat to get rid of body heat became useful. In this way, our forefathers’ genes changed.
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Ape, Lucy
The brain develops
Humans developed because of gene flow, reproductions and mutation. We got bigger brains, smaller jaws and other types of social groups. We controlled fire and invented tools. The environment changed more and more. When farming started around 10,000 years ago, our history changed a lot, and so did our genes. We could now produce our own food close to where we lived.
Changes to the human body
At Harvard University, researchers have looked at genes from 230 people that lived between 8,500 and 2,300 years ago. They found several differences in body, height and skin colour.
4,000 years ago, adult humans started to tolerate milk. Light skin became more common because people ate more plants and got less vitamin D. The immune system also changed.
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Neandertalere i et grønt og frodig landskap
Knowledge and culture change our surroundings
Genes are not the only thing that we pass on to other generations. We also pass on our culture. Our culture has helped us to fit in. We have made clothes and built houses, grown plants and tamed animals to get stable food sources.
We have built boats, cars and aeroplanes to explore the world. We have invented medicines to help with illness. We can even survive in space. The more we learn, the more our environment will change. We develop, but the question is, how will the way we live today affect the future?
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Remnants of evolution
Our body still has traces of past traits that we no longer need.
Ear muscles
It is the muscles in the ears of cats and dogs that help them direct towards sound. Some people can «wiggle» their ears, but this is not very useful for us anymore.
Arm muscles
Since we no longer climb trees, we don’t have the same need for underarm muscles as before.
Appendix
We don’t need the appendix to survive, but it can be good for healthy stomach bacteria.
Vomeronasal organ
Some animals discover chemical materials with this organ. We don’t know if it works for us anymore.
Wisdom teeth
Four extra teeth were useful for our forefathers, who had larger mouths and other types of diets. We don’t need them, and some people lack them altogether.
Coccyx
The human foetus has a tail, but it disappears before birth. So we are left with a short tailbone.
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Vrakgods fra evolusjonen, en illustrasjon av hva Kroppen vår har spor av tidligere egenskaper vi ikke trenger lenger
Sources:
- Historien om mennesket junior (2020)
Orage Forlag AS
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