 |
What is evolution? |
Our Planet
Evolution is a scientific theory about how all of the many different, diverse, and amazing animals, plants, and other living things on Earth came to have their special and unique features and traits. The idea behind evolution is that all things living today developed and adapted from their ancestors in earlier forms.
The way that living things adapt and change over time is known as Natural Selection. Natural Selection is the idea that living things with the most favorable features are more likely to reproduce and successfully pass on their good traits! As the strongest features are passed on over and over again, the species is said to evolve. Think, for example, about an animal who relies on running quickly to catch its prey. An animal from this species with a special curved foot who runs faster than the others is more likely to thrive and pass along its special features! When its offspring also thrive thanks to their special foot, they pass along their features too. If this keeps on happening over the course of a long time, the individuals who don’t have the curved foot will die out, and the species will have adapted and evolved into an animal with special curved feet!
According to the evolution theory, being able to evolve and change to meet new circumstances in the world makes it possible for living things to survive! Evolving also allows plants and animals to all be unique and have their own interesting, diverse features!
The way that living things adapt and change over time is known as Natural Selection. Natural Selection is the idea that living things with the most favorable features are more likely to reproduce and successfully pass on their good traits! As the strongest features are passed on over and over again, the species is said to evolve. Think, for example, about an animal who relies on running quickly to catch its prey. An animal from this species with a special curved foot who runs faster than the others is more likely to thrive and pass along its special features! When its offspring also thrive thanks to their special foot, they pass along their features too. If this keeps on happening over the course of a long time, the individuals who don’t have the curved foot will die out, and the species will have adapted and evolved into an animal with special curved feet!
According to the evolution theory, being able to evolve and change to meet new circumstances in the world makes it possible for living things to survive! Evolving also allows plants and animals to all be unique and have their own interesting, diverse features!
The theory of evolution is widely accepted by most scientists because it has been successfully tested and supported by much research. Some ways in which evolution has been examined include studying fossils to see the change in certain animals over time, and looking at the inherited traits (DNA) passed along to certain species by their ancestors. However, some people do not believe in this theory, often because of their religious beliefs.
Ch-ch-ch-changes!
What are some of the plants or animals you know about who have special features that help them to survive?
Cacti that are able to survive in the desert where there is very little water are one really good example, and camels who have special humps to store food and water for long trips in the hot desert are another one!
What about animals like cats and rodents, who mostly stay awake at night and have special eyes that are able to see better than others in the dark??
Can you think of any other good examples? Why do you think evolving to have these special features helped each plant or animal to survive?
- "Evolution." Britannica Junior Encyclopedia. Britannica Online for Kids. Encyclopædia Britannica, 2011. Web. 9 June 2011.
- “Evolution.” WGBH/NOVA Science Unit and Clear Blue Sky Productions. Public Broadcasting Service. 9 Jun. 2011
- “Darwin: Evolution Today.” American Museum of Natural History. 09 Jun. 2011
What is evolution? Yes--part of the answer is that "plants and animals have changed over time". But it's just as important to remember that when Charles Darwin wrote his book about evolution called "On the Origin of Species", he also said that plants and animals were related to each. He said that each type of creature on Earth--each species--shares an ancestor with other creatures.
For example, long ago, a species of warbler arrived at the Galapagos Islands, off the coast of Ecuador. Over time, that one species changed. This change lead to differences between birds. Some had bigger beaks, some had pointy beaks, and so on. The differences between the birds grew larger and larger until, today, there are a dozen different species of finches in the Galapagos. Some have large beaks for cracking big, hard seeds; others have pointed beaks for picking up small seeds from the ground. These finches all share a common ancestor--the first warbler species that arrived in the Galapagos Islands.
In the same way, if you look back in time far enough, we see that all animals share common ancestors: whales and hippos; hummingbirds and hawks; snakes and lizards; and, of course, humans and apes.
How did they change? We often say that animals adapt--but most people think that means animals change shape or behaviour during their lifetime. For example, before Darwin, some people thought giraffes had long necks because they stretched them to reach leaves high in trees. Their offspring would have the same long necks, and would stretch them when they ate. And so on, until we have today's loooong-necked giraffes.
But this isn't how species change. Instead, species change because of something called natural selection...but that's the subject of another question! For the time being, it's important to remember the answer to the question "What is evolution?" is simply that species change and that all species share common ancestors.