Shop Windows to the Universe

Earth Science Rocks! Select one of our four cool NESTA t-shirts from our online store, and express your love of Earth and space science!

Evidence of Evolution

This illustration of the three domains of life is like a family tree. The branches that are very far apart are not very similar. Branches that are near each other indicate closely related groups.
Click on image for full size
Windows to the Universe original image

What Is Evolution?

Evolution is the process of change through time. Many things evolve. Language evolves so that English spoken four hundred years ago during the time of playwright Shakespeare was very different than English spoken today. Technology evolves over time as new things are invented and modified. Scientific theories evolve as more data are collected and analyses are done. Life evolves over very long timescales as species change over many, many generations. This is called biological evolution. Evolution is the foundation for the modern sciences of paleontology (the study of fossils and the history of life), ecology (the study of ecosystems), and biology (the study of life) including medical science.

  • On a small scale, biological evolution is called microevolution and involves changes in the occurance of gene types in a population of the same species over several generations. These changes can lead to changes in the way a species looks over generations.
  • On a large scale, biological evolution is called macroevolution and involves the development of new species through cumulative genetic changes over many, many generations.

This Windows to the Universe Exploratour examines the scientific evidence for biological evolution. Click the “forward” button at the top of this page to continue the tour and learn more about the scientific basis of evolution.

Last modified May 15, 2009 by Jennifer Bergman.

Shop Windows to the Universe Science Store!

Our online store includes fun classroom activities for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist are also full of classroom activities on different topics in Earth and space science!

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Evolution Impacts Environment, Study Finds

Ecosystems have an impact on how living things evolve. And evolution has an impact on ecosystems too. Scientists have discovered the evolution of small fish called guppies affects the streams in which...more

Finding the Four-Footed Ancestors of Whales

Scientists have known for a long time that whales, the largest marine mammals, have distant relatives that lived on land millions of years ago. A team of scientists has been searching for fossils to better...more

How Many Species Have There Been on the Earth?

Scientists are interesting in knowing how many species can fit on the Earth. The number of species is called diversity. If there are a lot of species, then diversity is high. If there are few species,...more

Scientists Find Signs of “Snowball Earth” Amidst Early Animal Evolution

Near the Earth’s equator is where you could find some of the warmest places on Earth. But it wasn’t always like that. It used to be cold at the equator, so cold that ice formed on land and in the ocean....more

ExploraTour - Looking at the World in a Different Light

Look at the bed below the body of the sleeping man. You can still see where he was lying down. The heat from his body warmed up the bed sheets which are now radiating infrared light toward your eyes....more

ExploraTour - Looking at the World in a Different Light

All warm objects (not just people) release infrared light. Warmer objects give off more infrared light. Very hot objects radiate other types of light as well. Click on the picture to see the infrared...more

ExploraTour - Looking at the World in a Different Light

What kinds of light can people see? Our eyes can see visible light. When it passes into our eyes different types of visible light create different sensations that we see as colors. ...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA