3. Themes and Concepts of Biology

Learning Objectives

By the end of this section, you will be able to:

  • Describe characteristics that can be used to determine if something is living.

 

 

1-1-earth
Figure 1 This NASA image is a composite of several satellite-based views of Earth. To make the whole-Earth image, NASA scientists combine observations of different parts of the planet. (credit: modification of work by NASA)

Viewed from space, Earth (Figure 1) offers few clues about the diversity of life forms that reside there. The first forms of life on Earth are thought to have been microorganisms that existed for billions of years before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating 130 to 200 million years ago. Humans have inhabited this planet for only the last 2.5 million years, and only in the last 200,000 years have humans started looking like we do today.

References / Attributions

Unless otherwise noted, images on this page are licensed under CC-BY 4.0 by OpenStax.

Text adapted from: OpenStax, Concepts of Biology. OpenStax CNX. May 18, 2016 http://cnx.org/contents/b3c1e1d2-839c-42b0-a314-e119a8aafbdd@9.10

License

Icon for the Creative Commons Attribution 4.0 International License

3. Themes and Concepts of Biology by Lisa Bartee is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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