Lesson Plan - Get It!
Remember there was a time when people thought the world was flat? What other misunderstandings in science have we corrected since that time?
Our understanding of the natural world has grown significantly as we developed more technology and ways of studying the world.
A long time ago, people thought the world was flat because they didn't have the tools necessary to understand that it is a sphere.
In this lesson, we will discuss how our understanding of living organisms has changed over time. We start with Aristotle, a Greek philosopher, studying around 350 B.C.
Image [cropped] by Jastrow, via Wikimedia Commons, of marble bust by Lysippos in the Ludovisi Collection has been released into the public domain.
Aristotle, pictured above, was interested in organizing the living creatures in his environment. He developed the first classification system to give order to living organisms. As you learn about this system, answer the following questions on a sheet of paper:
- How did Aristotle organize living things?
- What were some major problems with his system?
Watch braingenie's 13.1.1 Aristotle and Early Classification to get answers to the questions:
Discuss your answers with a parent or teacher before moving on.
Aristotle was working during the 4th century B.C., which was a very long time ago! His system had two main groups: plants and animals.
- How did he divide the animals into groups?
His system was based on the presence or absence of blood fluid, as well as movement patterns.
- Did you know his system was used until the 1600s?
It was in place for a very long time before it was challenged and replaced!
- Why do you think Aristotle's classification system was so basic?
Think about the technology he would have access to during that time period. It would have been very simple, based heavily on what he could see with the naked eye and experience with his senses. This limited many explanations of natural processes at the time. This method of classification did not allow for much division, resulting in large groups like basic plants and animals.
Image [cropped], via Wikimedia Commons, comes from Wellcome Images and is licensed under the CC BY 4.0 license.
The modern father of taxonomy is considered to be Carolus Linnaeus, pictured above. Linnaeus built upon the system proposed by Aristotle, but added more levels and a clear hierarchy of living organisms. He also developed a system of naming, called "binomial nomenclature," where an organism is called by the genus and species name.
Genus and species are two categories of classification that we will cover in detail in the next Taxonomy of Living Things Related Lesson, found in the right-hand sidebar.
- "Species" is the most specific term because it defines a single organism.
- "Genus" is a collection of species similar in structure and function.
For example, the scientific name for dogs is Canislupis, because they are in the Canis genus and the lupus species. So, lupus applies to domesticated dogs, but the genus Canis would include other similar organisms, like wolves. We haven't really talked about genus and species yet, so now is a good time to introduce the idea of the taxonomic hierarchy.
Linnaeus was working in the 1700s, about the time that Aristotle's system was being challenged. He noticed similar characteristics in living things, and classified organisms based on these components. He created the term "kingdom" and outlined an animal and plant kingdom that were divided into smaller sections called "genera."
- Do you see a similarity to another word you have learned?
That's right, genera became genus. We still use Linnaeus' system, but we have added more kingdoms, levels of organization, and detail.
You've learned how Aristotle organized living things into plants and animals, and that Linnaeus built a system with more complexity and levels.
- What similarities and differences do you see between each system?
- Which one do you think the current system most resembles? Why?
In the Got It? section, you will spend time identifying features of each unique system.