2.1 Case Study: Why Should You Study Human Biology?

Created by CK-12/Adapted by Christine Miller

Case Study: Our Invisible Inhabitants

Figure 2.1.1 Lanying has the flu. Can she stop taking her antibiotics once she starts feeling better?

Lanying is suffering from a fever, body aches, and a painful sore throat that feels worse when she swallows. She visits her doctor, who examines her and performs a throat culture. When the results come back, he tells her that she has strep throat, which is caused by the bacteria Streptococcus pyogenes. He prescribes an antibiotic that will either kill the bacteria or stop it from reproducing, and advises her to take the full course of the treatment even if she is feeling better earlier. Stopping early can cause an increase in bacteria that are resistant to antibiotics.

Lanying takes the antibiotic as prescribed. Toward the end of the course, her throat is feeling much better — but she can’t say the same for other parts of her body! She has developed diarrhea and an itchy vaginal yeast infection. She calls her doctor, who suspects that the antibiotic treatment has caused both the digestive distress and the yeast infection. He explains that our bodies are home to many different kinds of microorganisms, some of which are actually beneficial to us because they help us digest our food and minimize the population of harmful microorganisms. When we take an antibiotic, many of these “good” bacteria are killed along with the “bad,” disease-causing bacteria, which can result in diarrhea and yeast infections.

Lanying’s doctor prescribes an antifungal medication for her yeast infection. He also recommends that she eat yogurt with live cultures, which will help replace the beneficial bacteria in her gut. Our bodies contain a delicate balance of inhabitants that are invisible without a microscope, and changes in that balance can cause unpleasant health effects.

What Is Human Biology?

As you read the rest of this book, you’ll learn more amazing facts about the human organism, and you’ll get a better sense of how biology relates to your health. Human biology is the scientific study of the human species, which includes the fascinating story of human evolution and a detailed account of our genetics, anatomy, physiology, and ecology. In short, the study focuses on how we got here, how we function, and the role we play in the natural world. This helps us to better understand human health, because we can learn how to stay healthy and how diseases and injuries can be treated. Human biology should be of personal interest to you to the extent that it can benefit your own health, as well as the health of your friends and family. This branch of science also has broader implications for society and the human species as a whole.

 As you continue reading, think about what you want to learn about your own body. What questions or concerns do you have? Make a list of them and use it to guide your study of human biology. You can revisit the list throughout the course to see if your questions have been answered. If not, you’ll have the tools you need to find the answers. You will have learned how to find sources of information about human biology, and you’ll be able to judge which sources are most reliable.


Chapter Overview: Living Organisms and Human Biology

In the rest of this chapter, you’ll learn about the traits shared by all living things, the basic principles that underlie all of biology, the vast diversity of living organisms, what it means to be human, and our place in the animal kingdom. Specifically, you’ll learn:

  • The seven traits shared by all living things: homeostasis, or the maintenance of a more-or-less constant internal environment; multiple levels of organization consisting of one or more cells; the use of energy and metabolism; the ability to grow and develop; the ability to evolve adaptations to the environment; the ability to detect and respond to environmental stimuli; and the ability to reproduce.
  • The basic principles that unify all fields of biology, including gene theory, homeostasis, and evolutionary theory.
  • The diversity of life (including the different kinds of biodiversity), the definition of a species, the classification and naming systems for living organisms, and how evolutionary relationships can be represented through diagrams, such as phylogenetic trees.
  • How the human species is classified and how we’ve evolved from our close relatives and ancestors.
  • The physical traits and social behaviors that humans share with other primates.

As you read this chapter, consider the following questions about Lanying’s situation:

  1. What do single-celled organisms (such as the bacteria and yeast living in and on Lanying) have in common with humans?
  2. How are bacteria, yeast, and humans classified?
  3. How do the concepts of homeostasis and biodiversity apply to Lanying’s situation?
  4. Why can stopping antibiotics early cause the development of antibiotic-resistant bacteria?



Figure 2.1.1

Photo (face mask) by Michael Amadeus, on Unsplash is used under the Unsplash license (https://unsplash.com/license).


Mayo Clinic Staff (n.d.). Strep throat [online article]. MayoClinic.org. https://www.mayoclinic.org/diseases-conditions/strep-throat/symptoms-causes/syc-20350338



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Human Biology Copyright © 2020 by Christine Miller is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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