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Human Actions and the Sixth Mass Extinction

The rise of homo sapiens on various continents coincides with a decline in other large animals.

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Human Actions and the Sixth Mass Extinction

This is one of the most powerful birds in the world. Could it go extinct?

The Philippine Eagle, also known as the Monkey-eating Eagle, is among the rarest, largest, and most powerful birds in the world. It is critically endangered, mainly due to massive loss of habitat due to deforestation in most of its range. Killing a Philippine Eagle is punishable under Philippine law by twelve years in jail and heavy fines.

Human Actions and the Sixth Mass Extinction

Over 99 percent of all species that ever lived on Earth have gone extinct, meaning they no longer exist anywhere on this planet. Five mass extinctions are recorded in the fossil record. They were caused by major geologic and climatic events. Evidence shows that a sixth mass extinction is occurring now. Unlike previous mass extinctions, the sixth extinction is due to human actions.

The present rate of extinction is between 100 and 100,000 species per year. In 100 years, we could lose more than half of Earth’s remaining species.

Effects of Extinction

The results of a study released in the summer of 2011 have shown that the decline in the numbers of large predators like sharks, lions and wolves is disrupting Earth's ecosystem in all kinds of unusual ways. The study, conducted by scientists from 22 different institutions in six countries, confirmed the sixth mass extinction. The study states that this mass extinction differs from previous ones because it is entirely driven by human activity through changes in land use, climate, pollution, hunting, fishing and poaching. The effects of the loss of these large predators can be seen in the oceans and on land.  The loss of big predators has likely dirven many of the pandemics, population collapses and ecosystem shifts the Earth has seen in recent centuries.  For example:  

  • Fewer cougars in the western US state of Utah led to an explosion of the deer population. The deer ate more vegetation, which altered the path of local streams and lowered overall biodiversity.
  • In Africa, where lions and leopards are being lost to poachers, there is a surge in the number of olive baboons, who are transferring intestinal parasites to humans living nearby.
  • In the oceans, industrial whaling led a change in the diets of killer whales, who eat more sea lions, seals, and otters and have dramatically lowered the population counts of those species.

Disappearing Frogs

Around the world, frogs are declining at an alarming rate due to threats like pollution, disease, and climate change. Frogs bridge the gap between water and land habitats, making them the first indicators of ecosystem changes. Meet the California researchers working to protect frogs across the state and across the world at http://www.kqed.org/quest/television/disappearing-frogs. Learn about the plight of the yellow-legged frog at http://www.kqed.org/quest/radio/plight-of-the-yellowlegged-frog.


In order to protect species we must first understand their status.  The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) creates a single, scientifically sound,  national classification of wildlife.  The first classification is species of special concern which means they may become threatened or endangered because of various identified threats. Currently in Canada there are 192 species that fall under this category including grizzly bears, polar bears, and the eastern wolf. Next we have 164 species that are considered threatened.  Threatened species are likely to become endangered if nothing is done to reverse the factors leading to their demise.  Examples of threatened species are wood bison, swift fox and rainbow spelt. Endangered species are wildlife facing imminent extirpation or extinction.  In Canada there are currently 298 endnagered species including the badger, woodland caribou, and wolverine. A species is considered extirpated when it no longer exists in the wild in Canada, but it exists elsewhere such as the blue whale. Lastly, a species is extint when it no longer exists anywhere in the world.  Examples of extinct species are the great auk and the blue walleye.

Further information on the status of species in Canada can be found at


How You Can Help Protect Biodiversity

There are many steps you can take to help protect biodiversity. For example:

  • Consume wisely. Reduce your consumption wherever possible. Re-use or recycle rather than throw out and buy new. When you do buy new, choose products that are energy efficient and durable.
  • Avoid plastics. Plastics are made from petroleum and produce toxic waste.
  • Go organic. Organically grown food is better for your health. It also protects the environment from pesticides and excessive nutrients in fertilizers.
  • Save energy. Unplug electronic equipment and turn off lights when not in use. Take mass transit instead of driving.


  • Evidence shows that a sixth mass extinction is occurring.
  • There are many steps you can take to help protect biodiversity. For example, you can use less energy.


Use this resource to answer the questions that follow.

  • http://www.hippocampus.org/Biology \begin{align*}\rightarrow\end{align*} Non-Majors Biology \begin{align*}\rightarrow\end{align*} Search: Global Challenges and Opportunities
  1. Describe the current mass extinction. What is causing this extinction?
  2. Why might the polar bear go extinct?
  3. What is the relationship between red algae, krill, and penguins?
  4. Why are penguin populations threatened?
  5. Why is the temperature rising faster at the poles than elsewhere?
  6. What is the role of biologists in facing these global challenges?

Review Questions

1. How is the sixth mass extinction different from all other mass extinctions?

2. Why are frogs of particular importance?

3.  What are three things you can do to help protect biodiversity?  Are these realistic?


Go to the website for the Canadian Wildlife Federation found at http://cwf-fcf.org/en/discover-wildlife/endangered-species/.  Choose  a species currently feature on this site and answer the following questions to share with the rest of your class.

1.  What is the cause decline?  What is the species being classified as (for example: special concern, threatened, endangered, extirpated)?  Explain what this term means.

2.  What are some programs being used to help this species?

Go to the section of the WWF website dedicated to the great bear sea area in Canada.  Answer the questions that follow based on the information you find.


  1. Where is the great bear region of Canada located and what is unique about this area?
  2. Why should oil tankers not be allowed to travel through this area?

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