Our world is a great incubator of life, yet it loves to go through periods of change where only those who are ready to adapt will survive. Already five times our planet has gone through periods of mass species extinction, forcing those who want to survive to adapt and overcome. We are now facing a sixth great extinction, not caused by a force of nature, but caused by a single species. We'll take a look at the first five great extinctions and then delve into the one that's happening right now. The first major mass extinction occurred approximately 440 million years ago and is known as the Ordovician-Silurian extinction event. This event was triggered by rapid cooling and the corollary effect of lower sea levels due to the formation of glaciers. Laurentian brachiopods were the most affected by this event as they lived in shallower sections of the ocean, making them the most exposed to the event. Since most life in that period existed in shallow waters, it's easy to see why this was the second largest of the five major mass extinctions. The second mass extinction occurred around 370 million years ago and is commonly called the Late Devonian extinction. 70 million years later, we have more complex life, which has moved from the ocean onto the land. The Late Devonian extinction is not a single event but a myriad of smaller scale extinctions such as the Kellwasser event and the Hangenberg event that combine to create the entire major extinction event. The third mass extinction occurred approximately 245 million years ago and is referred to as the Permian-Triassic extinction event. “More than half of the families of living things became extinct, and between 90 and 96% of the planet's marine species were lost. At the same time, p...... half the paper ...... and 8.7 million. The number of species lost each year multiplied by 20 and then divided by the total number of species shows a total loss of about 7% of the world's species. As climate change becomes more of a problem, this is expected to cause an increase in annual extinctions, making the sixth mass extinction an all-too-real scenario. The next step is to look at the sixth mass extinction and see how it differs from the previous one. five. The five mass extinction events were natural occurrences in the environment that saw the most adaptive creatures survive during the period in which the earth became equilibrated. The sixth mass extinction is the first time that species loss and climate change are due to one species. Hard to get mad at ants for ruining your home when you're a member of the species responsible for a mass extinction.