The Earth has endured several mass extinctions over the eons, and it's entirely possible that we humans are triggering another one. At least we can take comfort in the fact that we won't be the first species to do so. Trace Dominguez explains in today's DNews dispatch.
According to recently uncovered fossil evidence, metazoans -- the planet's very first animals -- were likely responsible for Earth's most extreme extinction event. The new research out of Vanderbilt University strengthens earlier theories that metazoans caused a mass die-off about 600 million years ago.
Some background: When metazoans appeared on the biosphere scene, they represented an entirely new and different order of life compared to what came before. Unlike the largely immobile marine life that dominated the planet at that time, metazoans could move spontaneously and independently. They also got into the habit of sustaining themselves by eating other organisms, or the materials that other organisms produce.
Researchers refer to metazoans as "ecosystem engineers" in that they gradually commenced to changing the environment to suit their way of life. (Sound familiar?) The subsequent Earth-shaking changes, known as the Cambrian explosion, resulted in the development of most modern animal species -- vertebrates, mollusks, etc. It was a kind of slow motion explosion, mind you. It took 25 million years or so.
RELATED: Big-Brained Mammals at Greatest Risk of Extinction
Alas, the metazoans' new world order also meant doom for most of Earth's previous life forms. The new fossil evidence from Namibia that more or less confirms the tragedy. Over the next several billion years, Earth would undergo additional life-form overhauls. You've got your Late Devonian extinction, your Permian extinction, your Triassic-Jurassic extinction.... Check out Trace's video for more details on these.
Meanwhile, researchers with the Vanderbilt study say there's a lesson for us humans in the metazoan saga.
"There is a powerful analogy between the Earth's first mass extinction and what is happening today," writes Simon Darroch, director of the research project. "The end-Ediacaran extinction shows that the evolution of new behaviors can fundamentally change the entire planet, and today we humans are the most powerful 'ecosystems engineers' ever known."
-- Glenn McDonald
BBC: History Of Life On Earth
Vanderbilt University: Newly Discovered Fossils Strengthen Proposition That World's First Mass Extinction Engineered By Early Animals
National Geographic: Will Humans Survive The Sixth Great Extinction