The sixth mass extinction in the history of life on Earth may be taking place right now, according to some environmentalists. Now, a new study suggests that humans beings may fall victim to this tumultuous event.
Despite the dominance (and prevalence) of human beings around the world, our species might not survive this latest incidence of species loss. Normally, extinctions are more likely to wipe out species with particular and small environmental habitats. Generally, those animals that have learned to adapt and survive have a wide variety of natural habitats. This advantage, however, does not provide complete protection against mass extinctions that can wipe out most forms of life on the planet.
Researchers examined the fossil remains of vertebrates from the Triassic and Jurassic periods in Earth's history. Around 200 million years ago, volcanic eruptions and climate change resulted in the loss of nearly 80 percent of all species extant around the globe at that time.
"Many groups of crocodile-like animals become extinct after the mass extinction event at the end of the Triassic era, despite being really diverse and widespread beforehand. In contrast, the dinosaurs which were comparatively rare and not as widespread pass through the extinction event and go on to dominate terrestrial ecosystems for the next 150 million years," said Alex Dunhill of the University of Leeds.
University of Leeds researchers examined the geographic diversity of animals as the extinction progressed, and compared that data to changes in the biodiversity of the animals. This provided them with the information they needed to develop a model of how geographic diversity relates to the risk of extinction.
In addition to the End-Triassic extinction 200 million years ago, Earth has experienced four other major periods of extinction. These are the Ordovician-Silurian extinction 439 million years before our times, which wiped out much of the sea life. This event was driven by spreading and melting glaciers. Next was the Late Devonian extinction that took place 364 million years before our time, hitting warm-weather species especially hard. Around 95 percent of all species on the planet were wiped out during the Permian-Triassic extinction, the most disastrous of these events. The last such extinction, the Cretaceous-Tertiary, ended the age of dinosaurs.
"Although we tend to think of mass extinctions as entirely destructive events, they often shake up the status quo, and allow groups that were previously sidelined to become dominant," said Matthew Wills of the University of Leeds.
"Something similar happened much later with the extinction of the dinosaurs making way for mammals and ultimately ourselves. However, our study shows that the 'rules' of survival at times of mass extinctions are very different from those at 'normal' times: nothing is ever really safe."
Analysis of how humans could fall victim to the current extinction event was profiled in Nature Communications.
Photo: Keoni Cabral | Flickr
