Uh-oh... New research on extinctions shows life doesn't always find a way

The Late Cretaceous's grand finale: an asteroid, a 1 500 m tsunami, and global wildfires.

- CAROLINE DELBERT

FIVE MASS EXTINCTION EVENTS ARE generally credited with the state of life on Earth today, but new scientific evidence suggests Earth's history may be marked by additional extinction events, as well as seemingly incidental population explosions.

Jennifer Hoyal Cuthill, PhD, a data scientist at the University of Essex in England, and her colleagues used a machine-learning algorithm to chart shifts in the diversity of life over time and found that life doesn't always rebound after extinction. This new research ‘goes against some of the traditional stories about evolution, which focus on mass extinctions and what happens immediately after them,' she says.

Scientists often assert that mass extinction events make way for mass adaptive radiation events, periods when surviving species evolve and flourish. When the dinosaurs went extinct roughly 66 million years ago, for instance, the rest of life on Earth had broader access to food and other resources. Those species thrived, and eventually gave rise to humans. The logic follows, but the new research says mass extinction events are not the sole cause of adaptive radiation events, if they contribute to those occurrences at all.