The Science of Extinction

Earth has always been a planet of comebacks. Life has thrived, collapsed, and reinvented itself in astonishing ways time and again. Scientists refer to the five major wipe-outs in our planet's history as the “Big Five”—massive extinction events that dramatically reset the trajectory of life on Earth.

These weren't just random disasters; they were pivotal moments that cleared the stage for new forms of life to emerge. Take the Permian-Triassic extinction, often called the Great Dying, which happened about 252 million years ago. It wiped out around 96% of marine species and 70% of terrestrial vertebrates, likely triggered by massive volcanic eruptions that released greenhouse gases and acidified the oceans. Yet, from the ashes rose dinosaurs and early mammals, proving life's remarkable adaptability.

Fast-forward through the others: the Ordovician-Silurian (about 444 million years ago), Devonian (around 372 million years ago), Triassic-Jurassic (201 million years ago), and the infamous Cretaceous-Paleogene event 66 million years ago, which ended the dinosaurs' reign—possibly due to an asteroid impact. Each time, biodiversity plummeted, only to rebound stronger, with survivors evolving into the diverse ecosystems we know today.

But what does this mean for us now? In an era of rapid climate change, habitat loss, and human-driven pressures, we're in the midst of what some call the sixth mass extinction. Unlike the Big Five, this one is unfolding at an unprecedented speed, threatening species before they can adapt. The lessons from the past? Resilience often comes from diversity—ecosystems with varied species are better equipped to weather crises. Conservation efforts, from protecting habitats to reducing emissions, could be our way of engineering a comeback.

As immunologist and podcaster Dr. Luke O'Neill explains in his Newstalk series Show Me the Science, understanding these ancient resets isn't just academic—it's a blueprint for safeguarding our planet's future. While life has always found a way, ensuring that our way persists requires action today.

For the full discussion, check out the original podcast episode.