Photo by: Getty Images

Getty Images

99 Percent Of The Earth's Species Are Extinct—But That's Not The Worst Of It

By: Ashley Hamer

There's been a vast diversity of life that has existed is now extinct.

August 01, 2019

If you were to list out every species that has ever existed on Earth—from the tiniest mold spore to the largest mammal—biologists estimate that somewhere around 99 percent of those species would currently be extinct.

How Do We Know?

Paleontologists are routinely finding fossils of new species that have never been discovered, not to mention the living species we're discovering every year. So if we don't know every species that has ever existed, how can scientists say how many are extinct? It's a numbers game. Scientists know that plants and animals only fossilize under special conditions: usually in sedimentary rock, and almost exclusively if the species has hard features like bone, shell, or teeth. They also know that a lot of fossils have been lost to tectonic activity, and many more still are just impossible for us to access. By combining their knowledge of these limits, how much rock is out there, and how many species we've already discovered, they can intelligently say that our list of known species is only a miniscule fraction of those that actually lived. That's why they say that the vast, vast majority of life that has existed is now extinct.

What Caused It?

Good news: according to experts, the vast majority of species died out from what is essentially old age. A species generally sticks around for anywhere from 1 million years (for mammals) to 11 million years (for marine invertebrates). But don't get too comfortable. The planet has also been through five mass extinction events, starting at about 440 million years ago. The worst was the third extinction, which took place around 250 million years ago and wiped out 96 percent of life on Earth. To paraphrase Jeff Goldblum, life found a way, setting the stage for the fourth and eventually the fifth extinction. That's the famous one that most experts think was caused by a huge meteorite hitting the Earth around 65 million years ago, killing off around 88 percent of then-existing species. Bye bye, dinosaurs!

What about now? Experts believe that a sixth mass extinction is on its way. Estimates vary, but somewhere between a few dozen to more than a hundred species go extinct every day. At that rate, it would only take a few tens of thousands of years to wipe out the same number of species as the third mass extinction. This time, however, we can't point to a meteorite as the cause. We only have ourselves to blame.

This article first appeared on Curiosity.com.

Next Up

The “Lungs of Our Planet” are Under Threat

World Rainforest Day is June 22, bringing awareness and action to save these precious ecosystems. But if the current rate of deforestation continues, will there be any rainforests in 100 years?

How the World’s Largest Delta Might Slowly Go Under Water

The uneven rise of the sea impacts communities in South Asia

Some Male Cuttlefish 'Cross-Dress' to Woo the Ladies

Learn about cuttlefish at Discovery.com

Living with People and Elephants in the Serengeti

There has been a lot of not-so-great elephant news out of Africa in the last couple of decades. Between 2006 and 2015, an estimated 100,000 elephants disappeared across the continent. However, the story of the Serengeti is slightly different to other national parks in Africa. Here's some insight as to why.

Big Sur Condors, A Conservation Comeback Story

Condors once ranged from Baja California all the way to British Columbia. But, in 1987, the last wild California condor was taken into captivity in order to preserve the species. Now, thanks to a breeding program in central California, the condors are finally returning to their natural habitat in Big Sur.

Almost Every Mammal Gets About 1 Billion Heartbeats

You only have a limited number of heartbeats in your life.

Maine: The Battleground for Preserving America's Wildlife

A whopping 55 species are under threat in Maine, and this is the story of the scientists trying to save them.

Why are Polar Bears Facing Severe Weight Loss and Having Fewer Cubs?

Here's what we can we do on International Polar Bear Day to honor and protect the species.

Why Islands Have The Most Unique Creatures on Earth

What is it about islands that makes scientists weak in the knees?

Octopuses Don't Have Tentacles!

What exactly do these cephalopods have then?