LOS ANGELES — “These are heel bones of the giant sloths,” Emily Lindsey said as she slid open a grey door at the La Brea Tap Pits. 

“Sabertoothed cats,” she said, opening another. There are multiple aisles lined with drawers, floor to ceiling, as far as the eye can see, and they all hold one thing.

“All bones,” Lindsey said, hurrying to locate another long gone species. “All bones.”

What You Need To Know

  • Scientists at La Brea Tar Pits believe drought, climate change and wildfires led to the extinction of some large mammals in Los Angeles

  • Giant sloths, ancient horses, dire wolves and saber-tooth cats all disappeared from SoCal around 13,000 years ago

  • Other research shows a significant increase in wildfires — likely caused by man — around that same time

  • Scientists around the world warn that we’re in an extinction crisis, at risk of losing more than a million species in the coming decades

It’s been thousands of years since giant sloths, ancient horses and dire wolves roamed through Southern California. They shared what is now Los Angeles with other large mammals, until, Lindsey says, a big change occurred.

“At the end of the Ice Age, something very dramatic happened, which is that almost everywhere, except for Africa, most of the big animals in those landscapes disappeared,” she explained. “And nobody’s really been able to figure out why.”

Until now. 

Lindsey is the associate curator and excavation site director at the La Brea Tar Pits. By studying the remarkably preserved bones unearthed at the site, she and her colleagues, including Interim Assistant Deputy Director and Assistant Curator Regan Dunn, were able to better pinpoint the timeline for the extinction to about 13,000 years ago.

“Which is a bit earlier than was previously thought,” Lindsey pointed out.

But the big “aha moment” was over why.

“I think it was when we saw the fire record,” she said

She’s referring to the work of UCLA graduate student Lisa Martinez, who was studying the area around Lake Elsinore and found a dramatic increase in fire around the time of the extinction. Something else was happening around the same time. 

“We see that this period of wildfires coincides with a time of significant growth in human populations that are very skilled at using tools,” Lindsey explained, “including the most powerful tool that humans have ever invented, which is fire.”

Prior to man’s arrival on the scene, she says there was very little naturally occurring fire in the region. Martinez found a 30-fold increase around the time in question.

Meanwhile, the climate was changing. Temperatures were warming and there was a prolonged drought, decades and in some cases even centuries, according to Lindsey.

Drought. Climate change. More frequent fires.  

“It’s a little bleak,” admitted Noah Greenwald, the Endangered Species Director for the Center for Biological Diversity. “Given recent events, just incredibly scary. What happened in Lahaina, what’s been happening in Canada, it’s clear that fire is becoming more prominent with climate change.”

And so is extinction. Scientists around the world are warning that we’re in an extinction crisis, at risk of losing more than a million species in the coming decades. A loss, Noah Greenwald, that could have devastating effects on everything.

“All of our food, most of our medicines, come from species,” he explained. “Species are the building blocks of ecosystems. They pollinate our crops. They moderate climate. And so we’re essentially, you know, we’re undermining the bedrock of our own existence.”

He sees the two crises — the extinction crisis and climate change — as being hand-in-hand. 

“Fixing these problems is very interrelated,” he said. “You know, we have to protect more of the natural world, and we have to leave fossil fuels in the ground. That’s the only way we’re going to get ourselves out of what’s a very concerning problem, and that is going to affect our quality of life and particularly for our children.”

In that sense, the past may hold a stark warning for the future. Lindsey hopes that by understanding what happened to these animals 13,000 years ago, we have an opportunity to correct some of these problems that exist today.

“Slowing climate change, preventing accidental fire ignitions in this ecosystem, and preserving the few remaining large mammals that we have today,” she explained, “will have a significant impact in slowing or preventing another ecological collapse.”