What happens when you freeze the Earth?You get the first animals.

Life on Earth is tough as nails.

From the crushing, soulless depths of the ocean to the highest reaches of the atmosphere, from boiling hot springs to Antarctic wastes — even in the radioactive heart of Chernobyl, life thrives. It finds a way. It laughs in the face of adversity.

Turns out, that amazing tenacity is kind of our birthright as Earthlings. To understand why, you've got to go back to Snowball Earth.

Saturn's moon Enceladus. 720 million years ago, Earth's surface might have looked strikingly similar. Photo from NASA/JPL-Caltech/Space Science Institute.


720 million years ago, the Earth was a pretty different place. For one thing, it was in the icy grips of something called the Cryogenian period.

Living on Earth would have been tough. For 85 million years, the planet was locked in a grinding cycle of massive freezing and thawing. This was no mere chill. At its height, the entire planet may have been frozen over with glaciers marching over even the equator. The alternative? Greenhouse conditions caused by massive volcanic eruptions.

Sounds like a bad time to be around. And, yet, life didn't just endure. This period happens to coincide with one of life's greatest moments — the jump from single-celled bacteria and microbes to multicellular life. Plants, animals, mushrooms, just about everything you can see in your day-to-day life is a descendant of this great leap forward.

But this triumph in the face of adversity wasn't a coincidence. At least, that's what a new letter published Aug. 16 in the science journal Nature says.

Life didn't just endure this cycle of ice and fire. It may have flourished because of it.

The reason, the authors say, has to do with algae. For the three billion years before, single-celled life had scrimped by on whatever energy and nutrients it could grab. There wasn't much to go around.

But things were going to change. As the glaciers marched back and forth across the surface of the planet, they acted like giant belt sanders, grinding mountain into powder — powder that was chock-full of minerals like phosphates. When the cycle flipped and the volcanoes took over, the glaciers melted and dumped all those nutrients straight into the ocean.

Where the algae could get it.

Which then spread like never before.

Which was then food for everything else. Suddenly there was plenty to go around and life began to eat. And thrive. And change. And, over time, that life made the leap from tiny, lonely microbes to the ancestors of all the multicellular life we see today.

We don't just endure hard times. They give us the fuel we need to grow.

This is just one possible explanation, but the scientists say it's backed up by evidence. Chemical signatures in the rocks show a massive algal bloom around this time. Other ideas might come in later and disprove it, of course — that's just how science goes.

But if this is true, then it just makes life on Earth that much more incredible.

Images courtesy of John Scully, Walden University, Ingrid Scully
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Since March of 2020, over 29 million Americans have been diagnosed with COVID-19, according to the CDC. Over 540,000 have died in the United States as this unprecedented pandemic has swept the globe. And yet, by the end of 2020, it looked like science was winning: vaccines had been developed.

In celebration of the power of science we spoke to three people: an individual, a medical provider, and a vaccine scientist about how vaccines have impacted them throughout their lives. Here are their answers:

John Scully, 79, resident of Florida

Photo courtesy of John Scully

When John Scully was born, America was in the midst of an epidemic: tens of thousands of children in the United States were falling ill with paralytic poliomyelitis — otherwise known as polio, a disease that attacks the central nervous system and often leaves its victims partially or fully paralyzed.

"As kids, we were all afraid of getting polio," he says, "because if you got polio, you could end up in the dreaded iron lung and we were all terrified of those." Iron lungs were respirators that enclosed most of a person's body; people with severe cases often would end up in these respirators as they fought for their lives.

John remembers going to see matinee showings of cowboy movies on Saturdays and, before the movie, shorts would run. "Usually they showed the news," he says, "but I just remember seeing this one clip warning us about polio and it just showed all these kids in iron lungs." If kids survived the iron lung, they'd often come back to school on crutches, in leg braces, or in wheelchairs.

"We all tried to be really careful in the summer — or, as we called it back then, 'polio season,''" John says. This was because every year around Memorial Day, major outbreaks would begin to emerge and they'd spike sometime around August. People weren't really sure how the disease spread at the time, but many believed it traveled through the water. There was no cure — and every child was susceptible to getting sick with it.

"We couldn't swim in hot weather," he remembers, "and the municipal outdoor pool would close down in August."

Then, in 1954 clinical trials began for Dr. Jonas Salk's vaccine against polio and within a year, his vaccine was announced safe. "I got that vaccine at school," John says. Within two years, U.S. polio cases had dropped 85-95 percent — even before a second vaccine was developed by Dr. Albert Sabin in the 1960s. "I remember how much better things got after the vaccines came out. They changed everything," John says.

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Simon & Garfunkel's song "Bridge Over Troubled Water" has been covered by more than 50 different musical artists, from Aretha Franklin to Elvis Presley to Willie Nelson. It's a timeless classic that taps into the universal struggle of feeling down and the comfort of having someone to lift us up. It's beloved for its soothing melody and cathartic lyrics, and after a year of pandemic challenges, it's perhaps more poignant now than ever.

A few years a go, American singer-songwriter Yebba Smith shared a solo a capella version of a part of "Bridge Over Troubled Water," in which she just casually sits and sings it on a bed. It's an impressive rendition on its own, highlighting Yebba's soulful, effortless voice.

But British singer Jacob Collier recently added his own layered harmony tracks to it, taking the performance to a whole other level.

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Images courtesy of John Scully, Walden University, Ingrid Scully
True

Since March of 2020, over 29 million Americans have been diagnosed with COVID-19, according to the CDC. Over 540,000 have died in the United States as this unprecedented pandemic has swept the globe. And yet, by the end of 2020, it looked like science was winning: vaccines had been developed.

In celebration of the power of science we spoke to three people: an individual, a medical provider, and a vaccine scientist about how vaccines have impacted them throughout their lives. Here are their answers:

John Scully, 79, resident of Florida

Photo courtesy of John Scully

When John Scully was born, America was in the midst of an epidemic: tens of thousands of children in the United States were falling ill with paralytic poliomyelitis — otherwise known as polio, a disease that attacks the central nervous system and often leaves its victims partially or fully paralyzed.

"As kids, we were all afraid of getting polio," he says, "because if you got polio, you could end up in the dreaded iron lung and we were all terrified of those." Iron lungs were respirators that enclosed most of a person's body; people with severe cases often would end up in these respirators as they fought for their lives.

John remembers going to see matinee showings of cowboy movies on Saturdays and, before the movie, shorts would run. "Usually they showed the news," he says, "but I just remember seeing this one clip warning us about polio and it just showed all these kids in iron lungs." If kids survived the iron lung, they'd often come back to school on crutches, in leg braces, or in wheelchairs.

"We all tried to be really careful in the summer — or, as we called it back then, 'polio season,''" John says. This was because every year around Memorial Day, major outbreaks would begin to emerge and they'd spike sometime around August. People weren't really sure how the disease spread at the time, but many believed it traveled through the water. There was no cure — and every child was susceptible to getting sick with it.

"We couldn't swim in hot weather," he remembers, "and the municipal outdoor pool would close down in August."

Then, in 1954 clinical trials began for Dr. Jonas Salk's vaccine against polio and within a year, his vaccine was announced safe. "I got that vaccine at school," John says. Within two years, U.S. polio cases had dropped 85-95 percent — even before a second vaccine was developed by Dr. Albert Sabin in the 1960s. "I remember how much better things got after the vaccines came out. They changed everything," John says.

Keep Reading Show less