There Is Something Hiding Inside Earth

We’ve found a new planet, home to octillions  of the most extreme beings living in the most absurd and deadly hellscape. In absolute  darkness, crushed by the weight of mountains, starved of oxygen, cooked alive, bathed  in acid, salt or radiation. And yet, they live for thousands, perhaps  millions of years!

It turns out, this planet is not in space –––  it is inside the crust of Earth! This is the deep biosphere and  we basically learned that it exists yesterday. Its volume is at least  twice as large as all the Earth’s oceans, home to more microbes than the rest of  the entire planet.

Their total biomass is more than 20 times greater than all  humans, livestock, and animal wildlife. Let’s descend into this mad, deadly world where none of the rules we  thought are mandatory for life apply. Going Deeper and Deeper Deep life seems to be everywhere we  look: below the oceans, near volcanoes, beneath the glaciers of Antarctica, under any  landscape we can imagine and anywhere we live.

We’ll use a special duck science drill and  start our journey in familiar territory: on land, in the soil, where plants grow  and animals roam. If earth were an onion, this is the very top of the very top layer.  Soil is a lavish four-way partnership of air, water, minerals and organic matter, bathed  in endless energy.

Life lives in luxury here. Plants exploit this paradise and produce more  than 30 times the biomass of all of Earth’s animals each year, in a constant cycle of growth  and decay. Only a tiny fraction of the biomass is buried deeper in the ground, supplying juicy  resources for almost half a billion years.

As we dig deeper, most of the  air has been squeezed out and we cross the water table into a  zone saturated with groundwater, rich in minerals and some organic matter. Roots  from the most ambitious plants reach down here, and the most common inhabitants are  scavengers living off decay. This layer can be pretty cold because it is still  slowly warming up from the most recent ice age.

Klunk We reach bedrock. A foundation of solid rock for  all the less solid stuff above, home to fractures filled with water . It can be exposed to the  surface, or buried hundreds of meters below stuff.

Here, in the dense bedrock, we’re in a weird  planet inside the planet. The most thrilling zone of the deep biosphere. As we drill further  down, temperatures gradually begin to rise, and soon it gets really hot and the pressure  rises.

Underneath 400 meters of rock, the pressure is similar to the surface of  Venus. We drill faster now, down to 1000 meters, deeper than the Burj Khalifa is tall. It is about  30°C , and there is almost no free oxygen left.

We continue and finally stop almost  4 kilometers down. Above us pressing solid rock weighing tens of thousands of  tons with pressures as intense as at the bottom of the Mariana Trench. Down here it is on  average 120 degrees C , even hotter if a magma plume is nearby.

The heat is a leftover from  Earth's formation and from from the decay of radioactive elements like thorium and uranium  that shower the crust with a constant wave of radioactivity. To make things worse some rocks  are mixed with extreme amounts of salt. Hell.

And yet. Life is thriving. Inside rock!

If we zoom  in, we see that solid rock is not actually solid! It’s traversed by cracks, voids and tiny pores.  Sandstone, limestone or basalt are so porous that up to 40 percent of their volume is actually empty  space.

But even much denser rocks like granite, can be split open by cracks and fractures.  We’ve found a gigantic planet spanning system of micro-caves, free real estate  filled with water and hardcore microbes! And these caves are moving.

Just like the atmosphere is constantly mixing  air to create weather, down here rocks are mixing to create rock weather. Submerged  mountain ranges are shifting and ripping, crashing and merging. Continents  smash into each other with the energy of millions of nuclear weapons  but as slow as your fingernails grow.

Countless tiny and not so tiny earthquakes  rip open tiny new fissures and passageways, creating new spaces for life and closing others  off forever. In this hot, moving pressure cooker, minerals are forged and baked, and  organic molecules are created and destroyed. An insane menu for anyone  brave enough to try to survive down here.

Let us venture into the system  of tiny caves and meet some of them. The Most Extreme Living Things We think that octillions  of microbes live down here, and naturally they are pretty hardcore.  The doomsday preppers of the underworld.

Some have big, bulky genomes, living entirely on  their own, basically forming their own ecosystem. Like the bacterium Desulforudis audaxviator.  It synthesises its own food by nibbling carbon or sulfur from the rock and turning it into  organic substances.

If the conditions get too extreme or if there is no food around,  it kills itself to survive, by forming an endospore. It divides into a big and a small part,  and swallows the small part again, forming a cell, within a cell. The outer cell then sheds its  water and kills itself, leaving the spore to float around, maybe for thousands of years until  it finds a good place to spring to life again.

Others like some company, like the archaea  with the clunky name Altiarchaeum hamiconexum, that have a rare double membrane covered in  weird materials that protect them against the extremes. They shoot out nano-sized  grappling hooks to tether themselves and seem to live in cracks and fissures filled  with water completely devoid of oxygen, harvest carbon dioxide to create  biomass, and may sort of eat hydrogen. The conditions in the deep biosphere are so  harsh that other microbes share the hard work by forming consortia.

They knit themselves  together in a biofilm – a very thin, sticky net that shields them against the extremes. They  are miniature cells, often with a small genome, but each good at one thing. One type of microbe  eats methane and excretes its electrons.

A second type eats these electrons and converts sulphate  into sulfite that is then eaten by a third microbe and so on. Some eat iron, others use electrons  to turn nitrogen or carbon dioxide into biomass. Life down here found ways to use stuff that  is poisonous to most animals to make food and energy.

But still, life is incredibly hard and  resources and energy are super hard to come by. So the most intense strategy for survival  down here is to live forever. Like monks who’ve taken a vow of poverty, deep microbes  consume very little and conserve their energy.

Their metabolism is up to a million times  slower than microbes at the surface. They had a meal when you were born and are still  digesting it. For most of their life they exist in a slow limbo – some even slowly cannibalise  themselves.

Until a sudden influx of resources arrives by pure chance – and then they spring  into action and reproduce. With this lifestyle it seems that extreme microbes can live for  centuries, maybe even for millions of years! If they are not hunted to death, of course. 

Because kilometers deep in limestone habitats, there seem to be spaces big enough for  multicellular predators. We found asexual worms, 100 times longer than microbes, hunting  and devouring bacteria. It's not clear if they originated down here or if  mini earthquakes opened up fractures for water to carry them into the deep. 

But there are other fierce predators like rotifers or arthropods in the  depths, hunting immortal microbes. We wish we could tell you more insane things  about life in the deep biosphere but there is a problem. We don’t know that much yet.

For one,  we can not really get a good look under kilometers of rock. Drlling down could contaminate  the samples with microbes from the surface. We found living ones in deep mines  and brought them into the lab.

But it is pretty hard to simulate the conditions  they feel comfy in – in boiling hot water, squeezed under mountains, submerged in  deadly chemicals – and still see them through a microscope. And the microbes live so  slowly, for so long that nothing might happen. A lot of what we know about them we  got from turning them into a slurry and looking at what their genes could do. 

Like “breathing” nitrogen or eating methane. We know that the diversity of life in the deep  biosphere must be staggering and that some of the most hardcore and extreme beings live down  there. This is a proper frontier of science, super hard to study and most of  what we know we learned in just the last 20 years.

There is so much  more undiscovered mystery for us, that could bring us progress in  medicine, energy, the climate, and more. Let’s end by moving our gaze from the inside  to the outside again. Since we now know how extremely large the deep biosphere is and how  life down there survives without light, oxygen, sane temperatures or not being covered  in poison… could there be deep biospheres all over the universe?

Maybe all you need is a  planet or moon with internal heat or radiation. And a chemical composition that allows  microbes to build the parts they need. Some scientists suggest that there could  be ten of them in the solar system, hiding beneath a seemingly dead and  frozen surface.

So as we learn more and more about the life below our feet, we may  accidentally learn about life in the universe. You're lucky. YOU dont need to drill dozens  of kilometers through solid rock to discover something mindblowing.

You can just order  some inspiration right to your doorstep. This is a science project crate from our sponsor  KiwiCo who deliver little adventures in a box. Let’s explore: there’s wooden components.

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