Surface. Southern California, 1920s.

Every Hass avocado is the same tree.

A mail carrier named Rudolph Hass planted a seed in his yard. He meant to replace it with something better. It didn't work, so he let the weird little tree grow.

That one mistake became nearly every Hass avocado on Earth.

They're all copies, cut and grafted from that single tree. So a Hass grove isn't really a crowd of trees. It's one living thing, repeated over and over.

dubrobot explains: the mother tree

Hass patented the fruit in 1935. It was tougher, richer and shipped better than anything else around. The original tree lived about 76 years before root rot got it in 2002.

The grove in this piece comes from that family, but it's been left alone to mature. Roots undisturbed, soil never turned. Most orchards never get that chance.

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6 inches down. Getting darker.

Trees talk underground.

Under an old grove, the roots are wired together by fungus, threads thinner than a hair running tree to tree. Through them, trees pass each other food and water. A big tree can feed a little one in the shade, meters away.

The roots also give off tiny electric signals. A slow, quiet conversation, going on right under your shoes.

dubrobot explains: the weather down there

The soil has its own weather. Microbes breathe and multiply in bursts. Worms tunnel through and let air in. Gases rise and fall. Water drifts around.

It all pushes and pulls on everything else, like a tiny climate. And it's been doing this forever without anybody listening.

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12 inches. Instruments buried here since late July.

So we planted ears.

For several weeks, sensors were buried all through the grove, recording everything the trees and soil were doing. Tap one to see what it heard.

• Temperature
• Microbes
• Worms
• Moisture
• Decay
• Gas
• Ultrasound

Seven streams of data. Seven voices that never had a way to speak.

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Fractal Feedback. Here's where it gets strange.

A mixer plugged into itself.

You know that screech when a mic gets too close to a speaker? That's feedback: sound looping back into itself. A no-input mixer does that on purpose. No instruments, no microphones. It just feeds its own outputs back into its inputs.

Left alone, it howls. But it needs something to steer it.

This is the unique part. So the grove steers. Every stream of data turns the knobs, opening some loops and closing others, at whatever speed the trees and dirt actually experienced life.

Nobody plays it. Nobody wrote a score. The music is the grove telling its own story through a machine that only knows how to reflect on itself.

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Listen, really. Listen.

Weeks of soil recordings, squeezed into minutes.

Most of this stuff is way too slow for human ears. It only makes sense over weeks. So the big challenge was finding the right speed, fast enough that you can finally hear the grove's story on our timescale.

The first time it played, I didn't expect a grove of avocado trees to sound like this:

• crickets
• coyotes
• wind
• rain
• long humming drones
• sudden bursts
• sounds with no source at all

The sound is the recorded data of the grove, controlling a mixer that is feeding back on itself. We find these feedback loops all over the planet. Climate engines, geologic cycles, biologial cycles, cloud generation, among all other kinds of fractal feedback.

dubrobot explains: the part that surprised everyone

When the feedback started folding back on itself, layer on layer, you'd expect it to get harsh and robotic. It went the other way. It started sounding more natural. A machine fed on soil data started sounding like the outdoors.

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