Thursday, December 19, 2019

Gaia Bots and Plant Pots

It was long before artificial turf and breast implants that humans began losing their connection with nature.

There is a long history of our love affair with Mother Earth, and two variations on this theme for those interested in the subject could be the American Frontier and the English Garden (both circa 1700-1800's). In the former, the West was a force to be feared, explored, and eventually dominated. In the latter, the Garden was a symbol of the picturesque, idyllic and meandering qualities of nature, albeit designed and maintained by human intervention.

The picture-perfect English Garden isn't much different from pretty much anywhere else on Earth – it's all a hybrid. Everything on this planet has in some way been shaped by us. You want evidence? How about the serious debate by geologists trying to demarcate the beginning of the Anthropocene as a geologic epoch. We've been terraforming this place since the dawn of agriculture and have no plans on stopping (carbon dioxide be damned).

This is quite a lofty intro for a post about houseplants. But this is where we start because the myth that "houseplants filter indoor air" is tenacious. It's also a great example of what makes a meme sticky, because it's simple, easy to understand, and common to everyone. It's also wrong.

You can't blame us. We want the outside inside; we're all biophiles! We want it to be true that filling our house with plants will enhance our indoor environment in scientifically-supported, quantifiable ways.

But it's fake news. And in the manner of all news that is fake, the idea that houseplants clean our indoor air is not absolutely wrong. They do clean the air, just not enough to make a difference.

I mean, if you were on a spaceship, where ev-er-y-thing makes a difference, then sure. That's where this all started. Studies done for NASA showed that they could use plants as part of a larger air-cleaning strategy. And there you have it, memetic gold.

(You know what's not mememtically robust? The fact that it's the soil microbes doing all the dirty work, not the plants themselves!)

The bottom line is that the amount of clean, fresh air that can be delivered by a typical mechanical exhaust ventilation system is a few magnitudes more than that coming from our vegetal ancestors. Or, if you really insist on bringing the outside in, open a window.

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Post Script
We start domesticating plants 10,000 years ago as a part of the Neolithic or Agricultural revolution. The ancients of Egypt, India, China, Greece and Rome all put plants in pots, but most of these were used to decorate outdoor spaces (think Hanging Gardens of Babylon). We can trace the practice of using houseplants back to the 1600's with a book called The Garden of Eden. But Buckminster Fuller's 1967 Biosphere might have a lot more to do with their current ubiquity.

Post Post Script
Our indoor space as urban dwellers is vastly different than that of jungle huts. Obviously. But what you may not have known is that our walls and windows trap so much of our own metabolic excreta that we live in higher concentrations of our own filth than someone in a thatched hut.

You can’t really measure “filth” in this context, so the above statement is more hyperbole than fact. However, this collaboration between the Microbiology and Anthropology Departments at Rutgers University, New Jersey, painted a good comparative picture of our respective indoor environments.

They studied a remote Peruvian jungle village of thatched huts with no walls, a Peruvian rural town with wooden houses sans indoor plumbing, a Peruvian city of 400,000 residents, and the two million-strong metropolis of Manaus, Brazil.

They found that we have a higher diversity of chemicals from medications and cleaning products and of fungi associated with human skin, the mouth and the gut, whereas the rural and jungle homes had a greater variety of outdoor-associated bacteria and fungi typically found in water and soil.

This is because the walls themselves trap all this stuff as it floats in the indoor air. We also have warmer, wetter air than a jungle hut, as well as less sunlight and less fresh-air exchange. This plus the tons of dead skin cells we leave lying around all make a great incubation-chamber for fungi. So despite the fact that urban dwellers clean more frequently, their indoor environment is teeming with micro-organisms that live in and on our bodies.

The end result is that our homes, in the more urban areas, and in more modern times, are more like the human body than the body of Mother Earth.

Home chemical and microbial transitions across urbanization, Nature Microbiology (2019).

Walls talk: Microbial biogeography of homes spanning urbanization, Science Advances

Nov 2019,

1988, NASA and BC Wolverton.

RL Orwell, RA Wood, MD Burchett, J Tarran, F Torpy.
Water, Air, and Soil Pollution. 177 (1–4): 59–80. 19 September 2006.

**Buy Sir Hugh Platt's original 1675 book Garden of Eden, here for $3,500

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