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Comment by dilawar | Hacker News Reader

I few months ago I learnt something related that may be a common knowledge to many here. I feel silly that I didn't know.

Earth had a plastic like problem before. There were no fungi that eat cellulose so dead trees were just piling up without degrading. Those trees turned into ~petroleum~ coal that we consume now.

That trees somehow turned into ~petroleum~ coal, I learnt in school. I used to imagine trees were somehow buried under stand suddenly and before they could be degraded they turned into ~petroleum~ coal under heavy pressure.

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Yes, the Carboniferous Period! I learned about this a few years ago and was astonished.

> The world at beginning of the Carboniferous period was a humid, tropical place. Seasons, if any, were indistinct. The Carboniferous trees and plants resembled those that live in tropical and mildly temperate areas today. They grew in wetlands and were shallow-rooted. This, combined with their great height and ponderous weight, was a bad combination, because these enormous trees would regularly become uprooted and topple into the marshy ground, landing on other trees that preceded them.

> Here is where fate steps in. Although trees had evolved lignin and cellulose, no bacteria that could digest these woody substances had yet evolved. In fact, those bacteria would take another 60 million years to evolve. All this time huge trees kept growing, crashing into the swampy ground, and piling up on top of uncounted other trees, getting buried deeper and deeper into the ground. Over millions of years, subjected to the heat and pressure of deep burial, the carbon in these trees was converted into the fossil fuels we know and love today – coal, oil, and natural gas. All the fossil fuels we use were produced during this 60-million year period.

https://emagazine.com/carbon-in-trees/

All the fossil fuels? Aren't some made of dead dinosaurs?

There has been a lot more plant biomass over the eons than dinosaurs

Isn't that nuts? It took like 50 million years.

Meanwhile we got plastic-eating bacteria after like 100 years.

It could be that the bacterial life was less varied than now. Fewer starting points reduces the chance of a particular useful set of mutations coming together. The individual parts might have randomly occurred a great many times before they happened in one population.

Also the availability of other resources might have meant that even if eating the tree parts did develop earlier it just wasn't enough to be a key survival advantage, especially if initial “versions” of the process were inefficient. Perhaps what happening was in one strain it lost the ability to feed on the older sources but had the latent ability to consume the new ones, even if much less efficient, so switched and continued from there to quickly refine the process via further mutation. Changes in the availability of other components, which the trees themselves will have had a hand in, will have changed the balance but over a significant amount of time.

Furthermore, and perhaps more significantly the components of our plastics and how they hang together are not that novel, requiring less changes to come together in one individual or population to make consuming them practical.

Funny, we make plastics from petroleum, so it looks like some particular carbon atoms just don't want to go back in the circuit.

You mean coal. Petroleum was from the dead animals from millions of years ago.

Algae and phytoplankton, but mostly algae. Not large creatures, generally. You'd get massive blooms with phyto/zoo plankton die-offs, they'd settle, then get buried in sand and sediment. Over centuries and millenia, you'd get cyclic deposits, creating massive accumulations, and then over geologic timeframes, you get pockets of striated deposits of these decomposing materials in high heat and pressure conditions. Once the deposits liquefy, they all flow into a common area.

Depending on the conditions and chemistry, you can get coal from ancient algal sources, but you can't get petroleum / liquid oil from ancient forests - the chemistry doesn't work out. You need lots of water and heat and pressure, single cell structures. Lots of cellulose and lignin means you don't get the liquefaction and mixing, forcing the material to carbonize and compress instead.

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