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Comment by lm28469 | Hacker News Reader

Maybe its inefficiency is necessary. After all earth is a global eco system, it's all about balance, everything is inter connected. What if Rubisco stopped missing 2/3 and never missed instead ? What about the global CO2 levels ? Oxygen ? More plants = more food for some animals &c.

This sounds like the typical junior developer starting working on a 20 years old project saying 'Wait a minute, I can rewrite these 50k lines in 500 lines of _insert tech of the day_' while ignoring 20 years of side effects, special cases, well thought decisions, &c.

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> After all earth is a global eco system, it's all about balance, everything is inter connected.

Unfortunately, evolution doesn’t do balance, but rather local gradient descent. Species reliant on one prey or one plant can and do over-consume their food into extinction and then go extinct themselves. Even the oxygen we breathe was a toxic waste product when the earth was young, and while evolution found a pathway to consuming it, there’s never any guarantee of that.

Evolution has had a long time to find solutions, so it shouldn’t be ignored, but it’s also not a particularly smart system and it definitely isn’t directed with long-term goals in mind — evolution can create birds, but not birds which grow their own hypersonic ramjets.

Conversely, after the millions of years of evolution, it's not unreasonable to think that creating a more efficient Rubisco could have happened spontaneously in nature by mutation. Our logic suggests this would almost certainly provide some benefit; and yet, nearly all Rubisco enzymes show roughly the same level of efficiency.

To me, this implies some other limiting factor that we don't understand.

There’s lots of stuff we don’t understand, but our ignorance isn’t necessarily the reason evolution didn’t do it.

I expect us to find out why evolution didn’t do it by doing it to the plant genome ourselves — and that either it requires too many simultaneous changes for evolution, and/or it turns the plant into something irresistible to insects or fungi.

I'm sure there are many many more scenarios than the ones you listed. We're talking about editing the very thing that permitted life on earth, not renaming YourVarName to your_var_name across a codebase ...

Highly multivariate random walks are excellent at finding local optima, and poor at descending from those hills to find a higher one.

If something requires, say, five individually-deleterious mutations, each of low probability, it's quite plausible that these will never align in a single organism.

A localized entity responsible for the inefficiency doesn't sound like a local minimum, though. It sound like a place where you should (eventually through mutation) find the more efficient path.

There may be a more esoteric explanation... Imagine higher efficiency has a price : plant lives a shorter life, and reproduces less. Then you want to fine tune for the right amount of efficiency in your environment. Then it's advantageous to have a single efficiency lever, instead of a dozen systems to fine tune jointly... Just a guess - I know nothing about bio. :)

That is approximately why C4 photosynthesis hasn't swept the field and replaced C3 entirely: it's an advantage in high-light, dry conditions, whereas in wet, dark conditions, the more efficient use of ATP in C3 fixation provides a comparative advantage.

FWIW I'm quite bullish on the type of research in the Fine Article; humans have the ability to provide choice conditions to our crops, and so we can maximize yield without (much) concern for the tradeoffs experienced in the state of nature.

I'd predict, for example, that we'll have a C4 rice crop out of the lab and in the field in ten years or less.

This! The idea that nature is balanced is strange since nature changes locally all the time. The issue with global warming is that it is a global change that chances every local ecosystem in such a fast way that the evolutionary processes are not adapting. In many ways, each animal's birth rate is calibrated for its the local environment and how fast it changes. Since if the animal had too many babies too quickly it could die off or if it had too many babies too slowly it can die off. So animals that have survived their habitats for a long time have a calibrated birth rate.

Global warming is changing the rate of how fast local habitats change and therefore NO ANIMAL ON THIS PLANET is likely going to be able to handle the rate of change. Which is why we are in the 6th mass extinction.

In other words, animal life is locally calibrated, not globally and if you change the global system (therefore changing every local system quickly) you will get a bad bad situation.

Do you have a source for

> NO ANIMAL ON THIS PLANET

My guess is that cockroach will be fine. Perhaps no all species of cockroach.

Some animals have a wide distribution. Sparrows live in a wide range of climate, they have different size (in cold climates, they are bigger). Many birds migrate, some of them can probably change the extremes of the migration path and be fine.

I'm more worried for elephants and other animals with a long lifespan and small area where they can survive. (And I'm more worried about trees, because they can't move.)

Where have all the sparrows gone? https://blog.nature.org/science/2019/03/25/where-have-all-th...

A great example involves marsupials. I read once that marsupial evolution is restricted by their need to be able to crawl/climb into their mother's pouch. So, it's highly unlikely that there will ever be a hoofed marsupial.

Nature/evolution seems much better at long term goals than us seeing how much damage we've done since we discovered coal/gas.

> Species reliant on one prey or one plant can and do over-consume their food into extinction and then go extinct themselves.

Well, of course, I didn't say nature was immutable, just self balancing. I doubt you can deny that life as we know it is heavily reliant on plants and that doubling or halving plant photosynthesis efficiency would have consequences we simply cannot predict. When simple things such as reintroducing wolves in a park can unexpectedly change the course of rivers [0] I'm really wary of people wanting to "improve" the world by shaping it in such extreme ways and promising the results to be 100% beneficial.

[0] https://wilderness-society.org/wolves-change-flow-of-rivers/

> Well, of course, I didn't say nature was immutable, just self balancing

And that, specifically, is what I’m denying.

Think of it another way: humans are a product of natural selection, so every imbalance we cause to the environment is an example of evolution not being balanced.

> so every imbalance we cause to the environment is an example of evolution not being balanced

Not balanced ? You should look into global co2 level, how it's linked to cognitive performance, climate change, &c. The balance is about to smack us right in the face if you ask me.

https://en.wikipedia.org/wiki/Climate_change_feedback

That’s like saying high speed driving is balanced by roads being bendy because bendy roads force you to slow down or die.

And if you want to make that argument, you’re now arguing my point for me ;)

(My stance is that that doesn’t count as balanced. We can still figure out how to drive faster than the fastest land mammal).

> We can still figure out how to drive faster than the fastest land mammal

Sure, that's how we got one of the most polluting industry of the last 100 years, see, all balanced. We took one thing, transport, and made it a priority while ignoring every other aspect, and now we're all breathing polluted air.

Roads are bendy because they follow the topography of the terrain, cars aren't faster because we'll still get fucked by drag no matter how smart we'll get https://i.stack.imgur.com/PKkDf.jpg but we're getting off topic.

On a long enough scale the carbon we added to the atmosphere will get sequestered again, and using more efficient plants everywhere would cause a swing the other way to a reduction in CO2 and global cooling. That's a much easier and slower problem to deal with though.

That would be so far in the future though we can't even imagine what the earth would be like, or what we would be capable of, or what the population would be. Hopefully we decided it was important to leave large natural spaces on the planet.

> After all earth is a global eco system, it's all about balance, everything is inter connected.

Most of the oxygen is produced by cyanobacteria in the sea (not by trees as is a common misconception). These morons have already once produced so much oxygen that killed most life. https://en.wikipedia.org/wiki/Great_Oxidation_Event

If they could do it again because they discover how to make a more efficient photosynthesis, they would do it without hesitation.

Efficiency as a concept requires a lot of context. In this case, when the power source is free and unlimited (at least until you get close to utilizing all incoming solar energy), talking about efficiency as simply the output energy divided by the input solar energy is probably not the most useful concept.

Another common example is electric heat versus geothermal heat pumps. Electric heat is "100% efficient" in the sense that essentially all the electric energy is converted into heat. And yet, a GHP can provide the same amount of heating using less electric energy, because it's moving heat from an effectively free and unlimited source.

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