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Comment by Tuna-Fish | Hacker News Reader

Interestingly, warm-blooded animals (including humans!) tend to have simple genomes compared to cold-blooded ones or similar complexity. It's just much easier to get repeatable results during development when you can do all the trickiest parts at fixed temperature, a human can use a single gene to achieve what a frog needs half a dozen for.

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Moral of the story, if you notice you have to deal with a multitude of states, get out of that swamp first, get some foundations right and then iterate. Applies to both biology and coding.

On the other hand, the human body is super-reliant on very nearly exact temperature regulation. A few degrees can kill us easily. Cold blooded systems are substantially less reliant on pristine conditions.

Warm blooded systems though can power high energy activities like maintaining a large brain, which could figure out how to get warm.

A few degrees can kill a human only in theory, in practice a human would wear a jacket or seek shade.

A few degrees kills many, many people every year. I didn't say a few environmental degrees, I said a few degrees of regulated temperature. All it takes is a tiny little virus to make your immune system eat itself and kill you with your own heat. That's a very good example of a system that is highly reliant on the right environment to operate properly.

Octopi are cold blooded and smart

But they live in a fairly constant temperature environment compared to a land reptile for example.

Update: they do some funky stuff https://www.sciencedaily.com/releases/2023/06/230608120915.h...

> The octopuses achieve this by editing their RNA, the messenger molecule between DNA and proteins.

Lesson number two: if you cannot avoid dealing with multiple states, consider monkey patching. The result might resemble an eldritch horror, but at least it will work.

No wonder they die so young

So, expressing your genes at 37°C is a bit like running your code from Docker image?

"Well, it runs on my machine" - some small mammal, ca. 50 million years ago

The reason for this is that chemical reaction rates are temperature dependent, and cold blooded animals need different systems of chemicals/proteins to keep them operating over significantly different temperatures.

I wonder to what degree the competitive advantage of being warm blooded consists of the smaller genome vs. more obvious advantages like ability to stay active in colder climates.

Humans outsource a lot to the microbiome. We have to add up all that too!

As far as we know, all complex organisms have an accompanying microbiome of commensurate species, even the most basic ones like marine sponges [1]. Plants nurture these symbionts in their roots while animals do it in their digestive tracts (mostly, both have surface microbes too that do various things too).

[1] https://www.nature.com/articles/s41396-020-0591-9

So, indication of advanced evolution: outsourcing some of our development to other lifeforms (e.g. microbiomes)

I wonder if someone would take human DNA and all the necessary bits and cloned one on another planet completely alien to Earth: would that human being have a bad time because of the missing microbiomes or will they somehow grow their own (I'm thinking gut bacteria and microbiomes and so on)?

A lot of research is performed on “axenic” mice — mice without any biome.

I do not think this is generally true. Do you have a citation?

Endothermy vs ectothermy is much more about aerobic vs anaerobic metabolism.

Endotherms can sustain high levels of physical activity for hours and days. An ectotherm is lucky to go one minute.

Nick Lane’s fabulous book:

“Power, Sex, Suicide: Mitochondria and the Meaning of Life” is the right place to start.

This is super interesting! Can you share more info/resources?

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