> Biology is nuts.

for this particular case I 100% agree. I grew up to accept a wide range of complexity at the cell level, but this blew through the roof.

Dunno about mitochondria as a cell feature specifically. But there exists a similar constraint on the total size of the DNA in the cell nucleus (and therefore the ability of a species to survive polyploid mutations that double-or-more the amount of DNA per cell); and I believe we do (think that we) understand the cause of that one.

This polyploidy constraint only exists for animal cells, not for plant cells. Plants can — and frequently do! — get as polyploid as they want; but animals have a ceiling.

And that implies that the constraint has something to do with one of the main differences between plant and animal cells: namely, the fact that animal cells — specifically, blood cells — must move and flow along channels composed of other cells; while plant cells are fixed in place by their stiff cellulose membranes, with only fluids and tissues flowing.

The problem animal cells have with polyploidy, is seemingly that it makes their cells physically larger — and in so doing, causes biological architectural assumptions like "blood cells can travel through narrow capillaries to deliver oxygen to cells within extremity tissues" to just fail to hold. The capillaries, when composed of larger cells, are narrower; and the blood cells flowing through, composed of larger cells, won't fit.

(Evolution could in theory resolve this single problem by just scaling all features up in size. But that causes far more problems than it solves: the square-cube law requires huge changes to things like muscles and metabolism to keep up with increased size, if it's even possible; and some organs/tissues just require to be a certain size to function — like the nephrons of the kidneys — such that these instead need to stay the same size, evolving distinct adaptations to handle the increased size of the cells that travel to/through them.)

> Regarding messing with T-cells I wonder how evolution came up with the current number of mitochondria per cell.

An over active immune is generally a bad thing for the host. Maybe a higher number increases auto immune disease?

> Regarding messing with T-cells I wonder how evolution came up with the current number of mitochondria per cell.

Cells can increase their number of mitochondria in response to things (mitochondrial biogenesis). I don't know anything about how that works out in the immune system, but have read about it related to fat cells and exercise.

This was also my first thought, and it seems like "giving them extra batteries" accomplishes the same outcome

I really appreciate the commentary here on HN. The headline was awful enough, but the quotes, really let me know the level of horror movie aesthetic there is in the commentary supposedly about biology.

Thanks, NewAtlas, but it's just not the mixed metaphor I'm looking for.

> I wonder how evolution came up with the current number of mitochondria per cell

One of my probably-wrong ideas that I can't usefully ask* is if chronic fatigue/post-acute infection syndromes may be due to insufficient mitochondria for whatever reason.

* if I ask StackExchange, I'll probably phrase it wrong enough to have it closed; if I ask an LLM then it will probably make something up because if the answer exists at all it is probably behind a paywall, and even if it isn't they do that 10-20% of them time anyway.

Could it be just amount of energy available to the organism? Modern humans are in completely unique position relative to all history of life on Earth, having access to as much food (and energy) as we want, and having a widespread problem of eating too much. Evolution didn't have any chance to catch up with this reality.

How many do you have to have before you can start using the Force?

Completely spitballing here, but if bone marrow cells help charge up mitochondria (as this new study suggests), then strong healthy bones are a good defense against cancer. Resistance training (weightlifting being the most common variety) is well known to improve bone health so maybe this is another reason to practice it.

> So I wondered how one could increase the number of mitochondria

Lots of Zone-2 training. Inigo San-Milan & George Brooks are the two researchers to look at this for in humans.

Yeah, batteries was a funny metaphor given that everybody from my generation learned that Mitochondria are the "powerhouse of the cell" in Junior High.

Why? As a laymen (who knows nothing about "T cells") the analogy helps

To be fair, I'd prefer not to give the cancer cells extra batteries.

How is this related to the number of mitochondria in a cell?

nah. let's base the entire world diet on numbers of calories, provided by crops which are collected annually or biannually so we can have an efficient futures market :thumbsupemoji