Yet another Hacker News

Why is the liver so weirdly regenerative?

49 points jbotz 2 hours ago 38 comments

schnuri 1 hour ago | parent

I am in awe about how wonderfully engineered by evolution the body is. E.g., what we are able to do with it and how it heals itself when we have an injury. Sure, many people would not live long without external intervention, but many others would. I still want to see the robot that can survive 80 active years without maintenance.

chistev 49 minutes ago | parent

The human body can't survive 80 active years without maintainance. They take drugs, they see the doctor, etc.

CookieCrisp 42 minutes ago | parent

What did people do 500 years ago?

EduardoBautista 41 minutes ago | parent

Die as a child at alarming rates

lukan 35 minutes ago | parent

But those who did not, got quite old without ever seeing a doctor.

(If we are talking about hunter gatherers, not poor exploited peasants)

1attice 21 minutes ago | parent

Citation required

markyc 48 minutes ago | parent

no you don't

arcanemachiner 43 minutes ago | parent

Well, so much for that discussion.

dgunay 41 minutes ago | parent

Well, we do at least have to eat enough food and sleep ~1/3rd of our lives. That's kinda maintenance

micromacrofoot 29 minutes ago | parent

that's absolutely maintenance, without it you have a total system failure in a week

RobotToaster 41 minutes ago | parent

Humans don't last long without topping up their fluids and consumables.

ericmay 31 minutes ago | parent

When you watch those sci-fi shows and folks have nanobots implanted in them that heal wounds really fast or do other cool things I can't help but think in many ways we already have that technology we just need it to do more, faster as our brains and ability to create things have outpaced the rate of evolutionary change.

amluto 1 hour ago | parent

The lack of heart cancer might be more complex than the OP imagines:

https://www.science.org/content/blog-post/no-heart-cancer-th...

jaggederest 26 minutes ago | parent

Other animals do get heart cancer, which is fascinating. It's still very uncommon compared to other cancers, but not virtually absent as it is in people.

bbor 1 hour ago | parent

   I greatly resent having to be a biological organism and subject to all the poor engineering and design decisions that entails.

The first word of that sentence implies its absurdity quite beautifully. She resents, therefor she is.

And then this:

  Brains. After you reach adulthood, neurons don’t divide. If some of your neurons die—which happens every day—then they’re gone. If you get a brain injury, the other neurons will try to “learn around” the injury, but the neurons themselves are never replaced.

We need more neuroscience in schools! This summary is technically correct ofc, but to imply that the brain is missing some obviously-better option is absurd. We're meat that thinks, y'all; it's far from crap.

someonebaggy 29 minutes ago | parent

IIRC the slow loss of neurons is more than balanced by the additional fine-tuning - unless you get dementia, if course.

Loss of neurons isn't disastrous as long as it's not too many. Babies are born with several times more neurons than children have, and spend a few months letting all the useless ones die. Apparently it's better to start with a random tangle and prune it to shape (like cutting a box hedge) than to make a hedge grow in a box shape to begin with.

And IIRC brains can grow more neurons under some circumstances (certain drugs?) - they just normally don't.

rzzzt 14 minutes ago | parent

"While questions remain regarding the precise extent, rate, and functional relevance of adult neurogenesis in the human brain, as well as important methodological considerations, multiple independent approaches now converge in support of its persistence throughout adulthood."

https://www.sciencedirect.com/science/article/pii/S193459092...

done_lurking 18 minutes ago | parent

Why is it absurd to say that the human brain could be better? That seems obviously true to me.

dekhn 2 minutes ago | parent

the claim isn't complete, either. Recent research has demonstrated adult neurogenesis (growth of new cells that originate from neural stem cells).

card_zero 1 hour ago | parent

> Evolution decided the good outweighed the bad, and I expect that evolution was right.

We can expect evolution to do the right thing for the genes. Not for us.

cortesoft 46 minutes ago | parent

I get its just a framework to understand what is happening, but I always hate the phrasing of describing a 'decision' to a process like evolution. There are no decisions being made in the process, just a series of outcomes that lead in a direction

CookieCrisp 39 minutes ago | parent

Indeed, I’ve heard so many people misunderstand it because of this type of wording. Like there is still some plan and series of steps we’re following - which really misses the whole point and why it’s worth knowing in the first place

someonebaggy 31 minutes ago | parent

Evolution is literally just the observation that there are lots of things that self-replicate.

That's it. That's the entire thing. Plus some nuance about things that self-replicate faster than other things...

It occurs at all levels. Amyloid protein in Alzheimer's patients is self-replicating. So are cells. So are individual parts of cells. Sometimes things replicate by being parts of a larger thing that replicates, sometimes they don't. It's all one big chaotic tangled mess with no particular purpose or design. Human cells evolve, so do humans, so do human societies. So do rocks.

cwillu 27 minutes ago | parent

Rocko can't have kids, because Rocko is just a stupid rock.

vconnor 27 minutes ago | parent

The punishment for Prometheus stealing fire from the Gods and gifting it to humanity, was to be chained to a rock and having an eagle feed on his liver which would regrow the next day.

bheadmaster 8 minutes ago | parent

For what it's worth, Prometheus was a Titan, and Titan was immortal, so his liver regrowing the next day wasn't really that special. If eagle fed on his heart, or lungs, they would've regrown too.

The Greeks chose liver because it symbolized the defiance Prometheus had against gods.

seizethecheese 8 minutes ago | parent

Why would liver signal defiance?

agumonkey 24 minutes ago | parent

Anybody on HN knows platforms to discuss this ?

gchamonlive 20 minutes ago | parent

This is a platform and we are discussing this, which means such a platform isn't enough for what you need. Not judging, actually I've felt a degradation in engagement quality as of late, maybe it's personal bias, but the discussions seem more shallow or aggressive.

In any case, what would you expect from such a platform? That would help with recomendations.

Aeolun 15 minutes ago | parent

I feel like this is obvious. Eventually dying of all the weird body failures doesn’t inhibit your ability to procreate, but if you cannot survive alcohol or other various poisons you’ll never make it to a fertile age.