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Our closest worm kin regrow body parts, raising hopes of regeneration in humans

washington.edu

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Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#91

Post by hyko »

devoply wrote: post #82
xux wrote: post #74

A lot of people are focusing on the mechanics, but it seems like humans don't generate body parts just like cells don't generate organelles. The entity is not _meant_ to exist by itself, but form a cohesive living group. A cell doesn't need to repair itself, it can simply clone itself and then die. A human being doesn't need to regenerate itself because it can reproduce and be cleared away. Evolution evolved to ensur…

> Evolution evolved to ensure the survival of the species, not the individual. At some point in our evolutionary history the cells in our body made this choice. Evolution favors survival and potentially reproduction, because otherwise you are no longer in the game. So there was some evolutionary constraint that caused those genes not to regenerate parts. It's possible we can change things so that those genes are acti…

I agree with you but don't forget the role of genetic drift.

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#92

Post by vacri »

toasterlovin wrote: post #90
piptastic wrote: post #87

Earlier quoted context omitted.

You don't have to regenerate parts to live long enough to have offspring. You can do it at like 15 years old. So evolution isn't going to help in that regard much.

Living for a long time after you have children is incredibly useful from the standpoint of genetic fitness. After all, grandparents play an important role in pretty much every human culture. And a grandparent with all their body parts is a whole lot more useful than one without.

There are plenty of species where the male dies during mating, and squillions more where the male isn't around after mating.

Evolution only requires that you get to reproduction, however that happens. It doesn't require that you're happy, sad, whatever, just that you reproduce.

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#93

Post by Qantourisc »

From another research done on mice, the answer is mainly scar tissue. https://www.ncbi.nlm.nih.gov/pubmed/12557217

About the evolution part: we have a higher change to live with scar tissue, then we have without (shorter chance for infections).

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#95

Post by guitarbill »

m0llusk wrote: post #77
avodonosov wrote: post #35

It would be good to regenerate at least teeth.

Regenerating body parts doesn't happen because it is hugely expensive in terms of biochemical resources. Teeth are the most materially expensive parts of the human body. That is why teeth are often the most long lasting and best preserved human remains.

And yet, sharks do it. Also, the skeleton is similarly long lasting and that gets renewed.

So why not? Say a finger, which isn't too "expensive in terms of biochemical resources", why not regrow that? Take the acorn worm mentioned, in proportion to the worm regrowing itself must be really expensive.

I don't think this too expensive argument explains it.

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#96

Post by arcticfox »

vacri wrote: post #92
toasterlovin wrote: post #90

Earlier quoted context omitted.

Living for a long time after you have children is incredibly useful from the standpoint of genetic fitness. After all, grandparents play an important role in pretty much every human culture. And a grandparent with all their body parts is a whole lot more useful than one without.

There are plenty of species where the male dies during mating, and squillions more where the male isn't around after mating. Evolution only requires that you get to reproduction, however that happens. It doesn't require that you're happy, sad, whatever, just that you reproduce.

> Evolution only requires that you get to reproduction, however that happens. It doesn't require that you're happy, sad, whatever, just that you reproduce.

It requires that your offspring actually survive as well. Humans are, at least historically, exceptionally well-equipped to influence the survival of their offspring.

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#97

Post by guitarbill »

kazinator wrote: post #84
andars wrote: post #53

Earlier quoted context omitted.

This doesn't strike me as a reasonable analogy. 1) Microchips don't grow autonomously in the first place, unlike organisms. 2) The article's point is that not only do humans have the "mask artwork and silicon wafers", but also the genes that other organisms use to regenerate portions of their body. A closer equivalence would be "the instructions on how to rebuild the missing half of the microchip from what remains".

Microchips grow autonomously if you regard the entire fab and its staff as a big organism. And note that the blueprints for the chip do actually encode more or less what it looks like: as a genotype they resemble the phenotype. Yet such a repair is not feasible. DNA genes do not encode an arm or a leg directly, but a convoluted process by which the structure develops.

> Yet such a repair is not feasible.

Well, we don't really know, because we've never bothered to build a chip/fab process with that capability. It's cheaper to just throw broken ones away (edit: plus, it isn't morally reprehensible to throw them away because they don't have consciousness... yet). I guess the other thing is that a CPU is pretty simplistic compared to a big organism.

We do bin products and then e.g. underclock or disable parts of them accordingly. So there's the start of an "injury"-sensing mechanism. But microchips still have a few thousand years to go in their "evolution" at least :)

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#98

Post by richardw »

xux wrote: post #74

A lot of people are focusing on the mechanics, but it seems like humans don't generate body parts just like cells don't generate organelles. The entity is not _meant_ to exist by itself, but form a cohesive living group. A cell doesn't need to repair itself, it can simply clone itself and then die. A human being doesn't need to regenerate itself because it can reproduce and be cleared away. Evolution evolved to ensur…

Those mechanisms are good enough to have brought us to this point, but that has no bearing on what kind of future we choose to create for ourselves.

Metals rust and seep into the ground, but we dig them up and build spacecraft from them. Metals aren't _meant_ to do that, but we have some influence over our environment. We might end up having a similar influence over our cells.

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#99

Post by danans »

guitarbill wrote: post #95
m0llusk wrote: post #77

Earlier quoted context omitted.

Regenerating body parts doesn't happen because it is hugely expensive in terms of biochemical resources. Teeth are the most materially expensive parts of the human body. That is why teeth are often the most long lasting and best preserved human remains.

And yet, sharks do it. Also, the skeleton is similarly long lasting and that gets renewed. So why not? Say a finger, which isn't too "expensive in terms of biochemical resources", why not regrow that? Take the acorn worm mentioned, in proportion to the worm regrowing itself must be really expensive. I don't think this too expensive argument explains it.

It turns out that while sharks' teeth are functionally analogous to mammal teeth, they have an independent evolutionary origin - they are actually a specialized type of skin scale.

http://www.elasmo-research.org/education/white_shark/teeth.h...

It's apparently one reason why they can replace them constantly.

Re: Our closest worm kin regrow body parts, raising hopes of regeneration in humans

#100

Post by ThrustVectoring »

BurningFrog wrote: post #39
PeterisP wrote: post #2

Well, a plausible answer is that if we (or random mutations) re-enable those genes then the end result is simply a lot of cancer. A reasonable default assumption is that each switch in our "genetic configuration" is set to a quite good value. The only exception is if we see a feature that is beneficial at a high calorie cost - those features have been (reasonably) optimized away during our evolution, but would be use…

Another exception would be if a limb has fallen off or otherwise failed. Then it would be great to be able to turn regeneration on, for that limb only. Any added risk should be much smaller than the always-on version.

That's a bit much to expect out of evolution. First it needs a way to detect whether a limb has fallen off or otherwise failed. Then it needs to send a biochemical signal to the cells in the area iff the limb in the area failed. Then it needs to activate the regeneration iff the chemical signal is present. And each of these mutations has to be beneficial to the organism (or at least randomly there and costless). You can mush together the detection and signaling by having a local signal (like the biochemistry responsible for scabbing - iirc what happens is blood would do interesting chemistry while bleeding anyways, and so "turn into a scab when that chemistry is happening" is a worthwhile mutation), but still, it's a few too many steps.
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