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Some of our closest invertebrate cousins, like this Acorn worm, have the ability to perfectly regenerate any part of their body that's cut off - including the head and nervous system. Humans have most of the same genes, so scientists are trying to work out whether human regeneration is possible, too.
Regeneration – now that'd be a nice superpower to have. Injure an arm? Chop it off and wait for it to grow back. Dicky knee? Ingrown toenail? Lop off your leg and get two for one!
It sounds ridiculous, but there's a growing number of scientists that believe body part regeneration is not only possible, but achievable in humans. After all, not only are there plenty of animals that can do it, we can do it ourselves for our skin, nails, and bits of other organs.
Perhaps humans don't regrow body parts because, unlike worms, they have an idea 'how much that stings.'
(Score: 4, Interesting) by opinionated_science on Friday December 02 2016, @09:55AM
Another ludicrous attempt to get funding, without even a basic thought of the logic.
The species that *can* regrow limbs (Salamander) may have a much bigger genome (10x human), but they are also *much* smaller.
I will go out on a limb (sic) and say, that we could regrow a leg - only it would take 15 years and need a suitable environment to ensure the musculature, bones and venal system all become adapted.
Regrowing a tooth is relatively easy, but still might take 6 months.
One of the facts glossed over is just how much of our bodies *does* regrow on a regular basis - only it is a massively parallel action (everywhere, a little bit).
There is a colossal energetic cost to growing an animal the size of humans.
That is why it takes 20 years....
...and a great deal of beer!
(Score: 4, Insightful) by GreatAuntAnesthesia on Friday December 02 2016, @10:39AM
I'm pretty sure that most of your counterpoints could be addressed by technology, and even if not I don't think those restrictions make it entirely useless. 15 years to grow a new leg? Well, better than nothing, except for the very elderly. 6 months to replace a tooth? Yeah, I'd go for that right now if the cost was right (and in theory, the cost could be very low), I have several teeth that I'd like replaced.
Also, sometimes just a small amount of regenerated tissue could be life changing: Imagine if we could regenerate damaged spinal cords? Regrow missing fingers and toes? Genitals? Eyes and ears?
(Score: 3, Interesting) by opinionated_science on Friday December 02 2016, @11:01AM
I am working proximal to some of this technology - stem cells can repair some very subtle structures.
Organs will need considerable amounts cellular framework, but might be doable (heart, kidneys).
But a complex biomass such as a limb, has issues due to the fundamental mechanism of cellular growth.
My musing is that our technology might be able to "print" or otherwise give a major structural template, it maybe possible.
But to my original point, energetics will make it slow... (think of reverse entropy - you are turning a bag of chemicals into a tissue! That's some energetic incline...).
(Score: 3, Interesting) by GreatAuntAnesthesia on Friday December 02 2016, @12:49PM
> My musing is that our technology might be able to "print" or otherwise give a major structural template, it maybe possible.
In other words it's a choice between "growing a new leg" as in "start off with a tiny foetus-leg that gradually develops into an adult-sized one" and "growing a new leg" as in "skip the intermediate steps and just build an adult leg directly."
i.e. https://www.youtube.com/watch?v=h9OBbsLYGOE [youtube.com] vs https://i.ytimg.com/vi/sWr7rcoAWaQ/maxresdefault.jpg [ytimg.com]
(Score: 0) by Anonymous Coward on Saturday December 03 2016, @12:23AM
It's "build the new leg in the lab, then surgically attach" really.
(Score: 2) by geb on Friday December 02 2016, @10:48AM
Cold blooded creatures have far larger genomes than mammals because they have multiple overlapping layers of metabolism, to allow them to function at a range of temperatures. With a fixed body temperature, you can live with a single enzyme to do a single job. If the environment determines your body temperature, you need several enzymes, all tuned to operate at different temperatures.
Also, size has nothing to do with complexity. Many whales have about the same size of genome as humans.
(Score: 2) by opinionated_science on Friday December 02 2016, @10:57AM
I did not imply size had anything to do with complexity - I happened to work with the group that sequenced that beasty!
I was pointing out that novelties like huge genomes (this used to be used as grant justification..) , are not sufficient to overcome the energetics of the biochemical machinery required to achieve regrowth.
An interesting point about metabolic diversity, though I have not read anything that directly enumerates the enzymatic taxonomy of the non-mammalians.
(Score: 0) by Anonymous Coward on Saturday December 03 2016, @12:35AM
> Many whales have about the same size of genome as humans.
And they are -extremely- intelligent, and certainly some species not only have language but have oral traditions.
> size has nothing to do with complexity
Size has to do with complexity of regrowth actually. The larger the organism the larger its constituents at the high side (blood vessels, bones, soft organs) but the same size at the smallest (elephants don't have larger capillaries than mice; individual cell size doesn't scale with (multicellular) organism's size, etc.). So you end up with a 'deeper hierarchy' for blood, which is much more work to build than a shorter hierarchy eg. at the capillary level in human dermis (which we do regrow). You end up with innervation that branches more levels deep to control an elephant's hamstring vs. a mouse's (citation needed?). As someone else has pointed out the energretic cost matters: regrowth of a newt leg is like going to the gym for a few weeks, but regrowing an arm would be like going to the gym for years and years, and due to size scaling (note gestational and developmental times *do* correlate to size) by volume it gets costly, fast.
(Score: 3, Insightful) by q.kontinuum on Friday December 02 2016, @11:44AM
A cow in a feedlot becomes ready for slaughter after ~13 months. That's way more muscle an bone grown than would be necessary to re-grow a human bone.
Registered IRC nick on chat.soylentnews.org: qkontinuum
(Score: 2) by q.kontinuum on Friday December 02 2016, @11:46AM
I mean of course "[...] to re-grow a human arm or leg"
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(Score: 2) by opinionated_science on Friday December 02 2016, @11:55AM
well the block diagram in my mind has "bioreactor" , but yeah....
(Score: 2) by edIII on Friday December 02 2016, @06:25PM
I dunno about the rest of your post, but I do believe parents need a lot of beer to raise a child till 20.
Technically, lunchtime is at any moment. It's just a wave function.