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: 2, Insightful) by Anonymous Coward on Friday December 02 2016, @10:56AM
Could this be simply because regrowing limbs requires lots of stem cells, and those are limited in the number of divisions they can do, so regrowing something large would cut a lot of time off your expected life span. Meanwhile, getting rid of the limit to the number of divisions happen all the time by accident, and is named "cancer".
(Score: 3, Interesting) by Immerman on Friday December 02 2016, @03:01PM
Actually, stem cells have a much larger Hayflick Limit than most, potentially infinite for some of the more pluripotent strains if provided with the right "chemical soup" to allow them to stop or even reverse telomere loss.
I'm pretty sure most stem cells are also pretty localized, so even if regrowing a leg did drastically reduce the "downstream" cellular lifespan, it would mean only that *the leg* had a reduced life span, not the whole organism.
And eliminating the Hayflick Limit isn't what causes cancer - it's just what makes certain kinds of cancer particularly dangerous. What makes cells cancerous isn't just that they can replicate indefinitely, but the fact that they keep replicating without a reason, rather than waiting to be signaled to replicate in order to repair damage. It generally takes several independent mutations in a pre-cancerous cell line before it becomes truly dangerous, as various "checks and balances" get removed.
(Score: 0) by Anonymous Coward on Saturday December 03 2016, @12:42AM
> I'm pretty sure most stem cells are also pretty localized
Yeah, no. Turns out they can be extremely mobile, it's just very uncommon. IIRC this was done with mitochrondial swaps in local pluripotents, later found in pluripotents (and downstream) across the organism. I forget the location and model organism, I think it was mice though. One fascinating find was unipotence to pluripotence, I know it's old news now but it still impresses me.
(Score: 2) by Immerman on Thursday December 08 2016, @09:44PM
Seems like we're not disagreeing - very mobile in rare circumstances would not be inconsistent with fairly localized under normal circumstances.