[ExI] Homo radiodurans (was Maximum Jailbreak)
johnkclark at gmail.com
Fri Oct 26 17:03:10 UTC 2018
I don't doubt all that is possible with genetic engineering but it wouldn't
be easy, I expect by the time it could be done superhuman AI will be around
so Homo radiodurans will have serious competition. It will be a match
between biology and electronics and I think electronics will win.
John K Clark
On Thu, Oct 25, 2018 at 11:45 PM Stuart LaForge <avant at sollegro.com> wrote:
> John Clark wrote:
> >>> My question about living in space: what do you do about the
> >>> radiation for the long term?
> >> Simple, you genetically engineer your space humans to be black. Not
> >> African black and not just the skin, but pitch-black and including the
> >> internal organs.
> > That would give you some protection against ultraviolet light and maybe
> > even a little against soft X rays but no protection at all against the
> > most dangerous and hard to shield against type of radiation which isn't
> > electromagnetic at all, its high speed particles in the form of Cosmic
> > Rays.
> Yes. You are right and I am guilty of not properly explaining an idea that
> I have been kicking around for some time. That being how to best engineer
> and adapt humans to living in space for the long term. I imagined an
> offshoot of Homo sapiens called Homo radiodurans that would essentially be
> humans that had been genetically engineered to better survive the rigors
> of space travel and long term habitation.
> I named them for their resistance to radiation but I have imagined other
> adaptations as well. For example, they would be small by terrestrial
> standards perhaps 4 feet tall or so. Size is not an asset for people who
> live in cans. I also envision them being able to enter cryptobiotic
> suspension for long journeys and such.
> Homo radiodurans would owe its radiation resistance to being engineeered
> with specific genes from several known examples of extremophiles that can
> withstand several orders of magnitude more radiation than would be lethal
> for a human.
> You already know about the black melanin producing radiotrophic fungi that
> photosynthesize using x-rays and gamma rays and we might be be able to get
> away with simply over-expressing our own melanin genes. But you are right
> that such would be no defense for cosmic rays of the particulate variety.
> Therefore I have turned to other extremophiles such as tardigrades or
> "water bears" and the bacterium Deinococcus radiodurans, which inspired
> the name of these engineered humans, for solutions. Tardigrades are
> notable for having survived being directly exposed to the hard vacuum and
> radiation of space for several hours, so they would be the gold standard
> for what we could accomplish given the will to engineer our germline.
> Particulate radiation like high energy protons damage DNA by causing
> double stranded breaks and knocking electrons about generating reactive
> free radicals.
> Organisms that are highly resistant to radiation generally utilize a
> strategy of gene redundancy and extremely efficient DNA repair and free
> radical quenching. In other words, they have multiple copies of their
> chromosomes and several copies of every gene that encodes for DNA repair
> enzymes and antioxidant enzymes.
> Humans have DNA repair enzymes as well, but they are not as efficient or
> numerous as those of tardigrades. For example, humans have about 10
> varieties of superoxide dismutase (SOD) and enzyme that deactivates oxygen
> free radicals while tardigrades have 16.
> Tardigrades also have some unique DNA repair enzymes as well. One of which
> was actually already introduced into human cell lines a couple of years
> ago as reported in nature.
> The upshot of the experiment is that the transfected gene protected the
> human cells from radiation that killed off the control cells. This is
> proof of principle that Homo radiodurans is at least theoretically
> Other strategies would involve conditioning astronauts with gradually
> increasing dosages of radiation prior to sending them into space. There is
> some evidence that people can adapt to radiation in this fashion. The
> phenomenon is called radiation hormesis.
> However all these biological adaptations and strategies need to be used in
> conjunction with hardware like adequate shielding of spacecraft and
> habitations. At the end of the day, no matter what genes you have, a
> proton with the kinetic energy of major league fastball pitch is going to
> do some damage to your cells.
> Space is the most hostile environment we have ever faced. For that reason
> alone we must conquer it if for no other reason than to test ourselves
> against eternity.
> Stuart LaForge
> extropy-chat mailing list
> extropy-chat at lists.extropy.org
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