
Can Genetic Engineering Bring Back Extinct Animals? - sethbannon
http://news.nationalgeographic.com/2015/09/150920-book-talk-simon-worrall-genetic-engineering-passenger-pigeon-resurrection-science-neanderthals/
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tristanj
Genetic engineering can't bring back most extinct animals. DNA molecules have
a half life of around ~500 years and samples older than a few hundred thousand
years will have too many errors to recreate. Better statistical techniques
will push this bound but it's hard to argue against physics. It's estimated
that DNA older than 20 million years old will be fully unrecoverable.

Notice how all the author's examples are recently extinct species, not ancient
ones. I guess they don't mention this because it doesn't fit with their
worldview.

Some sources:

[http://www.the-
scientist.com/?articles.view/articleNo/32799/...](http://www.the-
scientist.com/?articles.view/articleNo/32799/title/Half-Life-of-DNA-Revealed/)

[https://en.wikipedia.org/wiki/Ancient_DNA](https://en.wikipedia.org/wiki/Ancient_DNA)

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giarc
Could you not produce viable samples by collecting multiple copies of the DNA
and overlapping them, thus removing the errors that would likely happen at
random locations?

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searine
Not likely. Dude to the chemistry of nucleotides, they can degrade in a
particular pattern that obscures the ancestral allele. For example the
deamination of cytosine to thymine can leave us with an ambiguity in what in
our read for the correct nucleotide is.

Was it thymine? Or was it cytosine that degraded to thymine? That means for
literally 50% of the genome we have a huge ambiguity and few ways to tell what
it really is.

We can use the ancestral allele from a nearby extant species, but then we miss
out on all the extinct variation (which is the important stuff).

We can try to increase coverage of the ancient genome to capture loci where
cytosines haven't deaminated, but thats tough for a dozen reasons, and in the
end you'll still have no confidence in 25% of the genome.

We can get very close to a full ancient genome, but never 100%. Maybe through
transgenics, selective breeding, and ancient sequencing we can re-create
ancient species, but we will never make them exactly as they once were.

~~~
meric

        we will never make them exactly as they once were
    

And maybe that could be good enough and better than not doing it at all...

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27182818284
Out of curiosity, does anyone know anyone else in real life that is _not_ open
to the idea of bringing back some extinct species?

I noticed this recently. Not a single person in my social network is against
the idea of trying to clone a mammoth or trying to clone an extinct cat or
dinosaur. There is some hesitancy when you bring up possibly reviving old
bacteria, but that's it that I've noticed.

~~~
asciimo
Myself. It's interesting that so many people take it for granted that
resurrecting extinct animals is a "good thing." Why is it a good thing? The
referenced article doesn't ask this question.

Ben Novak (the Passenger Pigeon researcher) said in an interview "... the
destructive force of the flocks led to a radical rejuvenation of forests.
Thick layers of pigeon droppings fertilized the soil, which soon led to new
growth." Is new forest growth currently an issue? Are Passenger Pigeon
droppings the only solution?

[http://www.spiegel.de/international/zeitgeist/scientists-
aim...](http://www.spiegel.de/international/zeitgeist/scientists-aim-to-bring-
the-passenger-pigeon-back-from-extinction-a-893744.html)

~~~
sehugg
One could also ask the question of whether humans need to behave in such a way
as to bring about the extinction of so many species. Certainly the passenger
pigeon wasn't made extinct for the common good.

Biodiversity is the only answer we have right now to the question of how to
maintain a healthy planet
([https://en.wikipedia.org/wiki/Biodiversity#Services_enhanced...](https://en.wikipedia.org/wiki/Biodiversity#Services_enhanced_by_biodiversity)).
Until we get a lot smarter, it's wise to learn how to better preserve as much
as we can.

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ams6110
_Changes are now happening so quickly that they appear to be driving some
species towards extinction because they can’t adapt fast enough._

Well, yeah -- that's how natural selection works.

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cpeterso
Stewart Brand and the Long Now Foundation have a deextinction research program
called Revive & Restore:

[http://longnow.org/revive/](http://longnow.org/revive/)

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vdutta
It's a well known fact that most ecosystems are very delicately balanced.
Introducing new species can often have devastating effects on existing ones.
So even if we did resurrect extinct species, they may have to remain
domesticated, as our toys.

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BurningFrog
Bringing back extinct species isn't cool. You know what's cool?

Designing brand new species in DNA!

