
The Lurker: How a Virus Hid in Our Genome for Six Million Years (2013) - Mz
http://phenomena.nationalgeographic.com/2013/05/10/the-lurker-how-a-virus-hid-in-our-genome-for-six-million-years/
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methodin
It seems plausible that our DNA hosts a myriad of capable dormant viruses than
be triggered by some external activator (or binder), much the same way we have
receptors for plants found in the wild (cannabis, nicotine etc...). It also
seems perfectly reasonable that the (m)(b)(tr)illions of viruses on the planet
are waiting in the wings for a host to get infected to start the process on a
new epidemic. I'd like to think this is some form of regulation but of course
that would necessitate the world as we know it as a part of a single system
that can regulate even the tiniest of members.

For a hypothetical we could imagine the scenario where viruses existing in say
a remote rain-forest, generally innocuous and self-contained. When
deforestation occurs the virus is now open and can potentially infect whatever
mechanism (human) that has disrupted it, binding to the same virus DNA that
has existed for millions of years.

It's not that far-fetched to think unintelligent systems have defenses that we
are largely unaware of - or cannot understand.

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evol262
You're affirming the consequent. We don't have receptors for plants found in
the wild (cannibis, nicotine, etc). Rather, compounds formed by those plants
match up with receptors we already have.

There's an entire endocannabinoid system, and it's not because pot is natural.
Nicotine broadly matches up with acetylcholine and nicotonic acetylcholine
receptors.

It's far more likely that plants evolved and selected for compounds which have
beneficial/detrimental effects on possible consumers, like nicotine as a
pesticide, than it is that we have receptors for plants found in the wild on
the off chance that we may have consumed them or that they would have been so
prevalent in the past that receptors for them would have been selected for.

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IndianAstronaut
If this topic interests you, I recommend reading "The Selfish Gene" by Richard
Dawkins.

~~~
curiously
what is the book about in a nutshell? will read it eventually.

~~~
mkramlich
note for the future: Amazon is a tab away and will give you summaries and more
of millions of books. mostly a solved problem. would not be surprised if
Wikipedia had a summary of it too.

~~~
curiously
if I wanted a summary from a non HN user I would've gone there. I think people
often miss the importance of someone summarizing it in their own words on a
network.

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karsus
It would be interesting to see if we could clean up (refactor) the human
genetic code into a more efficient form with less baggage, and maybe less
chance at getting hit by viruses just by virtue of having fewer random flaws
to exploit.

~~~
pmalynin
Actually that's an incredibly terrible idea. You see single base-pair (and
other) errors are very common during DNA replication. By having a lot of
"useless" (allegedly) zones in our DNA, decreases, statistically speaking,
chances of that error occurring in more important areas.

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Retr0spectrum
Could you explain why that is the case? It seems unintuitive.

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Snail_Commando
Imagine a general with a finite amount of artillery shells and a Howitzer on
the fritz (i.e. the intended trajectory of the shots are somewhat off the mark
today). Given the choice of where to deploy the artillery, the general may
choose to concentrate their fire on the narrow beachhead landing instead of
upon a widely scattered formation of units approaching across a vast plain.

The artillery that lands on the plain may strike an advancing unit, or it may
fall (possibly harmlessly) between a set of advancing units. The artillery
that lands on the narrow beachhead is more likely to hit a unit.

This analogy is far from perfect: sometimes mutations are good, which is one
primary driver of evolution. Non-coding regions and/or "baggage to be
refactored" (paraphrased great-great-gp comment) in DNA (the regions of the
plain/beach not occupied by an advancing unit) can absorb "errors". Also,
there are other types of mutations (insertions, deletions, ...), aside from
the single point mutations that this analogy was attempting to help convey.

The point is: it's like bunching up a lot of important things over a few
points of failure. If you increase "the genetic surface area", you lower the
chance of the important thing getting hit.

On evolutionary scales, viable DNA has been selected with a lot of non-coding
(and sometimes useful) regions, we know that if we reduce that down, we are
more likely to be susceptible to fatal mutations on coding regions (e.g. a
region that codes for a vital protein).

~~~
codeflo
I think that's not the best analogy. You're imagining a constant amount of
mutations (artillery shells) spreading over the size of the genome (the
beach). It doesn't quite work like that, which is why mutation rates are
usually measured in errors per base pair per generation.

In fact, copying DNA is more like downloading a large file over an unreliable
network. There's a certain chance that each individual bit is flipped and the
file becomes useless. You can reduce that chance by sending it multiple times,
or introducing checksums, both of which add redundant data. But simply adding
an extra TB of junk bytes to your download won't help preserve the integrity
of the original file.

~~~
jschwartzi
Does the number of mutations in a genome increase with the size of the genome,
or with the length of time the genome is "in use?" Let's assume that the
mutations are evenly distributed throughout the genome. If genetic mutation
count is dependent on the size of the genome then it fits your "unreliable
transmission" model.

However, if genetic mutation count is time-dependent but totally independent
of the size of the genome, then having a larger genome actually does protect
you from individual mutations, and it would do so exactly using the mechanisms
described previously.

Think of two genomes, one large and one small, both existing throughout time.
Both will accumulate a similar quantity of mutations from mutagenic processes
which are time-dependent like radiation exposure.

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ceejayoz
Greg Bear wrote a fun sci-fi novel Darwin's Radio
([http://en.wikipedia.org/wiki/Darwin%27s_Radio](http://en.wikipedia.org/wiki/Darwin%27s_Radio))
featuring these viruses.

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maradori
This is quite scary .__.

