
Sex Is a Coping Mechanism - dnetesn
http://nautil.us/issue/34/adaptation/sex-is-a-coping-mechanism
======
PepeGomez
That is blatantly false. Sex speeds up evolution exponentially with population
size. With sex, each beneficial mutation can spread across the species even
after arising only once. With asexual reproduction, beneficial mutations are
confined to that particular strain. Sex is enormously beneficial for the
ability to evolve and adapt quickly. This has been confirmed by mathematical
models.

~~~
jballanc
You're misunderstanding how gene flow works. Consider one individual with one
advantageous mutation that has 1000 offspring. In an asexual organism all 1000
will contain the mutation (minus any small frequency of the mutation
spontaneously reverting). In a sexual organism only 500 will carry the
advantage.

~~~
guard-of-terra
This individual invariably carries ten of disadvantageous mutations too. It
will pass all ten to offspring when reproducing asexually, but only five of
them on average to every sexually-produced offspring, and a dozen will only
get 2 or 3 such bad mutations.

This arithmetic becomes ugly fast for asexual reproduction.

~~~
jballanc
Again, it's the exact opposite. In an asexual species, a disadvantageous
mutation will be flushed from the population very quickly, as those without
the mutation will outcompete those with. You'll never get an individual with
ten disadvantages.

On the other hand, in a sexually reproducing organism, a disadvantageous
mutation can be masked if recessive, and selective pressure will only remove
homozygotes from the population. The end result is that harmful mutations can
stick around for a long time, and even accumulate in individuals.

~~~
guard-of-terra
"a disadvantageous mutation will be flushed from the population very quickly"

In asexual case, an individual with one advantageous mutation and ten slightly
disadvantageous will be flushed out.

In sexual case, such individual will produce some survivable offspring and the
advantageous gene has good chance of flourishing in the population.

~~~
jballanc
Correct. Sex is advantageous over the _long_ term. This is not up for debate.
The question is how to compensate for the considerable costs in the _short_
term so that sexual organisms are not immediately outcompeted by asexual
organisms.

~~~
guard-of-terra
Asexual organisms can outcompete some part of population, but doubtfully all
of it. And their competitive advantage shrinks as their numbers grow, due to
clone interference.

A lot of insects can reproduce asexually but they are also capable of sexual
reproduction. Ones who are not eventually die off.

~~~
jballanc
You're assuming that a population of asexual organisms was mixed with a
population of sexual organisms. In reality, asexual reproduction came first,
so the inability of asexual reproduction to overcome a large contingent of
sexual organisms is irrelevant.

And yes, optional sex is almost certainly how sexual reproduction arose. Even
today I'd wager there are more facultatively sexual organisms than obligate
sexual. That's a non-sequiter, though, as even optional sex would be bred out
of a population if it could not show a benefit in a small number of
generations.

~~~
PepeGomez
Imagine three populations of desert plants. One survives by growing longer
roots and storing more water. Another has roots that can extract water from
dryer soil. The third is adapted by breathing during the night and losing less
water.

It's obvious how a sexual plant that is able to obtain the beneficial
mutations from the other two populations would gain a major and immediate
advanage.

~~~
jballanc
_We all agree that sexual reproduction is advantageous over a long time
scale._ The question is what about a _short_ time scale. Even with selective
breeding, it'll be at least two (and more likely 3-5) generations before you
could get all three advantageous traits in the same plant. With random
partnering as would happen in the wild it could easily take an order of
magnitude longer.

This paper presents a hypothesis that explains how sexual reproduction could
be more advantageous than asexual reproduction _after one generation_. This is
what makes it novel and new.

~~~
PepeGomez
How more short term would you want it to be? The trait doesn't have to be
advantageous every single generation in order to spread.

It's two generation with or without selective breeding. The first generation
will have individuals with three or four beneficial mutations, the second will
have some with five. (assuming the traits are dominant)

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themartorana
By "coping mechanism" I originally clicked to read how it helps us cope with
the crushing reality that is life...

~~~
Cthulhu_
That's what alcohol and Netflix are for :p

~~~
_-__---
that + chill = more sex?

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pja
_“Until recently, science has basically ignored the fact that we are all
walking around with two genomes in every cell,” Dowling says, “that of our own
nuclear genome, and that of the mitochondria.”_

Really? I was taught about mitochondria in considerable detail as part of the
biology part of my undergrad science degree & mitochondria have clearly been
studied pretty intensively. That’s not to say that there aren’t gaps in our
knowledge or new things to learn, but the idea that the mitochondria have just
been ignored is clearly untrue.

I guess some researchers feel it necessary to talk up their own research
though - it’s a labrat eat labrat world out there.

~~~
debacle
In my high school biology class, which I would assume is still the highest
level of biology most people complete, mitochondrial DNA wasn't even
mentioned. Many high school level science courses are rife with
disinformation.

~~~
cmrdporcupine
I definitely was taught quite a bit about mitochondria in grade 10 (Canadian)
high school biology, in the early 90s. We were even told about at-the-time-
speculative-now-accepted theories that mitochondria were the result of a
primitive "capture" of a prokaryotic cell by the first early proto-eukaryotes.

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ommunist
There is a typo in the title. Sex is a Copying Mechanism. We just fail to
produce good copies, since the mechanism is broken.

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mangeletti
This is part of a greater dehumanization[1] agenda by the parts of the US
media industry. I don't have a conspiracy theory about why this is or who is
behind it, but it's been going on for a few years now. Once your reticular
activating system's habituation filter has opened up on something like this,
you cannot not notice such articles when they pop up.

I mean, click-bait or not, the idea of referring to an innate part of the
biology of animal life as a "coping mechanism" automatically leads to a form
of nihilism.

1\.
[https://en.wikipedia.org/wiki/Dehumanization](https://en.wikipedia.org/wiki/Dehumanization)

~~~
tsunamifury
I get the same general feeling, and I try not to be too paranoid about it.

I think it has a lot to do with the instrumentality capitalism wants from its
participants -- and we seem to want to use science to make us better cogs
rather than better humans. Its a pretty old idea stemming from the industrial
revolution -- it just seems that today we're more 'loosely coupled' into the
system which gives us just enough of an illusion of freedom. e.g. you can
choose a job, but you can't choose not to have a job, you can speak freely,
but you'll be monitored etc.

Because of this I have recently had a resurgence of volunteerism and religious
soul seeking. I've found it refreshing that these two arenas seek earnestly to
humanize through giving.

~~~
woah
Volunteerism and giving is great, but religion's purpose is to co-opt and
channel these altruistic impulses to make people believe that good things can
only come from religion (historically linked to the state). You still see this
brainwashing today, with people believing that atheists cannot be moral, or
that religion makes them a better person. In fact, the most religious are
frequently the most immoral. Look at the widespread sexual abuse sanctioned by
the Catholic Church, today and throughout history.

As an aside, OPs conspiracy theory about the article titles sounds really
silly.

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jballanc
While it is definitely too soon to consider this hypothesis even close to
settled, it's not as far out as it might seem at first glance. Indeed, what we
evolutionary biologists have always said is that the cost of sex is
compensated for by robustness in the face of evolutionary pressure.

All this group is saying, in essence, is that instead of that pressure coming
in the form of infrequent external events (plagues, floods, asteroids, etc.),
it is present for every generation in the form of dealing with mitochondria
that don't quite fit any longer. An interesting idea, to be sure.

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conceit
> Mitochondria are purely a maternal gift. Sperm do not pass them on; only a
> mother’s egg does.

Some species' sperm do pass mitochondria successfully. Human sperm passes
mitochondrial dna, but the egg kills it off.

~~~
ergothus
I think you meant the reverse Re: humans.

I'm interested in this though: do you know any examples off the top of your
head where the male passes on mitochondria? I thought the primary reasoning is
that sperm is little more than DNA with a tail and engine attached.
(poetically speaking)

~~~
conceit
What reverse?

No, I don't know.

~~~
ergothus
Ah...I misunderstood your comment and I misunderstood how it works. I thought
human sperm had no mitochondria. Turns out that is dramatically not the case,
but the sperm's mitochondria is killed off by the egg, and that's exactly what
you said.

I had thought you were saying the sperm had mitochondria and the egg killed
THE EGGs mitochondria off.

My mistake.

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dmichulke
Another reason why sexual reproduction is efficient is that it enables
division of labour.

A mother needs to provide a complete eco-system (uterus) for the baby to live
and grow which affects even the hormonal system.

A man doesn't need this, so he can use this energy or "program space" in his
genome for other things.

It's one of Dawkins theses in his superb book "The selfish gene" [1] where he
basically reduces evolution to game theory (without explicity saying so).

[1]
[https://en.wikipedia.org/wiki/The_Selfish_Gene](https://en.wikipedia.org/wiki/The_Selfish_Gene)

~~~
Cthulhu_
That extends to the genders' respective role in society as well, at least in
humans - men being the hunters or soldiers and dying a lot, that is.

On the other hand though, in e.g. lions, it's the females that go out hunting
the most. I'm not sure what the logic is there. Maybe the males die a lot in
fights for dominance and territory so they get to be lazy?

~~~
juliendorra
Up until recently, women died a lot… giving birth. (It really comes to life
when you read about history and queens or the classic plays and fairytales
where there's so many remarried older men)

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mulle_nat
Misread this as "Sex is a Copying Mechanism". Thought "duh!".

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yason
_All that is probably true, but the thesis has one flaw. While the benefits of
sexual reproduction tend to be subtle and become evident only over many
generations, its costs are heavy and immediate._

But isn't the "flaw" already taken care of: the heavy and immediate costs are
very much compensated by the pleasure and high stimulus which are as immediate
as anyone who has gone through puberty knows. (And which are not unknown in
the non-human part of the animal world either.)

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jokoon
Makes me think of the god meme, which reads "makes sex great -- forbids it".

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penny
Sex and death are both metabolic hacks. They offset one another in the
bioenergetic arms race tripped by the costs of complexity. Think about it.

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rbobby
Sex is how to hotfix mitochondria.

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guard-of-terra
"Ask any biologist—sex seems like a waste"

Stopped reading after this. If it's straw man, it's an especially stupid one.
If she is serious, that's not even funny.

~~~
breakingcups
Perhaps you should continue reading the article to find out.

~~~
oolongCat
Welcome to the internet, where people only read half the story and make up
opinions :P

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0xFFC
Off topic.I am student and in last year I felt this drawback.I spent almost
all of my day reading internet (scientific material, watching courses).But
recently I can feel internet makes person a shallow, without deep
understanding about topics.(I don't know how to express clearly). I recently
completely switched from internet to reading exclusively book/papers.

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o_s_m
Except for HN I suppose ;)

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0xFFC
Exactly, because there are huge differences between people in HN and other
people on the internet. most (not all) stuff in HN is quite good and the links
to books/papers are my favorite ones.

