
Humans evolved to tolerate smoke poisoning [pdf] - gwern
https://www.gwern.net/docs/genetics/2016-hubbard.pdf
======
Houshalter
Smoke still is bad for humans though, see this essay:
[https://www.samharris.org/blog/item/the-fireplace-
delusion/](https://www.samharris.org/blog/item/the-fireplace-delusion/)

>There is no amount of wood smoke that is good to breathe. It is at least as
bad for you as cigarette smoke, and probably much worse. (One study found it
to be 30 times more potent a carcinogen.) The smoke from an ordinary wood fire
contains hundreds of compounds known to be carcinogenic, mutagenic,
teratogenic, and irritating to the respiratory system. Most of the particles
generated by burning wood are smaller than one micron—a size believed to be
most damaging to our lungs. In fact, these particles are so fine that they can
evade our mucociliary defenses and travel directly into the bloodstream,
posing a risk to the heart. Particles this size also resist gravitational
settling, remaining airborne for weeks at a time.

>Once they have exited your chimney, the toxic gases (e.g. benzene) and
particles that make up smoke freely pass back into your home and into the
homes of others. (Research shows that nearly 70 percent of chimney smoke
reenters nearby buildings.) Children who live in homes with active fireplaces
or woodstoves, or in areas where wood burning is common, suffer a higher
incidence of asthma, cough, bronchitis, nocturnal awakening, and compromised
lung function. Among adults, wood burning is associated with more-frequent
emergency room visits and hospital admissions for respiratory illness, along
with increased mortality from heart attacks. The inhalation of wood smoke,
even at relatively low levels, alters pulmonary immune function, leading to a
greater susceptibility to colds, flus, and other respiratory infections. All
these effects are borne disproportionately by children and the elderly.

>In the developing world, the burning of solid fuel in the home is a genuine
scourge, second only to poor sanitation as an environmental health risk. In
2000, the World Health Organization estimated that it caused nearly 2 million
premature deaths each year—considerably more than were caused by traffic
accidents.

~~~
schiffern
>In 2000, the World Health Organization estimated that it caused nearly 2
million premature deaths each year—considerably more than were caused by
traffic accidents.

Everyone is rallying around autonomous cars to decrease unnecessary deaths
(and rightfully so), but relatively few folks are familiar with rocket stove
technology.

[https://richsoil.com/rocket-stove-mass-
heater.jsp](https://richsoil.com/rocket-stove-mass-heater.jsp)

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

Releasing smoke is energy inefficient, since it's literally unburnt fuel!
Considering the fuel savings, the lifetime cost of switching can be _negative_
in some cases.

In terms of cost per statistical life saved, it's an extremely compelling
technology.

~~~
blackguardx
Thanks for sharing those links. It looks like it would be hard to start the
rocket action correctly. You would have to preheat the circulator "chimney"
somehow. Until then, smoke would pour into your house.

This is a problem with normal wood-burning cooking stoves as well. Smoke
doesn't go into the chimney until you establish a convection draft or the wind
creates a venturi effect.

~~~
schiffern
Thanks! Great points.

Smoke free startup is an important design/operational consideration. There are
lots of videos demonstrating startup technique (search "rocket stove
starting"). Here's a couple good ones:
[https://www.youtube.com/watch?v=Ls_eqNB6d0Y&t=1m23s](https://www.youtube.com/watch?v=Ls_eqNB6d0Y&t=1m23s)
[https://www.youtube.com/watch?v=aSkUquOQt5w](https://www.youtube.com/watch?v=aSkUquOQt5w)

Note that the goal of the drafting chimney is _not_ to soak up a lot of heat,
but rather to be insulated and have low thermal mass to minimize heat loss.
The higher the air exit temperature from the riser, the stronger the draft.
The important thing for self-drafting is to heat the air in the riser, and
only secondarily heat the riser material itself.

A good design should make startup as "idiot proof" as possible. I've seen a
few builds that use a 12V case fan on the air intake. Since the goal is to
heat up the air in the riser (and that heating the riser... draws hot air into
the riser), all you have to do is "tip it over" into that stable equilibrium.

Imo there's a market opportunity for an inexpensive, compact, nice looking,
and easy to operate rocket stove. The open source (and excellently documented)
"batch rocket" design seems a good place to start.
[http://batchrocket.eu/en/](http://batchrocket.eu/en/)

------
a_bonobo
I don't buy the smoke poisoning angle.

They compared with Neandertal AHRs and found that human AHRs may have
undergone selective pressures since they're quite different, so the authors
tried to connect these changes with the invention of fire. However AHRs bind
to many things.

Also, Neandertals also used fire extensively (see for example
[http://www.pnas.org/content/108/13/5209](http://www.pnas.org/content/108/13/5209)
) so they should have undergone the same selective pressures, so they should
have the same or similar changes as humans?

~~~
AimHere
Might the selection pressure have been fire related, without necessarily being
just the use of fire?

If, for one speculative example, Neanderthals mostly used fire outdoors, while
modern humans used it indoors with correspondingly thicker smoke
concentrations, wouldn't that account for the difference? Or perhaps only a
few Neanderthals out of any given population used it regularly (for crafting
tools, say), while almost all modern humans could have used it for cooking
food.

~~~
a_bonobo
I see! But that's a bit hard to prove, isn't it? I don't think we have enough
archaeological sites with proven fire places to prove that assumption

------
fsloth
" Our findings reveal that a functionally significant change in the AHR
occurred uniquely in humans, relative to other primates, that would attenuate
the response to many environmental pollutants, including chemicals present in
smoke from fire use during cooking. "

So we have some genetic tolerance to bad stuff created from cooking? Cool.

This does, however, raise ever more questions about studying the effects of
chemicals on rats and primates and drawing conclusions from that to human
populations.

~~~
Bartweiss
This seems like a really good question to raise, and I'm embarrassed that I
didn't think of it at all. I know carcinogen studies are already touchy since
cancer risks vary so wildly, but this is a nice reminder that even within
primates you get this kind of problem.

------
belorn
Reminds me of a story where Robert Sapolsky, a professor in biology when he
was staying in a native African hut and decided to put out the indoor fire
before sleeping, since he was concerned about the smoke. Later during the
night he woke up, covered in driver ants, realizing very fast the reason why
the natives sleep with the huts full of smoke.

------
pcrh
This is interesting. I wonder if the tolerance of the mouth to heat (relative
to other areas with a thin epidermis) is also related to cooking.

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detritus
I've often wondered whether something similar might be at play in relation to
the supposed cancer risks from acrylamides forming in burnt food. Sure, the
stuff's poisonous to rats etc, but given our physiology has evolved smaller
intestinal tracts and larger brains in relation to cooked foods (particularly,
meat), might it also be that we're less susceptible to its cancerous potential
than other mammals?

------
Dowwie
Lung cancer?

------
VeejayRampay
The way the title is phrased is strange. To the young/uneducated reader (not
so many around here, but still), it reads like humans evolve to develop a
particular trait, when we know that people who developed that trait got an
evolutionary advantage and ended up spreading their DNA more than others on
average.

Not as catchy a title, sure, but at least, it doesn't misrepresent the
evolutionary process.

NOTE: I am not an evolutionary biologist, so there is most likely an even
better way to rephrase my rephrasing. I'd be glad for anyone to do so, the
more accurate, the better.

~~~
inimino
> humans evolve to develop a particular trait

> people who developed that trait got an evolutionary advantage and ended up
> spreading their DNA more than others on average.

The first is shorthand for the second.

~~~
iand
It's sloppy shorthand though because it can be (deliberately) misconstrued to
suggest agency and directional purpose.

