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Human powered flight is just about possible. Not very
fast,
high or far however. This is because humans are poor
substitutes for engines. Even the most committed
exercisers* can only burn 80ml/kg/min of oxygen. An
engine is 4000ml/kg/min without trying too hard. This is
why human powered
flight isn't so popular.
The power/weight equation would change dramatically
for racing sled dogs however. With VO2max at
~300ml/kg/min they're around 4-fold better than humans
at being engines. So let's have husky-powered aircraft.
Sled dogs already run in a nice aerodynamic 2x8 or2x10
formationa as if they were trying to tell us of their
aviation aspirations. Lets line them up on a treadmill,
link
up 90 degree bevel gearboxes and power a
couple of props.
Take off is initiated by the word "mush". Rapid climb-out
is
assured by inherent enthusiasm and the cruising altitude
should be about 10,000-15,000ft adjusted to maintain
-20C
for optimum powerplant reliability. Powerplant
performance improves following, and even in
anticipation
of, birdstrike events. Careful management of postal
workers and cats should be ensured to prevent un-
commanded runway excursions.
*If they aren't already committed, they should be.
The strongest living land creatures on Earth...
http://www.telegrap...o-weight-ratio.html
...measured by their power to weight ratio. [Wrongfellow, Jan 04 2018]
Man pulls plane
https://www.youtube...watch?v=tls-Jli6eQE
[bs0u0155, Jan 04 2018]
Damn, it still makes me tear up to read the Tevis link....
horcycle
[normzone, Jan 04 2018]
Mitochondrial Temperature
https://www.science...at-a-scorching-50-c
[bs0u0155, Jan 05 2018]
(?) Fat Metabolism Comparable to Aviation Fuels
https://en.wikipedi...:Energy_density.svg
[bs0u0155, Dec 31 2019]
Husky Respiration
https://www.ncbi.nl...rticles/PMC5405936/
[bs0u0155, Dec 31 2019]
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//at least 4-fold better than humans at being engines// |
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So, the question is, why? What do dogs do that people don't
(in the present context)? |
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Stay calm during finals, even though the airspeed's maybe a bit low and some more height would be nice, instead of panicking, screaming abuse, grabbing at the controls, hitting the Pilot Flying with a rolled-up map while they're preoccupied with setting the flaps and adjusting the throttle, and exhibiting markedly poor sphincter control ? |
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This may of course be due to the dog(s) being unable to interpret the airspeed indicator and altimeter, and too short to see how close the ground is RIGHT NOW as opposed to how close it should be twenty seconds in the future, when it would have all proper lights and tarmac and stuff, although they might well be disturbed by a human yelling "PULL UP ! PULL UP ! TOGA ! TOGA !" at the top of their lungs .... |
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Perhaps that depends on the dog. Has anyone measured the
ml/kg/min of a thirtieth-generation pampered lap-dog? |
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Anyway, big [+] for the idea, if only because I think the dogs would
enjoy it so much. |
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That depends on the setting of their tiny Iron Lung, for those times when nothing much interesting is happening and they can't be bothered to breathe for themselves. |
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//So, the question is, why? What do dogs do that people
don't (in the present context)?// |
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It's a bunch of things. Food (reducing equivalents)+O2 to
movement needs mitochondria and a physical/chemical
support system. So some muscles, heart, lungs and a
digestive system. Bigger hearts need more connective
tissue and valving strength. The digestive system is
useless weight, most of the time, so a carnivore-style tiny
one works, even better that carnivore food is made of
mitochondria fuel (ketone bodies in particular can build
up to mM and are barely limited by membranes). |
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What you don't want is bones that have to get
disproportionately heavy because bone is only just up to
the job, a great metabolically needy brain or a huge
gastric fermentation plant. |
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In detail, from v.limited studies, it looks like husky
mitochondria are real standouts. Elite racehorses aren't
any better than us at a cell level, the adaptation is all
anatomical. Husky's have double output from their
mitochondria. So huge amounts of extra OXPHOS
machinery, probably lots of interesting never-to-be-
studied details of mitochondrial reticulum morphology
and biophysics. It's particularly interesting that they're
standout athletes AND standout cold adapters. They seem
to be able to just lie, on ice, at -25 looking bored and not
shivering, odd. |
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Ultimately, for big animals, the limit is probably thermal.
It turns out that mitochondria operate closer to 60C than
37C, in hard working muscle mitochondria, who knows?
But being huge, or in a hot place, will not help. The husky
is probably in a lot of sweet spots all at once.
Incidentally, cardiac reperfusion is a thermal injury of
mitochondrial origin, well, in my mind at least, there
should be hypothesis patents. |
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//"PULL UP ! PULL UP ! TOGA ! TOGA !"// A husky go around
can involve some extreme bank angles and departures of
pitch and yaw. Even the Spitfire couldn't turn inside it's own
radius, but that doesn't stop dogs trying. |
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// Even the Spitfire couldn't turn inside it's own radius, // |
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... let alone the Starfighter, whos performance in that area has been succinctly summarized as "Banking with intent to turn ..." |
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// but that doesn't stop dogs trying. // |
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While technically not dogs, being more of an amalgam of a chipmunk and a personal attack siren, chihuahuas are capable of turning in much less than their own length, subject only to the maximum RPM and output power of the blender you've crammed it into. |
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Question: What animal has the greatest horsepower
to weight ratio? |
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If somebody points out that it's birds, which I think is
highly probable, I'll be disappointed for some reason. |
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// It turns out that mitochondria operate closer to 60C than 37C// |
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Whoa there. I mean, what??? Are you saying that mitochondria raise the local temperature to 60°C? If so, how "local" - internal to the Mt, or internal to the whole cell? |
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Local to the probe that's measuring it! and that is a
soluble mitochondrial matrix protein delivered using one
of the standard mito targeting sequences. Likely that's an
average of the whole matrix volume. The heat source is
likely membrane localized so slightly higher temperatures
still should be expected close to the inner membrane.
What's mito DNA thermal stability like? |
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//internal to the whole cell?// |
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say 30% of some cells is mitochondrial volume so it's likely
that there will be significant whole cell changes.
Especially if you cut oxygen, build up reducing
equivalents to maximum concentrations and then
reintroduce O2. I should copyright "Backdraft II:
heartburn". Anyhow, more careful measurements
obviously needed, funding please. |
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The problem with this method of air transport, and
the reason for its lack of uptake, is the
concomitant husky-poo sputtering of the flight-path
and those living there. |
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//Question: What animal has the greatest horsepower to weight
ratio?// |
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Apparently it's the oribatid mite, whatever they are. [link] |
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From the article: "It can resist a pull of 1,180 times its
own
weight - which is similar to a human pulling 82 tons" |
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So if humans could double that, they'd have to re do the
list?
<link>. Also, calibrating mite-sized equipment must be a
nightmare, and creating force is not the same as
horsepower. Force = torque and force moved through
distance = hp. VO2 is how much oxygen you burn, which is
a bit of a proxy since you can burn a ton of oxygen while
producing little mechanical power, like when you're on
fire. |
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//Local to the probe that's measuring it! and that is a soluble mitochondrial matrix protein delivered using one of the standard mito targeting sequences.// |
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That is probably the most awesome thing I've learned in the last fortnight, and I thank you. I'd always taken it as gospel that mammalian cells - and everything in them - need to be at 37°C give or take a bit, in order to work well. And yet you're saying that the mitochondria are basically thermophilic bacteria on holiday. That has almost completely blown my mind. 60°C is generally considered the minimum cooking temperature for poultry. |
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[Ian], it works better when [bs0] does the science and you do the pointless arty stuff. |
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[Ian], it works better when [bs0] does the science, [MB] pretends
to understand it, we sit on the sidelines indulging in gratuitous
sarcasm, and you ... well, here's some scrap paper, and a box if
crayons the nurses confiscated from [not_morrison_rm] ... see if
you can draw something recognizable this time. |
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//[...] the probe that's measuring it! and that is a soluble
mitochondrial matrix protein delivered [...]// |
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My crayons are broken again. |
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How do you use a protein to probe the temperature of
something? I think I might be doing it wrong, what with the
restraining orders and superficial scarring. |
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//never-to-be- studied details // |
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// How do you use a protein to probe the temperature of
something? // |
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Our understanding is that individual proteins de-nature
(irreversibly) at specific temperatures. Thus if A de-natures but B
does not, a temperature between the two known points must have
existed. |
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That's much better, [Ian]. In fact it's actually not bad. |
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//How do you use a protein to probe the temperature of something?// For once, I believe [8th] is not completely incorrect, sort of. Fluorescent proteins show a decline in fluorescence as a function of temperature, so that's one way. |
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[bs0] what was the probe protein used in mitochondria? |
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"Gentlemen ? What does he mean, Grytpipe ?" |
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//How do you use a protein to probe the temperature of
something? I think I might be doing it wrong, what with
the restraining orders and superficial scarring.// |
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There's whole lot of ways to do this. On a really basic
level, you could use say an egg to get some idea of the
temperature of a hot spring for example. Put the egg in a
sock, tie sock to rope, throw egg-sock-rope in spring.
Wait 15 mins and haul it out. If you're egg's cooked solid
all the way through, it's above 80C. If the yolk is solid but
the white isn't then it's in the 65-75C range, if it's totally
uncooked then you know it's below 62-ish C, if it's frozen
then you're looking at something below -5C. |
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Obviously eggs aren't that practical, but you could build a
working thermometer with them. Maybe homogenize the
white from a whole lot of eggs and seal some in small
metal capsules, now you will get faster readout because
the heat will penetrate faster. Then you could keep some
of your homogenized egg white back and calibrate it
carefully with known temperatures in say a water bath. In
that way you can probably get a really good
thermometer, but only between 78-81C. This is a small
dynamic range, lots of probes have this problem. Then
you might find out the spring is acidic and that
dramatically increases the rate of protein denaturation in
egg white, so you may be systematically overestimating
the temperature... BUT you could use that, maybe have
your egg white thermometer include egg white
measurements at 5 different pH values, calibrate them in
the lab and you'll probably have 5 curves stretching out
the dynamic range from say 60-90C. Maybe then search
the world for exotic egg whites from the Guatemalan
Honkybird and you might get 40-90C. |
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That's not far off how we work, only the proteins are
fluorescent and we do it all with light. There are lots of
additional tricks we pull because humans have light
pretty much worked out as a tool. One is anisotropy. Say I
have a green fluorescent protein, I shine blue light at it,
it shines green light back at me. Now, if I polarize my
blue light, line it all up vertically then the green
fluorescent protein will shine back with all its light lined
up vertically... Unless it rotated between receiving and
sending. That rotation is dependent on how viscous its
environment is, how the protein is anchored, if at all, OR
how warm it is. So with care, you can use that as an assay
for temperature. |
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Other tricks include fluorescence lifetime... temperature
has an effect on how long the reply is spread out. The
clever thing is to use a whole lot of these together,
preferably choosing the factors that are known artifacts
so that they work in opposite directions. |
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Right now, there's at least 5 ways of looking at
temperature in those kind of volumes. Quantum dots,
small molecules, fluorescent proteins etc, all multiplied
by the tricks I've mentioned and they all point at
mitochondria being pretty damned hot. It's at this point
that a nice systematic study across many many
cells, tissues, species & conditions would be useful. It
won't
get done though. |
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If you genetically-engineered groups of birds to
produce eggs with egg-white proteins that denatured
at different temperatures, you could then use an egg
from each different bird type to make a composite
egg-white protein thermometer |
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//If you genetically-engineered groups of birds to produce
eggs with egg-white proteins that denatured at different
temperatures, you could then use an egg from each
different bird type to make a composite egg-white protein
thermometer
// |
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sadly not very reversible. |
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Thinking about this, mitochondria must be pretty extraordinary. |
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Most bacteria (which is sort of what mitochondria are) will thrive only at certain temperatures; at higher temperatures they either shut down or die, and at lower temperatures they just slow right down. Frinstance, good old E. coli grows best around 37°C, gets quite slow at 20°C and is almost asleep at 4°C (which is why you have a fridge). Thermophiles that live at 60°C would be more or less dormant at 37°C. |
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Yet, apparently, mitochondria can work well at 60°C but they must be able to function reasonably well at 37°C (to keep things ticking over when the cell isn't working very hard). That's an impressive range - how do they do it? |
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//Thinking about this, mitochondria must be pretty
extraordinary.// |
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They are, in every measurable way and probably many
more. A big shift in thinking is happening, 50 years of EM
images of heart muscle told us that they have 1000's of
mitochondria. It turns out that was like slicing a plate of
spaghetti through the middle and counting the cut ends,
the real number is likely <10, maybe even 1 electrically
connected reticular network fusing and fragmenting
locally. That would mean that the electrical activity of a
heart cell is pretty small fry compared to the magnitude,
(+100mV, 3-10 fold the capacitance * many fold the
electrochemical capacity) of the mitochondria within. I
actually think the plasma membrane potential "bounces"
off the mito potential, with the two interacting
electrically for tuning various ion flux rates, wish I knew
an electrochemist. I also think mitos are excitable, I'm
studying transient mito depolarizations and they exhibit
every feature of an action potential. |
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//That's an impressive range - how do they do it?// |
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They have a lot of heat shock proteins, we even use
HSP70 as a standard. The original bacterium was never
going to have had as much heat generating machinery,
the amplification of the respiratory chain is clearly an
adaptation/specialization to their current role. They've
had a long evolutionary history to adapt, one strategy for
stability at high temps might be the "respiratory
supercomplexes" most of the proteins are found in
absolutely massive complexes, these fall apart in heart
attacks for example. |
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//they exhibit every feature of an action potential// |
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That would be utterly huge. I shall expect a guest-invite to Stockholm in about 20 years. Remember I asked first. And let me know if you want artwork for the Nature cover - I can do you something awesome. |
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//most of the proteins are found in absolutely massive complexes// You mean they're stabilized by being part of the complex? |
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// I can do you something awesome. // |
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No, you can't. There are lots of adjectives other than "awesome" that can be used - disgusting, revolting, sickenening, obscene, unnatural, hideous, pitiful, nauseating, illegal, inexplicable, revolting - but remember, we too have seen the Intercalary with no kit on and (despite extensive and repeated attempts to purge the image) we still consider that "awesome" is utterly inappropriate - unless the observer is in immediate need of extensive psychotherapy. |
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Which, having viewed same, any "normal" person would be ... |
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Would the complexes being so big mean the outer peptide chains are shielding active areas? Umbrellas under the sun, so to speak. |
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But [Ian's] inference that the complexes diffuse the heat around also sounds plausible. |
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//mitochondria can work well at 60°C but they must be able to function
reasonably well at 37°C// |
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Isn't this just a question of where you take the measurement? The
cylinders inside a car engine regularly see peak temperatures of
~1500°C, but if the average temperature of your whole car is 1500°C
then you might want to stop for a bit and let it cool down. |
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//Isn't this just a question of where you take the measurement? // |
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The point was that the mitochondria themselves get to 60°C. Yet, if the cell is just ticking over, or is watching TV or doing any of the things that cells do in their spare time, the mitochondrion is not going to be doing much, and so will be close to 37°C; yet it still has work to some extent at this temperature. |
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//things that cells do in their spare time// |
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I just asked a few of my cells what they do in their spare time, and
they replied, "Well, nothing really. I just sit here and swelter. It's
been bloody hot for these past few million years, hasn't it? I blame
all those bloody mitochondria, coming in here with their fancy
foreign climates. We should just send them all back to their own
bloody tidal pool, I tell you!" |
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So I conducted a fair, democratic referendum throughout my body,
and 52% of my cells voted to throw them all out. |
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Maybe you need to build a wall to stop them getting in ? |
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Endosymbiosis, I think. At least for the voltage; not sure about the current. |
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Somebody really has to do this. Either with this method or
the helicopter thing. Despite being a bit fun, this actually
would be a part of aviation history and the engineering
involved would be as noteworthy as the first man powered
flight. |
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What if you used a team of eight reindeer ... ? |
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Just occurred to me, the best non human pilot would be a
chimp. |
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Just make a scaled down version of the Gossamer
Albatros. |
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Plus you could dress them in a little pilot's uniform,
leather helmet, goggles, scarf. Actually, that might over
heat the little guy, never mind. |
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// the best non human pilot would be a chimp // |
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That would cause chaos in naval aviation. How would you discriminate between aircrew and Marines ? |
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Presumably the hairy arses would give it away (though some
chimps can be a bit hirsute as well). |
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Babboons, then. Nearly as intelligent as chimps, more intelligent than Marines, and distinctive red, hairless buttocks. |
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There might be issues with odd courtship rituals and mating behaviours, but that's probably just a matter of ensuring the Marines are properly supervised. |
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//Babboons, then. Nearly as intelligent as chimps// and
hopefully better at spelling. |
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That's because- unlike baboons- they have the extra spelling "b" ... |
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I wonder if the listen to Aba. |
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Notes that 8th has not returned the crayons... |
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Do the Iditarod rules specifically say the sled can't have wings? |
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