Re: Hands and brains

[T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)]

To Kelly:

>Yeah, Its assumed that you need a minimum size to have enough cells, for
>enough interconnections, to get a complex enough brain; But you also need a
>big enough brain to body ration so the brain has enough excess power to spare
>on complexity.

But why do elephants have such big brains (3 to 4 times larger than humans)?

>Dolphin Brains are bigger in size and ratio than human brains.  But human
>brains use a larger fraction (10%) on intelegence.  Dolphins sonar cortex is
>as large as the human visual cortex (30% of human brain), so even though the
>intelegence centers are far smaller, the total brain is larger.  

>I did a detailed breakdown of groceries per 20 years vs a selfsustaining farm
>and found the break even point was 20-30 years (depending).  I CAN'T FIND
>IT!!  Its probably in the LIT Newsletters, so if Dave finishes the search
>engine I can find it that way.  Or I might figure out where I put it on my
>hard drive.  Anyway I'll forward that when I can find it.

I've some 1.6 Meg of old newsletters (Older than miniLIT). If you know some
keywords, I can search them for you.

>Automation allows a few skilled people to do the work of a larger number of
>people without automation.  It does not allow the automation system to work
>by itself without people.  As long as their are people to fix and operate it,
>automate systems will work well and productivly.  Which is why all large
>manufacturing industries use them.

But that means that much less people can do the job


>> There are only 100-200 people needed to operate a submarine and they are
>> able to live more than 1 year isolated from the outside world.
>
>Submarines are much simpler than carriers, and they seldom operate more than
>3 months without coming into port.  Actually I can't think of one ever going
>a year submurged?  (RICK!! ??)

As far as I know they only come to the surface to recalibrate the navigation
systems. They even don't communicate with the home base so that their exact
position isn't known (They do receive messages though, but don't answer)
I've heard they sometimes don't harbour for more than a year, this of course
depends on the size of the submarine. (The largest Russian sub even has a
small swimming pool!)

>> 100 Times, I can believe, even cockroaches can survive that (Of course they
>> have a better armour than bacteria). Now I only wonder how radiation levels
>> can be that low in reactors. I guess these bacteria had found a well
>> shielded place behind some bolds.
>
>No, the bacteria remained directly exposed to the radiation.  The only
>shielding would be the cooling water batween them and the reactor core.

But then they must be exposed to maybe 1 million times the deadly radiation,
I really have to find that article...

>> Forget the predictions, it is proven than several gasses like CO2 and SO2
>> have very well insulating properties. So the fact that these gasses are
>> present in abundance on Venus means that a greenhouse-effect is 
>> responsable for the high temperature.
>
>No it doesn't, it just meen their are insulating gases in the air.  It
>doesn't even tell you if they are keeping heat in, or out.

It's keeping the heat in: Greenhouse gasses are more opaque planetary
radiation than for solar radiation. Solar radiation is what directly comes
from the Sun and planetary radiation is what is reflected from the planet's
surface. When solar radiation hits the surface of the planet, the main part
is absorbed, after a while the soil heats up and start radiating but this is
largely infra-red radiation while the incoming radiation had more shorter
wavelengths.

As for the debacle about Earth's greenhouse effect, there are only doubts
about the quantity of the temperature increase caused by the greenhouse
gasses. Also it is argued if the greenhouse gasses are the only reason for
temperature increase.

>> Yes, but that is because Earth has a biosphere. If Earth had to do without
>> that and it would be moved to the place of Venus, then is would heat up and
>> once the greenhouse-effect took over there wouldn't be a way back.
>
>No, earth biosphere trims its temperature a bit, but not by hundreds of
>degrees!  If that were true Earth would have been unable to ever evolve life.

To that I agree, but as long the greenhouse effect is not too large the
temperatures will not become so high that no live can exist. At the
light-side of the moon you will freeze to death (assuming you weren't
choking first) this is because there are no gasses to keep the heat in. The
only heat there is radiative heat.

>> OK, indefinatly, so a humble 60 years would be possible for a single way
>> mission :)
>
>Well, you wouldn't starve anyway.

The Dutch word "sterven" means to die. For "to starve" we use a completely
different word: "verhongeren" ("go hungry" is what comes nearest)

>> Oh, I thought you were referring to those bacteria living near
>sea-vulcanos.
>
>Some are there, or in stagnent pools (like parts of SanFransico bay) that
>have little or no oxegen.  But no large ecologies can develop in such
>isolation.

Indeed, so the chances for much evolution are also limited.

>>>In a world without photosyntisis the non-oxegen forms could still
>>>dominate.
>> 
>> How? If they used chemicals for their energy, then the supply of those
>> chemicals better be almost infinite. Most of the chemicals that organisms
>> use these days are recycled by using photosyntesis. Only a small fraction
>>of chemicals is freed by vulcanos, hardly enough to sustain a group of
>>lifeforms.
>
>Depends on the planets and its chemistry.

I think that if chemicals are not recycled any amount is used up in a
relative short period. (If water and carbondioxide where not recycled by
plants, animal (non photosynthesis) live would very soon die away).

>> No, we were apes before we had big brains, and apes are not preditors.
>
>We evolved from chimps, which are predators.  (Unlike Gorillas.)  Those
>chimps evolved (after some odd twists) into plains preditors and scavengers.

I've never heard that before, so I'm not certain.

>We developed that (and primative tool making), before our brains expanded
>much.

I've seen a TV-series (again :) ) that tried to explain that the human brain
expanded as soon as it began standing up. The reason for that was the
temperature difference between 0.8 metre (on 4 legs) and 1.5 metres (on 2
legs) above the ground. In Africa where they assumed the first "humans"
lived there first was a quite nice green landscape, but then relative sudden
(10,000 years or so) a 1000 kilometre mountain ridge appeared in the middle
of Africa, that had influence on the weather and at one side it became a
rather dry prairie landscape with only a few bushes. The distance between
those save bushes where rather large, so the apes living there has to move
relative large distances (for apes which are not very good at walking). So
after a while the started moving on 2 legs, which gave them more speed and
thus more survival-chances because they had a larger area to feed from. Now
it comes: Because the temperature at 1.5 meter was much lower (5 degrees or
more, because of the wind etc.) than on 0.8 metre the brain could be cooled
better and thus could now expand.
So to be short: The apes had to walk on 2 legs to have better survival
chances, then they got a cooler head and had the possibility to become a
larger brain.

One question remains however, why didn't they get a bigger brain while in
the forest before the mountain ridge appeared?

>They have about 6 - 8 claws, but the inner ones are very small and
>specialized for tearing down food for the mouth.

OK, but a crabs brain is just to small to become intelligent.

>> A larger brain needs a larger body, larger bodies need larger legs. Having
>> more than 4 legs will mean a disadvantage because of the extra weight.
>> Even if they had more legs they probably couldn't miss more than 2 of them
>> to permanently free them for hands.
>> 
>> Also it would be unlikely that animals that stand on 4 legs would have only
>> a stump to stand on. Having a few small extremeties at each leg gives much
>> more stability.
>> 
>> So while there are creatures with more than 4 legs, they aren't likely to
>> support a big brain.
>> That leaves only 2 legs to support the hands. If these 2 hands want to do
>> anything constructive, they better have more than 2 fingers.
>
>???!! You have some strange and unsupported assumptions there.  MOst of
>earths walking life forms have more than 4 legs.  Almost all of the rest have
>4.  Given that humans are fairly small as animals go, I can't see any
>justification in assuming large 4 or six limbed creatures are impossible.
> Hell we have predatores in north america that are almost a ton!

- First I said that only larger animals could support a brain large enough
to become intelligent. (I think a mouse-brain is too small)
- Then, I said that more that 4 legs were a disadvantage for larger animals
because of the extra weight.
- After eliminating all creatures with more than 4 legs, I said that that 2
of those 4 legs had to be used for tool-making etc.

>>I also wonder if creatures with gills (using oxigen in the water) could have
>>a large brain. In the water you would need very large gills to get enough
>>oxigen for that brain. Only very large underwater animals could have a big
>>brain, but what would the advantage be for them? They already are at the top
>> of the food-chain.
>
>Gills in water actually need les body mass than lungs in air.

I think that's because fish need much less oxigen. One of the reasons is
because they are cold-blooded. One of the biggest fish are sharks, but they
have to swim (slowly) all the time to get enough oxigen ot of the water.

>> Indeed, most of our brain isn't devoted to anything as far as we know. --
>
>Actually we do know what all the centers of the brain do, just not how they
>do it.

Why have I heard so many times that 90% of the brain (or did they mean the
cerebrum) is unused?

>> --- I
>> meant that a large part is devoted to what you can do with your hands.
>> Suppose you have a large brain, but no hands/legs to make use of it. There
>> would not be any advantage then to have a bigger brain, so it would not
>>evolve.
>
>The biggest section of the human brain evolved to use the eyes, not hands.
> Niether are used in itelegence, that evolved separatly.

Yes, I'm slowly seeing that size is not the most important factor and that
the largest part of the brain was and is already available. Could it be that
the use of hands and its applications involved a completely new way of
neuron interconnection which had intelligence as convenient side product?

If I'm not right about this hands->brain connection, then why did we get a
bigger brain?

Timothy