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  #71  
Old March 18th 18, 04:00 PM posted to uk.tech.digital-tv
Java Jive[_2_]
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On 18/03/2018 15:50, Norman Wells wrote:

On 18/03/2018 14:25, Java Jive wrote:

Both have evolved under different evolutionary pressures, and while we
may have only come to understand such things within the last 200 years
or so, probably from the earliest times we've associated red fruits
with good eating, but small red animals with bad eating.


That doesn't hold water either, though.

If garish colours mean 'don't eat' then, because we are omnivores, dull
colours must mean 'eat me' surely.* Yet we don't eat rats or moles or
hedgehogs, do we?


Well, different people in different circumstances eat different things.
We are very 'spoilt' today - our 'hunting' is mostly confined to the
aisles of the supermarket! However, I've certainly heard somewhere or
other of both rats and hedgehogs being eaten, not sure about moles, but
their skins were certainly used, so maybe the skinned carcass was
sometimes put in a pot as well. If you're hungry enough, you'll eat
anything that's edible, and, being all three mammals, all those are meat
to a carnivore.

Most animals are on someone else's menu, and naturally don't want to
get eaten, so they have evolved cryptic colours that makes them blend
in with their surroundings.* However, obviously fair numbers must
still get eaten, because otherwise the predators would have starved
into extinction by now.* However if you're very, very poisonous
indeed, like some Amazonian frogs whose mucus is used by Native
Amerindians to poison their blow dart tips, then even one oral contact
by a predator is probably going to end badly for the predator, but it
may also end badly for the frog, so it pays them to stand out from the
crowd,


Well, I'm not sure about that.* You see, for the good of the species as
a whole it would be a good move for some really poisonous frogs to look
good to eat so that in time all the predators are eliminated before all
the other frogs can be eaten.


Survival of the fittest means in actual practice survival of the fittest
genes - any one particular animal is just a temporary repository for
its genes, a means of their maintaining themselves by being passed on to
future generations. In your scenario, neither the genes in any
particular poisonous frog that was eaten nor in the predator that died
trying to eat it would ever get passed on, so evolution could not take
place in the manner you describe.

Although sometimes people talk about evolution as though it is some
god-like intelligence decreeing what should survive, in the manner that
you do above and perhaps also unintentionally I may have lapsed into up
thread, actually there's a significant happenstance element to it.
Changes happen by chance both in the environment and in the genetic
mixing during mating of the environment's inhabitants. If some of those
changes happen to favour one set of offspring better than others, then
they are more likely to survive and pass on their genes to future
generations, and so some of the changes that originally happened by
chance get fixed in the living populations, to give the appearance of
their being there by design, but of course they're not.

and adopt garish colours to show that they are very different from
normal prey. Predators that survive learn very quickly to associate
such garish colours with a bad experience, and steer clear.


I think you're insulting the intelligence of predators there.* If they
can do what you say with bright colours, why couldn't they work out that
dull brown things lead to a bad experience, if they do?


It so happens that generally they don't. However ...

Not all poisonous animals are garish, so to answer your question let's
take a look at what happens when they are not, for example at what has
happened in Australia since the human introduction of the cane toad.
These are fairly normal looking toads, but are highly poisonous, so very
poisonous that indigenous predatory fauna, used to the non-poisonous
indigenous toads, die even after fairly minimal contact with them, and
therefore cannot learn to avoid them, and are being wiped out. However,
although I can't remember details now, I recall that some scientists
trying to tackle this problem have discovered that you can train
individual predatory animals by somehow giving them a reduced potency
'taste of cane toad' which makes them suitably ill, but doesn't kill
them, and then releasing these animals back in the wild. AFAICR, not
only do these human-trained animals survive, but they pass on their
painfully learned knowledge to their offspring, thus offering a path of
hope for the future.

So this story gives us a two-way answer to your point. First that
poisonous animals tending to have a garish appearance does indeed help
predators enormously in discriminating between what is edible and what
is not. But also second that predators can learn to avoid poisonous
animals of normal appearance, but only if they survive in enough numbers
to pass on not just their genes but also their learning to their offspring.

Not at all, it's just Darwinian evolution at work.


No, I think there's an element of humans inventing a narrative and
perpetuating it despite loads of inconvenient evidence to the contrary
which they find more convenient to ignore.


Well obviously we weren't around when 99.9% or more of this was
happening, so in a sense all our narratives are invented, but I think
what matters here is that you haven't come up with an alternative
explanation that fits the known facts better.
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  #72  
Old March 18th 18, 04:21 PM posted to uk.tech.digital-tv
Java Jive[_2_]
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On 18/03/2018 16:03, Norman Wells wrote:

So, bright colours attract consumption except when they don't, and dull
brown things are OK, except when you step on them.


Unless you step on my blue suede shoes ...
  #73  
Old March 18th 18, 07:35 PM posted to uk.tech.digital-tv
Max Demian
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On 18/03/2018 15:39, R. Mark Clayton wrote:
On Sunday, 18 March 2018 13:33:47 UTC, Max Demian wrote:
On 18/03/2018 12:31, NY wrote:
"Woody" wrote in message
news
(*) I remember it using the mnemonic Bye Bye Rosie On You Go,
Birmingham Via Great Western, but I'm buggered if I can remember what
the letters stand for - there are three Bs and two Gs. There's a
brown, a black and a blue, and there's a green and a grey. I *think*
it's black, brown, red, orange, yellow, green, blue, violet, grey,
white - but I could well have got the green and the grey swapped round.

Black=0
Brown=1
Red=2
Orange=3
Yellow=4
Blue=5
Green=6
Violet=7
Grey=8
White-9

and I didn't even have to look it up!

I think you might have got your blue and green the wrong way round (it
doesn't fit the mnemonic), but otherwise it looks as if we've both
remembered it the same - and that matches what a Google search gives.


I remember the colours of the rainbow intuitively on the basis that,
e.g. orange looks like it has a bit of red and a bit of yellow in it, so
I can remember the colour codes for 2-7 OK and just have to add the
others. In any case when I did electronics I just /knew/ them. Nowadays
it's more difficult as resistor are so tiny that the colour bands look
rather similar. Or maybe the colours they use aren't so distinct. And if
they don't have a silver or gold one end I don't know which end to read
it from.


Silver meant 10% and gold 5% precision, occasionally another brown / red meaning 1 / 2%.

As it happened without a precision band there were only certain well established values (E12 series from 1952): -

1– 1.2 – 1.5 – 1.8 – 2.2 – 2.7 – 3.3 – 3.9 – 4.7 – 5.6 – 6.8 – 8.2

so there were only a few values that could be confused (e.g. 4,700 and 270,000 ohms), OTOH an 18k ohm could not be misread as 380 ohm as 380 was not in the series.


I meant if it was a 1% or 2% resistor - not that I would actually want
such precision - so there would be 5 bands with a brown or a red one end.

--
Max Demian
  #74  
Old March 18th 18, 07:43 PM posted to uk.tech.digital-tv
Max Demian
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On 18/03/2018 14:55, Martin wrote:
On Sun, 18 Mar 2018 14:33:59 +0000 (GMT), charles
wrote:

In article ,
Max Demian wrote:
On 18/03/2018 06:43, Geoff Pearson wrote:


I am colour-blind so find electronics a bit of a chore (although a
licensed radio amateur). Mains cables have three wires, blue, striped
and the other one (which is live). Traffic lights have the top one
(sometimes recognisable as red), the middle one (probably orange or the
same as the top one) and white (at the bottom). City night driving can
be tricky. Ethernet cables have brown, green and orange pairs, so I am
told - impossible.


There was a boy at my school who was colour blind; when we did prisms
and the spectrum he complained that he could only see three colours,
instead of six (or the Newtonian seven). I think he was told to shut up
rather than it being a matter for discussion.


Supposedly the colour blindness gene is retained in the population as
some predator camouflage doesn't work so well for people with the common
kind of colour blindness (usually called red/green), just as there is a
colour vision card that only colour blind people can decipher. The extra
colours confuse the brain.


I understand that 1 on 10 men have colour blindness of a sort - but only 1
woman in 100. This is unfair and the proper authorities need to investigate
and equalise matters.


Only men have testicles. Maybe men could trade a testicle in exchange for an eye
that is not colour blind. Thought not.


Technically it's because in mammals males are heterogametic. (The gene
for common colour blindness is on the X chromosome.)

--
Max Demian
  #75  
Old March 18th 18, 08:32 PM posted to uk.tech.digital-tv
Vir Campestris
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On 17/03/2018 11:38, NY wrote:

"Fuel pump", "battery" and "oil can" icons on car dashboards are fine:
they are readily understood as fuel level, ignition/alternator, oil
pressure. But different cars have different colours and conventions for
dipped headlights, front foglights, rear foglights. Some cars have all
the front lights facing one way and all the rear lights the opposite
(good) but others have all the lights on the icons facing the same way,
so you have no way of deducing which light relates to front fog and
which to rear.


My wife was recently puzzled by the tyre pressure warning symbol on her
new car. She's never seen a tyre in cross section, and thought it was a
horseshoe. She says it ought to be round like a tyre.

Andy
  #76  
Old March 18th 18, 08:32 PM posted to uk.tech.digital-tv
Vir Campestris
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On 16/03/2018 22:55, Max Demian wrote:
On 16/03/2018 21:51, Vir Campestris wrote:
On 16/03/2018 17:00, Chris Green wrote:
I agree, I hadn't even realised until recently that there were two
different levels called yellow and amber.* Traffic light middle light
is called both yellow and amber so one would assume they're the same.

Traditionally railways use yellow, and roads amber, for the name of
the intermediate colour,

Surely red, orange, yellow would be more obvious.


And if you happen to be red-green colour blind, like about 10% of men,
they're near as dammit identical. Which is why red is _always_ at the
top.


Unless they are horizontal, as in Japan and parts of Canada. And
railways everywhere, where the red is at the bottom, and the yellow is a
warning of red ahead rather than an intermediate.

Otherwise you're right. ;-

I did actually know about the railways. But I'm surprised about the
horizontal ones.

fx googles

https://en.wikipedia.org/wiki/Traffic_light

In the Canadian province of Quebec and the Maritime provinces, lights
are often arranged horizontally, but each aspect is a different shape:
red is a square (larger than the normal circle) and usually in pairs at
either end of the fixture, yellow is a diamond, and green is a circle.
In many southern and southwestern U.S. states, most traffic signals are
similarly horizontal in order to ease wind resistance during storms and
hurricanes.[28] The Canadian province of Alberta, and the Yukon
territory also use this horizontal arrangement.

Japanese traffic signals mostly follow the same rule except that the
"go" signals are referred to as 青(blue), which they historically were in
fact, but this caused complications with the international "green for
go" rule, so [29] in 1973 a decree was issued that the "go" light should
be changed to the bluest possible hue of green, thus making it factually
greener without having to change the name from 青(blue) to 緑(green).

Andy
  #77  
Old March 18th 18, 08:39 PM posted to uk.tech.digital-tv
Vir Campestris
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Posts: 439
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On 18/03/2018 12:14, Woody wrote:
Black=0
Brown=1
Red=2
Orange=3
Yellow=4
Blue=5
Green=6
Violet=7
Grey=8
White-9

and I didn't even have to look it up!


ROYGBV is a typical view of the spectrum.

Andy
  #78  
Old March 18th 18, 09:03 PM posted to uk.tech.digital-tv
NY
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Posts: 1,329
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"Vir Campestris" wrote in message
news
On 18/03/2018 12:14, Woody wrote:
Black=0
Brown=1
Red=2
Orange=3
Yellow=4
Blue=5
Green=6
Violet=7
Grey=8
White-9

and I didn't even have to look it up!


ROYGBV is a typical view of the spectrum.


Richard Of `York Gained Battles In Vain.

I find it very difficult to give separate names to the blue end of the
spectrum whereas distinguishing between red, orange and yellow is fairly
easy.

  #79  
Old March 18th 18, 10:03 PM posted to uk.tech.digital-tv
Johnny B Good[_2_]
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Posts: 513
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On Sun, 18 Mar 2018 11:46:05 +0000, NY wrote:

====snip====



(*) I remember it using the mnemonic Bye Bye Rosie On You Go, Birmingham
Via Great Western, but I'm buggered if I can remember what the letters
stand for - there are three Bs and two Gs. There's a brown, a black and
a blue, and there's a green and a grey. I *think* it's black, brown,
red, orange, yellow, green, blue, violet, grey, white - but I could well
have got the green and the grey swapped round.


I actually taught myself the resistor colour codes several years prior
to learning of the following aide memoir:

"Black Boys Rape Our Young Girls But Virgins Go Without."

Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White.

In fact, my knowledge of the colour sequence was so ingrained, I often
have to use it as an aide memoir to recall the aide memoir! :-)

There were alternative, less contentious, aides memoir which I'd heard
but are now long forgotten (one (redundant) aide memoir was quite
sufficient, thank you very much!).

--
Johnny B Good
  #80  
Old March 18th 18, 10:11 PM posted to uk.tech.digital-tv
Johnny B Good[_2_]
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On Sun, 18 Mar 2018 12:14:47 +0000, Woody wrote:

====snip====


Black=0 Brown=1 Red=2 Orange=3 Yellow=4 Blue=5 Green=6 Violet=7 Grey=8
White-9

and I didn't even have to look it up!


You should have done. You got the 5 and 6 colours switched. :-)

--
Johnny B Good
 




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