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From: Warp
Subject: Biology question
Date: 12 Nov 2009 19:02:31
Message: <4afca217@news.povray.org>
Why is it that when a dead animal rots, it's one of the strongest and
worst smells in existence (so bad that it even sticks to any surfaces
nearby and is extremely hard to get rid of), but when a dead tree rots,
the smell is not bad at all (in fact, it could even be considered pleasant)
and doesn't stick so much?

-- 
                                                          - Warp


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From: Darren New
Subject: Re: Biology question
Date: 12 Nov 2009 19:35:20
Message: <4afca9c8$1@news.povray.org>
Warp wrote:
>   Why is it that when a dead animal rots, it's one of the strongest and
> worst smells in existence (so bad that it even sticks to any surfaces
> nearby and is extremely hard to get rid of), but when a dead tree rots,
> the smell is not bad at all (in fact, it could even be considered pleasant)
> and doesn't stick so much?

My guess is that you're asking why a dung-beetle isn't repelled by dung.

I'd guess people who hung around dead bodies wound up getting sick, and the 
farther away you stayed the better off you are.  You can't catch very much 
from dead trees, and you generally don't try to eat trees anyway. Hence, the 
idea that the scent is unpleasant got selected by evolution.

I recently read a finding that lots and lots of insects are all repelled by 
the same scent of death. So you can take a particular rotting lipid from a 
butterfly and it'll keep away roaches and ants and pretty much every insect, 
so that probably evolved way way early on. I don't remember whether it was 
the same thing that smells bad to mammals and such, but if so, one would 
have to guess it actually evolved before life left the water.

If you haven't read this:

http://www.amazon.com/Stiff-Curious-Lives-Human-Cadavers/dp/0393324826/

it's very amusing and looks into various ways dead bodies get used. I bring 
it up because in it she mentions just how strong the odor is.

-- 
   Darren New, San Diego CA, USA (PST)
   I ordered stamps from Zazzle that read "Place Stamp Here".


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From: Warp
Subject: Re: Biology question
Date: 12 Nov 2009 20:27:28
Message: <4afcb5ff@news.povray.org>
Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >   Why is it that when a dead animal rots, it's one of the strongest and
> > worst smells in existence (so bad that it even sticks to any surfaces
> > nearby and is extremely hard to get rid of), but when a dead tree rots,
> > the smell is not bad at all (in fact, it could even be considered pleasant)
> > and doesn't stick so much?

> My guess is that you're asking why a dung-beetle isn't repelled by dung.

> I'd guess people who hung around dead bodies wound up getting sick, and the 
> farther away you stayed the better off you are.  You can't catch very much 
> from dead trees, and you generally don't try to eat trees anyway. Hence, the 
> idea that the scent is unpleasant got selected by evolution.

  I'm not so convinced that the answer is simply "we evolved to perceive
the smell of rotting flesh as unpleasant but not the smell of rotting wood".
I think that rotting meat has a much more potent odor even when measured
in a completely neutral absolute scale compared to the odor of rotting wood.
I really think there's an absolute difference in composition and severeness
of the smell, and it's not just a question of subjective perception. (Well,
unless I see some actual references of measurements that show that the amount
of smell is about the same in an absolute scale in both cases.)

  I'm just wondering why that is. Naturally the composition of wood is quite
different from the composition of meat, but both are organic living material.
Why is their rotting process so different?

-- 
                                                          - Warp


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From: Fredrik Eriksson
Subject: Re: Biology question
Date: 12 Nov 2009 21:24:54
Message: <op.u3babrjq7bxctx@e6600>
On Fri, 13 Nov 2009 02:27:28 +0100, Warp <war### [at] tagpovrayorg> wrote:
>
> Naturally the composition of wood is quite different from the
> composition of meat, but both are organic living material.
> Why is their rotting process so different?

http://en.wikipedia.org/wiki/Decomposition#Plant_decomposition



-- 
FE


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From: Vincent Le Chevalier
Subject: Re: Biology question
Date: 12 Nov 2009 22:00:29
Message: <4afccbcd@news.povray.org>
Warp wrote:
> I really think there's an absolute difference in composition and severeness
> of the smell, and it's not just a question of subjective perception.

Composition sure, but how would you measure the severeness of a smell 
objectively?

-- 
Vincent


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From: Neeum Zawan
Subject: Re: Biology question
Date: 12 Nov 2009 22:02:45
Message: <4afccc55$1@news.povray.org>
On 11/12/09 18:02, Warp wrote:
>    Why is it that when a dead animal rots, it's one of the strongest and
> worst smells in existence (so bad that it even sticks to any surfaces
> nearby and is extremely hard to get rid of), but when a dead tree rots,
> the smell is not bad at all (in fact, it could even be considered pleasant)
> and doesn't stick so much?

	Dead animals have few good uses (unless you cook them before they rot). 
Dead plants have lots of good uses.

-- 
Hipatitis: Terminal coolness.


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From: Le Forgeron
Subject: Re: Biology question
Date: 13 Nov 2009 03:52:24
Message: <4afd1e48$1@news.povray.org>
Le 13/11/2009 04:02, Neeum Zawan nous fit lire :
> On 11/12/09 18:02, Warp wrote:
>>    Why is it that when a dead animal rots, it's one of the strongest and
>> worst smells in existence (so bad that it even sticks to any surfaces
>> nearby and is extremely hard to get rid of), but when a dead tree rots,
>> the smell is not bad at all (in fact, it could even be considered
>> pleasant)
>> and doesn't stick so much?
> 
>     Dead animals have few good uses (unless you cook them before they
> rot). Dead plants have lots of good uses.
> 
Dead animals do not have smell. The HUGE set of bacteria, mushrooms and
other in their blood & intestine does develops the smells. (without a
live regulation anymore, it's a great war in there!)

Given the molecular reactions involved, most produced compounds from
animal are heavy weight sulfur/nitro/iron/salt... highly reactive with
your smelling sensors.

With a plant, most compound are a lot of carbon and a few nitro, barely
noticeable, for us!


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From: Orchid XP v8
Subject: Re: Biology question
Date: 13 Nov 2009 04:42:51
Message: <4afd2a1b$1@news.povray.org>
>> I really think there's an absolute difference in composition and 
>> severeness
>> of the smell, and it's not just a question of subjective perception.
> 
> Composition sure, but how would you measure the severeness of a smell 
> objectively?

Well, you could measure how volatile the end products are I guess...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*


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From: Gilles Tran
Subject: Re: Biology question
Date: 13 Nov 2009 05:35:28
Message: <4afd3670@news.povray.org>

news:4afca217@news.povray.org...
>  Why is it that when a dead animal rots, it's one of the strongest and
> worst smells in existence (so bad that it even sticks to any surfaces
> nearby and is extremely hard to get rid of), but when a dead tree rots,
> the smell is not bad at all (in fact, it could even be considered 
> pleasant)
> and doesn't stick so much?

After death, proteins are hydrolysed and break down into aminoacids and then 
into a variety of toxic, foul-smelling molecules (amines) aptly named 
putrescine, cadaverine and such.
Plants rot too, but because their composition is different (fibre and 
carbohydrates and much less fat and and protein) so the bacteria and fungi 
responsible for the decomposition are not the same and give different 
byproducts.
Why amines are foul-smelling to us may have something to do with evolution 
(i.e. animals associating the smell of death with danger). Note that some 
plants have evolved to produce cadaver smell as a defensive mechanism.

G.


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From: Orchid XP v8
Subject: Re: Biology question
Date: 13 Nov 2009 05:37:45
Message: <4afd36f9$1@news.povray.org>
Gilles Tran wrote:

> Note that some plants have evolved to produce cadaver smell as a 
> defensive mechanism.

Or even as a means to attract insect polinators. (E.g., Refflesia.)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*


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