Billy wrote:
In article ,
"David Hare-Scott" wrote:

Jeff Layman wrote:
On 09/08/2013 04:19, David Hare-Scott wrote:
Higgs Boson wrote:
Have often wondered how plants with dark foliage, like the dark
red
canna, handle chlorophyll.

Wikipedia has a long article; this is the first graph:

Chlorophyll (also chlorophyl) is a green pigment found in
cyanobacteria and the chloroplasts of algae and plants.[1] Its
name
is derived from the Greek words É‘É…É÷Éœός, chloros
("green") and φύλλον, phyllon ("leaf").[2] Chlorophyll is
an extremely important biomolecule, critical in photosynthesis,
which allows plants to
absorb energy from light. Chlorophyll absorbs light most strongly
in
the blue portion of the electromagnetic spectrum, followed by the
red portion. However, it is a poor absorber of green and
near-green
portions of the spectrum, hence the green color of
chlorophyll-containing tissues.[3] Chlorophyll was first isolated
by
Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[4]

Read the whole thing if interested, and make any
comments...appreciated.

HB

The third section on why chlorophyll is green not black is quite
interesting to me. The explanation given, which I think is widely
accepted in the botanical community, is that some (apparently
superior) structures and functions of living organisms have not
been reached by evolution because there was no evolutionary
pathway from where they came from to get there. This accounts for
the less than optimal structure of many aspects of life, eg the
human eye and the giraffe's neck. In fact it is characteristic of
a process that proceeds by many small connected steps to have such
inferior
outcomes. A process of design (such as human engineering) can
abandon a bad design and take a completely different approach.
Evolution cannot do that.

It's interesting that nature didn't come up with the wheel, one of
the most energy-efficient ways of moving around (or did I read a
few years ago that there was some strange organism which could move
like a wheel? I believe that there are some desert spiders which
can escape predators by pulling themselves into a ball shape and
rolling down sand dunes, but that not really the same thing as a
wheel). It's probably because the moving parts of a wheel are
completely separate from each other, and it would not be possible
to repair the revolving part of the wheel if it was damaged, as it
would have no blood supply.

Evolution is undirected and has no 'final' target nor does it look
to the future as an engineer does, it can only work incrementally
on choosing which variation of structure or function is better
suited
to the environment the organism is in at that time.

That's not quite true. If it is assumed that life started in the
sea, it should have stayed in that environment, but it didn't.

I see no evidence of either of those statements.

That biological reactions are carried out in aqueous solutions, and
that vast amounts of water would allow divergent compounds a
proximity to
each other with the chance of interacting?

Can you think of another crucible in which disparate amino acids, and
ions could interact and then multiply?

I wasn't clear. The two statements I see no evidence for a

1) "that's not quite true"
2) "it should have stayed in that environment"


Some
animals changed (evolved?) to make use of land. Even more oddly,
some changed back (eg seals) to make lesser or greater use of their
"old" environment, whilst others, such as dolphins evolved (or
should that be regressed?!) to become totally dependent on their
old marine environment.

In saying they regressed (went backwards) you are saying there is a
particular direction that is "right". It ain't so.

Once you have reached total randomness, you need less entropy, before
you can have more again. If she no goes up, how she gonna come down?


I see no relation between your reply and what I said. I said evolution is
undirected. Saying dolphins "regressed" suggests that when they (their
ancestors really) were land animals they were 'higher' than as aquatic. The
same goes for tapeworms that had ancestors that had not lost so many
functions (that the tapeworm no longer needs). Fitness depends entirely on
environment and only has meaning in the context of an environment so one
organism is not more evolved in absolute terms but better or less fit for a
specified environment.


"Natural selection" isn't the only game in evolution, the occasional
mutation can participate as well, but it is of necessity a minor
player
as most mutations are not beneficial.

True but I don't see the relevance to this matter of regression.

D