Evolutionary news

[marduk]

Release Rodger

we have no Rudolph the Red nosed Reindeer

[Forum Monk]

http://en.wikipedia.org/wiki/Evolution
I think you ought to read this

Due to my confession of being unfamilar with MODERN evolution theory I have taken time to carefully review the one credible link you have provided in this discussion. The article discusses the theory from its Darwinian origins and addresses some of the newer ideas which provide answers to the weaknesses of Darwin's original idea which were essentially 'incomplete'. I have seen that most of the new ideas which provide 'proof' are genetic mechanisms which it appears fall into two categories:
1. Mechanisms which explain how mutations (i.e. evolution) can happen. These seem to be theories without observation but deduction from observing similar mechanisms.
2. Same as #1 except with direct observation which support the theory which defines the mechanism. These in fact are cited as proof that in some cases, scientists may be witnessing evolution as it occurs(actually the mechanism which supports the theory of evolution).

It seems as you peel back the layers of the onion, there are more layers; that is, more theories. I don't think this is unusual. It is very common in complex cosmological theories also. One thing we have learned in cosmology however, is there are often exceptions which require formation of more layers and from time to time an observation is made which requires a complete reconstruction from the ground up.

It seems to me, that the science of evolution is relatively young, and requires many more observations and experiments. Also in my opinion, a theory can stand as long as it is remembered it is not LAW in the strictest scientific sense. To state it is proven seems a bit premature to me.

I do want to thank you guys/gals for challenging me to look deeper and deeper. As for me, I think the jury is still deliberating.

[marduk]

I have taken time to carefully review the one credible link you have provided in this discussion

so in other words you read one wikipedia page and decided that creationism still could be possible
why not actually apply yourself and find out more
http://evolution.berkeley.edu/evolibrary/article/evo_01
this may be easier to understand and its a berkeley.edu link which is about as credible as they come
and the jury isn't still out
they just returned an overhwelming plea of guilty on evolution with only one person abstaining
that one person is you

if you were to present evidence in that court remember that all of it would be stricken from the record because your personal belief is inadmissable unless backed by credible evidence of which you have none
and if the judge finds out that you're biased for some reason you'd get held in contempt
so
go directly to jail
do not pass go
do not collect $200

[stan]

as there are many changes that can affect genetic make up
and you don't even know what they are
so the fact that you misheard something on uktv probably doesnt make you an expert
yet you're demanding answers to something that isn't true
heres your answer
learn about genetic mutation first
and then if you don't understand it
then ask a relevant question

...saith marduk.

This is pretty harsh, Steve.
..how about learning a little patience?
And learn that you don't convince people by shouting and name calling.

[Digit]

Some days ago I asked Marduk to critique a book I am writing, which he kindly did and I have taken on board. Here in the UK, at the moment critisism of Islam can get you killed! The usual argument against that approach is if it is too weak to stand crititsism then it is probably wrong.
In my book the hero throws out a challenge, I offer it here.
Why are trees tall?

[marduk]

how about learning a little patience?

theres been 38 pages in this thread so far
what do you suggest
100 maybe

Here in the UK, at the moment critisism of Islam can get you killed

thats a complete lie Digit
who's been killed for criticising Islam in the Uk
they didnt even get Rushdie

Why are trees tall?

better to ask why they stop growing don't you think

Like other plants, trees grow in a different way to animals. Animals have a set pattern of development that produces a full-grown adult with a preordained body plan: a set number of legs, for instance. Plants, in contrast, are modular organisms that can produce large numbers of almost autonomous branches, twigs and leaves. They could theoretically keep growing forever. Yet trees do in one respect show a pattern of growth that is very similar to animals. They have an S-shaped growth curve, growing slowly when young, much faster at intermediate ages, and slowing down as they mature until they level off at a maximum height. So why do trees stop getting taller?

There must be a genetic component, because some tree species grow taller than others: oaks are bigger than hollies. However, there must also be a connection with the environment, because trees of the same species reach very different heights depending on where they are growing. An oak tree growing in good soil in lowland Britain grows rapidly and can reach up to 30 metres in height, while one of the gnarled oaks of Wistman's wood on upland Dartmoor, in southwest England, by contrast, grows slowly and reaches only around 10m. Similarly, Sitka spruce trees grow up to 60m tall in California, but trees of the same species growing in Alaska rarely reach 10m.

Bristlecone pines Pinus longaeva are extremely hardy trees that grow on semi-arid mountains from the Mexican border northwards to Colorado, where their growth is limited by the extreme cold and drought. (Image: John Shaw/Auscape)
Poor conditions reduce both growth rate and maximum height. Several theories have been put forward to explain what limits the height of trees.


Respiration hypothesis
One theory is that trees grow more slowly as they get taller because they have more wood to maintain. Therefore, as trees grow, more of their photosynthetic production has to be diverted to allow the trunk, branches and structural roots to respire; eventually all of the sugars will be needed just to maintain them and the tree will stop growing. This theory certainly ties in with the correlation between tree growth rates and maximum heights; fast-growing trees produce more sugars and so could maintain a larger trunk. However, recent research has contradicted this theory; wood is so full of dead material that it requires only around 5-12 percent of the sugars to maintain it, even in large trees. In any case, the theory cannot explain the fact that the trunks of mature trees continue to increase in diameter long after they have reached their maximum height.

Nutrient-limitation hypothesis
Coppicing
Coppicing is a technique that makes use of the fact that many species of angiosperm trees, such as hazel (hazelnut), chestnut, oak and ash, do not die when they are cut down. Instead they sprout buds from around the base of the trunk to produce large numbers of narrow poles. Growth of these poles is very rapid because the tree already has a fully developed root system to supply it with water and nutrients, and there is no trunk to use up energy or reduce the water supply to the leaves. Coppicing therefore promotes the production of large numbers of narrow woody stems that can be harvested every ten years or so; they are used to make poles, hurdles, tool handles and other small implements, or may be burnt as firewood or to make charcoal.

Coppicing as an industrial practice became economically unviable in the early twentieth century, but the practice is currently making a come-back in woodlands owned by conservation bodies because it promotes high species diversity. In any one wood, only a small proportion of the coppice is cut each year, so the woodland is a patchwork of coppice of different ages; the habitat will range from newly harvested areas which form an ideal habitat for light-loving flowers and butterflies, to heavily shaded areas where more typical woodland vegetation is favoured.
A second theory is that tree height is limited by the availability of nutrients. As trees grow, they take up nutrients and sequester them in their leaves and woody tissues; this reduces their availability in the soil. As a consequence, larger trees would have to divert more of their biomass to their roots to maintain the nutrient supply and they may not get enough to produce new leaves or branches. There is some evidence for this theory; older forests often do have higher root biomass than young ones, and their soils do tend to have lower nitrogen levels. Furthermore, adding more nitrogen to mature woodland can result in the trees resuming their vertical growth. However, the theory does not explain why young trees can grow perfectly well in old forests if they get enough light. Nor does it explain why parkland trees, which have plentiful nutrients and water, eventually stop growing. The theory cannot therefore be a complete explanation.


Maturation hypothesis
A third idea is that trees stop growing because the tips of their shoots, where the tree extends, mature, and their rate of cell division decreases. The slow-down is thus genetically programmed. Trees certainly mature; older shoots are less twiggy than young ones and have lower growth rates. These differences are genetic in origin as they remain even if a mature shoot is grafted onto a juvenile tree's rootstock. However, the transition to maturity occurs well before height growth slows down. In any case, shoots grow extremely rapidly from the bases of coppiced trees (trees that have been cut at the base of the trunk, a method which stimulates rapid wood production), even when they are several hundred years old. This shows that trees do not age and lose their vigour in the way the hypothesis suggests.


Hydraulic-limitation hypothesis
The theory that is best supported by the scientific evidence is that height is limited by the supply of water to the leaves. In taller trees there is higher resistance to water flow because it has further to go up the trunk and because it has to be raised higher against gravity. Because water is dragged up trees under tension, the taller the tree the higher the tension has to be; air bubbles are therefore more likely to form in the xylem vessels, causing loss of their conducting ability. To prevent this, taller trees have to close their stomata earlier in the day or earlier in a drought; this limits photosynthesis, and so slows tree growth.
All of the aspects of this theory have been verified by experiment. Taller trees do indeed have greater hydraulic resistance, and water is under greater tension in their trunks; their stomata do close earlier in the day, and tall forests do have reduced rates of water loss and photosynthesis as a result. What is more, the idea also helps explain three other facts. First, it explains why old trees have flattened tops with gnarled, slow-growing branches and twigs, whereas further down the canopy growth is more rapid. This occurs because photosynthesis and new growth are most severely reduced at the very topmost twigs where the hydraulic resistance is greatest. Second, it can also explain why trees growing in nutrient-poor habitats or in cold or dry conditions have a lower maximum height than trees of the same species that are growing in good conditions. These factors will reduce the growth rate of the tree, which will therefore lay down less new wood each year; the result will be a reduction in hydraulic conductivity, particularly since slow-growing trees lay down relatively more late wood, which has narrower cells. Future growth is consequently reduced and height is limited.

The giant redwood Sequoiadendron giganteum from the western slopes of the Sierra Nevada, California. Growing up to 96m, it is slightly shorter than the Californian (coast) redwood Sequoia sempervirens which grows up to 102m. (Image: Diccon Alexander)
Finally, the theory can help us explain why the two tallest species of tree in the world are the Californian (coast) redwood, Sequoia sempervirens, and the Eucalyptus trees of the Australian temperate rainforest. The climate is ideal for year-round growth in both areas: the eucalypt forest is relatively warm and has plentiful rainfall all through the year; in coastal California there is abundant winter rainfall, while in summer the trees obtain their moisture from the fogs that move in from the sea. Both areas also have fertile soils.

The evidence therefore suggests that limited water supply to the leaves is the most important factor that curtails tree growth. However, size is not everything, and many trees are adapted to be short. Small evergreens such as hollies and box trees thrive in woods under a canopy of larger species, while small deciduous trees such as rowans and birches are ideally suited to a life on wind-blasted heaths and moors. Small is definitely beautiful for the birches and willows of arctic tundra which reach only a few centimetres in height, so keeping out of the icy blast!

thats just the short answer
http://www.nhm.ac.uk/nature-online/life ... sion5.html

[Forum Monk]

who's been killed for criticising Islam in the Uk
they didnt even get Rushdie

Come on over here where you can buy guns in a department store - its happened!

Nice tree post btw.

[Digit]

Please Marduk I'm not a liar. The fact that they didn't get Rushdie doesn't mean they didn't try and you cannot deny that 'Hook' and co haven't promoted the point, can you. So please, forget the insults and return to acedemia, please?
Your post, though interesting dodges the question. There has to be a hydraulic limit to tree height. I didn't ask why they stopped growing I asked why they grew so tall.
In my book the colonists meet sentient 'seals', and the hero points out that natural selection has time on its side and an infinite number of trial runs, and that there can only be one most efficient shape for progress through a dense fluid.
The fact that all fast swimming animals, past and present, share that shape is massive support for Darwinism.
Trees. According to natural selection their height must promote some advantage. The spend 30 yrs plus before they can contribute to the gene pool, during which time they are at risk from fire, flood, drought, barking and felling by Beavers etc, and they use massive resourses to achieve their height.
That sounds like a pretty lousy survival strategy to me.
If Darwinism can't answer this and other questions then either we are asking the wrong questions or Darwinism is not the full answer.
That does NOT make me a creationist. Just curious.

[marduk]

Please Marduk I'm not a liar. The fact that they didn't get Rushdie doesn't mean they didn't try and you cannot deny that 'Hook' and co haven't promoted the point, can you. So please, forget the insults and return to acedemia, please?

fyi captain hook is now in prison
and what you said is a lie
its Islam bashing
thats not allowed here and neither is telling lies about the catholics or the buddhists or anyone else
theres actually a law against it
especially when you write it on a public forum
the times that you may think I have bashed a religion I have had actual evidence that supports my conclusions or I have on some rare occaisons degraded someone for their lack of understanding due to their religious faith
this is an entirely different thing to saying that criticising Islam can get you killed in the UK
it can't
it hasn't
and it won't
long before that day arrives I will be standing at the border with a machine gun and a bad attitude


and for the last time Roy
Darwinism is not the be all and end all of evolution
if you will you go back and read the links I have posted you will then not need to keep repeating the same out of date idea
also thats a very nice concept about the seals but animals and plants do not follow the same evolutionary princliples
and y'know i don't think theres a great percentage of trees at risk from beavers either

According to natural selection their height must promote some advantage.

it does
it allows Photosynthesis
http://en.wikipedia.org/wiki/Photosynthesis
all life is dependant on this process
it is not an evolutionary step
it is in fact the reason that we have life on this planet
it hasn't evolved at all being a chemical reaction so its not covered by anything Darwin ever said about anything

[Digit]

It is NOT Islam bashing. It is bashing the intolerance of Islamic extremists!
I reiterate. I am NOT a liar simply because you are as intolerant of discussion as some God freaks!

[Charlie Hatchett]

Here's a nice freebie I found on Google Videos (for those that don't already have it):

http://video.google.com/videoplay?docid ... ins+of+man

[marduk]

It is NOT Islam bashing. It is bashing the intolerance of Islamic extremists!
I reiterate. I am NOT a liar simply because you are as intolerant of discussion as some God freaks!

heres what you said Digit

at the moment critisism of Islam can get you killed

doesnt say anything about extremists
and the fact that extremists are not sanctioned by their religion says nothing of intolerance in anyone but you
you're labelling all moslems as extremists
thats not true
anything that is not true is a lie
i stand by my original statement that criticising a moslem in this country will not get you killed
are you still standing by yours that it will if so then can you provide a reference that says criticising the islamic religion and anyone who adhers to it in the united kingdom will get you killed
just so i know how careful to be next time im at the corner shop

[Digit]

You accuse me Marduk of not reading your posts. Look up! I said it CAN get you killed.
I probably have a greater respect for people's beliefs than you have demonstrated.
Certainly, as I pointed out, and you've ignored, such actions have been promoted within the Islamic community. Yes or No? The bombs in London
were used to kill, I think that is extremism. Don't you?
I HAVE read your posts. Each of them has, not unreasonably, been selected to support your views, I accept that.
You say that Darwinism is not the be all and end all. Is that not what I have been suggesting since yesterday?
You mention photosynthesis, surely that is a function of leaf area, not trunk length? You point out that it is chemical function. I agree, but surely the increase in plant species IS a function of natural selection?
You say I haven't read your posts, I asked you why trees grow tall, you replied with a lecture on why they stopped growing.
I asked you if you could explain to me how the time scale for separation of man from Chimp was arrived at. No answer.

[Minimalist]

Why are trees tall?

What does Islam have against trees?

[Digit]

Who knows?