Why were dinosaurs so large?

[Pyrotex]

Gosh! It appears that I am not needed here! Thanks, guys!

 

Another point should be made here, by one who used to be a proud Bible thumper (me):

 

KreativeKorner almost certainly gets his "science" through his religious connections. He is told what Science "says" not by Scientists and their books, but by Religionists and their books. And the Religionists pick and choose what folks like KreativeKorner will be allowed to know, and they also provide the interpretations of that knowledge.

 

So KreativeKorner is left with the confident feeling that he is stating facts and using good logic. He is unaware of the vast, vast, vast, vast body of evidence that has been meticulously gathered over the last 1.5 centuries to underpin our current explanations of evolution and life. To him, a fossil in the rock is nothing more than an old bone left over from the Flood. To us, it is hardcore data. To him, mister Paley and his watchmaker are the "last word" in evolutionary logic, and it's just "common knowledge".

 

We do not need to insult KreativeKorner, but we do need to be firm with him and his brothers and sisters. He has been rooked. He has been cheated out of his birthright of a decent education. He has had his understanding stolen. And like me, if he is to recover all that is rightfully his, he will be thrown out of the family and community that raised him to be one of their own. For many folks, that price is just too high.

[HydrogenBond]

Evolution is not heading for a goal.

 

Let me give an example of goal orientated evolution. The current thinking has the earth originally without an O2 atmosphere. Photosynthesis is what created the O2. Let us begin at the point in evolution when the first O2 is being generated.

 

Using O2 as the terminal electron acceptor for metabolism gives any cell energy efficiency with respect to any given amount of food. Cells can metabolize anaerobically, but O2 allows a boost within the cell's energy supply, since the O2 allows the fuel to go further down the energy curve, all the way to H2O and CO2. Because a higher energy output per unit of food, will give any cell an advantage, as soon as O2 appeared the goal of evolution was set. The laws of chemistry said he who harnesses O2 will get a turbo boost in energy and outrun those who don't.

 

This might be a good experiment for evolutionary cause and effect. We will start with an anaerobic bacteria and slowly add O2. Over the course of the experiment we will see if cause and effect works and whether the bacteria which evolve the ability to use O2, take over the vat with selective advantage.

[Pyrotex]

Let me give an example of goal orientated evolution. ....

The example you give has certain merits. Indeed, O2 makes a better oxidizer than sulfur or acids. Any organism that uses O2 is likely to have advantages over a similar organism that uses HCl.

 

However, you miss the point. A "goal" is a semantic object, not a natural object. Goals do not "exist" in the natural world. A goal only exists within a sentient environment (like a cat's brain), or within a programmed environment created by a sentient being (like the targeting computer in a cruise missile). A goal requires knowledge of the distinctions "present" and "future": I am at a location in the present, X, and I want to be at a different location in the future, Y. A goal requires some intelligence, either natural or artificial to operate within, so that the intelligence can guage whether or not it is approaching its goal, whether or not it will reach its goal, what it must do to achieve its goal.

 

Evolution has none of these. DNA is not, nor does it contain, a semantic environment wherein a "goal" can exist. DNA has no distinction of present, future, location, status, progress or failure. DNA just builds a critter. Period.

 

Evolution works whether or not there is some external intelligence that does understand "goals". In fact, evolution works better if there is no external guidance at all.

 

Neither evolution nor DNA had a clue what Oxygen was. Neither had a clue as to the chemistry of O2 and what advantages it could confer. Neither had a clue how the ability to use O2 would result in "better" critters. Neither had a clue what "better" meant.

 

There was no hand on the tiller. There didn't need to be any hand on the tiller.

 

The presence of O2 simply meant that there was a different chemistry possible in the environment that wasn't there before. Mutations happened. Many critters dealt with the O2 in many ways. Some had advantages, some didn't. Some survived, some didn't. The survivors passed on their genes, the dead did not.

 

Evolution is a mindless machine. It automatically tries EVERYTHING. Almost all these random experiments die. The survivors multiply.

 

There is no goal.

There is no goal keeper.

There are no umpires.

There are no lines on the field to indicate "better" or "worse".

There are no bleachers, no spectators to make judgements.

There are no defined directions or goal zones.

 

There is the ball on an infinite field.

 

There is time.

 

The ball moves.

 

That's all.

[Moontanman]

`I also recommend creationists read "The Greatest Show On Earth" by Richard Dawkins. Packed full of evidence for evolution.

 

We have a living dinosaur here in New Zealand - Tuatara - so if your 'perfect God' was just practising (perfection needs practise?) he forgot to clean up after himself.

 

 

The Tuatara is not a dinosaur, not even close try again my friend....

[stereologist]

Changing the atmosphere from a reducing atmosphere to an oxidizing atmosphere was hardly a worthy goal at the time it happened. The oxygen was a waste product poisoning the world. The waste product was likely to have been highly toxic to the organisms of the time.

 

At some point in time organisms arose that were able to exploit this bountiful waste product.

 

As Pyrotex points out it was not a goal. It certainly was not a goal to poison the world and then hope that something would deal with the poison.

[HydrogenBond]

Say the DNA is blind and generates only random possibilities. The potential of the environment determines which is these throws of the dice will be beneficial. As an analogy, say I give you a dice. I say for every six you throw, I will give you one dollar. The throw of the dice is random, but when sixes appear, jackpot. One feels a release each time you get a dollar, but frustrated each time you miss. The release is the lowering of a potential.

 

The O2 had chemical potential for the future. The DNA does not know this, but it is trying things in a random way, totally blind. But it will periodically throw a six in the process and get a dollar. The O2 is an oxidizer, so it can also do harm. Some of those lucky DNA sixes will need to help minimize oxidation damage.

 

The O2 was creating new problems but also had the potential for a major upgrade within the motor of a cell. The DNA was throwing the dice and as history shows, satisfied both potentials.

[Buffy]

The O2 was creating new problems but also had the potential for a major upgrade within the motor of a cell. The DNA was throwing the dice and as history shows, satisfied both potentials.

 

But you were asked how this demonstrated "goal seeking": "satisfying potentials" is determined after the fact and is therefore by definition not intentional seeking of a prespecified goal.

 

If at first you don't succeed, failure may be your style, :phones:

Buffy

[stereologist]

HB you've got the basic idea here. Evolution is not a goal oriented process. Sometimes things work out well. Other times it does not. The transformation of the atmosphere into a poisonous, noxious oxygen laden atmosphere happened. It was not a goal. It simply happened.

[Qfwfq]

Animals do not become larger to use a resource. That is LaMarckian as in the suggestion that the giraffe's neck is longer so that it can feed on the crowns of trees. So dinosaurs do not increase in size to increase the size of a 'fermentation tank'.

Much as it is necessary to beware of teleology, I must say that ever since I actually read The Origin of Species I realized there are some misconceptions around about what Darwin did and didn't say, including the Darwin vs. Lamarck issue.

 

Lamarck simply proposed that adaption occuring an individual's lifetime might be inheritable and considered this as The way in which evolution occured. This was a far more obvious idea than that of natural selection which Darwin proposed. Guess what, Darwin did not refuse Lamarck's idea, he had no grounds for it, wasn't aware even of Mendel's observations and repeatedly mentions "our total ignorance of how the reproductive system works". He regarded adaption by use and disuse as possibly being one part of the mechanism.

 

We know now that an individual's efforts are not inherited in the sense that they don't change the DNA. So the giraffes with the longest necks survived better, yes, but they survived better for that reason; the difference isn't whether or not they currently have a long neck because it bears that advantage it's only a matter of how it evolved in this way.

 

Further, we must not neglect that any individual adaptability is related to genome and certainly helps with chances of survival. A neck won't become much longer during lifetime, by competing for leaves, but muscular strength, accumulation of lipids, pigmentation, fur, things like these being variable can make the individual succumb less to changed conditions and so constitute a more immediate survival advantage. Selection might wipe out e. g. the individuals who can't become more muscular when necessary even before they've had offspring in which some could be a bit more muscular. Individuals which can adapt more easily to new conditions will still be more favoured than those who can adapt enough, but barely. Darwin's mechanism does apply.

[HydrogenBond]

Selective advantage is based on the context of an environment. What defines selective advantage near the poles, is not the same as what has selective advantage at the equator. We can swap species-locations to prove this. Each environment set the constraints of what would work. If know what works, you also know what systems to evolve. The details may not be clear, but some directions are obvious. I know for any animal to survive and thrive near the poles it needs to evolve good insulation. We could have predicted that before there were many animals there. We can't predict all the diversity of forms from this. The environmental cause and effect, works to a certain point.

 

There is another thing that is left out. Say an animal uses their brain to discover a way to get food easier, like a stick. The better food supply will give them an advantage. This advantage may not be genetic based, but is due to the brain. Humans do not need to have a science gene to learn science. There is no relationship to an exact gene and an exact thing we learn. If we go back to our animal, the advantage allows it to breed more and pass on its genes, due to something learned, not directly related to genes.

 

Mother animals often teach their young. Without this brain to brain transmission, the genes she passed on to her young may not be enough. But if they learn, they may have an advantage. This allows them to breed and pass on genetics. Conceptually, that family can pass on a zig-zag pattern in fur, which has no basis in selective advantage. It simply due to gene propagation from brain/learning based selective advantage/breeding.

 

If we try to explain that fur pattern as random DNA, the actual cause was due to teaching, copying and learning, allowing a family to pass certain genetic flukes forward as a side effect. The cause and effect is more subtle.

[stereologist]

Again HB this is wrong thinking except for your last thought.

 

First, insulation is not a prerequisite for life in cold climates. Fish are not insulated. There are many phylums that live in the arctic oceans that are not insulated. You meant to say that land animals would freeze unless insulated. Fine, but that does not mean that an animal looks at the freezing zones and decides that it better evolve an insulation to head to polar regions. Only those that are able to survive do survive.

 

Your 'stick' example still does not support goal oriented evolution. Nothing is out there saying, "wow if we were smarter we'd be better off" and then evolution does the

the Jin-thing and poof there is an evolutionary trend toward fulfilling "the better mouse trap".

 

The important issue you discuss in the example of the "zig-zag pattern" is that evolution does not pick a good or better way. Those that survive pass on their traits. That's it. Those that survive pass on their DNA. The genes passed on may be important or not. They may be problematic, as in leading to disease. It doesn't matter if you survive long enough to breed and pass on your genes.

+

[Qfwfq]

I think you are being overly restrictive Stereologist. Recall that there is sexual selection in many species, it has been included in the game since Darwin's book and he discussed it quite in depth for that, in order to explain many of the striking differences between males and females of some species. He discussed the cases in which males directly compete with each other and those where females choose them according to charm and fancy.

 

Intelligence is one thing I left out of my list of things can increase or decrease in an individual's lifetime. When it is advantageous in a habitat, individuals of species that have any potential intelligence will quite naturally exercise it and some will need to strain harder, others less, according to genetic predisposition. This will allow more individuals to meet necessity, although not quite as favoured as the ones who's intellectual potential is greater. We might say that natural selection acts more "elastically" on these genotypes than on those for which the phenotype consists of a more rigidly fixed trait.

 

There can of course be opposite cases, contrary to a stable equilibrium, where an environmental adversity stunts the individual development of what is needed to overcome it, for instance bad nourishment can make it all the harder to compete for or reach better nourishment so selection becomes even harsher. In this case the population can be decimated all the more, rather than less.

[Getting A Life]

My 1st page post of this thread did sound a bit Lamarkian. Not my intention must learn to be more careful with my wording when talking about evolution. I meant to imply if food is nutritionally poor those who could hold more of it (or digest more efficiently) would have had selective advantage with more energy for mating defense range etc.

 

Moontanman - Not trying to spread disinformation I was quoting my university lecture from last week - "the Tuatara is the only dinosaur." Why she would state this 'untruth' while teaching a lecture is a bit beyond me. This reptile is commonly referred to as a living dinosaur... you'd hope a lecturer does their homework... Dr's are falible too. It is known tuatara are reptiles that have survived since the age of the dinosaur. The order Sphenodontia to which it belongs includes only one extant genus - Tuatara. I saw one yesterday. Only small, about a foot and a half, but it is not a lizard, they are of the order Squamata.

 

Interestingly, as we are on the subject of evolution, Tuatara are said to be the fastest evolving animal...

 

New Zealand's 'Living Dinosaur' -- The Tuatara -- Is Surprisingly The Fastest Evolving Animal

 

If an organism is faster to evolve than the organisms surrounding it would have advantage over them over long periods of time as abiotic factors changed. The Tuatara survived while the rest of the order went extinct. Along with all of those huge dinosaurs. This relates to the previously mentioned idea of watching anaerobes in a vat as oxygen is introduced. The fastest to adapt to the changing environment will have advantage.

 

Adaptations/mutations are the way evolution works. I assume an organism that evolves faster has more genotypes and subsequent phenotypes expressed over a given time giving advantage as changes take place - like drifting continents, thinning atmosphere and changing temperatures.

[Moontanman]

I agree it's sad when animals like the tuatara are referred to as dinosaurs, dinosaurs were a distinct group of animals related to reptiles but were not actually reptiles no more than mammals are reptiles. Both groups evolved from reptilian ancestors but were not in themselves reptiles. From our point of view Mammals seem to be distinctly less reptilian than dinosaurs but living dinosaurs were quite distinct and separate from the modern animals we call reptiles. As to why some dinosaurs were so large ( I think we established not all were large) certain environmental, ecological, physiological parameters favored large size in some dinosaurs both flesh eating and plant eating. nailing down those parameters should give us a good handle on why natural selection favored those animals that were large. I think it should also be noted that there did seem to be a lower size limit on dinosaurs. If i remember correctly there were no dinosaurs smaller than the size of a chicken (hmmm tastes like chicken!)

[HydrogenBond]

Interestingly, as we are on the subject of evolution, Tuatara are said to be the fastest evolving animal...

 

This is new to me and makes me think; I see a trend of random genetic changes decreasing as life on earth evolved , based on the observation that this ancient animal has the ability to change faster than modern animals. The question becomes, what selective advantage does nature create by limiting the rate of genetic changes, as time moves forward? This suggest the brain playing more of a role, since it allows real time adaptations and does not have to wait for a genetic roll of the dice.

 

Humans are at the top of the food chain. We do not wait for the roll of the genetic dice to grow fur when cold. We use the brain and put on a coat. Today there is no advantage to growing fur since there is no need. If it does occur, the brain will treat it like a medical condition and try to reverse it.

[Getting A Life]

HB you take great liberty with that link and leap to conclusions that make no sense.

 

If a reptile is cold it will move to someplace warmer, humans are not the only animals with brains enough to come in out of the weather. Migration and hibernation are prime examples where animals deal with abiotic factors proactively. This behaviour is stimulated by environmental change and biological clocks. Human have much behaviour patterns also affected by biological clocks.

 

The brain affecting genetic change is hokum. Genetics affecting the brain is not - See Huntington's, a trinucleotide repeat disorder - CAG mutations lead to improper folding of proteins leading to polyglutamine deposition, mitochondrial dysfunction and oxidative stress, this leads to selective cell death in the cerebellum and striatum which causes brain dysfunction which more often than not presents with psychiatric symptoms (amongst others). A gene affecting behaviour. Not vice versa.

 

The assumption that evolution is slowing down because an ancient creature shows an accelerated rate of evolution doesn't pan out either. That creature is alive now, and by your supposition it's 'evolution' would have slowed to be on par with all the 'slowly evolving' creatures now.

 

Humans are not the top of the food chain, that is an illusion created by sentient thought and vanity. The planet and all other forms of life could survive without us. We would all die without bacteria, or without fungi, or without arthropods, or without plants....

 

We are the 5th level consumers an ecosystem cannot properly support. About as intelligent in securing our future as lemmings appear to be.

[stereologist]

Qfwfq, I appreciate your input. Although evolution is not directed it can be modified by the participants through factors including mate selection. Thanks.