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Author Topic:   Evolution doesn't make sense.
mark24
Member (Idle past 3982 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 6 of 80 (2245)
01-16-2002 8:29 AM
Reply to: Message 5 by Lorenzo7
01-16-2002 7:58 AM


Lorenzo7,

You're confusing abiogenesis (life from chemistry) with evolution. Since evolution is in the title, I'll confine my answer to that.

What is evolution?

http://www.talkorigins.org/faqs/evolution-definition.html

"In fact, evolution can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next."
- Helena Curtis and N. Sue Barnes, Biology, 5th ed. 1989 Worth Publishers, p.974"

"Evolution is a process that results in heritable changes in a population spread over many generations."

This process is VERY SIMPLY put as random mutation offered up to non random natural selection. There's an experiment I usually quote in these circumstances that proves the above (simple) mechanism.

http://www.accessexcellence.org/AB/BC/Bacterial_Mutations.html

"Today bacteria are an important tool in the study of genetics and biotechnology, but for 40 years after the rediscovery of Mendel's work and the rebirth of genetics, they were considered too simple to have genes, undergo mutation, or reproduce sexually. This is not surprising - bacteria are so small that it's very difficult to study individuals. Scientists had long observed differences between bacterial colonies, but had never realized that these differences were the results of mutations.

"It was well known that if a bacterial virus was added to a flask containing bacteria, the liquid in the flask would become clear, as if the virus had killed all the bacteria. However, with time, the flask would once again become cloudy as the bacterial population rebounded - now composed of virus-resistant bacteria. This happened even when all the bacteria in the flask were the clonal offspring of a single bacterium. Although such bacteria should have all been genetically identical, some of them were susceptible to the virus while others were resistant.

Two explanations for this unexpected variation confronted the scientific community: either (1) exposure to the virus had caused some small proportion of the bacteria to become immune and able to pass this immunity on to their offspring, or (2) the virus-resistant form already existed in the colony prior to the introduction of the virus - having arisen through mutation - and it was selected for by the addition of the virus.

To determine which explanation was correct, Salvador Luria and Max Delbruck, working together at Cold Spring Harbor during World War II, devised a test. According to Luria, his inspiration for the test was his observation of a colleague playing at a dime slot machine at a faculty dance. After consistently losing for some time, his friend finally hit the jackpot. Luria realized that if the slot machine distributed payoffs randomly, according only to chance, the payoff would usually be zero, occasionally be a few dimes, and almost never be a true jackpot. However, the machine he was observing had clearly been programmed to return an excess of both zeros and jackpots.

Luria returned to the lab and set up a large number of bacterial cultures, starting each one from only a small number of cells. He allowed the cultures to grow for a while, then added virus and counted how many bacteria survived (were resistant). He reasoned that if resistance was induced in bacteria randomly, in response to contact with a virus, it would be expected to occur at a zero or low level in all cultures - like the zero or small payoffs from a slot machine operating by chance. Alternatively, if resistance was the result of a mutation, the results would be analogous to the payoff from a programmed slot machine. Most bacteria in most cultures would not mutate, but if one did, it would reproduce and when the virus was added there would be many survivors - a jackpot! By looking at the fluctuations in the pattern of payoff (viral resistance), he and Delbruck could determine whether they were governed purely by chance or if the game was "rigged" by mutation.

It turned out that the number of resistant bacteria varied greatly between cultures; the fluctuations in payoff were far too great to be accounted for purely by chance. These fluctuations proved that bacteria did undergo mutation - and that the resistance to the virus they used in the experiment (a T1 bacteriophage) arose through such mutation.

By analyzing their data further, Luria and Delbruck were also able to determine the rate of bacterial mutation from virus-sensitive to virus-resistant. The likelihood of any single bacterium mutating during each cell division was extremely low - only about one in a hundred million, explaining why it was so difficult to detect and study bacterial mutations. Luria and Delbruck were successful because they created a method that screened for the outcomes of such rare events. They screened for the mutation from virus-sensitive to virus-resistant by exposing the cultures to the fatal virus. Other mutations, for which there was no such screening method, would have been almost impossible to detect. "

Evolution happens. I suspect your problen is that you can't see how a long slow collection of mutations can bring about large change.

I'll leave it here for now.

Mark

------------------
Occam's razor is not for shaving with.


This message is a reply to:
 Message 5 by Lorenzo7, posted 01-16-2002 7:58 AM Lorenzo7 has not yet responded

  
mark24
Member (Idle past 3982 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 15 of 80 (2298)
01-16-2002 2:14 PM
Reply to: Message 11 by Darwinboy
01-16-2002 12:58 PM


quote:
Originally posted by Darwinboy:
It is in fact the tilt of the earth that determines the temperature along with distance from the sun. The tilt of the earth does not change. Only the position of the sun rays hitting the earth as it revolves. So should the tilt of the earth change, we would burn or freeze to death. Seasons have little to do with the tilt. Climate is what results from tilt. Seasons have to do with the revolving of the sun. Evolution can't explain this, but it explains other things.

Actually, axial tilt does change, in a cyclic manner. We're currently in the mid range of that tilt change.

http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

"Axial tilt, the second of the three Milankovitch Cycles, is the inclination of the Earth's axis in relation to its plane of orbit around the Sun. Oscillations in the degree of Earth's axial tilt occur on a periodicity of 41,000 years from 21.5 to 24.5 degrees.

Today the Earth's axial tilt is about 23.5 degrees, which largely accounts for our seasons. Because of the periodic variations of this angle the severity of the Earth's seasons changes. With less axial tilt the Sun's solar radiation is more evenly distributed between winter and summer. However, less tilt also increases the difference in radiation receipts between the equatorial and polar regions.

One hypothesis for Earth's reaction to a smaller degree of axial tilt is that it would promote the growth of ice sheets. This response would be due to a warmer winter, in which warmer air would be able to hold more moisture, and subsequently produce a greater amount of snowfall. In addition, summer temperatures would be cooler, resulting in less melting of the winter's accumulation. At present, axial tilt is in the middle of its range."

Mark

------------------
Occam's razor is not for shaving with.


This message is a reply to:
 Message 11 by Darwinboy, posted 01-16-2002 12:58 PM Darwinboy has not yet responded

  
mark24
Member (Idle past 3982 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 16 of 80 (2300)
01-16-2002 3:54 PM
Reply to: Message 9 by Lorenzo7
01-16-2002 12:06 PM


quote:
Originally posted by Lorenzo7:

Second, darkcolored variants of a certain moth species evaded predation by birds because their color matched the sooty tree trunks of industrial England.

Although light and darkcolored moths did vary in expected ways in some regions of England, elsewhere they didn't. Further,
textbook photographs showing moths resting on tree trunks in the day, where birds supposedly ate them, run afoul of the fact that the moths are active at night and don't normally rest on tree trunks. After learning about the problems with this favorite Darwinian example, an evolutionary scientist wrote in the journal Nature that he felt the way he did as a boy when he learned there was no Santa Claus.


1/ That they are active at night demonstrates nothing. Background camouflage isn't going to work during flight anyway.

2/ They have to rest somewhere during the day, they don’t just dissapear, if its not on tree trunks, then somewhere else. This is when camouflage is important. When they rest. That they are, or are not on tree trunks is irrelevant. It is the surface colour that is important.

3/ The greatest testament to the use of the Peppered Moth as an example of natural selection is that the lighter moths are again resurgent, in accordance with reduction of pollution levels.

http://www.wm.edu/biology/melanism.pdf

“Textbook accounts of industrial melanism too often dwell in the past. They begin with pre-industrial England and end with Kettlewell. As a footnote they might add that melanism has been on the decline in recent years following clean air legislation. Yet, it is the record of the decline that is by far the strongest. During the last century and the early part of this one few people kept records about morph frequencies, so our picture of the rise and spread of melanism is sketchy. Documentation for the decline in melanic frequencies is vastly more detailed (e.g., Clarke et al. 1994, Cook et al. 1999, Grant et al. 1996, 1998, Mani and Majerus 1993, West 1994). No other evolutionary force can explain the direction, velocity and the magnitude of the changes except natural selection. That these changes have occurred in parallel fashion in two directions, on two widely separated continents, in concert with changes in industrial practices suggests the phenomenon was named well. The interpretation that visual predation is a likely driving force is supported by experiment and is parsimonious given what has been so well established about crypsis in other insects. Majerus allows that the basic story is more complicated than general accounts reveal, but it is also true that none of the complications so far identified have challenged the role assigned to selective predation as the primary explanation for industrial melanism in peppered moths. Opinions differ about the relative importance of migration and other forms of selection. It's essential to define the problems, to question assumptions, and to challenge dogma. This is the norm in all active fields of research. Majerus has succeeded admirably in communicating this excitement to the reader. I would add this: Even if all of the experiments relating to melanism in peppered moths were jettisoned, we would still possess the most massive data set on record documenting what Sewall Wright (1978) called
“…the clearest case in which a conspicuous evolutionary process has been actually observed.”

Mark

------------------
Occam's razor is not for shaving with.


This message is a reply to:
 Message 9 by Lorenzo7, posted 01-16-2002 12:06 PM Lorenzo7 has not yet responded

  
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