Just ONE question on evolution

reply to post by jiggerj


Here is the problem. You are looking for particular differences. Maybe those are not the ones of interest. They might be of interest to you, but do not represent a change in a species, but only the variance within a species.

Consider human kidneys. Inside are nephrons. Some people are healthy with 150,000 while others are healthy with 1.25 million. That's a 9X range and shows the high variability between humans in that part of the body. Species often have large differences between individuals.

The idea to follow is the meaning of species. That is the crux of the issue. When are 2 groups of animals different species? From there we have to see how that definition fits with the fossils that are located. Only the harder parts of a specimen are usually preserved. That leaves us with the bones to separate out species. One of the questions might be just how well can species be identified from bones? After that we are asking how well we can infer the connections between species from the bones.

There are lots of background issues that need to be addressed and have been discussed in the scientific literature for over a century.

reply to post by jiggerj

Evolution has yet to be describe to me in a way that sticks in my head. Can someone explain IN LAYMAN'S TERMS what I am about to ask. In evolution I would expect to find many samples of a species with gradual changes that has taken place over millions of years.

I'll try from another tack.

Suppose you have a population of brown moths. They are quite successful living around a little muddy pond and eating whatever stuff they eat around that pond. The pond is formed by glacial melt run off and empties into a little stream surrounded black ironbark trees. The moths flitter around the area and sometime they stop for a rest on the glacier or on the trees. Some take up fairly permanent residence on the ice and some on the trees.

One year two of the moth mothers are affected by the cosmic rays from a solar flare and a random mutation occurs in each. One moth mother produces all white moths, the other produces all black moths, other mothers are unaffected. So now there are three varieties of moth in the population, brown, white, and black. A few generations later and the population is still mostly brown, but the white and black strains still show up in each generation. All the moths, of whatever color, are still quite successful in their little environment. Color doesn't help or hinder them in anyway; the mutation simply makes no difference.

Then one day a magpie shows up and notices the moths flying around and decides that this is the place to raise a brood of young magpies. As she goes out hunting for food, she notices that the black moths are particularly easy to find against the ice. She doesn't even notice the white moths on the ice. On the other hand, the white ones can be picked off pretty easily against the black bark of the trees, are there even any black ones there? Both the black and the white ones can be found pretty easily near the muddy pond, and the brown ones are relatively easy against the ice and the tree, but not so easy in the mud.

Very quickly then, the black moths dominate in the forest, the white ones on the ice, and the brown ones on the mud. The population has started to split from the mere introduction of a new predator in the area. In their local area they breed true to their color. The occasional 'off color' individual gets knocked off pretty quickly by the magpie. Likewise mixed couple breeding is limited too, the Magpie is going to find the individuals that stray out of their territory for some extra curricular cuddling pretty easily.

The Ice Moths will over a few generations, favor those individuals that can survive best on the food that the glacier can afford them, which is likely quite different than the Mud Moths. Likewise for the Forest Moths. In a remarkably short time you will have three different populations that don't interbreed and rely on different food sources. This doesn't take millions of years, or even thousands of generations. Very few generations are required for this level of change.

If the Magpie goes away and is not replaced by some other moth predator, the Moth populations could still interbreed probably, but given enough generations and enough other differing environmental problems that are either handled or not handled by the randomly occuring mutations and they may well evolve far enough apart that they can't or won't. This is the generally accepted notion of speciation; they split population changes enough that the populations won't or can't interbreed and produce offspring that can themselves breed. However, Biologists have pretty much stopped using the concept of species because there are too many instances of what were considered different (but closely related) species producing viable offspring that the entire concept just became too difficult to define sufficiently.

Finally, suppose lightening strikes in the forest and the resulting fire destroys the entire Black Moth population. An entire branch just died out. The brown and the white continue on till today evolving more and more so they no longer resemble the original brown moths in more than a superficial way. One day digging near the pond finds some of the moths encased in the ice where they were trapped during a long ago storm. There are white ones, brown ones, and black ones. Are they the ancestors of today's moths? Which is the original population? Were they always different populations? Why aren't they still here in the same form? What killed off the black ones? What cause the white ones to double in size compared to its ancestor? What caused the brown ones to start skimming the pond surface?

I hope this was helpful.

reply to post by rnaa

One year two of the moth mothers are affected by the cosmic rays from a solar flare and a random mutation occurs in each.

Is random mutation an acceptable theory within evolution? Or, sudden metamorphosis?

reply to post by rnaa

Very quickly then, the black moths dominate in the forest, the white ones on the ice, and the brown ones on the mud.

Huh? You make it sound like each moth CHOSE the safest environment. Is that possible?

One thing to remember about evolution is that it isnt "sentient" - meaning, it isn't "aware" of the changes happening. An organism doesn't "evolve" because it says, "Hey, if I had claws, I could climb a tree" or "If I had sonar, I could navigate in the dark".

Evolution is a series of genetic mutations which benefit and allow that generation of organism to survive within its environment. These mutations could be a result of external stimulus (natural radiation) or perhaps a defect in the genetic code during the animal's development.

For example, you have 4 animals. Each born with a genetic mutation. The first has a stubby leg, the second exceptionally small eyes, the third has a set of arms with webbed skin or feathers and the fourth scaly skin.

The first and second die very quickly within their lives, perhaps they are easily killed by predators due to the inability to see efficiently, or perhaps they couldn't run away as the stubby leg hindered them. So that generation of mutation ends there.

The third and fourth survive because they can either escape from predators by gliding/flying from harm or their toughened skin renders them immune from their normal predators. So they mate, maybe with each other (chances are slim!) or with others of their kind and that "mutation" is passed down to the next generation. And so on, and so on. Eventually some other mutation happens which either a) allows the animal to survive or b) renders it susceptible to predators and it dies.

And this is how evolution works. There's nothing inherently "sentient" about it. Well, maybe aliens were involved, who knows..

OP

Several of us have explained evolution in varying levels of layman's terms. I must ask, are you going to accept ANY explanation, or are you just determined not to believe it ? I mean that is your prerogative, it is your mind after all. However those of us who have answered have shown evidence, indeed some of mine has passed the 4 or 5 levels of significance tests for scientists/statisticians.

reply to post by Noinden


Hey I found the part about chimps almost never getting cancer fascinating. What do you think lead to humans being extremely prone to developing cancer? During our evolution what do you think happened that mutated our genome so that we develop cancer so easily? Do certain variances of the human genome get cancer in higher numbers than other humans?

How much of a factor do you feel mans exposure to chemicals in quantities it never would in the wild effects cancer if at all in humans. Do other animals that live side by side with humans develop cancer as easily as we seem to? We appear to get cancer more than any other animal on earth.

Just thought the mention of the chimps never getting cancer was really interesting and something I've never heard before. Thanks for teaching me something for today!

Originally posted by BASSPLYR
reply to post by Noinden

 

Hey I found the part about chimps almost never getting cancer fascinating. What do you think lead to humans being extremely prone to developing cancer? During our evolution what do you think happened that mutated our genome so that we develop cancer so easily? Do certain variances of the human genome get cancer in higher numbers than other humans?

How much of a factor do you feel mans exposure to chemicals in quantities it never would in the wild effects cancer if at all in humans. Do other animals that live side by side with humans develop cancer as easily as we seem to? We appear to get cancer more than any other animal on earth.

Just thought the mention of the chimps never getting cancer was really interesting and something I've never heard before. Thanks for teaching me something for today!

The researchers seem to think it is a mixture of the gene differences we have with the chimps being (a) less stable (a small change = bad) to normal transcription (copy) changes and (b) environmental. Man has had an increase in cancer rates from industrialization onward, so yes chemicals and radiation are a factor.

If it helps I had not heard the cancer thing either, but it was in last weeks New Scientist.

reply to post by jiggerj

Is random mutation an acceptable theory within evolution? Or, sudden metamorphosis?

Random mutation provides the raw material on which natural selection works. It is not just acceptable to the theory of evolution, it is fundamental to it.

It helps to understand what a mutation is. It is a copying error made when a living cell duplicates itself by division. They appear in somatic (body) cells as well as gametes (sperm, eggs, pollen and suchlike). Copying errors in somatic cells can kill the organism; cancer is an example of this. Copying errors in gametes may make offspring unviable, or cause them to evolve new traits, such as stubby legs or variations in wing colour, that either help or (more likely) hinder them in the struggle to survive and bear offspring.

Natural selection works on these variations and the result is evolution.

You make it sound like each moth CHOSE the safest environment. Is that possible?

Of course not. What happened is that all the moths sat everywhere. The ones that showed up in contrast to their backgrounds got eaten. The ones that blended in did not. So in the end the white moths were left on the snow, the brown moths were left in the mud, and the black moths were left in the forest. After a few generations their descendants adapted to their respective environments – surviving longer, reproducing more – and became habituated to them.

The behaviour looks like willed choice to the casual observer, but closer inspection shows that the moths are actually responding to more or less random variations in their external environment.

Natural selection works on these variations, too, and again the result is evolution.

*

Well done, jiggerj. These two questions of yours go right to the heart of the second most important problem people tend to have with the theory of evolution – how random changes, usually very small ones, can bring about such vast and apparently nonrandom results. The answer is that mutation is random but natural selection is not.

I think these apparently naive question threads of yours do wonders to further people's understanding of controversial scientific topics. And I choose to believe that is why you start them. Three stars and a flag for you.

What a pity the biggest problem most people have with evolution – that it contradicts religious dogma, or seems to – is not so easily disposed of.

reply to post by Noinden

I hope you won't mind if I pick a nit.

Man has had an increase in cancer rates from industrialization onward, so yes chemicals and radiation are a factor.

I would not necessarily come to this conclusion. The incidence of carcinogens and other dangerous substances in urban environments has been high since Roman times at least, and almost certainly earlier. Indeed, some mediaeval and early modern environments were probably more toxic than their equivalents today. People cooked in lead pots, ate mercury to cure their diseases and did all kinds of crazy things.

The low incidence of cancer in former times is more likely to do with the fact that cancer is mainly a disease of late maturity and old age, and until fairly recently most people did not live long enough to experience it.

This is not to dispute that epigenetic factors are important in the aetiology of cancers; but equally, one should not be too quick to explain away the apparent relative immunity of chimpanzees. Cancer is a scourge that most, if not all, many-celled animals and even plants suffer; perhaps the chimps have some special evolutionary secret.

Originally posted by Astyanax
reply to post by Noinden

 

I hope you won't mind if I pick a nit.

Man has had an increase in cancer rates from industrialization onward, so yes chemicals and radiation are a factor.

I would not necessarily come to this conclusion. The incidence of carcinogens and other dangerous substances in urban environments has been high since Roman times at least, and almost certainly earlier. Indeed, some mediaeval and early modern environments were probably more toxic than their equivalents today. People cooked in lead pots, ate mercury to cure their diseases and did all kinds of crazy things.

The low incidence of cancer in former times is more likely to do with the fact that cancer is mainly a disease of late maturity and old age, and until fairly recently most people did not live long enough to experience it.

This is not to dispute that epigenetic factors are important in the aetiology of cancers; but equally, one should not be too quick to explain away the apparent relative immunity of chimpanzees. Cancer is a scourge that most, if not all, many-celled animals and even plants suffer; perhaps the chimps have some special evolutionary secret.

Just quoting the researchers. My own back ground is in manufacture of Pharmaceuticals (PhD in synthetic chem plus a decade in industry), and Bioinformatics (mostly genomics, Masters plus some more work) plus Hazard assessment and Management.

Oh and elemental mercury is far less dangerous than the vapor. Now organic compounds of Mercury? There is a great way to go mad

The English language cannot possibly originate from the proto-Germanic language because we observe lack of 10s of thousands of transitional languages between the English language and the proto-Germanic language, right?

Originally posted by Astyanax

Well done, jiggerj. These two questions of yours go right to the heart of the second most important problem people tend to have with the theory of evolution – how random changes, usually very small ones, can bring about such vast and apparently nonrandom results. The answer is that mutation is random but natural selection is not.

I think these apparently naive question threads of yours do wonders to further people's understanding of controversial scientific topics. And I choose to believe that is why you start them.

Well, my first hope is for these questions to generate conversations that everyone can enjoy and glean bits of knowledge from them. However, though I could work out the answers in my own mind, these questions are genuine. They are not geared to disregard religious beliefs.

For me, knowledge is like a hot cup of coffee. A careful sip here and there is delicious, but gulping the whole cup tends to burn while going down.

reply to post by jiggerj

Huh? You make it sound like each moth CHOSE the safest environment. Is that possible?

Did you miss the part where I explained that the magpie found the white and brown moths easier in the forest?
Did you miss the part where I explained that the magpie found the black and brown moths easier in the glacier?
Did you miss the part where I explained that the magpie found the white and black moths easier in the muddy pond?

This means that the magpie was able to eat the white and brown moths in the forest easily, but the black moths were left (mostly) alone, and thus able to reproduce consistently with other black moths. Likewise with the brown moths at the pond, and the white moths at the glacier.

The individuals didn't choose the 'safe' environment, they just wandered around and went where ever they went. When the magpie showed up the individuals that were in the 'safe' environment survived better than the individuals that were in the non-safe environment. No proactive choice is involved just chance.

Even after the magpie shows up, some 'wrong' colored moths will wander to the other micro environments, and they will be easily picked off by the magpie. Those that for some reason have a gene that keeps them on their 'home' turf will tend to survive and pass that gene on to their offspring. So over just a few generations, natural selection will weed out that part of each sub-population that wants to continue to wander around and reward those who stay put.

That is what is called 'natural selection'.

reply to post by jiggerj

Is random mutation an acceptable theory within evolution? Or, sudden metamorphosis?

Absolutely. Random mutation supplied the 'gene pool' with a multitude of traits. Each generation is just a little bit different from the previous generation.

Usually those little differences are completely unimportant, like the color change in the moth population before the magpie showed up.

Every once in a while a mutation happens that has an immediate impact, either good or bad, or sometimes the mutation doesn't do anything for a long time, but then becomes very important when the environment changes in someway, like the color change in the moth population after the magpie showed up.

Random Mutation provides the 'tools'. Natural Selection filters those tools for usefullness. That is the fundamental engine of evolution. There are other mechanisms involved, but these are the basis for everything.

reply to post by jiggerj

These words by Richard Dawkins may help explain how species evolve into other species.

We have a common ancestor with chimps who lived 6 million years ago. If you imagine holding the hand of your mother, who holds the hand of her mother, who holds the hand of her mother, and you go on and on to the common ancestor, the line would stretch a few hundred miles. And in its other hand the grand ancestor holds her daughter’s hand who holds her daughter’s hand, and you go forward to modern chimps. As you go back, every one of those mother-daughter relationships would include members of the same species. Source

Species don't turn into other species overnight.

Maybe slightly off topic, sorry if it is OP, but while we are talking in layman's terms, could someone explain to me what the Cambrian explosion is? My current understanding is that millions of species appeared 'overnight'.

Originally posted by DaesDaemar
Maybe slightly off topic, sorry if it is OP, but while we are talking in layman's terms, could someone explain to me what the Cambrian explosion is? My current understanding is that millions of species appeared 'overnight'.

A period around 580 - 500 million years ago when numerous new species appeared as witnessed by the fossil record. There are many hypotheses to the causes of this rapid diversification of life in a relatively short period.

reply to post by Noinden


So basically, the chimps get less cancer because their genome is more stable due to living in a rather static environment for the last thousands of generations. Where as humans moving from one type of environment to the other constantly changing locals etc lead to higher degrees of stress on our genome making it more prone to developing cancer?

Interesting.

Originally posted by BASSPLYR
reply to post by Noinden

 

So basically, the chimps get less cancer because their genome is more stable due to living in a rather static environment for the last thousands of generations. Where as humans moving from one type of environment to the other constantly changing locals etc lead to higher degrees of stress on our genome making it more prone to developing cancer?

Interesting.

I wouldn't say so. I think the main reasons cancer is so high frequent in humans are that we are more exposed to carcinogens, and thanks to modern medicine, live unnaturally long, which makes it possible for more mutations to accumulate.