The Barbarian
Crabby Old White Guy
- Apr 3, 2003
- 29,047
- 12,959
- 78
- Country
- United States
- Gender
- Male
- Faith
- Catholic
- Marital Status
- Married
- Politics
- US-Libertarian
But if beneficial mutations are so rare how do they come in such a short time.
Lots of mutations. You and I have a dozen or so that didn't exist in either of our parents. And huge numbers of bacteria, with very short generation times, makes it easier to track.
Also as noted in Halls experiment the new function in lactose tolerance was associated with existing genetic info.
Yep. That's how evolution works. Everything new is merely a modification of something already there. That's what Darwin discovered.
That sort of makes more sense if it happened fast as the change does not have to mutate new genetic info which would require a trial and error process.
Every mutation is new information. Do you know how information is determined in populations? Could you tell me what you think happens?
If it was a case of Darwinian processes only then this should not happen fast.
I'd be interested in seeing your data for that. What do you have?
AS Darwin himself said it is a slow and gradual process.
It was indeed gradual. But it's the fastest known example of evolution of a new trait. Show us the numbers that say it can't happen in a few decades.
According to many that are exactly what is produced by Darwinian evolution. But that is not what I meant. I mean that what may be interpreted as a random mutation producing the changes may be some other mechanism.
It always comes down to evidence. What do you have?
If that’s the case then it seems strange that what began as a single-celled organism can evolve into something that certainly has increased genetic info that was not there, to begin with. You can only recombine and re-jig existing info so much.
Can you show us a population that is at its limit of variabilty and can change no more? If so, show us how you know.
Also, we have HGT especially with bacteria.
In this case, that didn't happen. Would you like to know how we know?
Yes, please.
Because the culture came from a single bacterium. Hence genetically identical at the start. You can assure this by serial dilution until the innoculation of a plate produces only a few discrete colonies. Each of them come from a single bacterium.
But didn’t humans already have that ability to utilize lactose as infants and then gradually lost that ability. So they can get it back again.
Right. The gene that normally expresses lactase is suppressed in humans. Some populations evolved a means of reversing that suppression. A lot of evolution is like that.
What I find hard to believe with these types of changes is that for random mutations to produce the right genetic changes to get that rare beneficial change in producing that spiral valve it has to also be able to produce non-functional mutational changes.
Almost certainly, it did. Can you guess why we don't see them around, today?
Yet any non-functional change to a sensitive feature like a valve for digestion could be lethal.
Nope. It's a way of increasing the surface area of the gut without lengthening it. So lots of possible mutations, none of which would be lethal. It's like the evolution of streamlining in rapidly-swimming organisms. Lots of convergence. Sharks have a similar structure.
It makes more sense that the Lizards development mechanism responded to the pressure the lizard was under and produce the right feature in one go without a trial and error of Darwinian processes.
Twenty years is a lot of lizard generations. So not one go.
I thought the evolution of new traits takes thousands if not millions of years.
It can happen in a single generation. Depends on the trait.
If it happens in a few decades, then why do scientists say that for example most of the main phylum came about over ½ a billion years ago
Phyla. The plural is "phyla."
and many have taken 10 million years to change from one to another to get today's creatures.
There have been hominins around for more than 10 million years. The world is a lot older than you seem to think.
If mutations are random and beneficial ones are very rare then they are not going to throw up anything of use for some time.
No, that's wrong. For example, Hall's bacteria quickly evolved a gene with somewhat better lac activity. But over time, it got better and better. A lot of evolution is like that. When we became bipedal, another set of arms would have been great. But there's apparently no way to evolve it by Darwinian means. It could be done your way, but apparently, that way doesn't actually exist.
Also, a trait is not going to happen in one go.
Like a second pair of arms. You see each stage would have to be at worst, neutral. And that's not possible for new arms to evolve.
Like the eye example that started as an eye patch. It took time for each stage to get to the complex eye.
Yep...
Not so fast -- researchers find that lasting evolutionary change takes about one million years
It determined that rapid changes in local populations often don't continue, stand the test of time or spread through a species.
Often they don't. But sometimes, they do. For example, blue eyes in humans.
New research shows that people with blue eyes have a single, common ancestor. Scientists have tracked down a genetic mutation which took place 6,000-10,000 years ago and is the cause of the eye color of all blue-eyed humans alive on the planet today.
Blue-eyed humans have a single, common ancestor
I emphasized the part you missed, in red.
Darwinian evolution works by modifying things that are already there.
Yes but that existing genetic info will only produce certainly limited results. For example, for an eye patch to evolve into a complex eye there needs to be more genetic info then what an eye patch contains.
Eye patches don't have "information." What happens is that if the sensitive patch is slightly depressed, it can give the organism information about the direction from which the light is coming. And that's quite useful. So a rather tiny mutation can quickly spread through a population, if it's as advantageous as that.
It has to come from outside from somewhere.
It's merely that a light-sensitive spot in a depression is favored by natural selection, since it increases the likelihood that the organism will live long enough to reproduce. It gives the organism more useful information, and that is favored by natural selection.
Natural selection is good at explaining the survival of the fittest but not the arrival of the fittest.
No, that's wrong. Natural selection determines what alleles will survive for the next round of reproduction, and thus determines what direction evolution will take. But only roughly. It will lead to streamlined tails that provide propulsion in large animals that move about in water, but precisely how that will happen is partially random mutation, and partly what is already there. This explains why whales have horizontal flukes and fish have vertical tail fins. Would you like to learn how this happened?
Barbarian asks:
Why would anyone suppose that other soil organisms would not produce resistance to penicillin? Penicillium was using it to kill off competitors. Of course, some of them would evolve resistance.
Then why do some use this as an example of evolution by saying that this is a new adaptation
Because we see it evolving in organisms that formerly did not have it. And there are different alleles in bacteria that confer resistance in different ways. Like the whale flukes and fish tails. Different paths to the same effect. Because it's random mutation and natural selection. If it was directed, we'd see one efficient way, and that's not what we observe.
because antibiotics have only been around since recent time for bacteria to evolve resistance to the antibiotics.
No. They've been in soil organisms for a long, long time. We just find them, and use them against new organisms that don't have any protection against them. Sometimes we chemically modify them to get around resistance.
Then why do these papers talk about antibiotic resistance happening thousands of years before Fleming discovered antibiotics.
Because they existed in microorganisms, as a means of defense against other microorganisms.
So if bacteria were able to resist antibiotics thousands of years ago chances are they have been able to do this all along.
If that was true, then penicillin would never have worked. As Flemming noted, natural selection tends to produce new modes of resistance.
But there should be way more dysfunctional outcomes than functional ones because harmful mutations are 1000's of times more likely.
So let's look at that. We have a maybe 2 dozen mutations each, that didn't exist in either parent. Let's say 10 to be conservative. Let's say a population of 10,000 individuals, and a generation time of 20 years. So in one generation, 100,000 mutations, or by your numbers, 100 useful ones.
In a thousand years, 5,000 useful mutations, and in a million years, five million of them. Seems like a lot. And those are conservative estimates.
From what I have read most living things are well defined and functional. Can you give some examples?
Humans have suboptimal lower backs, hips, knees, feet, and hands. And if you live long enough, you will almost certainly have trouble with one or more of them. It's because we are only partially adapted to bipedalism. Our bodies are not completely adapted to an upright posture. For much of my working life, I was an ergonomist and spent a lot of time working around the limitations of our bodies.
I thought I posted the link. Around at least 15 million years before scientists had attributed bipedal apes. The strange thing is that it is more about how this happened rather than when it happened. It seems that there was a change in the control gene that produces either a 4-legged body plan or a 2 legged one.
There was a whole suite of changes that happened pretty much in concert. Not because of some teleological principle, but because a single gene or a few of them retarded maturation.
We retain a lot of juvenile ape traits, among them relatively longer legs and a foramen magnum (where the spinal cord enters the skull) that is far forward under the skull, instead of back, as it is in adult apes.
Both of these are important adaptations to bipedalism.
So it may have been that a 2 legged infant aged was born and walking around with their siblings who were still unable to walk upright.
Today's apes can walk upright. It's just clumsy for them, as adults. While there were bipedal apes from a long time ago, none of them had the adaptations that make humans effectively bipedal, and able to move long distances quickly. Even the advanced Australopithecines retained traits that made them less effective than any species of Homo.
Yes but it is the ability of a random process to produce that second beneficial mutation. It is when one random mutation has to rely on a second or third on etc to make the beneficial change which is often the case.
Can't think of one. At worst, the mutation could be generally neutral. Bipedalism for example, shows a slow path toward our (still imperfect) condition. And it moved not in one direction, but several. Oreopithecus, for example, has ape-like feet, along with an upright stance, which would have required a very different sort of bipedal locomotion.
This is consistent with random mutation and natural selection, but not directed evolution.
Research shows this is very hard and probably impossible to do
Hall's bacteria show otherwise. The fossil record of whales also shows otherwise. Your assumption is not consistent with the evidence.
The waiting time problem in a model hominin population
So for a string of five, this means it is necessary to wait until almost 1,024 mutations have occurred within the same short stretch of a given DNA molecule.
That's pretty close to what Hall observed to happen in his bacteria. And it fits the numbers for human mutation in a small population.
The infinite monkey theorem states that a monkey hitting keys at random on a typewriter keyboard for an infinite amount of time will almost surely type a given text, such as the complete works of William Shakespeare. Evolutionary biologist Richard Dawkins employs the typing monkey concept in his book The Blind Watchmaker to demonstrate the ability of natural selection to produce biological complexity out of random mutations.
I haven't read that book; would you mind quoting Dawkins and give the page where he said that this was a good model for evolution? I don't agree with him on much, but I don't think he's stupid.
I have heard of Aquinas and sort of understand his contingency concept but can you explain this in layman's terms for me as I find it hard to fully understand.
A contingent event is one that is possible, but one which we cannot predict it. Aquinas writes that the essential nature of divine providence is that something will happen. So, he writes, such things can be such that they arise from necessity or from contingency. God does not have our limitations so that which is conceived by Him to happen by necessity happens by necessity, and that which is conceived by him to happen by contingency, happens by contingency.
I am meaning the actual process of evolving life from that first organism to complex ones like us. They say this evolution has no purpose, direction and end goal.
In the sense that gravity has no purpose, direction, and end goal. Nevertheless, it's essential for us to be here. If God made the universe so as to ultimately bring us about, that's good enough. He doesn't have to pull everything around to fit His intentions; He can just create it to do so.
It is just blind, pitiless and without any God or intelligence behind it.
That is a religious belief; science can't make such determinations.
Upvote
0