Intelligent Design

[aleCcowaN]

Nature is the living evidence of evolution: massively and redundantly it points to the only, way self-evident truth.

Yet, we're discussing about "intelligent design", where the intelligence is all invested in designing a cultural product that ignorant masses can consume ... pretty much like Donald Trump's. They wanted to build a wall to keep the apes apart from the real sons of goD ... and make the apes to pay for it, mainly by passing collection plates on Sunday .

 

[zooterkin]

One thing has always concerned me...

Let's say a 4-legged creature has a simple mutation giving an extra pair of legs. Let's further say that an extra pair of legs gives a very slight survival advantage.

But who does this creature mate with? He's a 6-legged island in an ocean of 4-legged creatures. It seems like his advantage would be diluted away in subsequent generations, in a sort of regression to the mean.

And yet it does happen. Maybe it's only the very rare occurrence of a new population being isolated. Or a gene so dominant that only one parent needs to possess the 6-legged gene?

Not debating it does happen that way, it's just always puzzled me a bit.

When you look in detail at how DNA actually works, you find that the difference between species is a lot fuzzier than you might think. For example, humans have 23 pairs of chromosomes, other great apes have 24; at some point, presumably one human ancestor had a child with two fused chromosomes, but that child was able to mate successfully with other human ancestors that still had 24. I'm not going to pretend that I've got it straight in my mind exactly how that works out; I might ask Adam Rutherford or Kat Arney the next time I see either of them speak.

ETA: Another possibility is something about the environment that triggers the same mutation in more than one individual at the same time, which would increase its chances of spreading.

 

[Delvo]

humans have 23 pairs of chromosomes, other great apes have 24; at some point, presumably one human ancestor had a child with two fused chromosomes, but that child was able to mate successfully with other human ancestors that still had 24. I'm not going to pretend that I've got it straight in my mind exactly how that works out

From another thread...

Chromosomes have been known to break into smaller chromosomes or fuse into bigger ones, and those changes have been known to stick in separate lineages, which is why it's possible for different mammal species to have different chromosome counts after having descended from the original mammal common ancestor. A species in which one of those transitions in chromosome count is still underway will consist of some individuals with different chromosome counts.

For example, domesticated horses have 64 chromosomes apiece (32 pairs), and their wild counterpart, Przewalski horses, have 66 (33 pairs), and they're perfectly interfertile. Their offspring have 65 chromosomes: the 31 pairs that both "species" have in common, and single chromosomes apiece from each of the other leftover pairs that only one parent had (1 from the domesticated parent, 2 from the Przewalski parent). That leftover chromosome in the domesticated horse corresponds with both of the leftover chromosomes in the Przewalski horse, containing the equivalent genes in the same order, with the two Przewalski chromosomes in a single line end-to-end. During mitosis in the offspring's cells, the two lone Przewalski chromosomes even physically line up end-to-end next to the single longer chromosome from the domesticated parent.

Nobody knows whether this situation resulted from the long chromosome breaking apart in Przewalski ancestors or the two shorter ones fusing in the domesticated population's ancestors. But, whichever population the change happened in, it must have experienced a stage in which there were individuals with three different basic chromosome layouts:

1. 64, producing gametes with 32
2. 66, producing gametes with 33
3. 65, producing gametes of both kinds

And, taking both together as a single population living today, that is still the current situation.

Similarly, humans have a single chromosome pair corresponding to two chromosomes pairs in other living great apes. We can tell that it got that way by fusion of two in our ancestors who had had 24 pairs til then, not only because the 24-pair arrangement is common to other living great apes, but also because a degraded form of the caps that normally go on the ends of chromosomes is still stuck in the middle of it. So, at some point in the last few million years, our ancestral population consisted of a mix of individuals with 46, 47, or 48 chromosomes, producing either 23-chromosome gametes, 24-chromosome gametes, or a mix of 23-chromosome and 24-chromosome gametes.

 

[Oystein]

When you look in detail at how DNA actually works, you find that the difference between species is a lot fuzzier than you might think. For example, humans have 23 pairs of chromosomes, other great apes have 24; at some point, presumably one human ancestor had a child with two fused chromosomes, but that child was able to mate successfully with other human ancestors that still had 24. I'm not going to pretend that I've got it straight in my mind exactly how that works out; I might ask Adam Rutherford or Kat Arney the next time I see either of them speak.

ETA: Another possibility is something about the environment that triggers the same mutation in more than one individual at the same time, which would increase its chances of spreading.

Is that ETA something real that you learned from a studied source, or just an idea? I ask because it goes against the grain of all that I have learnt: that mutations are not triggered (caused) by the environment, they rather happen randomly, and rarely. So rarely it is unlikely to an immense degree that same mutations arise twice in a population AND its bearers mate. Instead, mutations survive and spread when positively selected for. Or, if neutral, through chance and gene drift. There is probably no advantage nor any disadvantage to 23 vs. 24 chromosomes as such.

Sent from mobile phone through Tapatalk

 

[aleCcowaN]

When you look in detail at how DNA actually works, you find that the difference between species is a lot fuzzier than you might think. For example, humans have 23 pairs of chromosomes, other great apes have 24; at some point, presumably one human ancestor had a child with two fused chromosomes, but that child was able to mate successfully with other human ancestors that still had 24. I'm not going to pretend that I've got it straight in my mind exactly how that works out; I might ask Adam Rutherford or Kat Arney the next time I see either of them speak.

ETA: Another possibility is something about the environment that triggers the same mutation in more than one individual at the same time, which would increase its chances of spreading.

Human chromosome 2 has the remnants of a second centromere. The whole chromosome accounts for 8% of all ADN info. Maybe it was this weakening centromere what trigger a lot of instances of "gene lumping", so to speak, with multiple cases of compatibility enough to allow viable offspring.

Whatever the reason it's not so far in our evolutive past, as Neanderthals and Denisovans had 24 pairs and not 23 like we have.

What teaches us that sometimes you become daring and intelligent just by un-growing a pair (if caused by a designer, he's a buffoon and a prankster)

 

[zooterkin]

Is that ETA something real that you learned from a studied source, or just an idea? I ask because it goes against the grain of all that I have learnt: that mutations are not triggered (caused) by the environment, they rather happen randomly, and rarely. So rarely it is unlikely to an immense degree that same mutations arise twice in a population AND its bearers mate. Instead, mutations survive and spread when positively selected for. Or, if neutral, through chance and gene drift. There is probably no advantage nor any disadvantage to 23 vs. 24 chromosomes as such.

To be clear, I'm talking about the environment at the molecular level, which might affect the way DNA gets replicated, not acquired characteristics à la Lamarckism. Yes, mostly speculation on my part, but those random changes may be triggered by something (radiation, abnormal levels of a chemical), and it's not impossible that a particular genome is susceptible to a particular environmental factor at a a particular time, such that the same mutation happens more than once.

 

[Fast Eddie B]

I don't believe that there has been such a case. Different fixed numbers of limbs have arisen from different backgrounds in different cases, but apparently not by changing from earlier fixed numbers.

Interestingly, I was thinking about posting an example this morning, albeit of digits and not limbs: polydactyl cats.

https://en.m.wikipedia.org/wiki/Polydactyl_cat

It's not hard to imagine that if some sort of catastrophe (no pun intended!) caused a severe bottleneck in the cat lineage, or if polydactyl cats were somehow isolated as a group, some day all cats might have extra toes.

 

[Tassman]

My brother in law insists that the eye proves intelligent design and cannot conceive how it might have evolved from "why we would need to see". Make of that what you will.

That's just nonsense and based upon the so-called irreducible complexity argument of the likes of Behe. Its an Argument from Ignorance. First of all, the evolution of the eye is understood. It was a step-by-step, cumulative development developing in incremental stages. .


.

 

[SusanB-M1]

ETA: Another possibility is something about the environment that triggers the same mutation in more than one individual at the same time, which would increase its chances of spreading.

I thought it was that if a mutation happened to turn out to be a useful adaptation when conditions changed then that was a lucky chance?

 

[Thor 2]

All this talk of DNA puts me in mind of discussions I had with my born again, evolution denying, nephew.

My suggestion was that the almost identical DNA we share with our close cousins in the animal kingdom is very strong evidence for evolution. If we were made in the image of God, I suggested, would we not have distinctly different building blocks?

He then suggested we were made in a similar way because God had perfected this method and would stick with it. So I suggested if we are made in God's image then we have the same DNA?

Changing tack my nephew then suggested we were not made in God's physical image but in his mental image which I countered with - "But that's were we fell down in the Garden of Eden wasn't it? We were not up to the mark and made the wrong decision."

Some foot shuffling ensued.

 

[Peregrinus]

Thousands of gods over thousands of years & not one shred of credible evidence.

Next topic?

 

[Aridas]

Just cut it out. You're in danger of annoying the hell out of people who want a discussion of the subject "Intelligent Design", whilst doing nothing whatever to address the question I posed.

Which one? I'm pretty sure that all of the points of uncertainty that you've made known have been answered well past the point of reasonability.

I have literally zero interest in your answer now anyway, (it was never more than an aside), and this stupid nonsense is a classic ISF multi-page "I'm right and you're wrong" ego-fest. You've managed to take a simple "sorry, I don't understand the point you are trying to make" and turn it into 3 days of tedious bollocks. Congratulations.

Asking for clarification was one thing. Ignoring what was said to make up unindicated nonsense was something totally different. Trying to criticize me for you not paying attention is no less unimpressive now than it was the first time, though. Whatever, though, moving on.

 

[Aridas]

One thing has always concerned me...

Let's say a 4-legged creature has a simple mutation giving an extra pair of legs. Let's further say that an extra pair of legs gives a very slight survival advantage.

But who does this creature mate with? He's a 6-legged island in an ocean of 4-legged creatures. It seems like his advantage would be diluted away in subsequent generations, in a sort of regression to the mean.

And yet it does happen. Maybe it's only the very rare occurrence of a new population being isolated. Or a gene so dominant that only one parent needs to possess the 6-legged gene?

Not debating it does happen that way, it's just always puzzled me a bit.

Your scenario reminds me a fair bit of 6-fingered hands in humans. That gene's dominant, too. Of incidental value to this thread, a creationist relative once tried to argue against the trustworthiness of science by referencing a case where the child of a 6-fingered person was born with only five fingers, even though the gene's supposedly dominant, as part of a litany of things that really just showed how ignorant he was on the various topics. With that said, though, it's worth remembering again that evolution is not quite "survival of the fittest." It's more about what ends up makes the most fertile offspring, which is just usually related to which is the fittest.

 

[Aridas]

When you look in detail at how DNA actually works, you find that the difference between species is a lot fuzzier than you might think. For example, humans have 23 pairs of chromosomes, other great apes have 24; at some point, presumably one human ancestor had a child with two fused chromosomes, but that child was able to mate successfully with other human ancestors that still had 24. I'm not going to pretend that I've got it straight in my mind exactly how that works out; I might ask Adam Rutherford or Kat Arney the next time I see either of them speak.

ETA: Another possibility is something about the environment that triggers the same mutation in more than one individual at the same time, which would increase its chances of spreading.

Looks like Delvo beat me to it, but a shorter and more succinct way to put it is that the number of genes is not as relevant as the content of the genes. If you cut a painting in half vertically, then cut only one of the sides into two or more pieces horizontally, you can still fit the pieces together and it will still effectively be the same painting.

Is that ETA something real that you learned from a studied source, or just an idea? I ask because it goes against the grain of all that I have learnt: that mutations are not triggered (caused) by the environment, they rather happen randomly, and rarely.

If by rarely, you mean that there's not much change overall, then yes, though there are factors that can increase the rate of mutation even within an individual (some forms of radiation come to mind as an easy example). However, given the size of DNA, a notable number of mutations occurs in every offspring, regardless, and, of course, DNA doesn't need to match perfectly to breed successfully.

So rarely it is unlikely to an immense degree that same mutations arise twice in a population AND its bearers mate.

The exact same, perhaps, much as some kinds of mutations are more likely than others in some situations. Epigenetics is an important thing to take in account when it comes to that, though. A bit separately from that, though, there are frequently multiple ways to produce similar functions and, as was just noted, DNA doesn't need to match perfectly to breed successfully.

 

[Aridas]

That's just nonsense and based upon the so-called irreducible complexity argument of the likes of Behe. Its an Argument from Ignorance. First of all, the evolution of the eye is understood. It was a step-by-step, cumulative development developing in incremental stages. .


.

It's probably tracable back further, to at least Darwin's The Origin of Species. Spreading around a quote mined from there about the eye seems to have remained fairly popular for a long time. What worse is that the very next sentence answers the quote mine, which means that it pretty much had to be a completely and intentionally dishonest use of the quote, initially.

 

[Skeptic Ginger]

One thing has always concerned me...

Let's say a 4-legged creature has a simple mutation giving an extra pair of legs. Let's further say that an extra pair of legs gives a very slight survival advantage.

But who does this creature mate with? He's a 6-legged island in an ocean of 4-legged creatures. It seems like his advantage would be diluted away in subsequent generations, in a sort of regression to the mean.

And yet it does happen. Maybe it's only the very rare occurrence of a new population being isolated. Or a gene so dominant that only one parent needs to possess the 6-legged gene?

Not debating it does happen that way, it's just always puzzled me a bit.

Previous answers notwithstanding, here's a simpler scenario:

Assuming your hypothesis, 6 legs having an advantage, the creature mates with 4 legged creatures. That is the nature of DNA and evolution, a change or two doesn't make a new species.

Some offspring then have 4 legs and some 6 legs. If the advantage is significant, eventually the 6 legged animals will dominate. And if that continues long enough, 6 legged animals will replace all the 4 legged animals.

The fact this hasn't happened with mammals is evidence 4 legs is ideal. Two legs frees up the other two and we get bipedal animals with arms.

In insects, 6 legs can evolve into 4 legs and 2 antenna, or two legs, two wings and two antenna.

 

[zooterkin]

The fact this hasn't happened with mammals is evidence 4 legs is ideal.

No, it isn't.

For one thing, growing an extra pair of legs for a mammal is a much more complicated mutation that it is for an insect or other arthropod, where it is essentially, I believe, just a simple repetition of a section of DNA.

 

[Aridas]

The fact this hasn't happened with mammals is evidence 4 legs is ideal. Two legs frees up the other two and we get bipedal animals with arms.

Or that the mutation for that kind of a change either isn't likely at all in the first place or is such that the fetus unlikely to survive. As for bipedal animals, 6 legs doesn't even enter the picture?

In insects, 6 legs can evolve into 4 legs and 2 antenna, or two legs, two wings and two antenna.

Hmm? Do you have any examples? As a general rule, all insects have 6 legs, at last check, which are separate from any wings, antenna, and so on. Arthropods in general have notably more diversity, but... that would seem to be a little different than what you just said.

 

[Skeptic Ginger]

No, it isn't.

For one thing, growing an extra pair of legs for a mammal is a much more complicated mutation that it is for an insect or other arthropod, where it is essentially, I believe, just a simple repetition of a section of DNA.

Leaving insects out of the discussion, you don't think a couple billion years of mammal evolution is enough to conclude if 6 legged mammals were going to evolve they would have?

As for the complexity of growing an extra pair of legs, it's not that much different from growing six fingers on both hands. The genetic control for how a finger develops is different from the genetic control of how many fingers develop. Therefore when a mutation occurs in numbers of fingers, you don't get extra fingers that are only bones with no skin or muscles.

A little more complex, sure, or we'd see more 6 legged bunnies that weren't failed twins. But a couple billion years? That was enough time for mammals to return to the sea.

 

[Skeptic Ginger]

Or that the mutation for that kind of a change either isn't likely at all in the first place or is such that the fetus unlikely to survive. As for bipedal animals, 6 legs doesn't even enter the picture?

Hmm? Do you have any examples? As a general rule, all insects have 6 legs, at last check, which are separate from any wings, antenna, and so on. Arthropods in general have notably more diversity, but... that would seem to be a little different than what you just said.

Sorry, I wasn't paying attention to details when posting concepts. My bad.

Insect appendages and comparative ontogenetics

Abstract
It is arguable that the evolutionary and ecological success of insects is due in large part to the versatility of their articulated appendages. Recent advances in our understanding of appendage development in Drosophila melanogaster, as well as functional and expression studies in other insect species have begun to frame the general themes of appendage development in the insects. Here, we review current studies that provide for a comparison of limb developmental mechanisms acting at five levels: (1) the specification of ventral appendage primordia; (2) specification of the limb axes; (3) regulation and interactions of genes expressed in specific domains of the proximal–distal axis, such as Distal-less; (4) the specification of appendage identity; and (5) genetic regulation of appendage allometry....

... Despite specializations into multiple appendage types, such as antennae, legs, and mouthparts, modern insect appendages are considered to be serially homologous structures that retain anatomical and developmental aspects of their common evolutionary origin (Boxshall, 2004; Snodgrass, 1935). An additional feature of limb evolution in insects is that limbs have been suppressed from the abdomen in a majority of insects.

I don't want to look up the sources, I've posted them in the past, but a lot of fetal development genes are interchangeable. So, for example, rabbit genes that code for eye development in the fetus have been inserted into fruit fly larvae with the eye development gene removed and normal insect eyes developed in the flies.