Evolving the Musculoskeletal System

For the most part it was random mutation and natural selection. Those whose genes best allowed them to compete survived and passed those genes on to the next generation, with slight modifications due to mutation, of course.--Percy

Keeping in mind that the topic is how the musculoskeletal system evolved, it sounds like you're asking for evidence that random mutation and natural selection were responsible. It's really just an extremely common rational inference. Given that matter and energy behaved the same in the past as they do today (in other words, given that the natural laws of the universe haven't changed measurably over time), random mutation and natural selection would have been operating in the past just as they are today.The same inference is used in all science. In geology the same erosive forces operating today to wear down mountain ranges are thought to have worn down ancient mountain ranges in the past. In astronomy the same forces of gravity that keep the planets in orbit around the sun today are thought to have kept them in orbit in the past. In physics the forces responsible for particle physics today are thought to have been responsible for it in the past.Across all the sciences the way we figure out what happened in the past is to study how our universe works today and project the forces and processes we find back in time. When we discover evidence of new forces and processes then we'll include those, too.--Percy

It is estimated that 99% of all species that have ever lived are extinct. That's a lot of "false starts," though that's the wrong term. It would be like calling the Egyptians, Greeks and Romans false starts on the road to modern civilization.Your question can be answered at the individual level, too. Some significant number of fertilized eggs are spontaneously aborted because of deleterious mutations. Some are aborted before coming to term for the same reason. Some number of offspring do not survive to adulthood due to deleterious mutations. And some adults compete poorly with their peers and so leave few or no descendants, making it less likely their genes will survive into future generations. Your belief that the processes of random mutation and natural selection are insufficient to produce the diversity of features observed in modern species is driving you to repeatedly ask the same exact question in thread after thread. I don't know if anyone has ever done what you ask regarding skeletal joints, but it's certainly been done for the eye. I'm sure you've seen descriptions of eye evolution before, but for reference here's a link to the Wikipedia article: Evolution of the eye. What seems different to you about the accumulation of small changes over time in skeletal joints as opposed to the eye?--PercyEdited by Percy, : Typo.

Uh, inferences are made from evidence. That's how all science works. Inferences are not proof, and science doesn't attempt to prove anything. If science could prove things then its theories wouldn't be tentative, they'd be proofs.The obvious inference is that the processes we see operating in the here and now, whether in space or on earth or at the particle level, are the same processes that operated in the past. All the evidence we have supports this inference.So if you have evidence that infers something else, just tell us what it is.You seem to be drifting off topic with your other comments about "minor variations within a kind" and transitional pre-humans. You might want to raise those questions in threads where they'd be on topic.Evolution proceeds at a snail's pace with the accumulation of tiny changes over many generations. Each tiny change that passed through the filter of natural selection provided some advantage in the environment at that time. It feels like what you would find helpful would be if someone did for, say, the evolution of the knee joint what the Wikipedia article on the Evolution of the eye does for the evolution of the eye. Do I have that right?--Percy

For some reason you and ICDESIGN both concluded that inferences are something made up. You two seem to be two peas in pod so far as your misunderstandings of science and even simple English. Inferences are not made up. They're drawn from evidence gained via our senses. For example, you come home to find a broken lock and infer that someone has broken in. Without the evidence of the broken lock you would not have made this inference.The inference that the same processes operating today were the same ones operating in the past is because the evidence we find is precisely what we would expect if that were so. For example, if it were true that radiometric decay was much faster in the past then we would expect to find evidence of that. But we don't. All the evidence we have, both from our own planet and from our observations of stars (including the sun) and galaxies and nebula indicates that the same processes have been in play unchanged since the beginning of time. Yes, RM and NS are occurring all the time. Almost every single reproductive event produces mutations. Everything that produces progeny has passed through the filter of natural selection.--Percy

It may be an obvious inference, but it is still an inference. This is a fine example of inference, too. Now it's becoming unclear what you're asking for. Are you asking how random mutation and natural selection *might* have produced something like an eye or a joint, or you asking how they actually *did*. If the former, then that's what we're trying to do. If the latter then that's not possible. DNA doesn't leave evidence behind.--Percy

All science works through inference.--PercyEdited by Percy, : Correction.

You agree even with the errors?When evolution talks about random mutation and natural selection, it is not talking about the selection of mutations acquired during an organism's lifetime. It is talking about how mutations passed on to offspring affect their survival chances.So Bolder-dash's example of a smoker experiencing mutations that kill them is an incorrect example of how evolution works. The vast majority of mutations acquired by offspring occur in the production of gamete cells by their parents (sperm and egg for animals) or in the union of gamete cells (coming together of sperm and egg for animals).In other words, it isn't the mutations acquired by an organism during it's lifetime that are important to evolution. It's the mutations produced as part of the reproductive process that are acquired by offspring that are important.If I could make a point again that has often been made before, you don't have to accept evolution to understand it. But you do have to understand it before you can make criticisms that make sense. Otherwise you might end up endorsing a wrong-headed post from Bolder-dash.--Percy

Hi ICDESIGN,I know you don't accept the answers you've been provided, but before you can legitimately repeat your question you have to explain why you reject those answers. We honestly believe we're giving you the correct answers, and until you help us understand why those answers are wrong we'll continue to believe that they're the correct answers.Evolution is a slow process of gradually accumulating change. Whatever mutations get selected to pass on to the next generation must be due to their conferring a greater survival advantage than mutations that were not selected. Concerning skeletal joints, a couple of adjacent bones (perhaps for defense) of an organism must have been more advantageous when additional structures like proto-cartilege or proto-ligaments or proto-lubricant appeared between them through random mutation, and they would have been selected for. Anything that helped the joint confer a survival advantage would have been selected for.In the past you've rejected explanations like this with expressions of incredulity. We clearly understand that you believe evolutionary processes to be woefully insufficient to produce things like skeletal joints, but to convince others of this you need to move beyond expressions of incredulity to precisely explain what makes it so wildly impossible.--Percy

Evolution proceeds in tiny, tiny steps. Most mutations cause no change or very little change, too tiny a change to be noticeable in creatures like mammals and birds and reptiles. In order to see the tiny effects of mutations you have to study tiny creatures like bacteria, so tiny that tiny effects are apparent.It is inevitable that this process of continuous tiny change must happen. For example, your average human has about 100 random mutations. There's nothing that can stop this. Almost every sexual offspring is an imperfect combination of its parents genes. Inevitably some of these mutations must occur in genes that affect joints, and some of them will cause tiny, tiny changes in the lubricant or the cartilage or the ligaments. But these tiny, tiny changes are like minuscule needles in immense haystacks. There's no way to know which individuals receive mutations that affect joint lubrication by some tiny, tiny percentage without conducting expensive testing on very large populations. The mutations that get studied are those whose effect is so significant that it is obvious who the affected individuals are, such as with Down syndrome or cystic fibrosis. Most people posting replies to you can back up what they say, but you need to be specific about what things you'd like additional support for. We're telling you many things that we think are true, and if you can tell us which of those things you doubt then we can provide the supporting evidence.--Percy

Just a quick note. Did you know that when referencing an old message in the same thread that you can say [msg=71]? When you do that then you get a link to Message 71. If you put a minus sign in front of the number then it leaves out the message's subtitle, if it had one.So anyway, I've taken another look at Message 71 and I can't see where you precisely explained what makes random mutation and natural selection wildly impossible as the processes largely responsible for "the over 1200 components" of the musculoskeletal system.Evolution doesn't produce sudden new structures. Evolution is a slow process of gradually accumulating change. Whatever mutations get selected to be passed on to the next generation must be due to their conferring a greater survival advantage than mutations that were not selected. What is it about mutations causing the area between a couple of adjacent bones to take on gradually more favorable characteristics through generations of natural selection that seems impossible to you?--Percy

Evolution doesn't produce half-formed organisms. With evolution, all successful organisms are sufficiently well adapted to their environment to reproduce. If they were half-formed they couldn't reproduce. Jar picked up a long time ago that you and Bolder-dash think evolution produces half-formed creatures, which is why he keeps asking you what happens to half-formed creatures. The answer is that they die and leave no offspring. Their genes die with them. Natural selection has passed them by and that's the end of the line. The source of your problem is your misunderstanding of how evolution works. You are quite correct that evolution couldn't possibly work the way you think it does. We can't explain how your misconception of evolution works because we agree with you that it's quite unworkable. Each tiny little change had to be sufficiently functional in its existing environment to enable the organism to survive to reproduce, otherwise the tiny little change would have died with the organism. For instance, you might ask what good is an underdeveloped hip joint that allows our legs to splay out a bit to the sides, making it impossible for us to run fast. But chimps have that kind of hip joint and they get along just fine.All the variety of systems that make up a living organism are all evolving simultaneously in tiny, tiny steps from one generation to the next. Mutations cannot be prevented and so this incremental change over time is inevitable genetically, and combined with environmental demands that changes the requirements of adaptation, morphological changes are also inevitable.--Percy

Barring genetic mistakes, all organisms are born with everything they need to grow into "fully formed" organisms according to their species, but what constitutes "fully formed" is different for every species. Evolution is just one species evolving into another over and over again. The changes these species experience are driven by changing environments, and each species is "fully formed," that is, adapted, to its environment. The fossils we find in the ground are like snapshots taken at random times, and all those fossils were "fully formed," well adapted, to their environments.The first "organism" was probably just a collection of chemicals held within some kind of membrane, and that "organism" was "fully formed." "Organisms" that experienced mutations that enabled them to create more copies of themselves would come to dominate. In any population of these "organisms" those best at reproducing would outcompete those less good at it, and so the populations would tend to consist of the most successful organisms. As the environment changed those "organisms" best able to cope would outcompete the rest, and their offspring would come to dominate the populations. Change over time with increasingly good adaptation to the current environment is what happens. And of course at some point the some population of these "organisms" passes through some threshold of complexity where we would feel comfortable calling it life.Once we have the first simple life then true evolution takes over, but at all points in time the organisms are evolving in tiny increments and are always well adapted to their environment. There are never any half-formed organisms. Each generation of organisms is just very slightly different from the proceeding one. This is absolutely true, because individuals don't evolve. Change happens during the imperfect copying of reproduction. If you're using people as an example, I can't imagine any selection pressure that would select for something that might eventually become a new skeletal body part, but there is a rather good example from another species, the panda. The panda's thumb is not actually a thumb at all, it's an extension to the wrist bone. The panda's actual thumb is just another digit lined up with its other digits. The fossil record and genetic analysis tells us that the giant panda and the red panda are distantly related creatures that evolved the thumb feature independently. Fossils tell us that the "thumb" evolved while the panda was still carnivorous and so was used for a purpose other than stripping bamboo, perhaps for climbing or grasping prey. Here's an article with some interesting details about it: The Other Panda’s ThumbThe important point to take from this is that evolving a new feature takes many, many generations, and that at each point along the way the change must provide some advantage, otherwise it won't be selected and will be lost. The advantage the feature provides may also change over time. A little stretch of cartilage that was originally selected because it provided stiffness for swimming may later find that variants that are bigger and thicker become advantageous when a predator moves into the environment. The cartilage did not originally evolve to provide protection, but later it does. That is the way evolution works, by tweaking what is already there to provide some advantage. With complex creatures new body parts are not going to evolve because they would provide no advantage. But with the multicellular blobs that began to appear six or seven hundred million years ago the advantages of any specialized body parts at all would be immense. Any little hard parts or light sensitive parts or communication parts (nerves) that a mutation might provide would likely be strongly selected for. In relatively huge and complex creatures like ourselves and all vertebrae that consist of billions and billions of cells and many complex interacting systems, it is not that likely for a single mutation or short sequence of mutations to cause a new feature. The most that can be reasonably expected is something like what happened in Tibet with the mutational change responsible for improved adaptation to altitude.In order to get a new feature in a short period of time with just one or a few mutations you need a relatively simple organism, like bacteria. Bacteria are sufficiently small and simple that new features can evolve from small genetic changes, such as the nylon eating capability.--Percy

Making inferences from evidence is what science does. I can tell by the references to "double talk" and "David Copperfield" that you don't accept what I told you, but you provide no indication why. Can you be a bit more specific? What I described was just a couple basic evolutionary principles, and if you can explain what it is that makes them difficult for you to accept then I could respond to that. Offspring are not identical to their parents because the genetic copying that takes place during reproduction is imperfect. Every offspring has its own unique set of mutations. Mammalian genomes usually have billions of base pairs, and a common rough estimate of the average number of mutations in offspring is around a hundred. That's an error rate of one in ten million. These errors represent a tiny, tiny change. To the extent that the difference provides a survival advantage it will be selected for because the organism will be more likely to produce offspring or will produce more offspring than others of its species, and the changes will become more and more represented in the population in subsequent generations. To the extent that the difference confers a survival disadvantage it will be selected against because the organism will be less likely to produce offspring or will produce less offspring than others of its species, and those changes will become less and less well represented in the population in subsequent generations. By "development" you mean evolutionary change? If so, then new bones are unlikely to show up in complex creatures like ourselves, though there are ways it can happen. I think someone showed a picture of a boy with six fingers, so duplication is one way to produce new bones in a wholesale fashion.But if you're asking how a bone first begins from scratch then possibilities were described earlier in this thread. Start at Message 173 and read back. But again, it seems unlikely to happen in complex creatures. It is much more likely in the earliest multi-celled life as body plans were evolving. Our evolutionary descendants are going to be pretty much stuck with the current body plan of 2 arms and 2 legs and all that. Selection is just a natural and inevitable process. All reproduction is imperfect. If the imperfections confer a disadvantage, such as an arctic hare that loses the ability to turn white in winter, then the creature will be less likely to survive to produce offspring and the trait will be rare and probably go extinct. If the imperfections confer an advantage, such as a hawk with more closely spaced retinal cells for higher resolution, then the creature will be more likely to survive to produce offspring and the trait will become more common in the hawk population.Notice there's nothing directing the process. Advantageous traits give a creature a competitive advantage, and so through the generations you'll gradually see more and more creatures with that trait. The opposite is true for disadvantageous traits - they'll tend to disappear from a population.--Percy

I can't tell where you're going with this, so ICDESIGN may be unsure, too. Maybe some clarification? Do you think the problem is that ICDESIGN thinks evolution teaches that one kind can give birth to a different kind? Or that he doesn't understand that all reproduction involves change? Or that evolutionary change is almost always gradual?--Percy