Why is evolution so controversial?

That's one of the reasons I've started using 'magic' in response, where magic would be defined as "anything not occurring according to natural laws" ...'magic water' sorts fossils and carves canyons deep underwater ... deposits gravels on top of silts ... flows in 'magic' paths not defined by geographical or tectonic features ...Nothin like a little mushroom eh?Edited by RAZD, : stars

Curiously genetics was unknown by either Darwin or Mendel, and Mendel had some results from his experiments that did not fit into his neat boxes -- new mutations.Science has advance in the intervening years, and we now have evidence of mutations occurring, mutations causing new variations in breeding populations, and no apparent barrier to evolution occurring. Another, slightly more complete version, is Now this is the process of how evolution occurs and it has been observed and documented, but this is not the Theory of Evolution ...Enjoy.

There are other animals that exhibit these abilities, and the difference is more a difference in degree of ability than a different kind\type of ability.The one characteristic that differentiates man from other species is the same characteristic that differentiates any other species from all other species -- reproductive isolation of the breeding population.But destruction of habitat is coming in a close second ... (and that isn't very intelligent imho)Enjoy

We also know that humans have undergone strong (runaway) sexual selection putting higher than average selection pressure on mating, and that this is still going on.Among other things, strong (runaway) sexual selection explains the apparent hairlessness, the neoteny and the large brain.See Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution for more information in this regard.Such runaway sexual selection in addition to normal survival selection is more than sufficient to cause a higher U value than would otherwise be expected.Enjoy

When you consider timing, Ardi is about when the genetics says the divergence event happened, thus it is very likely that she is close to that population splitting phenotype.But also remember that this is an artistic rendition, and that Ardi was fully capable of living in trees:Ardipithecus - Wikipedia

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... Two fossil species are described in the literature: A. ramidus, which lived about 4.4 million years ago[2] during the early Pliocene, and A. kadabba, dated to approximately 5.6 million years ago (late Miocene).[3] Behavioral analysis showed that Ardipithecus could be very similar to those of chimpanzees, indicating that the early human ancestors were very much like chimpanzees in behaviour.[4]

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The toe and pelvic structure of A. ramidus suggest to some researchers that the organism walked upright.[7]

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According to Scott Simpson, the Gona Project's physical anthropologist, the fossil evidence from the Middle Awash indicates that both A. kadabba and A. ramidus lived in "a mosaic of woodland and grasslands with lakes, swamps and springs nearby," but further research is needed to determine which habitat Ardipithecus at Gona preferred.[7]

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Some people put the split at 6 million years ago.Ardi is also how we know that our ancestors were pre-adapted to walking upright before the Savannah period, and thus was able to take advantage of the new habitat.Enjoy

New evidence on Neanderthal mixing

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New research on a 45,000-year-old Siberian thighbone has narrowed the window of time when humans and Neanderthals interbred to between 50,000 and 60,000 years ago, and has shown that modern humans reached northern Eurasia substantially earlier than some scientists thought.

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Prior research had given scientists evidence of two possible rates, one twice as fast as the other. Because of this large range, dates obtained from genetic studies have tended to be quite uncertain. By measuring the number of mutations missing in this individual and comparing with people now, Fu was able to obtain an accurate estimate of the rate that mutations accumulated over time. Her work came down definitively on the side of a slower mutation rate, corresponding to between one to two mutations per genome per year.

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Reich said the findings on mutation rate have sweeping implications, and provide a basis for reinterpreting key dates in human prehistory. Instead of humans and Neanderthals becoming distinct offshoots sometime between 270,000 and 380,000 years ago, for example, the slower rate would put that shift much further back in time, between 550,000 and 770,000 years ago. Similarly, the slower rate pushes back estimates for the date of the separation of African and non-African populations.

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Not really. What it shows is that the rate since 50,000 to 60,000 years ago has been slow, it does not say what it was before that time. Extrapolations are highly questionable and would need further evidence to support.

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The slow mutation rates indicate that the present-day subdivisions among human populations date back to almost 200,000 years ago, well before the period around 50,000 years ago when the archaeological record documents art and new styles of toolmaking, Reich said. The implication is that the spread of modern human behavior must have been cultural, at least in part. Based on the genetic dates, it cannot be the case of a single population that developed modern human behavior spread all around the world replacing the other humans who already lived there.

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OR the assumption of a constant slower mutation rate before 60,000 years ago is false. Mutation rates are not constant and the rates at which mutations are mixed\fixed in a breeding population is related to selection pressure.

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In examining the ancient Siberian’s ancestry, Fu found about 2.3 percent of his DNA came from Neanderthals. That is a bit higher than found in modern humans living outside Africa today a level that ranges from 1.7 to 2.1 percent but too small a difference to be statistically significant, Fu said. Her findings on the date of human-Neanderthal mixing dramatically narrowed the likely range to between 50,000 and 60,000 years ago, a much tighter window than the previous range of between 37,000 and 86,000 years ago.

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What 2.3 percent represents is an overall average of a variable rate for the last 45,000 years, and if later rates are closer to 1.7 to 2.1 then that would indicate that the rate of mutation 45,000 years ago was higher.Curiously this is also about the time for that bottleneck event ... when high survival pressure would have increased both mutation selection and made hybridization more likely.Enjoy.

Not so much "monkey-like" as becoming more adapted for tree\jungle habitat, and that is consistent with a division of apes into savannah apes and forest apes as they diverged.This also means re-emergence of knuckle-walking on the ground and shortened rear legs as they become more adapted to branch swinging (like gibbons and orangs).Knuckle-walking - Wikipedia

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There are differences between knuckle-walking in chimpanzees and gorillas: juvenile chimpanzees engage in less knuckle-walking than juvenile gorillas. Another difference is that the hand bones of gorillas lack key features that were once thought to limit the extension of the wrist during knuckle-walking in chimpanzees. ...

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It has been suggested that chimpanzee knuckle-walking and gorilla knuckle-walking are biomechanically and posturally distinct. Gorillas use a form of knuckle-walking which is "columnar". In this forelimb posture, the hand and wrist joints are aligned in a relatively straight, neutral posture. In contrast, chimpanzees use an extended wrist posture. These differences underlie the different characteristics of their hand bones.[6]

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Enjoy

Worse. It is actually contradicted by known population levels and other evidence.A chain is as strong as it's weakest link, and a population can only grow to the limits of it's least available food\nutrient supply. Once the grass is gone the cows die.Enjoy.

First off, let's be honest and start off with proper representation of the quoted material. Should have been edited to indicate the superscript used in the article quoted by using ^and codes as follows (use peek function to see): OR by using the ^ to indicate superscript as in N = ne^rt as quoted from dwise1.Second you have to admit that you are definitely wrong here: Curiously, the curve formulas you reference are exactly the same type of curve that dwise1 was criticizing you for using -- or are you quibbling over calling it "pure-birth" vs "continuous-growth"?Let me help you with that: Are you kidding? Are you really that clueless? Don't you know what that equation is? It is the continuous-growth model. The one that doesn't work because it doesn't take the environment's carrying capacity into account.Is that better? Clear now? Capisce?Put bacteria in a petri dish on a consumable substrate and what happens?Put the same bacteria in a completely sterile petri dish and what happens?What happens to the first dish when the consumable substrate is gone\eaten\used?Do you get the same results? Do you get unlimited continuous growth? No? Then the N = ne^rt model is insufficient to account for the differences.EnjoyEdited by RAZD, : capisce not capiche

And after the first generation the numbers are different, so -- according to you and your way of approaching this -- you would need to calculate a new r for that generation ...... and the next generation ... etc etc etc :: each generation would have a different r value by your calculations.Curiously if you plot that r value against generations you will see that it declines ... in an exponential decay curve. But not exponential math apparently.Enjoy.

This is really bad thinking and bad math. Yes you can bastardize the formula to give you correct beginning and end results, but it will NOT model the actual population growth pattern of a population with a limited necessary resource. There's another earth available? Actually, (a) the growth curve does not work "for bacteria in a jar with limited growth media" because that growth is not exponential after the bacteria has spread out (substrate becomes unavailable for new growth at the center, for instance, breaking the assumptions for continuous growth, and this become critical as the bacteria fill the "jar" and now new growth is possible and old bacteria die), ...... and (b) there are starving people in the US and around the world -- the ability to create food is offset by the need to distribute it and by the land requirements for other uses -- how much food is grown in a parking lot? How much food is grown in New York City?People are dying of starvation. How does your model account for deaths?Even IF food is not a limiting factor there is the issue of space per person.Finally, I have already shown this graph on Message 182 on another thread:

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This is a graph that I drew for my Master's Thesis in 1972 (before home computers were readily available).

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You can clearly see the population explosions and then capping as population saturated the available ecology, first for hunting, then for agricultural, followed by the industrial revolution and the (current) global revolution. Population grows to fill the ecological niche, and then the next innovation occurs that allows more population.

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The middle line represents the growing proportion of humans living in an urban non-food producing habitat, a habitat that precludes the land from being used for agriculture so the amount of land available for food growth is shrinking. Just like the quantity of substrate available for the bacteria decreases over time.Curiously it is based on actual population and population density data. Humans differ from other animals in their ability to innovate new ways to produce and distribute food, but it is still an exhaustible resource.You just cannot model population size with a single simplistic formula.Enjoy

And it would be stunning if you couldn't, seeing as the numbers are generated from specified r values.The challenge for you is to explain why these numbers do not represent actual population numbers for those dates but rather impossible ones:436 people to build the pyramids? really? Curiously I don't need to argue that "zero population growth in humans from a initial population of 10,000 over 50,000 years" occurred to know that your model is false. This is a straw man, as it is not what is being argued afaik. Certainly it is not critical to you being wrong.What the argument involves is whether we use real population numbers or fantasy numbers and whether we model real population growth patterns versus an imaginary growth patterns.And I have and I can use real numbers (see Message 633) while your numbers are imaginary. So you are not here to learn but to pretend to know. Looks like Coyote has you pegged.EnjoyEdited by RAZD, : ...Edited by RAZD, : ...

First off any species in equilibrium with their ecology will oscillate around an average value due to perturbations in climate etc. Moose and wolves on Isle Royale for example as one of thousands of case studies.Second, agriculture was the second revolution in providing sustenance, the first was hunting and the technology for making weapons, when hominids went from scavengers to killers. See my graph.Enjoy

What 50,000 year period was that? Or don't you realize that the two sets of data you give ...

• 50,000 to 100,000 years ago the population was 3,000 to 10,000 people and
• circa 70,000 years ago the population was 1,000 to 10,000 people

... are different estimates talking about the same bottleneck event? Don't you realize that they are actually in agreement within their ranges of error?Or don't you realize that the statement "between 50,000 and 100,000 years ago, human populations sharply decreased to 3,000—10,000 surviving individuals" means that at some time between 50,000 and 100,000 years ago the population hit that level, not that it held at that level for the whole 50,000 year period?Really? Except that it isn't purely exponential. It doesn't matter to me what foil you use on your head, your argument is wrong, demonstrably wrong ... Glad you liked it (was it a good feast?): it shows graphically that the human race has not grown along a purely exponential curve, but has plateaued several times as the resources have run down for supporting further growth.What your simplistic approach fails to account for are the effects of the death rate and how that varies with food supply and climate and plague etc. Curiously ANY species that remains at effective zero growth rate for ANY extend period of time is actually doing a lot better than the majority of species that have gone extinct.EnjoyEdited by RAZD, : clrty

And yet the graph that you supped on shows this to be a false statement. What reality shows is population growth that takes off when a new adaptation reduced constraints on growth, and then constrained growth as those adaptations reached their maturity. Curiously, the oldest anatomically modern humans date to 160,000 years ago, not "50,000 or 70,000" years ago. Why is that? Or are you under the common creationist misunderstanding that evolution must cause continual change? The natural history of life on earth is littered with species in virtual stasis for much longer periods; this is something that usually occurs when (a) the species is well adapted to their habitat and (b) there are no changes to that habitat. You will note that humans have taken the need to adapt to changing or different habitats out of the equation by adapting technology to provide the necessary fitness adaptations, thus there is not much need for any visible physical adaptations.You might want to read Sexual Selection, Stasis, Runaway Selection, Dimorphism, & Human Evolution ...... and I think you will find that the human population does continue to evolve: certainly it evolves immunities to fight diseases (do I need to discuss the effect of immunity to disease on the invasion of the Americas by Europeans?).If you think that humans need to adapt and change physically, then what pressure would be behind that need and what would you expect to see.For myself I see further development of the brain, something that can change a lot without showing much difference in fossils because the change is in the soft tissues. I also note that certain athletic records are consistently broken by newer generations. Evolution does not have to be dramatic to occur: it just needs opportunity (mutations) and fitness (selection).Humans have been selecting for larger heads to the point where further head enlargement often results in death to mother and\or child (see section on runaway sexual evolution in thread above), a problem not seen in other species, certainly not in other apes.Humans have also been selecting for barer and younger appearing people, especially women, to the point where there are now whole industries built around providing artificial adaptations and exploiting sexual selection via "photo-shopping" of models until they no longer look the way real people look -- that runaway sexual selection is still operating. You seem to be under a mistaken impression that human selection is for intellectual improvement: that Nobel Prize winners are major sex symbols rather than the pop music rock stars ... or have you just not thought about it ... ?What is much more likely (and more in alignment with the evidence) is that sexual selection is for young creative people -- the singers and the dancers, the artists and the musicians -- and that brain size and attendant intellectual growth came along for the ride. Technology reared it's head when the first tool was used. Or the last 200 years when we learned to apply the scientific method to understanding the world around us instead of myth and magic thinking. What we have learned is built on the foundations of what was known before, whittling away the concepts that don't pan out to leave us with a better and better approximation of the nature of reality.Or the last 50 years when we learned to make machines to think and solve problems?Enjoy.Edited by RAZD, : clrty