One of the most shrill arguments from alarmists is the idea that climate change will wipe out species because they can’t adapt. The claims run from polar bears to tortoises, to plants and coral. Yes, if we listen to these arguments, Nature so poorly equipped it’s creatures that they can’t adapt to a slightly warmer future.
Except when the last ice age ended, and it got warmer, and the saber-toothed cats got bigger because the prey got bigger…instead of disappearing due to “climate change”.
From the Natural History Museum of Los Angeles County
La Brea Tar Pit fossil research shows climate change drove evolution of Ice Age predators
LOS ANGELES — Concerns about climate change and its impact on the world around us are growing daily. New scientific studies at the La Brea Tar Pits are probing the link between climate warming and the evolution of Ice Age predators, attempting to predict how animals will respond to climate change today.
The La Brea Tar Pits are famous for the amazing array of Ice Age fossils found there, such as ground sloths, mammoths, and predators like saber-toothed cats and powerful dire wolves. But the climate during the end of the Ice Age (50,000-11,000 years ago) was unstable, with rapid warming and cooling. New research reported here has documented the impact of this climate change on La Brea predators for the first time.
Two new studies published by research associates at of the Page Museum document significant change over time in the skulls of both dire wolves and saber-toothed cats. “Different tar pits at La Brea accumulated at different times,” said F. Robin O’Keefe of Marshall University, lead author on the dire wolf study (Palaeontologia Electronica, April 9, 2014). “When we compare fossils deposited at different times, we see big changes. We can actually watch evolution happening.”
After the end of the last Ice Age, La Brea dire wolves became smaller and more graceful, adapting to take smaller prey as glaciers receded and climate warmed. This rapidly changing climate drove change in saber-toothed cats as well. “Saber-toothed cats show a clear correlation between climate and shape. Cats living after the end of the Ice Age are larger, and adapted to taking larger prey,” said Julie Meachen of Des Moines University, lead author on the sabertooth study (Journal of Evolutionary Biology, 2014).
The two scientists discuss their work in a video here: http://www.youtube.com/watch?v=jK_DKSNbgR4&feature=youtu.be
“We can see animals adapting to a warming climate at La Brea,” said O’Keefe. “Then humans show up and all the big ones disappear. We haven’t been able to establish causality there yet. But we are working on it.”
The emerging links between climate change and evolution needs further study. There are many unanswered questions; such as why predators change in the ways that they do, the importance of factors other than climate, and whether the arrival of humans played a role in the mass extinction at the end of the Ice Age. “There is much work to be done on the specimens from the tar pits. We are working actively to bring together the researchers and resources needed to expand on these discoveries,” says John Harris, chief curator at the Page Museum. “Climate change is a pressing issue for all of us, and we must take advantage of what Rancho La Brea can teach us about how ecosystems react to it.”
O’Keefe, F. R., W. J. Binder, S. R. Frost, R. W. Sadleir, and B. Van Valkenburgh. 2014. Cranial morphometrics of the dire wolf, Canis dirus, at Rancho La Brea: temporal variability and its links to nutrient stress and climate. Palaeontologia Electronica.
Palaeontologia Electronica was the first peer-reviewed online paleontology journal in the world and has been in publication for 17 years. On April 9, visit palaeo-electronica.org/content/2014/723-canis-dirus-craniometrics
Meachen, J. A., F. R. O’Keefe, and R. W. Sadleir. 2014. Evolution in the sabre-tooth cat, Smilodon fatalis, in response to Pleistocene climate change. Journal of Evolutionary Biology 27: 714-723. Visit http://onlinelibrary.wiley.com/doi/10.1111/jeb.12340/abstract
About the Natural History Family of Museums
The Natural History Family of Museums includes the NHM, the Page Museum at the La Brea Tar Pits (Hancock Park/Mid-Wilshire), and the William S. Hart Park and Museum (Newhall, California). The Family of Museums serves more than one million families and visitors annually, and is a national leader in research, exhibitions and education.
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Richard Sharpe says (April 10, 2014 at 10:32 pm): “The paper that makes the claim about 1.2 million years more recently…”
Thanks for the link, Richard.
I suspect that at least part of the prejudice against evolution is based on conscious or unconscious revulsion that we’re so closely related to–quoting Charlton Heston in “Planet of the Apes”–“damn dirty apes”. I’ve also wondered if evolution would be more acceptable to some if it turned out we were actually more closely related to something cuter, like dolphins. 🙂
I thought this was a science blog? Well, people are entitled to their religious beliefs, but they should not confuse them with science. If you don’t believe in evolution then that is great, but it has nothing to do with the subject of this post – a very weak paper based on little data that makes ludicrous claims that have nothing to do with evolution. This is just licking the spittle of the CAGW orthodoxy. It is hard to blame the authors too much. Why not give it a go? The editors and reviewers of the journal are the ones who are really to blame – this paper should have been turfed.
For those of you who are pepper-moth-challenged try these sites:
Grant BS. 1999. Fine tuning the Peppered Moth Paradigm. Evolution 53: 980-984. http://bsgran.people.wm.edu/melanism.pdf
Majerus MEN. 1998. Melanism – Evolution in Action. Oxford University Press, NY. http://www.amazon.ca/Melanism-Evolution-Michael-E-Majerus/dp/0198549822
Miller K. The Peppered Moth – An update. http://www.millerandlevine.com/km/evol/Moths/moths.html
For BioBob – nice to see you are on the side of science (in your curmudgeonly way), but reticulate evolution is very common even among Eukaryotes. Look at the interbreeding tendencies amongst the Canidae. If you want to be really grossed out, try plants (all Eukaryotes). Some plants (especially those that use the winds for sex – probably not coincidentally including many ‘species’ we depend on for food) are about as indiscriminate in their sexual proclivities as you could imagine, even if you live in California (I have, so no complaints about bias, I am speaking from experience). Speciation can be instantaneeous when allopolyploidy occurs.
There is no reason why anyone trying to make sense of the world has to believe in evolution by natural selection (traditional Darwinism). Many evolutionists do not – they think drift or meiotic drive or some other preferred method is more important. However, all of these scientists do agree that populations change over time and that the world we see around us today is the result of change over time. No one who tries to use the scientific method as the basis for their analysis of nature claims that the natural world is fixed and cannot change. That is clearly in contravention to the facts.
If you believe otherwise, then unless you can support your beliefs by testable hypotheses, then probably they are not science. If you think that ‘evolutionists’ are bullying you or your children into accepting Darwinism as gospel, then I suggest you re-evaluate the problem. I bet its is mostly (mad dogs like Dawkins and his ilk excepted) government bureaucrats who are the problem. They are force-feeding your offspring what they think is politically correct, just as they do with CAGW. Evolution by Natural Selection should never be taught as more than the most generally excepted scientific theory to explain the diversity of life, not as an absolute explanation for life. Alternative theories not based in the scientific method, however, do not belong in science classes.
Dear evolutionists, variability is not evidence for undirected variability. Windows XP installments vary greatly but the variation is all dependant on the action of an intelligent agent (the programmer). Your framework is Complexity = a*Natural laws + b where b is noise.
The intelligent design framework is Complexity = a*Function + b, where b is statistical noise.
Accordingt to the evolutionist framework, there can be no intent or real control since every variable is dependent on the others, thus science is impossible since the variables are fed to scientists by the environment. Science requires controlled settings, control implies teleology, teleology is incompatible with evolution since evolution denies teleology. Science requires reason, reason reqires free thought, free thought requires free will, free will requires supernaturalism. You can’t test something while in the test tube. You have to disconnect yourself from the subject of your observations. You can’t do that in a naturalist setting since you are a product of the very thing you try to observe.
ferd berple says: @ur momisugly April 10, 2014 at 12:43 pm
But I would like to see some proven observations showing evolution in action.
>>>>>>>>>>>>>>>
Here is one:
http://news.rice.edu/2013/12/16/superbugs-found-breeding-in-sewage-plants/
another:
http://www.ultimateungulate.com/cetartiodactyla/Caprinae.html
(not my area of expertise just a passing interest.)
There also squirrels.
Squirrels used to zig-zag to avoid predators. Then came fast autos and many squashed squirrels. During my lifetime I have seen the behavior go from zig-zag to a mad dash across the road for squirrel populations near high use roads.
I still see zig-zag squirrels but only in the country with low use roads.
Catherine Ronconi says: @ur momisugly April 10, 2014 at 4:24 pm
Mod:
If my long comment wasn’t blocked…..
>>>>>>>>>>>>
Catherine, long comments that take a long time to type especially those with more than two links get shoved into the spam filter by WordPress and a human has to physically fish them out again.
It is darn frustrating, I spend a lot of time in moderation, but you will find it all over the net on WordPress hosted blogs.
Hang in there. There are plenty of intelligent people here but as long as everyone stays polite no one is censored. A brisk interchange of ideas is always useful.
For those of us without any back ground in biology (I am a chemist) the ideas you bring are interesting.
You can replace h*t*t*p://www. with (wwwDOT) to provide a link without getting kicked into the ether.
Also I do not compose in the WordPress window or if I do I copy and remove it and then put it back before pressing the [post comment]
Gail Combs says:
Also I do not compose in the WordPress window or if I do I copy and remove it and then put it back before pressing the [post comment]
Why?
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I know I said this before but here’s another example.
“When glaciers calve, alarmist have a cow. That explains all the bellowing.”
Regarding Darwin or dire wolves having smilodon pups and bacteria becoming algae, the science was settled and the consensus formed a hundred years or so ago.
Hockey Sticks don’t hold a candle to embryology and Nebraska Man.
Janice Moore says:
April 10, 2014 at 4:51 pm
Dear Duster,
“evolution” does NOT = “Darwin’s Theory of the Origin of Species”
It is (essentially): Change over time with-IN species via NON-directed mutation and natural selection.
“[T]he varieties of dogs you see being walked every day… ” came about from highly DIRECTED genetic selection.
Who’s the “religious” one, here? Takes a WHOLE lot of faith to believe in Darwinism (even as refined by later scientists).
Why did you bring in pastors and stuff like that anyway?
Sincerely,
Janice
The point, Janice, is first, “Darwinian evolution” is a misnomer. It emerged mostly as a strawman argument used by 19th century opponents of “progessive” evolution, the idea that “evolution” Darwinian or otherwise, some how lead to “progress.” That was an implication that the more recent a form was, the “better” it was, which is empirical nonsense, and not even good science fiction.
The concept was driven by a deep seated, egotistic belief that modern man was superior to early forms, and in fact that the modern man was morally superior to less modern man. This naturally got up the noses to the religious leaders of the time. Both England and the US were also undergoing fundamentalist reactions at the time, and the idea that society or even individuals could “progress” without external help was quite anathema – and still is, viz. this thread.
It is (essentially): Change over time with-IN species via NON-directed mutation and natural selection.
That is so profoundly wrong I can’t imagine where you learned it.. You are discussing several issues all at once conflated under one rubric. Selection is a filtering process [“directed” assumes an agency which is not supported empirically], and the only thing Darwin addressed as a cause of speciation, which is why “Darwinian evolution” is such a stupid term. He observed that off spring do not necessarily closely resemble either their parents or each other. He knew that human selection (by farmers, animal breeders, horticulturalists, etc.) could elicit new, and profoundly different forms. He argued that natural circumstances could act in a similar manner, and that since these generational changes (slow antelope vanish as cheetahs eat them and don’t have little antelope) seemed largely irreversible, that they would lead to either extinction or new species. That is the short version of Darwin’s theory. That theory of natural selection has not been refined in any profound way since it was first propounded. The range of selective processes has broadened, the idea that changes were necessarily irreversible has been challeneged, and the entire definition of “species” has been altered.
My point about dogs addresses the fact that prior to very modern tools, species were defined comparatively. Thus a paleontologist – even modern one in the case of dogs – if constrained by skeletal data alone, not only would, but would have no choice but to conclude that extreme varieties of dog are are different species. Even if you derive DNA from the bones or teeth of a very small and a very large breed and determine that they are genetically nearly identical, as long as the bones can be identified as adult animals, the empirical evidence, based on body size alone, is that the two breeds must belong to separate breeding populations, and the AKC does its best to make this true. This same situation exists in nature. There are well known examples of natural species that are completely genetically compatible, but do not interbreed because of behavioral distinctions alone. Others, just as well known, include clades of related subspecies where each neighboring subspecies is compatible, but members of geographically separated populations are not.
Darwin’s argument was that these filters, and in proper Victorian fashion, he emphasizes conflict more than other kinds of filters, act upon variation within a population, determining which forms are successful under what conditions. That property, the ability of the species to meet selective pressure is what makes it possible to breed chihuahuahs, bull dogs and great danes from a basic wolf. Mutations, methylization, and other properties of DNA establish new “variation” within a breeding population.
More seriously, if you wander into a hospital and wander out with an MRSA resistant infection, you have been a victim of the selective pressures to which a hospital subjects bacteria and other infectious beasts. You can not make evolution go away by redefining the “theory” and then by telling those of us who deal with the reality every day that it really doesn’t exist. That is the difference between reality and religion. Religions come and go, reality keeps reaping.
The reason I bring preachers into it is that 1) my oldest friend is a fundamentalist and we have had discussions on this topic that stretch over decades. Every one of his misconceptions derives from an earlier misconception by a religious teacher who inturn acquired it from a pastor; 2) I married a woman, many of whose relatives are members of a fundamentalist sect, and who have been remarkably eager to tell me what evolution is, and then tell what is wrong with the “theory.” Consequently, I have over 50 years of experience in dealing with the misconceptions you advance. You cannot redefine a theory and then argue about with any coherency.
Your concept of is evolution wrong. I agree. My definition however is not based upon your assumptions or misunderstandings, nor those of the people who taught you, nor do your criticisms of what you conceive the theory to say constitute a criticism of my understanding of the theory. In fact, claiming that I simply “believe” in an outmoded (unrefined) version of the theory, is possibly a unique argument that I don’t recall encountering. It seems almost postnormal.
Hi, Gunga Din!
Yeah. It is AMAZING what Darwinists believe — in the face of solid evidence refuting them.
The key really is at the CELL level (good source is Dr. Stephen Meyer’s work, one book of his is: The Cell). DNA is where Intelligent Design is startlingly obvious. And DNA, not a very incomplete fossil record, is where to look for clues about species. For instance, re: Mr. Hladik’s assertion about apes and humans, this relies largely on morphological similarities. At the DNA level: humans and apes are not even CLOSE to being similar; our DNA has as much (maybe more) in common with fruit flies.
While some “creationists” can be disgustingly obnoxious, it is, intriguingly, the anti-religious Darwinists who usually bring religion into the debate. This makes, sense, though, for their paradigm requires a lot of faith to maintain it. ID requires no faith at all (see, e.g., David Berlinski on Intelligent Design — he is either an agnostic or an atheist).
Good to see you, here,
Janice
*****************************************
Gail Combs! Hi!
Did you get An-tho-ny’s e mail about my being done with your answer? It is 37 pages long. I don’t want to post it on WUWT (LOTS of formatting, also). I’ll assume you don’t want it if I don’t hear from you. I spent an awful lot of time on that, though… . Sigh.
Perhaps, you won’t be back to this thread — I sure won’t be. In case you did NOT receive A.’s e mail, I’ll keep trying to flag you down when I see you on other threads. (grrr — that is the frustrating thing about a WordPress blog — so hard to “get ahold” of someone! — I’ll keep trying, though…)
I hope that your busy spring is happily so. Any babies born?
Janice
Janice Moore says:
April 11, 2014 at 11:12 am
Now you’re piling even more preposterous lies on top of your prior ridiculous lies.
“Intelligent design” is not only not obvious in DNA but is totally absent. Only a startlingly stupid designer would work the way genetics does. DNA is itself a fossil record.
You really need to study biology before commenting upon it, or at least do an Internet search before making laughably false assertions. Humans & the other apes are just as similar genetically as morphologically. Humans are closer to chimps than to any other organism on the planet. Your lie about what we have in common with fruit flies is absurd. Humans & chimps do share many gene sequences with flies, but much more so with each other.
You apparently are not the least bit interested in the truth, but here are the facts:
http://en.wikipedia.org/wiki/Chimpanzee_Genome_Project
“Typical human and chimp homologs of proteins differ in only an average of two amino acids. About 30 percent of all human proteins are identical in sequence to the corresponding chimp protein. As mentioned above, gene duplications are a major source of differences between human and chimp genetic material, with about 2.7 percent of the genome now representing differences having been produced by gene duplications or deletions during approximately 6 million years since humans and chimps diverged from their common evolutionary ancestor. The comparable variation within human populations is 0.5 percent.”
Caswell JL, Mallick S, Richter DJ, Neubauer J, Schirmer C, Gnerre S, Reich D (2008-04-18). “Analysis of Chimpanzee History Based on Genome Sequence Alignments”. In McVean, Gil. PLoS Genet. 4 (4): e1000057. doi:10.1371/journal.pgen.1000057. PMC 2278377. PMID 18421364.
When you look at individual base pairs, the similarity becomes even more startling. Humans share more mutations of all kinds with chimps than with gorillas (although we do share the MNO blood groups with them), more with gorillas than with orangutans, more with orangs than with gibbons, more with gibbons than with Old World Monkeys, more with OWMs than with New World Monkeys, more with monkeys than with other primates, more with other primates than with other mammals, more with mammals than with “reptiles” (to include birds), more with reptiles than with amphibians, more with amphibians than with lobe-finned fish, more with lobe-finned fish than with ray-finned fish, etc.
By contrast, only about 50% of fruit fly protein sequences have mammalian homologs.
Reiter, LT; Potocki, L; Chien, S; Gribskov, M; Bier, E (2001). “A Systematic Analysis of Human Disease-Associated Gene Sequences In Drosophila melanogaster”. Genome Research 11 (6): 1114–1125. doi:10.1101/gr.169101. PMC 311089. PMID 11381037.
So you’re off by a factor of at least 20 regarding relative similarity between human & chimp genomes v human & fly.
Human & fruit fly genomes also vary in other important ways, such as in share of repetitive v. non-repetitive DNA.
Duplications play a major role in genomic evolution, as I tried to teach you re. polyploidy, ie whole genome duplication. Duplication may range from extension of short tandem repeats, to duplication of a cluster of genes, and all the way to duplication of entire chromosomes or even entire genomes. Such duplications are probably fundamental to the creation of genetic novelty, giving evolution more material upon which to work.
http://en.wikipedia.org/wiki/Genome#Genome_evolution
Your total disregard of facts, to the extent of not even looking for them but willfully ignoring them, is not only unscientific but anti-scientific. You could start by reading real science instead of swallowing hook, line & sinker the lies of the Discovery Institute. That is, if you actually are searching for the truth, which you so painfully obviously are not.
This discussion has been stimulating, so thanks to all participants. While many might disagree, it seems to me that the subject is understood only minimally by any branch of the debate. I’ve taken the first steps to alleviate my ignorance and am now the owner of a 1952 volume of two of Darwin’s works, The Origin of Species and The Descent of Man. I’ve also looked around the web a bit for answers and am stunned by the depth and furor of the controversy. I was surprised to find that Darwin himself was puzzled by some of the same questions which have arisen for me. I haven’t yet found if he (or anyone else) ever figured out the answers to my questions
I’ve always been a technical/machine person, able to solve just about any issue, but was uninterested in evolution. Now, I’m confronted with my own inability to satisfy my curiosity and find that there may not yet be viable answers from any source and that I may be peering into the abyss of man’s ignorance.
“””””…..Janice Moore says:
April 10, 2014 at 11:08 pm
Dear Mr. Smith,
Thank you for clarifying that. Given the context, I assumed wrongly that your advocating the one I attempted to refute was silent disapproval and disrespect for all my arguments. I’ll try not to do that again…….”””””
Janice, I typically do not “take sides” if there is an on going difference of position of two or more parties; and in particular when it is a subject in which I am a total novice.
And if I do decide to join a debate, I would always cite the two (or more) positions I am taking a stance on.
No I don’t slam someone, by “supporting” someone else’s position. If I did slam, it would be directed at the specific position I disagree with.
As for my sister; I have two, each living a half a world away from me, and also from each other.
Neither of them (both are hardened world travelers) is now able to travel again; could never get on a plane again. So my two sisters, will never see each other again for the rest of their lives.
I can travel; but I can’t afford to travel, and I don’t like to travel, because where I would like to go, is not where I might need to go, or where other family members might want to go. And if immediate present family wanted to go with me; that would raise the cost by at least one order of magnitude, and make the travel unacceptably unwieldy; so I just don’t travel.
But yes; it went from “can I get there in time, to maybe this does have a light at the end.”
Thanks for your words.
Hey, forget about the Tar Pits, just go down the road a bit to Tommy’s at Beverly and Rampart, and generate some methane afterwards….can also visit Macarthur Park, but there probably isn’t any cake left over (btw, the strawberry or grape soda at Tommy’s goes great with a burger…).
LA has so much more to offer than CAGW tripe…
Alan Robertson says:
April 10, 2014 at 10:33 pm
Butterflies make good subjects for studying evolution. They form new species through hybridization readily & are subject to sometimes intense natural selection, with short generations, & reproductive isolation. The evolutionary process of Batesian mimicry was first discovered in Brazilian butterflies.
As with most species, butterflies, including monarchs, have a lot of genetic variation upon which evolution can work. Monarchs are somewhat unusual in taking four generations to complete an annual migration, with four life stages in each generation (which of course is not unusual).
Evolution through natural selection works on the variation inherent in each species or population’s genome, along with the new mutations that arise in every generation. Some of the sources of mutation are random, but natural selection is “directional”, ie, selective forces in the population’s environment affect which alleles & base pairs will be passed on to the next generation in which frequencies. The definition of evolution is change in allele frequencies. This process cannot help but happen, even in an unchanging environment, since besides “directional” evolution, there is “stochastic” evolution, ie purely statistical processes by which reproductively isolated populations accumulate genetic differences even if their environments are effectively the same. This is not theoretical but a fact observed both in the lab & in the field.
There are populations & species of jays (& other organisms, of course) which are just as well or better adapted to life where they live than the mother species from which they descend (& which may or may not have gone extinct). Jays are a member of the crow family, like ravens, magpies, etc. Four subspecies of blue jay are recognized in North America. There is also the closely-related species (same genus) Stellar’s Jay, found in the West, with 17 subspecies recognized from Nicaragua to Alaska.
Cladistic analysis of corvid (crow family) DNA sequences has helped resolve evolutionary relationships in the past decade or so. Corvids & their nearest relatives are “Australasian” in ancestry.
Ericson, Per G.P.; Jansén, Anna-Lee; Johansson, Ulf S. & Ekman, Jan (2005). “Inter-generic relationships of the crows, jays, magpies and allied groups (Aves: Corvidae) based on nucleotide sequence data”. Journal of Avian Biology 36 (3): 222. doi:10.1111/j.0908-8857.2001.03409.x.
Adaptation is an evolutionary process. It can lead to the formation of new species, or not. But there is nothing in organisms’ DNA to keep one species from evolving into another. Indeed, either that has to happen eventually or the species will go extinct. Evolution is a consequence of reproduction.
Alan Robertson says:
April 11, 2014 at 2:10 pm
It’s always helpful to read important works in the history of science, but reading Darwin to learn about evolution today is comparable to reading Newton to learn about gravitation. To find out the most about present understanding of evolution, a modern text would educate you more rapidly & thoroughly. Darwin was hampered by not knowing how heredity works, so while he got the big picture right, some of the details eluded him. Same as with Newton, who lacked relativity.
There is no controversy in science about the reality of evolution any more than there is about gravitation. Both theories of course are constantly undergoing refinement.
“Start with posting some verifiable observations. I am not a biologist, and I don’t have a dog in this fight. But I would like to see some proven observations showing evolution in action. I’m interested, that’s all.”
Here’s one of a series on the long-term experiments with populations of E. coli (search the PNAS site for Lenski, RE), where they report a completely new characteristic that evolved, the ability to metabolise citrate:
Zachary D. Blount, Christina Z. Borland and Richard E. Lenski, Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli PNAS 2008 105 (23) 7899-7906; published ahead of print June 4, 2008, doi:10.1073/pnas.0803151105
http://www.pnas.org/content/105/23/7899.full.pdf+html?sid=e591d677-938b-4d19-a942-c69cc047ddb3
I know that the concept of species is dodgy with bacteria; I know that these are still E. coli and not some totally new type of bacterium; but this was a notable new character which developed in roughly 31,000 generations (this report comes about 20 years – 44,000 generations – after the start of the experiment), less than a blink of an eye in geological time.
Those poor sabertooths ran into an apex predator, a forward thinking toothless, clawless biped with a definite preference for preemptory strikes. It is no coincidence that all the surviving large predators species instinctively avoid man, its the only way their ancestors survived long enough to give birth to them.
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Who needs teeth and claws when you have CO2.
Gunga Din says:
April 11, 2014 at 4:38 pm
But, wait! There’s more!
Giant herbivorous megafauna die off, removing an important source of CO2 from the atmosphere. Plus, all the uneaten vegetation draws down even more CO2. So climate got colder, right?
Uh, no. The vast continental ice sheets melted even faster. Fail!
Not to mention all the methane that the megafauna used to emit.
Fabulous info, thanks.
—-
“natural selection is “directional”, ie, selective forces in the population’s environment affect which alleles & base pairs will be passed on to the next generation in which frequencies.”
______________________
How are those selective forces interpreted and by what mechanism within the organism in order to produce specific adaptation of the organism for an exact purpose? Do those changes begin only in one individual, or across a population subject to the same forces?
I very much appreciate this knowledge that you have shared. Thanks for the advice. I’m becoming reacquainted with taxonomic rank and have realized the naivety of some of my previous questions. I’ll look for the latest information and perhaps find an internet forum, although Darwin is turning out to have a fascinating mind and character.
You told me once that you weren’t affiliated with Milodon Engineering, yet I can’t help but think of you cruisin’ around in a li’l deuce coupe.
Alan Robertson says:
April 11, 2014 at 4:50 pm
The selective forces aren’t interpreted by measured. The frequency of alleles from one generation to the next shows which traits controlled by them are more “fit” in the environment prevailing at the time.
For instance, a Pleistocene steppe mammoth population isolated from other steppe mammoth populations in the northern part of the species’ range was under selective pressure in each succeeding generation as the climate cooled to grow longer coats, lay down more subcutaneous fat, develop shorter ears, change the surface of their teeth & the shape of their trunk fingers because those differences were more adaptive in the new environment. Mammoths with these traits, or especially more of them, tended to survive better & reproduce more offspring, so in each succeeding generation the northern race of steppe mammoths diverged ever more from southern subspecies, until enough differences added up for a new species to emerge, the woolly mammoth.
The connection between the heritable traits being selected for & against are usually obvious. Natural selection cannot not happen under changing conditions affecting survival & reproductive success. IMO only willful obtuseness could prevent this fact from being obvious.
Adaptation is not for a “purpose”, but simply a response to differential survival & reproduction rates within the evolving population. The mechanism within the organism in order to produce specific adaptation can be natural selection (ie, “directional” evolution) or “directionless” stochastic processes (such as the founder’s principle, genetic drift, etc & reproductive isolation).
Beneficial mutations could arise in a single individual or among a number of them in a population. The larger the population the more likely any single mutation would be. But most species have a lot of existing genetic variability, so new mutations aren’t always necessary for speciation to occur. One caveat is that selection acts on the whole genome of an individual, so that even if a steppe mammoth had smaller than average ears, it might not be as “fit” (ie, leave as many offspring in the next generation) if its hair were wispy, or it didn’t get as fat, etc., as some of the others in its evolving population, despite carrying a trait under positive selection. But it is the whole population which evolves, not an individual, even if new mutations arise in its germ cell line during its lifetime.
I hope this answers your questions. By all means read Darwin, a good writer, brilliant scientist & very decent man, but please bear in mind that biology has learned a lot more about evolution since the time of his & Wallace’s insight on natural selection. The fact of evolution was recognized long before 1858, but there wasn’t a good scientific explanation for it before natural selection, which is now known to be just one of the evolutionary processes.
(Cont.)
No little deuce coup or chopper, although I’ve owned them in the past. Currently drive a truck or an SUV. Doing my bit to stave off the next glacial advance.
Regarding Darwin’s not knowing how heredity works, I’ve thought about how great it would have been had he somehow found the paper by Mendel, J.G. (1866). Versuche über Pflanzenhybriden Verhandlungen des naturforschenden Vereines in Brünn, Bd. IV für das Jahr, 1865 Abhandlungen:3–47. And had it translated from German.
Perhaps with the aid of his polymathic cousin Sir Francis Galton, FRS, “Father of Statistical Analysis”, Darwin might have been able to advance biology & statistics by a life time. Instead of having to wait for Sir R. A. Fisher, FRS, to invent 20th century statistical analysis in order to forge the Modern Evolutionary Synthesis in the 1920s & ’30s, it might have happened in the 1860s & ’70s.
But the Internet didn’t exist in 1866, so Darwin never encountered Mendel’s work or learned about his “factors”, now called genes. But then again, maybe cytology also had to catch up with Darwin’s giant leap into the 20th century.
It is interesting but evolutionary adaptations are really just a process, to help a species to survive.
Like humans. We have three major races, Asian, Negroid, and Caucasian. With many branches within that category. Such as Australian Aborigines are actually in the Caucasian group. It only takes 5,000 years for any human race to adapt to their new climate and natural environment. We can interbreed, but unless their is some genetic flaw, we don’t produce hybrids, like horses and donkeys and mules.
However with regards sharing the DNA with animals, it might be a surprise to everyone, that we share 98% DNA with Chimps. (Vive la difference) We also share with gorillas, Whales, pigs, and even fungi. Around 40 different species to some degree. This makes me believe, that living organisms came once way back shared an ancestor similar or same life form. (Not ET as some believe).
Indeed monkeys were the first to appear well before the apes, yet we are all primates. Wolves, bears, cats, foxes, canines all share a very distant prehistoric ancestor. Australia is a great example how evolutionary processes missed our marsupials and monotremes, the mainland was cut off so there was no diffusion to present day mammals like elsewhere.
But to abate religious differences, the Bible and Genesis, is right in evolutionary processes. They forgot to add 000,000,000 years. We didn’t walk with dinosaurs, as Sarah Palin suggested, but their death certainly aided mammals and marsupials to develop.
In fact, it was an interesting point, chimps and human babies look very similar in the womb until the final months. Our spine didn’t grow into a tail.