Fascinating stuff…read this paper in PNAS, Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage, or this short summary, or John Hawks' excellent explanation of the concepts, it's all good. It's strong evidence for selection in human ancestry for a gene, and just to make it especially provocative, it's all about a gene known to be involved in brain growth, and it's also showing evidence for interbreeding between Homo sapiens and Neandertal man.
The short short explanation: a population genetics study of a gene called microcephalin shows that a) it arose and spread through human populations starting about 37,000 years ago, b) this particular form of the gene (well, a small cluster of genes in a particular neighborhood) arose approximately 1.1 million years ago in a lineage distinct from that of modern humans, and c) the likeliest explanation for this difference is that that distinct lineage interbred with modern humans 37,000 years ago, passing on this particular gene variant that was then specifically selected for, a process called introgression.
The work looks sound to me, and I'm convinced. The one thing to watch for, though, is that there will be attempts to overreach and couple possession of this gene to some kind of intellectual superiority. We don't know what this particular variant of the gene does yet! All we can say at this point is that some abstract data shows that a particular allele spread through the human population at a rate greater than chance would predict, that the gene itself has as one of its functions the regulation of brain growth, but that it is highly unlikely that that particular function is affected by the variant. Whatever it does, I expect the role is more along the lines of subtle fine-tuning rather than simply making people smart.
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This is why some people sit at a green light...and go to church on Sunday. (Is this what you mean by over reaching?)
HEY! I sit at green lights sometimes!
I stop at green lights, usually when there's no other cars around. And it's not because I'm R/G colorblind, either: I know they're green, and I stop anyways. Why? Not sure.
Stogoe - Kent Hovind has the answer for why you sit at green lights! Your Neandertal gene recognizes that your great grandfather, Fred Flintstone, had to watch out for the scary green dinosaurs that he lived with, so you are hard-wired to be afraid of green.
Unfortunately for me, I must be hard-wired to be afraid of green painted portraits of dead presidents...
Anyone who's been paying attention to talk radio knows that Neanderthal genes express themselves in modern homonids.
Anyone who's been paying attention to talk radio knows that Neanderthal genes express themselves in modern homonids.
Hey, don't slander our Neanderthal cousins so by conflating them with these talk-radio chimps.
Hey, don't slander our chimpanzee cousins so by conflating them with these talk-radio leeches.
Hey, don't slander our annelid cousins...
How come if Neandertals had the gene they didn't get big brains and therefore survive as a species?
...interbreeding between Homo sapiens and Neandertal man.
OK, enough. This has been popping up back-and-forth in front of me for about four years now. Do Neanderthals constitute a separate species (Homo neanderthalensis) from modern humans, or a sub-species of modern humans (Homo sapiens neanderthalensis and Homo sapiens sapiens)?
Context: species are real, subspecies represent significant breakpoints in distributions of variance of phenotypes. Populations represent significant breakpoints in interbreeding, without necessarily any significant difference in phenotype.
How come if Neandertals had the gene they didn't get big brains and therefore survive as a species?
If I remember my college anthro classes correctly, Neandertals did have a greater average cranial capacity than modern Homo sapiens. There must have been another factor besides brain size (which wouldn't necessarily correlate exactly with intelligence) that caused them to be outcompeted by our branch.
I remember hearing that the evidence for the higher-intelligence of Homo sapiens to Neanderthals was that Homo sapiens buried their dead with religious rituals. And I thought, "maybe the Neanderthals just weren't religious." Then I thought of the map of the world of where the most non-religous people are and, yes, they are in northern Europe. Coincidence? or is it an atheist, Neanderthal ancestry!
Maybe the Neanderthals really *were* smarter, but were the victims of the first crusade!
Ha ha only serious - the fact that sapiens is still around now and neandertalensis isn't indicates that *something* happened, but "outcompete" isn't necessarily an accurate description of what that was. Neandertalensis could have been destroyed by disease, climate change that they didn't adapt to as quickly, or any number of other factors that have nothing to do with relative intelligence - or they may indeed have been victims of genocide, although it may have taken the form of ongoing "low-intensity" conflict rather than a single organized war, which ancient humans of either (sub)species didn't begin to have the logistics for. (I should mention that this is only speculation on my part since I am not an archaeologist.)
P.S. If genes from Neandertals were incorporated into the modern sapiens genotype, doesn't that prove that they weren't a separate species, since if they were, by definition the offspring of such interbreeding would have been infertile and incapable of passing the genes on to the rest of the sapiens population? Or has the definition of "species" for sexual organisms changed since I learned it?
Milford Wolpoff, professor of Anthropology at The University of Michigan, has, for years, been touring the country giving a lecture entitled "A Neanderthal in Your Closet?".
(Just a comment. Although I am a U of M grad, I have no connection with him.)
It does not sound sooo convincing to me... for now let's be kind and grant that no one has screwed up in the time calibrations of sequence differences (of course!).
Genes older than the split of all modern humans may have remained in the genetic diversity of the lineage leading to modern humans, without it implying introgression.
Are there no biological explanations to why a gene may fail to recombine other than that it has been in an isolated lineage?
If more versions of these genes are being found where there were no neanderthals, are we going to accept this or not as a way of putting to test the alleged mixture from neandertals that gave europeans these allegedly super advantageous brain genes?
Indeed, what are we accepting as evidence that may refute the whole thing? The fact that NO genetic evidence for human-neandertal hybridization may ever turn up does not seem to worry Hawkes too much. Nor does the fact that all recovered neandertal genes are veeeeery different, unrepresented in human populations.
Can sequence comparisons of microcephalin alone be trusted as evidence of two major biological events: 1) mixture with the neandertals 2) selective advatages for humans with the D microcephalin gene, despite the fact that what these davantages would be is totally murky, since people without that gene seem to do fine.
Please allow me to remind the alternative: Other, less spectacular explanations may exist for these patterns in sequence comparisons...specially if combined with drift. Can drift be confidently discarded? I mean, what a coincidence... that the D version is only common in populations that came out of africa... hmmm
Can we lay all our trust into the comparisons of the microcephain gene for all this without confirmation from nenadertal genes nor any other reliable independent source of data? Sorry, that's way too much for my level of skepticism. Artifact, alternative explanation suspected.
I would sincerely appreciate a more explicit statement on what evidence could effectively DISCARD this hypothesis.
don't slander...
neanderthals
chimps
leeches
...
everytime I see one of these lists, it always ends up with nobody agreeing on what is lower than ultra-conservative talk radio hosts.
I suggested Giardia ( http://www.cdc.gov/Ncidod/dpd/parasites/giardiasis/factsht_giardia.htm ) once, and that seemed to be acceptable for most.
I've been a fan of Wolpoff for a while, it's good to actually have some evidence behind him rather than a really good idea. It seemed that regional variations in the homo sapien population with constant gene flow would easily explain everything we see in the fossil record without the new species out of Africa that took over the world again every few hundred thousand years.
Just need some more... and better evidence.
Say Torbjoern, I finally noticed a late, ill-educated, and undiscerning reply that you made to me a while back. I responded here:
http://scienceblogs.com/pharyngula/2006/06/please_go_laugh_at_uncommond…
Please learn the various meanings of the term "mass" in English and in science (and no, I wasn't strictly discussing physics there, since I have to correlate physics and other ways of looking at things during such discussions). And learn a little bit about voltage-gated channels before you demonstrate how little you know about neuroscience.
For that matter, I thought you would actually recognize that voltage is a measure of an electrical field, hence voltage-gated channels would consequently be responding to electrical fields.
Sorry for the intrusion here, but I don't know how else to get to him to suggest that he should learn about neuroscientific matters before criticizing those who have taken the trouble to know what we're writing about (I wouldn't have bothered with this, Larson, if you didn't feel the need to attack me yet again with your little learning on goodmath).
Glen D
http://tinyurl.com/b8ykm
Well, there is work being done to sequence the Neanderthal genome, and one hopes that eventually our early genome will also be sequenced. Only that will tell us near-definitively if Neanderthals are the source of microcephalin. Even if we picked it up by interbreeding with non Homo sapiens, surely other suspected Homo species (H. floresiensis?) could be the source, rather than Neanderthal.
Anyway, it's unquestionably a good explanation for the present, particularly because it seems to agree with known paleo-archaeological evidence.
Glen D
http://tinyurl.com/b8ykm
Fascinating indeed! The earlier main theory of no intermixing as Hawks describes has made it hard to fathom the extended time Neanderthals and humans coexisted. (So hard in fact that I made a wrong comment on this the other day - a little learning is dangerous. :-) The extensive anatomical and genetic evidence he cites makes the case for introgression, and Neanderthal specifically, easy to accept.
"How come if Neandertals had the gene they didn't get big brains and therefore survive as a species?"
They had big brains, larger than us. Here is a nice graph illustrating hominin cranial capacities since A. afarensis onwards: http://www.pandasthumb.org/archives/2006/10/fun_with_homini_2.html .
Hawks discusses this too:
"1. Late Neandertals certainly weren't stupid. Consider the Châtelperronian. And the European Mousterian includes basically all the elements that are thought to represent cognitive sophistication in MSA Africans.
2. Neandertal brains were big, and their heat generation requirements means that energetic constraints were very different from other archaic populations."
But the main argument that he repeats several times is that adaptive introgression "occurs when adaptive alleles are selected, and broken apart from their genetic background". Which is presumably why the Neanderthal anatonomical features disappeared, but some alleles survived and become successful in the new genome.
Clastito:
"Are there no biological explanations to why a gene may fail to recombine other than that it has been in an isolated lineage?"
I'm not a biologist, but didn't the paper (and Hawks) discuss this? They mention "balancing selection", whatever that is, as an alternate explanation "for maintaining the coexistence of D and non-D alleles". In other cases this can't be discarded (though Hawks seems to disagree) but here it can be shown to be highly unlikely due to the lack of the main mechanism for suppressed recombination. ( p 4.)
"Can drift be confidently discarded?"
Again, outside my domain by far, but the paper seems to say so. They use this as the null hypothesis. (p 4.) "simulations of ancient admixture showed that an archaic genetic contribution <0.1% is unlikely to be detectable" (p 1.)
Hawks discusses a lot of alternative hypotheses. His conclusion: "Complete replacement is completely out. "Mostly" replacement, or "assimilation" is still in, but with the observation that archaic human genes had substantial evolutionary importance in the adaptation of modern humans.
In other words, we have moved the ball down the field. Time to line up for the next play."
Fascinating indeed! The earlier main theory of no intermixing as Hawks describes has made it hard to fathom the extended time Neanderthals and humans coexisted. (So hard in fact that I made a wrong comment on this the other day - a little learning is dangerous. :-) The extensive anatomical and genetic evidence he cites makes the case for introgression, and Neanderthal specifically, easy to accept.
"How come if Neandertals had the gene they didn't get big brains and therefore survive as a species?"
They had big brains, larger than us. Here is a nice graph illustrating hominin cranial capacities since A. afarensis onwards: http://www.pandasthumb.org/archives/2006/10/fun_with_homini_2.html .
Hawks discusses this too:
"1. Late Neandertals certainly weren't stupid. Consider the Châtelperronian. And the European Mousterian includes basically all the elements that are thought to represent cognitive sophistication in MSA Africans.
2. Neandertal brains were big, and their heat generation requirements means that energetic constraints were very different from other archaic populations."
But the main argument that he repeats several times is that adaptive introgression "occurs when adaptive alleles are selected, and broken apart from their genetic background". Which is presumably why the Neanderthal anatonomical features disappeared, but some alleles survived and become successful in the new genome.
"Are there no biological explanations to why a gene may fail to recombine other than that it has been in an isolated lineage?"
I'm not a biologist, but didn't the paper (and Hawks) discuss this? They mention "balancing selection", whatever that is, as an alternate explanation "for maintaining the coexistence of D and non-D alleles". In other cases this can't be discarded (though Hawks seems to disagree) but here it can be shown to be highly unlikely due to the lack of the main mechanism for suppressed recombination. ( p 4.)
"Can drift be confidently discarded?"
Again, outside my domain by far, but the paper seems to say so. They use this as the null hypothesis. (p 4.) "simulations of ancient admixture showed that an archaic genetic contribution <0.1% is unlikely to be detectable" (p 1.)
Hawks discusses a lot of alternative hypotheses. His conclusion: "Complete replacement is completely out. "Mostly" replacement, or "assimilation" is still in, but with the observation that archaic human genes had substantial evolutionary importance in the adaptation of modern humans.
In other words, we have moved the ball down the field. Time to line up for the next play."
Glen:
Whoa! I don't see why you get so upset. Well, actually I do, since I discussed and criticized some of your ideas. But that shouldn't be construed as a personal attack.
This however feels like one, so I think I'm entitled to go OT and answer in detail:
"And learn a little bit about voltage-gated channels before you demonstrate how little you know about neuroscience."
Fact: I don't know more about neuroscience than any interested blogger.
Fact: I have 17 years of work on voltage-controlled components, from a PhD in electronics to CMOS VLSI industry, producing, testing, constructing, patenting and using. Now, when you say voltage-gated channels, I presume you don't talk about MOS or FET channels, but voltage dependent potassium, sodium or calcium channels that open and close depending on membrane potential. I'm not familiar with those, but I expect to be able to make a reasonable discussion about EM and material properties.
I think it is fair and a good ground for further discussion to now ask what is your background, and how has your ideas been accepted?
The http://students.wwcc.edu/~glendavidson/website/links_page.htm seems to be a part of Walla Walla Community College in Washington, "highlighting enology and viticulture". (Grapes, umm, delicious...)If you have anything specific pertaining to EM and neuroscience, you don't cite it. Though from your blog comments you seem interested and well versed in philosophy, certainly more so than I am.
I also think it is fair that I try to answer in any discussion I may have started, up to and including the usual academic lengthmeasuring about whose work is most cited that you seem to want. I looked at the linked comments, and it is an old exchange with long comments. I will see if I can comment something worthwhile under these circumstances.
"you didn't feel the need to attack me yet again with your little learning on goodmath"
Fact: I have amassed a lot of math courses through the years, more than 3 consecutive years of them. I think it explains my interest, apart from my programming, and ability to discuss some of the topics on a nonspecialist math site.
I don't think I have attacked you on what I think is "Good Math, Bad Math" which I frequent, also because it deals with pseudoscience and creationism as Pharyngula does. In fact, I can't remember seeing you there. I may however have mentioned your site and the ideas you have published during discussions. That must be considered normal - or do you expect an invitation into such discussions? Since you didn't link I take it it will be enough to continue discussing as above, on the link you provided.
"1. Late Neandertals certainly weren't stupid. Consider the Châtelperronian. And the European Mousterian includes basically all the elements that are thought to represent cognitive sophistication in MSA Africans.
I love this blog. Seriously, I was reading about this very subject in my anthro textbook literally half an hour ago. Had I read this earlier today I would have had no idea what you were talking about.
This has happened to me like three times this semester.
'Fess up. You're all inside my head. I'm in the matrix or something, right?
Aren't the authors assuming neutrality of the gene when they estimate 1.1 million years old for its origin and 37,000 for the introgression?
Larsson,
I am not talking of drift over the point of whether microcephalin D is the result of transgression, but on the claim that its increased frequency in non-african populations really is the result of selection.
But about the alleged transgression, one point: calibrations of the dates of divergence of genes is no small issue...
For instance, I heard a lot of speculation about the supposed difference in the time of divergence of all Y chromosoems, which was more recent than that of mithochondrial genes. After reading many crazy hypotheses about how Y chormosomes spread to ALL of humanity by selection, cultural means, etc. I found one small comment in a Cavalli-Sforza paper in nature... that it was an interesting possibility that the discordance in the dates of them may come from an artifact in callibration and estimation of their divergence. So, hypotheses of technical artifacts do not get as much attention as fantastic explicative scenarios.
you should have taken the blue pill.
"suggested Giardia ( http://www.cdc.gov/Ncidod/dpd/parasites/giardiasis/factsht_giardia.htm ) once, and that seemed to be acceptable for most."
[Obligatory "Hey! Don't slander our metamonad cousins!" remark.]
" . . .a lecture entitled "A Neanderthal in Your Closet?""
Don't tell Rev. Haggard. Or a substantial proportion of the GOP . . .
Clastito, all I can say is, look at the (really pretty straightforward and unambiguous as such things go)data and see if you can come up with another reasonable hypothesis to explain them. I don't pretend to be an expert, but I do have some understanding of these things, and I can't come up with one. There really is a tremendously glaring mismatch betweent the coalescence age of the D variant and its divergence from other forms of the microcephalin gene. The data for both sides of the equation look very solid, and there just aren't a whole lot of ways to explain those observations, at least that I can see, unless a grave error has been committed somewhere.
Glen:
Whoa! I don't see why you get so upset.
Of course you don't. I haven't lied about you, you lied about me, so you aren't the victim of illiterate and dishonest attacks as I am.
Well, actually I do, since I discussed
"Discussed", is it? Is misrepresenting "mass" in the vernacular sense as "physical mass" a discussion? Is claiming that voltage-gated channels don't rely upon electrical fields a discussion? Mere cut and paste, with ignorant lies thrown in as commentary doesn't count as discussion.
and criticized some of your ideas. But that shouldn't be construed as a personal attack.
What are you saying, that you regularly misrepresent others, and tell disgusting lies, as a matter of course? Maybe you do, and if so you are appalling.
This however feels like one, so I think I'm entitled to go OT and answer in detail:
Oh gee, you get the science wrong, the English wrong, and proclaim that you were right to call me "whacky" and "crackpot" in the beginning, and I'm not supposed to attack your ignorance and dishonesty? Of course it's personal, for you have done little but tell falsehoods and demonstrate your incompetence in these matters.
I fail to see where you respond in "detail". Rather than owning up to your dishonesty and ignorance, you try to shift the subject to credentialism and other non-evidence based matters.
"And learn a little bit about voltage-gated channels before you demonstrate how little you know about neuroscience."
Fact: I don't know more about neuroscience than any interested blogger.
No kidding. That doesn't explain why you didn't connect voltage with electrical fields.
Fact: I have 17 years of work on voltage-controlled components, from a PhD in electronics to CMOS VLSI industry, producing, testing, constructing, patenting and using. Now, when you say voltage-gated channels, I presume you don't talk about MOS or FET channels, but voltage dependent potassium, sodium or calcium channels that open and close depending on membrane potential. I'm not familiar with those, but I expect to be able to make a reasonable discussion about EM and material properties.
You quoted from wikipedia regarding voltage-gated channels. Obviously you don't know anything about them, but you ought to be sufficiently cognizant about physics to know that voltage refers to electrical fields.
Why do you think to declaim about subjects of which you know so very little? We fault IDists for doing that, yet you feel free to take a page from their tactics to cut and paste what you don't understand, then to comment about what you know virtually nothing.
I think it is fair and a good ground for further discussion to now ask what is your background, and how has your ideas been accepted?
Do you understand anything about the ideals of science? One discusses theory and evidence, in the ideal, not credentials, backgrounds, or the acceptance of radically new ideas.
Still, in the practical sphere, there are matters of background worth discussing. I have a BA in pre-med, hence a good many biology courses, some of which included neuroscience. Not so much as to be an expert (which I have never claimed--I'm interested in the physics), but enough to set a good foundation for learning beyond my courses, which I have done. And you have done neither, but simply cavilled, and ignorantly and dishonestly made judgments which you cannot back up.
And yes, I have a fairly good knowledge of classical physics, from courses and outside study. And especially I have a lot of philosophy courses/knowledge (grad school level). See, I recognized that understanding consciousness depends both upon the knowledge of science, and how it can and does relate to "subjective experience". You faulted me for a multi-disciplinary approach, as I'd expect of one so lacking in learning, but I have always insisted on its importance.
The http://students.wwcc.edu/~glendavidson/website/links_page.htm seems to be a part of Walla Walla Community College in Washington, "highlighting enology and viticulture". (Grapes, umm, delicious...)
Yes, I knew that this would be meaningful to a non-scientific authority-believing herd animal. I took some courses at the local community college after I dropped out of New School University's grad program (I realized that I wasn't willing to spend my life discussing "high level" philosophy, which generally is meaningless and unnecessary interpretation laid over the useful philosophies of Hume, Kant, Nietzsche, and one might say (with caveats), Husserl. My grades were good).
Specifically, I took a web course at CC (a couple wine course, too--tasty), since my knowledge of computers was (and still is, though less so now) rather poor. I created the website in the course, which is why it looks experimental (I didn't do anything to put it on the search engines, as I probably would have changed a number of things first--and now it has become difficult to change thanks to my software situation, and especially due to time constraints). It is. But it's still a pretty good overview of my ideas, and somewhat of consciousness altogether, and since they allow me to keep it on their own website (as long as I ask each quarter), I do so.
Of course this runs the risk of people blowing off good work based upon their hideous prejudices and lack of ability to understand what is at issue in consciousness. So it has always been, for the main reason radically new ideas are generally hated is not religion, it is because people prefer to stomp on anything that looks socially vulnerable, and have little real interest in thinking things through. That you don't rise above the level of pettiness and attempts at bullying is appalling, but not unexpected.
As to how my ideas have been accepted, ask Lynne Margulis, Nietzsche, Darwin in the early years, and Daniel Koshland Jr., how truly relevant such a question is. If you can't deal with the evidence, but have to rely on authority to "value" something, you are much less a scientist than a scholastic (actually, another reason I dropped out of philosophy is that scholasticism is not dead in grad school, and dissent is not very acceptable).
The truth is that one of the biggest problems I have is that a multi-disciplinary approach tends to be disparaged by the various specialists, because they don't like what they don't know, much as it is with you. Then too, they really do have trouble evaluating wide-ranging arguments. Yet I can't see how consciousness can be approached in any other way.
If you have anything specific pertaining to EM and neuroscience, you don't cite it.
As noted above, I have the foundations, and I do not deal with the specifics of neuroscience much, but with the physics. Consciousness has to be a fairly widespread phenomenon, as it incorporates a good amount of information, thus one needs a general hypothesis, not one concerning the intricacies of neurotransmitter release at the synapses.
Of course you would be mainly concerned about credentials in the old specialties, when one is forging beyond the old and into the new. You're a logocentrist, not a scientist. The fact is that there is no set "science of consciousness" simply because no hypothesis has taken hold. That is to say, none of the ideas in consciousness is well-accepted, and the main concepts out there are highly inadequate causally, and appear to hold sway due primarily to academic control and competition (I'm not surprised that of such is your "basis" for judgment).
Though from your blog comments you seem interested and well versed in philosophy, certainly more so than I am.
Yes, too bad you don't understand the importance of philosophy in forging into something as interpretation-laden as consciousness study, but rather had to fault me for bringing philosophy into the discussion (in truth, I have been moving away from philosophy in later discussions, since philosophers typically know very little about science, and ultimately that is what I am about).
I also think it is fair that I try to answer in any discussion I may have started, up to and including the usual academic lengthmeasuring about whose work is most cited that you seem to want.
A total fantasy in your deluded mind. I want to disuss evidence and modeling, you want to discuss credentialism, encyclopedia summarizations, and anything but the science and philosophy relevant to consciousness. Or at least this is how it appears so far.
I looked at the linked comments, and it is an old exchange with long comments. I will see if I can comment something worthwhile under these circumstances.
You haven't yet.
"you didn't feel the need to attack me yet again with your little learning on goodmath"
Fact: I have amassed a lot of math courses through the years, more than 3 consecutive years of them. I think it explains my interest, apart from my programming, and ability to discuss some of the topics on a nonspecialist math site.
Non sequitur. Do you even think before you start your irrelevant bragging?
I don't think I have attacked you on what I think is "Good Math, Bad Math" which I frequent, also because it deals with pseudoscience and creationism as Pharyngula does. In fact, I can't remember seeing you there.
Only yesterday did I discover the two ill-informed attacks that you made, via a search engine (well, the goodmath link I had seen, but had never visited). I had never been to Goodmath before then.
And I suppose it behooves you to discuss pseudoscience, since that is what you engage in when discussing neuroscience.
I may however have mentioned your site and the ideas you have published during discussions. That must be considered normal - or do you expect an invitation into such discussions?
It would only be fair to invite me if you're telling lies about me and my site. True, fairness would not be expected from someone as beholden to herd thought, and opposed to evidence-based science if it is new, as yourself. So you try to blow off your tawdry little attacks as if they are reasonable.
But of course the web allows you to make dirty attacks on others, as we know from IDists and yourself. It doesn't make it right, though.
Since you didn't link I take it it will be enough to continue discussing as above, on the link you provided.
That would be fine, if you intend to discuss actual science rather than to engage in scholastim, credentialism, and your inability to infer electrical fields where voltage is indicated. We shall see if you are capable and willing of doing better than the IDists.
Glen D
http://tinyurl.com/b8ykm
and the evidence that could discard this hypotheses is...?
I do not deny the possibility of introgression, I think it is an interesting and somewhat overlooked source of evolutionary innovation. But, I believe it is normal scientific procedure to figure as many independent sources of data that may prove consistent with such colorful hypotheses, rather than rely entirely for example on estimates derived from computer simulations (where failure to model reality always lurks).
For instance, evidence that birds are dinosaurs has been available for many years, but the best thing about that story is how succesive challenges have been met by evidence confirming over and over agains its airtight consistency, in the face of decades of persitent opposition.
That's why, while knowing I may be wrong, I consider I do good in demanding evidence of the D microcephalin ( or simply just ANY human gene) in a neanderthal, I demand a clear effect and selective advantage between someone that has the D and someone that does not (just "assuming" an almost invisible slight fine tuning does not work). I truly worry when rather than strain for different sources of confirmation, some ALREADY settle into saying "this may be as good as the evidence will ever get". If that is indeed true, this means to me that the whole idea is condemned to the hypothetical realm and may never cross the line into fact.
Stay alert: More inconsistencies in divergence dates for genes may show up, such that we may have to postulate more and more introgressions, with other ape-men lineages: I know this was already proposed for admixture with chimpanzee ancestors...once we have all possible introgressions, we may not always find actual availability of apemen, in time and space, to provide the "archaic" genes. And then what?
There was some media buzz a few years back re a supposedly Neanderthal ginger gene for red hair and freackles.
http://www.highbeam.com/doc/1G1-74940006.html
Well, again, you can't replace a theory with nothing, only with a better theory. Assuming the data (divergence times) hold up, what's your alternate explanation?
A good standing hypothesis can be proven wrong even if there is no alternative hypothesis to replace it. One of the things that bothers me is precisely that no well-defined card is being played that may prove this one wrong, which makes me think, it's not so good as a hypothesis.
Divergence times could indeed be wrong. A better question is, if we think they may be wrong, how then can we explain the patterns of sequence differences when comparing the microcephalin genes without introgression, and at the same time, dealling better with the fact that no great biological differences or advantages exist for those carrying the D versions of the gene?
Hehehe, evil me. I think I'll keeep that one to myself. Sorry.
Well I like his paper, it's interesting. :) If you don't like then all I have to say is "Suck it up Sally, Life is a sexually transmitted disease." :)
how many times has the same gene appeared as the result of mutation in the course of evolution? answer plenty.
ever taken a good look at far eastern europeans. if they don't look neaderthalic, i don't know who does....http://news.bbc.co.uk/olmedia/1995000/images/_1997872_brezhnev150.jpg
Is this gene present in _all_ modern humans? If so, then all modern humans share that common ancestor (a person likely living in Europe.)
For a gene to so successfully dominate precursors and variants it must have conferred tremendous competitive advantage to those who posessed it.
>>How come if Neandertals had the gene they didn't get big
>>brains and therefore survive as a species?
They had in fact larger brains than we have today.
> There must have been another factor besides brain size
>(which wouldn't necessarily correlate exactly with
>intelligence) that caused them to be outcompeted by our
>branch.
It's odd how all through the early hominides up to homo erectus the growing brain size is always correlated with growing intelligence. But talking about neanderthal people, all of a sudden everyone stresses that despite their large brains they needn't have been very intelligent.
What else should all that energy-consuming brain have been good for? A big head, giving women extra trouble in childbirth, and the constant demand of energy, proteins and minerals for the brain's metabolism, need to be balanced by some advantage.
I'd go for other factors to explain why they disappeared.
Assuming with their larger and differently shaped heads they had a more difficult childbirth, one could guess a higher mortality for women. That would mean a slower population re-growth after hard winters or other catastrophes. A modern human population living nearby may have grown more quickly, filling the vacated territory before the neanderthal population could rise to the previous number.
Additionally, neanderthals with their larger brains and sturdy build apparently needed more energy/food than modern humans. On the same space, fewer of them could make a living. Regarding tribal warfare, or inventions needed to adapt to changing climate / wildlife, it's of course important how many people there are to fight, or discuss new tools and hunting techniques.
>I remember hearing that the evidence for the
>higher-intelligence of Homo sapiens to Neanderthals was
>that Homo sapiens buried their dead with religious rituals.
Neanderthal people apprently sometimes carried de-fleshed skulls with them. One could assume some kind of ancestor worship.
>I thought of the map of the world of where the most
>non-religous people are and, yes, they are in northern
>Europe. Coincidence?
Yep. :)
But: Neanderthals had big, prominent noses - likely an adaptation to cold dry air. Since they developed in Europe and lived here through several cold periods, one can guess they were fair-skinned (white skin producing more vitamin D than dark skin, an important advantage in places with little sunshine). Now compare where Neanderthals used to live, and where white, long-nosed people originate from.
Ah, but larger creatures tend to have larger heads, and while the Neanderthals were certainly highly intelligent, their larger brain doesn't imply that they were any smarter. The ratio of their body size to brain size gives us a better indication of intelligence than size alone.
It is entirely possible that, as you state, humans won out because they were more efficient - not necessarily smarter, but not necessarily dumber either.
It seems that way too much emphasis on religion, or the "discovery" of religion has influenced the scientific take on intelligence. As mentioned in an earlier comment:
>I remember hearing that the evidence for the
>higher-intelligence of Homo sapiens to Neanderthals was
>that Homo sapiens buried their dead with religious rituals.
This statement tends to make a link between the practice of religion and intelligence--that the practice of religion indicates higher intelligence and the lack of, or the failure to display the practice of religion indicates a lower intelligence. Has anyone ever stopped to think that religion is no more than a vice- a "crutch" or an excuse created by HomoSapiens, and -- much like the animal world, had no place in the Neandertal world?
Maybe those larger brains were capable of such thought as to allow them to reason out religion and bypass it, finding it unnecessary, an annoyance or just plain stupid. The need to "explain" our existence through supernatural make-believe may have not been on the Neandertal agenda. Perhaps they used their larger brains for more constructive purposes -- who knows. But to claim Neandertals were lesser a form of human species simply because they did not practice a form of "religion" is plain idiotic and extremely arrogant towards Homo Sapien "racial" superiority over the Neandertal, which at this time science cannot prove or disprove.
As to Neandertal genes, I myself would be proud to find out one of my ancestors was a Neandertal. Because Neandertals were BAD to the BONE, and well, someone has to carry the club! (it must be why I'm so big and BAD...besides, I look like a Neandertal...)
WolfmanSpike
wolfhead, you do know you are a neaderthal don't you?? (j/k). i'm sure both the neaderthals and cro-magnon's had their spooks anfd fairies. but no respectable cro-magnon woman did it with a neaderthal, whereas cro-magnon males were pigs (and still are).
I'm not too convinced of the Neanderthal / Sapien pairings hypothesized by this finding either.
I don't doubt that such pairings did occur -- male sapiens have been known to copulate with sheep, goats, and pigs, albeit in small numbers (I think...). But I do doubt that they would have resulted in pregnancies, or if they had, that any genetic exchanges would have survived to the present day.
One thing I would like to see (and maybe this has been done but hasn't been publicized) are comparisons for existence and frequency of these alleles in sapien populations that separated from the Euro/Afro/Asian world prior to hypothesized cross-breeding 40,000 years ago. Perhaps such people could be found amongst the Andamanese, New Guinean, or South American Indian populations?
>Ah, but larger creatures tend to have larger heads, and while
> the Neanderthals were certainly highly intelligent, their
>larger brain doesn't imply that they were any smarter. The
>ratio of their body size to brain size gives us a better
>indication of intelligence than size alone.
Modern humans range from pygmy to sumo wrestler. Neandertal people were within that range. Yet, they had larger brains than the modern average.
>It is entirely possible that, as you state, humans won out
>because they were more efficient
I'd put it as "less demanding", regarding the amount and quality of food, a stable climate etc
>Maybe those larger brains were capable of such thought as
>to allow them to reason out religion and bypass it
>Perhaps they used their larger brains for more
>constructive purposes -- who knows
People tend to spend a lot of their brain capacity on interaction with their fellow humans.
Perhaps Neanderthal men were very talkative and charming, easily winning the heart of every poor neglected African immigrant woman whose husband was out to craft a new club (or shag a woolly rhino), leaving her to paint the cave on her own?
>I don't doubt that such pairings did occur -- male sapiens
> have been known to copulate with sheep, goats, and pigs
Excellent point. :)
I don't think you understand. All other things being equal, brain size is related to body size. This is why men tend to have larger brains than women - they don't work any better, but they're bigger.
The issue is not whether Neanderthals were within the modern normal range, but whether their normal range was greater than the normal range of anatomically modern humans at about the same time. It was - as their brains are proportionally larger. That doesn't mean that they worked any better.
Given both the nature of the associated phenotype and the divergence date of 1.1 mya, it's much more likely that this gene derives not from Neanderthals but from Homo floresiensis.
>All other things being equal, brain size is related to body
>size. This is why men tend to have larger brains than women
> - they don't work any better, but they're bigger.
Yes, but that's beside the point I was trying to make.
As far as I know, it's usually only the brain volume that gets compared, not the brain/body-mass ratio. (Which would indeed be difficult since there are not enough complete skeletons of many sorts of hominids to determine with reasonable certainty how tall and how massive they were.)
Chimpanzees have small brains, some early hominids' brains were about the same size, homo habilis had larger brains, homo erectus much larger still, and this is usually correlated with growing intelligence. Then comes the neanderthal man, and all of a sudden this assumption that larger brain means more intelligence, which was not questioned in any other case (chimpanzee/habilis, habilis/erectus), is happily abandoned and people scrape for arguments of the contrary.
This looks to me as if many people just want the neanderthals to have been dumb.
Glen:
It is unfortunate that I revisit this issue this late, but family business intruded and I have but slowly taken up all of the blogging again. I'm quite certain you will pick this up again, though. :-)
"As to how my ideas have been accepted, ask Lynne Margulis, Nietzsche, Darwin in the early years, and Daniel Koshland Jr., how truly relevant such a question is."
The Galileo defense. If it can't pass peer-review, it has failed as science.
You have presented an hypothesis without any experimental evidence what I can see, and proceeded to write a book about it. Now you rant because my evaluation of this is negative, behaving like a crank here and elsewhere in the comment. Since you don't explain or defend your ideas or present data, I don't see anything to discuss further.
Glen:
It is unfortunate that I revisit this issue this late, but family business intruded and I have but slowly taken up all of the blogging again. I'm quite certain you will pick this up again, though. :-)
"As to how my ideas have been accepted, ask Lynne Margulis, Nietzsche, Darwin in the early years, and Daniel Koshland Jr., how truly relevant such a question is."
The Galileo defense. If it can't pass peer-review, it has failed as science.
You have presented an hypothesis without any experimental evidence what I can see, and proceeded to write a book about it. Now you rant because my evaluation of this is negative, behaving like a crank here and elsewhere in the comment. Since you don't explain or defend your ideas or present data, I don't see anything to discuss further.