A superb new fossil from Dmanisi, Georgia

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D4500-oblique.jpg

A new paper was recently published, and widely reported in the media, about a hominid skull discovered at the Dmanisi site in Georgia in 2005 (Lordkipanidze et al, 2013, Gibbons 2013). The fossil, D4500, is believed to belong to the same individual as a lower jaw fossil, D2600, previously found at the site. The combined skull, designated by the authors as “Skull 5” (the 5th skull from Dmanisi) is almost completely and perfectly preserved, making it one of the most spectacular finds in the entire hominid fossil record. And Dmanisi is rapidly becoming one of the most important sites ever found in the study of human evolution.

Skull 5’s brain volume of 546 cm3 is very small. The other Dmanisi skulls are between 600 cm3 and 730 cm3. (Earlier papers gave the size of the largest one as 780 cm3, but that estimate appears to have been reduced. By comparison, the average modern human brain size is 1350 cm3.) However the fossil also has a large and robust jaw bone, and a large and projecting face. This combination of a very small brain and a large face differs from all other known Homo fossils. The fossil is of a mature adult, and because of the robustness of the skull it is thought to belong to a male.

Scientists are naturally delighted at the discovery of such a superb fossil, but the real impact of Skull 5 comes from the conclusions that the authors have drawn from it.

The Dmanisi fossils are different enough from each other that had they been found at different locations, they might have been classified into different species. Similar differences have been used to create species such as Homo habilis and Homo rudolfensis in the past. The authors believe that the Dmanisi fossils all belong to one species, both because they all come from the same time and place, and because the pattern and amount of variability found between the skulls is similar to that found in populations of modern humans, chimpanzees, and bonobos.

Following that line of reasoning, they conclude that since a similar pattern of variation exists for all early Homo fossils in Africa, and in the absence of any evidence that the supposed different species of Homo were adapted to different ecological niches, the default and most parsimonious assumption should be that all of these fossils belong to a single highly variable lineage (though they recognize that this claim remains to be tested, and alternative scenarios exist). This would mean that Homo habilis, Homo rudolfensis, Homo ergaster and some other more obscure names did not really exist as separate species. The name of that single species would, for reasons of priority, be Homo erectus. Specimens allocated to H. ergaster would then be called Homo erectus ergaster, as a time-limited subspecies. The Dmanisi scientists had previously named a new species, Homo georgicus, for the Dmanisi fossils, but now retract that name and suggest that because the Dmanisi fossils arose from an ergaster population, they should be called Homo erectus ergaster georgicus.

Most scientists appear to accept the claim that all the Dmanisi skulls all belong to the same species, but even that is not a given - Ian Tattersall of the American Museum of Natural History, for example, believes that Dmanisi could include more than one species, and that Skull 5 could be a new species (Gibbons 2013). And Donald Johanson, the discoverer of Lucy, disagrees with the Dmanisi scientists on one of their points, and argues that

the entire collection of specimens of early Homo species from East Africa shows “considerably more variation than you see in this sample [from Dmanisi], which is not surprising, because you’re looking at fossils from very different regions.”

He, and a number of other scientists quoted in various online articles, either disagree with or are still withholding judgement on whether all early Homo fossils should be merged into Homo erectus. For example Chris Stringer of the Natural History Museum in London believes the Dmanisi scientists may well be proven right that some early Homo fossils could join a variable Homo erectus, but doubts that all of them will, given the vastness of Africa, the depth of its fossil record, and evidence of species-level diversity prior to two million years ago.

If the Dmanisi scientists win the day on this argument, it really will be a significant change in the way that scientists view the details of the history of human evolution. If nothing else, it will certainly be a shot in the arm to the multiregional model of human evolution, which in recent years has fallen out of favor compared to the competing Out-of-Africa model.

What have creationists had to say about this skull?

Not much. The young-earth creationist organizations Answers in Genesis and the Institute for Creation Research seem to have ignored it, but a couple of Intelligent Design sites have addressed it.

This is the reasoning in an extraordinarily clueless article from Uncommon Descent:

News Wrote:

Here’s the kicker: The level of variation between the skull remains at Dmanisi could well be matched among modern humans waiting for the bus in a multicultural city.

What makes the find controversial is that much ideology around human evolution depends on a variety of not-quite-human species that once walked the Earth (but one rose above its fellows or prevailed over them). If there is no real evidence for more than one human species, ever, well, the unity of the human race is more consistent with traditional non-materialist assumptions than modern materialist ones.

Even if there is no evidence for more than one Homo species at any given time, that doesn’t mean that that species has stayed static though time. And if there was only ever one Homo species, it clearly has changed through time, rather dramatically. Even though the Dmanisi fossils show quite a bit of variability, none of them comes close to being looking like a modern human skull, and no modern humans look like, or are found at the time of, the Dmanisi fossils.

The claim that human evolution “depends” on having multiple species is also nonsense - it doesn’t require multiple species for evolution to happen. As the Dmanisi authors explictly pointed out:

Lordkipanidze et al. 2013 Wrote:

The hypothesis of phyletic evolution within a single but polymorphic lineage raises a classificatory but not evolutionary dilemma … (my emphasis)

And quite why anyone would think that the similar level of variation of the Dmanisi fossils and modern humans is a “kicker” is a puzzle. One might find a similar level of variations in populations of mice and capybaras too, but I don’t think creationists would argue for “the unity of the rodent race” as a consequence.

The News writer appears, in arguing for “the unity of the human race”, to be suggesting that the Dmanisi fossils are actually human. If so, he/she should perhaps ponder why it is that the Dmanisi fossils look so much more similar to australopithecine fossils than they do to modern humans.

Casey Luskin’s article at Evolution News and Views is hardly any better. There is little explanation of the significance of the Dmanisi fossils, and what there is mostly comes from the lengthy quotes he included. He misrepresents Donald Johanson by claiming that that he “disagree(s) that these [Dmanisi] skulls all represent one species”, when what Johanson actually did was to express doubt that all early Homo fossils should be merged into Homo erectus. Luskin has adopted a “small target” (indeed, “microscopic target”) strategy. Although he makes plenty of criticisms, and drops in words like “spotty”, “sketchy”, and “gap(s)” as frequently as possible, he avoids saying anything about how the Dmanisi fossils should be classified. He says that the qualified statements of scientists “hardly inspire confidence”, though if they had made confident assertions I’m sure that he would have complained about that too. Luskin may like to talk about “gaps”, but look at Figure 4 from the Dmanisi paper:

Dmanisi2013Fig4.png

The horizontal axis of the chart goes from projecting (prognathic) faces on the left to vertical (orthognathic) faces on the right, and from small brains on the bottom to large brains on the top. Modern humans are in the polygons on the top right; chimps and bonobos are in the polygons on the bottom left. There certainly is a sizable gap between modern apes and humans. The trouble, for Luskin, is that it is filled with specimens from the hominid fossil record. In particular, the Dmanisi skulls (the circles containing the numbers 2, 3, 4, and 5) are scattered fairly widely throughout that gap. Luskin has, in the past, argued that the Dmanisi hominids are apelike, but he was only able to make that claim by dint of serious cherry-picking and misrepresentation of the evidence.

So my question for Casey Luskin is: you claim there is a gap between humans and apes. If so, this should be a really easy question to answer: on what side of that gap do you classify the Dmanisi fossils?

The Dmanisi fossils, and other similar fossils from Africa are very powerful evidence of creatures that are transitional between earlier apelike creatures and modern humans. This remains the case regardless of how many species all these specimens are classified into.

Further reading

Paleoanthropologist John Hawks has a long and thoughtful post: The new skull from Dmanisi.

Science writer Carl Zimmer: Christening the Earliest Members of Our Genus has an interesting discussion of population structure in widespread species/groups of species, and points out that resolving such questions can be difficult even for modern groups for which we have vastly more data than we will ever have for fossil humans.

References

Gibbons, A. (2013): Stunning skull gives a fresh portrait of early humans. Science, 342:297.

Lordkipanidze D, Ponce de Leon M. S., Margvelashvili A., Rak Y., Rightmire G.P., Vekua A., Zollikofer C. P. E. (2013): A complete skull from Dmanisi, Georgia, and the evolutionary biology of early Homo. Science, 342:326.

Previous Panda’s Thumb posts about the Dmanisi fossils:
Dmanisi skulls and creationism (2005)
Dmanisi fossils - more transitional than ever (2008)
Dmanisi and Answers in Genesis (2008)
Dmanisi in the news (2009)

79 Comments

The young-earth creationist organizations Answers in Genesis and the Institute for Creation Research seem to have ignored it

I don’t know about AiG, but the ICR tends to take two or more weeks before getting to a story like this - they will likely have an article on the way.

Praise the Designer!

That pretty much sums up the creationist response, including the ID response when no “materialist” is supposed to be looking.

Why and how are always known, before scientists even bother with any evidence. Because god wanted it that way, and by design.

Glen Davidson

Two little points:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

2. This also is a fine poster child for the difficulty of identifying and demarcating species in the fossil record, especially (but by no means only) when we try to extend a species very far in either space or time.

Why would this be a shot in the arm for multiregionalism? The decisive evidence the mostly-but-not-entirely Out of Africa model comes from genetics, and isn’t affected by this find.

At UD, I believe “News” is Denyse O’Leary. The apparent confusion displayed there is pretty typical for her.

eamon.knight said:

At UD, I believe “News” is Denyse O’Leary. The apparent confusion displayed there is pretty typical for her.

As is the fixation on materialism. I assumed it was probably her, but don’t know for sure.

Think of all the Wikipedia edit fights that are going to go on over whether to keep, delete, or merge all the articles for each Homo “species.” It’ll make the back-and-forth between anthropological lumpers and splitters seem like unanimity!

Steve Schaffner said:

Why would this be a shot in the arm for multiregionalism? The decisive evidence the mostly-but-not-entirely Out of Africa model comes from genetics, and isn’t affected by this find.

I guess it would help the argument that Homo erectus was a widespread species across Africa and Eurasia that gradually evolved into later forms. However, yeah, the genetics is overwhelming that most of our genes came from an African population, whether or not that population was in the “same” or “different” species from the hominids that were widespread 0.5 Ma ago.

Actually the reasoning to reduce them to a single species is better then the old ideas. Creationists welcome that. Is it a primate or man looking. They bring up about brain size and so the old assumption brain size defines relationship in primates/man because of indicating smartness. I don’t agree brain size is relevant to smartness. If the average human brain size is a number then what aboyt the spectrum? what about this fossils spectrum. Could there not be overlapping by the extremes in both populations? who has the smallest human brain on record and who in this fossil group had the biggest brain? If this fossil is a person I’m sure they are within the ranges. The thing to note also is how only NOW are they correcting old misunderstandings of how variable skulls can be in species. A important point for creationists to stress here. Better investigation will correct former wrong ideas.

Joel Duff has a post on the context of the Dmanisi fossils at Naturalis Historia. He had done a lot of posts on geological context and the trouble that it would create for the young earthers if they bothered to look. http://thenaturalhistorian.com/

John Harshman said:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

Why is that? Is it because they show gradual change in the physical form of hominids?

Is it possible that in these fossils we see the competing effects of two different selection pressures both working in the same population?

It’s plain that there was selection pressure towards greater intelligence in our nearest ancestors. That means, physically, towards larger brains and hence larger crania. But there’s selection pressure against that, too: larger crania means greater birth difficulty, and hence higher birth mortality.

In modern humans, this is met with a typical evolutionary kludge - human neonates are born in a far less developed state, and take far longer to reach independence than our nearest relatives. This necessitates a much greater input from parents - both parents. Other adults, too. In that fact lies the germ of the human family unit, and of much of human society. It also means that larger brains and the somewhat different fetal development pattern must evolve simultaneously.

Is it possible that for many generations, we might expect to see the expression of both pressures? That only a relatively small proportion of larger-brained individuals would survive, at first, and that only slowly would their post-childhood advantage of greater intelligence confer natural selection, while other, smaller-headed, smaller-brained cousins might persist because of their advantage of easier birth and quicker development?

Are they sure this fossil belongs to a human? The size of it is too small in comparison with current human brain. Maybe it belongs o an animal which doesn’t exist yet?

Andy White said:

Are they sure this fossil belongs to a human? The size of it is too small in comparison with current human brain. Maybe it belongs o an animal which doesn’t exist yet?

Perhaps you could rephrase your comment to removed the implication of time travel! Did you mean to say “Maybe it belongs to a previously unknown but long extinct species of ape” If so can I ask you the question proposed for Casey Luskin in the original post. If you are trying to claim there is a gap between humans and apes, on what side of that gap do you classify the Dmanisi fossils? And why?

Andy White said:

Are they sure this fossil belongs to a human? … Maybe it belongs to an animal which doesn’t exist yet?

This is one of several skulls found in Dmanisi, and I think bones from the lower skeleton and associated stone tools were also found [someone please correct me if I am wrong on those points]. One can conclude that members of this population walked erect b/c of several features, including the forward position of foramen magnum opening under the skull. The convention is that if an upright walking primate has a certain minimum brain size and uses stone tools, then it is placed in the genus Homo and is also referred to as ‘human’. The specimens should meet these criteria. Members of our genus also have a face that is smaller and less projecting than other genera like Australopithecus, and these had faces and brains like other members of our genus from Africa. There is no compelling need to create a new species name for the Dmanisi fossils.

Great chart. I can certainly see how the SC1 “distance’ between points 4 and 5 is arguably comparable to the SC1 range amongst modern humans (eyeballing, I get a deltaSC1 of 0.1 for both groups). So I can see the authors’ argument as somewhat persuasive, at least as far as skulls are concerned. Still, with only a few skulls and lots of other body parts to consider, I don’t think this is the final nail in the coffin.

You know what this is? A great area for additional research. :)

I’ve been following this story in various media outlets with enormous interest. I really can’t wait for further finds and analysis, man I wish they find dozens of such well-preserved skulls not just Dmanisi but also throughout East Africa and Asia, this is such a dramatic development, correct me if I’m wrong, but from my layperson reading, the trend *had* been towards thinking there were a lot of overlapping hominid species.

I’m also surprised the creationists haven’t jumped all over it, besides the canard that “scientists change their minds all the time so you can’t trust any of it”, you’d think they’d use a ridiculously skewed reading of this to support their claim that “see? they [hominid fossils] are ALL really one species, i.e. Homo Sapiens”

Rhazes said:

John Harshman said:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

Why is that? Is it because they show gradual change in the physical form of hominids?

Well since there are many examples of gradualism, one more wouldn’t be a problem for punctuated equilibrium. If OTOH someone had claimed that human evolution followed a PE model, I guess this would be a problem for them. Of course there would still be all of the other fossil evidence to explain as well, so it would be just one more problem among many for such a hypothesis. EIther way, it doesn’t seem to be an issue for the Out of Africa hypothesis.

John Harshman said:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

Could you elaborate on that please John.

Does “punctuated equilibria” have a more specific meaning to a professional than it does to me? As I understand it, it is the idea that in a stable environment evolutionary change would be slow, but could potentially become rapid as environmental change opened up new niches. But that environmental change would not exclude intensified competition from a near cousin that had rapidly evolved (without fossilisation) in a niche at a remote location. If humans became extinct would not the next intelligent species, knowing only of European fossil hominids, conclude that modern humans evolved rapidly from Neanderthals. A text book example of punctuated equilibrium.

DS said: If OTOH someone had claimed that human evolution followed a PE model, I guess this would be a problem for them.

I’m not sure. PE is a tempo argument, right? Fig.4 (above) is a comparison of two physical features, not a chronology, so I don’t draw any ‘tempo’ info from it. To test PE vs. gradualism, I guess the thing to do is to come up with a single ‘physical variability’ metric and plot it vs. time (on Y-axis). Gradualism should give one or more deep Vs, with relatively continuous slopes. PE should give one or more horizontal lines or shallow Vs, with sudden slope changes between them.

Dave Luckett said:

Is it possible that in these fossils we see the competing effects of two different selection pressures both working in the same population?

It’s plain that there was selection pressure towards greater intelligence in our nearest ancestors. That means, physically, towards larger brains and hence larger crania. But there’s selection pressure against that, too: larger crania means greater birth difficulty, and hence higher birth mortality.

In modern humans, this is met with a typical evolutionary kludge - human neonates are born in a far less developed state, and take far longer to reach independence than our nearest relatives. This necessitates a much greater input from parents - both parents. Other adults, too. In that fact lies the germ of the human family unit, and of much of human society. It also means that larger brains and the somewhat different fetal development pattern must evolve simultaneously.

Is it possible that for many generations, we might expect to see the expression of both pressures? That only a relatively small proportion of larger-brained individuals would survive, at first, and that only slowly would their post-childhood advantage of greater intelligence confer natural selection, while other, smaller-headed, smaller-brained cousins might persist because of their advantage of easier birth and quicker development?

I’ve also seen it suggested that a selection pressure/influence is ability/reliance on cooking. Brain size and jaw size appear to be mutually exclusive - tool use/fire/cooking allowed for broader diet (a broader niche), reduced tooth/jaw size (and the muscles needed to power them). I’ve also seen it suggested that that suite of traits (allowed for by the technology of fire) that should define the genus Homo.

I wonder where in that spectrum of hominoids on the graph we first see language/complex social interactions developing (intuitively I want to assume that we need to see a more gracile jaw for smaller/fine motor musculature required for speech and brain size that correlates to the cognition required to ‘drive’ language/formation of societies.

eric said:

DS said: If OTOH someone had claimed that human evolution followed a PE model, I guess this would be a problem for them.

I’m not sure. PE is a tempo argument, right? Fig.4 (above) is a comparison of two physical features, not a chronology, so I don’t draw any ‘tempo’ info from it. To test PE vs. gradualism, I guess the thing to do is to come up with a single ‘physical variability’ metric and plot it vs. time (on Y-axis). Gradualism should give one or more deep Vs, with relatively continuous slopes. PE should give one or more horizontal lines or shallow Vs, with sudden slope changes between them.

You are correct. A chart with a time axis is needed. Of course ancient DNA sequences would help as well.

According to Creation Ministries International (creation.com) the “New Dmanisi Skull Threatens to Bring the House Down.”

Rhazes said:

John Harshman said:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

Yes, but mostly because it’s change without speciation. Since according to PE change is coincident with speciation, that’s a problem. Why is that? Is it because they show gradual change in the physical form of hominids?

I seem to be having trouble with blockquote lately. Let’s try again:

Rhazes said:

John Harshman said:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

Why is that? Is it because they show gradual change in the physical form of hominids?

Yes, but mostly because it’s change without speciation. Since according to PE change is coincident with speciation, that’s a problem.

Dave Lovell said:

John Harshman said:

1. This discovery and its interpretation don’t pose any threat to evolution, but they do for punctuated equilibria, if there’s still anyone who’s into that.

Could you elaborate on that please John.

Does “punctuated equilibria” have a more specific meaning to a professional than it does to me? As I understand it, it is the idea that in a stable environment evolutionary change would be slow, but could potentially become rapid as environmental change opened up new niches. But that environmental change would not exclude intensified competition from a near cousin that had rapidly evolved (without fossilisation) in a niche at a remote location. If humans became extinct would not the next intelligent species, knowing only of European fossil hominids, conclude that modern humans evolved rapidly from Neanderthals. A text book example of punctuated equilibrium.

The central idea of PE is that significant evolution occurs mostly during speciation events, in small populations peripheral to the main population. If there is only a single lineage of hominins (which is what is being proposed here), then there’s no speciation and should be no evolution. PE has nothing to do with stability of the environment, though that might be an alternate explanation for the phenomenon of stasis. I don’t know what the rest of your post (starting with “But that environmental change…”) means.

eric said:

DS said: If OTOH someone had claimed that human evolution followed a PE model, I guess this would be a problem for them.

I’m not sure. PE is a tempo argument, right? Fig.4 (above) is a comparison of two physical features, not a chronology, so I don’t draw any ‘tempo’ info from it. To test PE vs. gradualism, I guess the thing to do is to come up with a single ‘physical variability’ metric and plot it vs. time (on Y-axis). Gradualism should give one or more deep Vs, with relatively continuous slopes. PE should give one or more horizontal lines or shallow Vs, with sudden slope changes between them.

No, PE is not a tempo argument, at least not mostly. The central ideas are 1) species spend most of the time in stasis; 2) they undergo rare episodes of rapid evolution (“punctuations”); and 3) punctuations are coincident with speciation, meaning the splitting of one species into two. Of these, the third is the crucial element that makes PE different from other theories. Without the third we have a competing idea, punctuated anagenesis. Your test would separate “gradualism” (a caricature of constant rates of change that nobody believes in) from stasis and punctuation, but is irrelevant to PE itself. PE is falsified, at least in this case, if there is a single evolving lineage.

DS said: If OTOH someone had claimed that human evolution followed a PE model, I guess this would be a problem for them.

This is in fact what S. J. Gould claimed about the human fossil record.

John Harshman said: No, PE is not a tempo argument, at least not mostly. The central ideas are 1) species spend most of the time in stasis; 2) they undergo rare episodes of rapid evolution (“punctuations”); and 3) punctuations are coincident with speciation, meaning the splitting of one species into two. Of these, the third is the crucial element that makes PE different from other theories.

Ah, thanks for the explanation. I was indeed thinking more about 1 and 2 and was not aware of 3.

Casey Luskin has for a long time said that Homo habilis is obviously an ape and Homo erectus is obviously human. As anyone who has read Mr. Foley’s prior article on the Panda’s Thumb as well as what he wrote his Fossil Hominids site knows that he has been pointing out for a long time how the Dmanisi finds are transitional between H. habilis and H. erectus. Now we have a study which suggests that they should be lumped together. If Luskin has any consistency then he must utterly deny this conclusion.

If creationists want to consider H. habilis as a mere race of humans, then they conceded an enormous amount of evolution. I don’t see anyone today walking around with a brain less than 600 cc with those eyebrow ridges. Nothing even remotely close. And then how to then say H. habilis has is unrelated to austalopithicines even after many creationists, including Luskin, having long claimed they are similar or the same. As it is Todd Wood thinks that Australopithecus sediba is part of the human “baramin.”

It must be a horrible time to be a creationist on human evolution. They are facing years of results from Dmanisi and Malapa (the A. sediba site) which are producing high-quality fossils that can’t be dismissed as scraps or the imaginations of scientists. The Little Foot skeleton will eventually be published even if it does seem to take forever. Of course other sites will continue to generate results. Make a few years worth of popcorn because this is going to be good.

Marilyn said:

Is it possible with fossil bones that they could become contaminated from the surrounding substances such as soil or rock that is much older or younger than the fossil so that when a fossil bone is carbon dated it takes on the age of the surrounds rather than the actual date of the bone. Has anyone ever analyzed the soil around fossils for one thing to see if it contains anything that could be associated with the fossil. I haven’t noticed any mention of any other body parts been found.

Actually, Marilyn, true fossils aren’t carbon dated, since they seldom contain much of the original organic material and in any case classical “carbon dating” only really works well out to about 50-75,000 years ago. Past that there’s too little C14 left to accurately measure.

There’s a lot of really good information on radioisotope dating on Wikepedia, including a long list of factors that can lead a reading astray and how to correct for them.

But as for fossils, far from being contaminated by the surrounding soil and rock, fossils are often explicitly dated by their surroundings, since you can usually assume that a fossil cleanly entombed in a rock layer has been there since that layer formed, and there are a variety of dating schemes (many of which use other isotopic decay chains with longer time scales) which can be applied to old rocks.

There are, of course, ways for younger samples to be imbedded in older rocks (the classic examples are fossil packrat middens in the desert southwest) but enough work has been done (and enough researchers have been burned) that dating errors of the scale you’re speculating about just don’t happen any more.

Marilyn said:

Is it possible with fossil bones that they could become contaminated from the surrounding substances such as soil or rock that is much older or younger than the fossil so that when a fossil bone is carbon dated it takes on the age of the surrounds rather than the actual date of the bone. Has anyone ever analyzed the soil around fossils for one thing to see if it contains anything that could be associated with the fossil. I haven’t noticed any mention of any other body parts been found.

As stevaroni touched on, the overwhelming majority of fossils are much too old for direct Carbon 14 measurements. In these cases, other forms of radiometric dating are used, although not on the fossils themselves but rather on strata adjacent to the fossils.

Actually, geophysicists have discovered over three dozen different types of radiometric dating besides Carbon 14 dating. This allows multiple ways of crosschecking the different radiometric dating methods. If the different methods gave widely varied results, that could put radiometric dating in question. The fact that the different methods tend to strongly agree gives geophysicists high confidence that radiometric dating is highly accurate.

Yes, radiometric dating can be cantankerous to use. Carbon 14 dating in particular can be contaminated by outside elements. But these contaminates are well know thus such results can be safely discarded. Furthermore, Carbon 14 dating can often be crosschecked by non-radiometric dating methods such as tree ring chronology, lake varve chronology, and even items of known ages like the wood from King Tut’s coffin.

Marilyn, you might find this link helpful as it explains the mainstream view of radiometric dating. It is written by a physicist that is also a Christian; the article is posted via ASA which is an organization of Christian scientists.

http://www.asa3.org/ASA/resources/wiens.html

Tenncrain said: Actually, geophysicists have discovered over three dozen different types of radiometric dating besides Carbon 14 dating. This allows multiple ways of crosschecking the different radiometric dating methods. If the different methods gave widely varied results, that could put radiometric dating in question. The fact that the different methods tend to strongly agree gives geophysicists high confidence that radiometric dating is highly accurate.

And there are yet other methods which do not depend on the measurement of the products of radioactive decay.

See the Wikipedia article “Geochronology” for a survey of the main methods.

And of course one can figure out the ordering and order of magnitude of geological time intervals, without having exact measurements of their lengths. That’s what they did before radio dating was invented.

Henry J said:

And of course one can figure out the ordering and order of magnitude of geological time intervals, without having exact measurements of their lengths. That’s what they did before radio dating was invented.

I believe that there were estimates made on processes like weathering and deposition. Didn’t Leonardo Da Vinci make some estimates like that?

The point I would like to see made more about punctuated equilibrium is that even during these suggested “rapid” periods of evolution, the speed of change is still imperceptibly slow at a human scale. It’s only *relatively* rapid. I think referring to this still glacially slow speed of change as “rapid” is a bit misleading.

If you’re interested, the latest from the Institute for Creation Research is that Dmanisi skull 5 is really that of an Australopithecine that anthropologists are fraudulently claiming is human.

So first creationists claim it’s a human, then they claim it’s an ape, all the while still claiming that there is a “gap”! And they don’t see how this corresponds precisely to what is predicted if humans evolved. The big tent flap just whipped around and smacked them in the face and they still don’t seem to realize it. How do these clowns sleep at night?

DS said:How do these clowns sleep at night?

In the case of Thomas of the ICR, very soundly, I have no doubt. Unless, while getting into his pajamas, he should happen to drop his wallet on his foot.

Dave Luckett said:

DS said:How do these clowns sleep at night?

In the case of Thomas of the ICR, very soundly, I have no doubt. Unless, while getting into his pajamas, he should happen to drop his wallet on his foot.

Maybe we should ask him if he is willing to debate the author of his previous paper.

DS said:

Dave Luckett said:

DS said:How do these clowns sleep at night?

In the case of Thomas of the ICR, very soundly, I have no doubt. Unless, while getting into his pajamas, he should happen to drop his wallet on his foot.

Maybe we should ask him if he is willing to debate the author of his previous paper.

Since he appears to have no formal training or any real publications in anthropology or paleontology, I think he could wipe the floor with him.

DS said:

So first creationists claim it’s a human, then they claim it’s an ape, all the while still claiming that there is a “gap”!

Not only that, but in each instance they claim the answer they’re supporting (at the time) is reasonably clear. It wasn’t just a human, it was obviously a human. And now it’s not just an ape, but there are seven “basic obvervations” which show it must be an ape; any other answer is a result of some evolutionary assumption: “The assumption that skull 5 represents an ancient human permeates the original report and the news, but it ignores the seven basic observations that refute it.”

Its amusingly similar to the way fundies talk about biblical meaning: each sect asserts they understand the true meaning of the text (while others that disagree with them don’t)…and every single one of them claims the meaning is clear. ;)

Well that nonsense might work in Sunday school, but do they really think it is going to fool the real experts. You know, the guys who do this for a living, the guys who have been doing this professionally for decades, the guys who actually discovered and described the fossils? Even the rubes who want to be fooled must realize that this is just so much contradictory hogwash.

DS said:

Dave Luckett said:

DS said:How do these clowns sleep at night?

In the case of Thomas of the ICR, very soundly, I have no doubt. Unless, while getting into his pajamas, he should happen to drop his wallet on his foot.

Maybe we should ask him if he is willing to debate the author of his previous paper.

Or see if he will debate other anti-evolutionists that can’t get their own stories straight about which skulls are “clearly human” and those that are “clearly ape”.…

eyeonicr said:

If you’re interested, the latest from the Institute for Creation Research is that Dmanisi skull 5 is really that of an Australopithecine that anthropologists are fraudulently claiming is human.

Thanks for the heads-up, eyeontheicr (and for the link to your commentary, which I thoroughly recommend). I had seen the already released articles on Dmanisi by ICR and AIG, but not this one yet. Thomas and Sherwin’s earlier effort on Dmanisi was already markedly incompetent even compared to AIG’s response, but this new article is diving to the Earth’s core when it comes to plumbing new depths of cluelessness. Responding to these is going to be so much fun…

eyeonicr said:

If you’re interested, the latest from the Institute for Creation Research is that Dmanisi skull 5 is really that of an Australopithecine that anthropologists are fraudulently claiming is human.

Ummm… so it can’t be a million year old human that was almost an ape because it was actually an million year old ape that was almost a human?

Riiigghhtt…

Now I understand.

stevaroni said:

eyeonicr said:

If you’re interested, the latest from the Institute for Creation Research is that Dmanisi skull 5 is really that of an Australopithecine that anthropologists are fraudulently claiming is human.

Ummm… so it can’t be a million year old human that was almost an ape because it was actually an million year old ape that was almost a human?

Riiigghhtt…

Now I understand.

It doesn’t matter if the creationists don’t make a fragment of a parvo of sense in their denial of evidence for evolution, all that matters to creationists is that they deny that there is any evidence for evolution, logic, coherency, or common sense be literally damned.

So they deny logic and coherency as well as evolution? ;)

apokryltaros said: … or common sense be literally damned.

And to show just how literal this can be, it may be instructive to look to the House Committee on Science, Space, and Technology’s Paul Broun. See this video. Whenever someone is said to ‘demonize’ a thing, you can usually take that as a figurative description of their vehement opposition. Here it’s very literal. He’s demonizing evolution.

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This page contains a single entry by Jim Foley published on October 29, 2013 4:00 PM.

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