Thursday 25 October 2012

ScienceMag's The Great Debate: How Human Were Neandertals?

This conversation took place at noon PDT on Thursday, October 25, 2012. It's moderated by Michael Balter, who writes for Science, and features Harold Dibble and John Speth as the experts. Yours truly gets a mention and asks a totally lame question, not imagining for a million years that it would be chosen. Ah, well. It wouldn't be the first time the world thought I was a crazy man!


How Human Were Neandertals?
(10/25/2012)
Thursday October 25, 2012
2:57
Michael Balter: Welcome everyone, to what I am confident will be a very lively discussion. Our guests are two anthropologists who have studied and thought about Neandertals for many years. While both men have great respect for Neandertals and their abilities, they differ somewhat on the extent to which our evolutionary cousins engaged in symbolic behavior. Thus Harold Dibble, who has worked extensively at Neandertal sites in France, has recently questioned whether Neandertals really buried their dead, as most researchers had long assumed; while John Speth, who has worked at Neandertal sites in the Near East, argued in a widely read article somewhat facetiously entitled “News Flash: Negative evidence convicts Neandertals of gross mental incompetence” that many researchers use a double standard when comparing modern human and Neandertal capabilities. I see our readers already include some anthropologists and archaeologists who are famous in their own right. Let the debate begin!

2:58
Harold L. Dibble: Hi Michael -- thanks for the invitation to this.

2:59
John Speth: Hello everyone, thanks for having me as part of this chat too. These are interesting issues and this should be fun.

3:00
Comment From John Shea
In what ways, if any, were Neandertal adaptations superior to those of the Homo sapiens populations with whom they were contemporaries between 30,000->200,000 years ago? (They can't have have been inferior across-the-board, otherwise Neandertals would have been out-competed to extinction shortly after the two hominins bumped into one another in the East Mediterranean Levant around 120,000 years ago.)

3:01
John Speth: Good but also tough question. Neanderthals survived for a long, long time, much longer than our "modern" form has been around, They also expanded over a huge area. Thus, given their presumed technological limitations compared to later humans, they did amazingly well.

3:01
Harold L. Dibble: Hi John -- I think that first of all, you're right that they have shown themselves to have been successful for a lot longer than we have yet. But to me, one of the more interesting aspects to their adaptation is their ability to respond to such a large number of varied conditions. It is as if they were using their intelligence to assess their conditions and make appropriate responses as needed, rather than following particular patterns over and over again.

3:04
Comment From Lyn Wadley
Greetings to the three of you. Would you like to comment on the cognitive implications of hafting by Neanderthals using bitumen and/or birch bark tar? It is my understanding that the preparation of the resin involves sophisticated heating processes. The planning and multi-tasking required would imply cognition not unlike our own.

3:04
John Speth: Hi Lyn, welcome aboard. I worry about keeping score on the cognitive significance of various technologies and technological traits. Is hafting more complex than controlling fire or Oldowan flaking technologies, given all the variability that is being recognized of late.

3:05
Michael Balter: We're working on your questions as fast as we can!

3:05
Comment From Diwiyana
I am interested in the linguistic ability of Neanderthals, something that leaves no clear trace in the fossil record. Years ago, it was said that the Neanderthal vocal tract differed from ours, preventing them from making the full range of sounds now used in human languages. Is this still generally accepted or has it been refuted? Concerning "art," are there any examples that are certainly the work of Neanderthals? Paintings recently dated in Spain may be and there are at least some possible uses of animal teeth and sea shells as personal ornaments. But any that are definitely Neanderthal?

3:06
Harold L. Dibble: I'm quite skeptical that there is any unequivocal evidence of Neandertal art or symbolism in general. There are many claims, of course, but for the most part they can be challenged in any number of ways. Even the biological evidence has not led to a clear answer to this question. For the moment, then, I'm going to remain doubtful that they used language in any way that could be seen as ours.

3:07
Michael Balter: We will answer as many as we can, unfortunately can't do all but appreciate everyone's input!

3:08
Comment From Adam Jagick
Has the over-reliance on terms like 'modernity' influenced our understanding of variation in the Palaeolithic? Given the incomplete nature of the fossil, archaeological and molecular records of extinct hominins and our ever changing views on the evolution of Homo sapiens, it seems to me that 'human' is now a term used to describe a moveable measuring stick. Do you see any way a species-neutral system discussing hominin evolutionary trends can be created?

3:08
John Speth: Hi Adam, Modernity is an incredibly thorny term that may be a red herring in many contexts, esp. if it is approached as a kind of trait list, regardless of what traits we stick in there. It has gotten even more slippery now that we have data, seemingly increasing rapidly, that Neanderthals and other archaics interbred with so-called moderns. Also modernity as it is often used is based on a French Upper Paleolithic yardstick. If we had started with East Asia or pre-Holocene Australia, we might have a very different set of questions as to what constitutes modernity, both culturally and biologically.

3:10
Comment From Vitaly Kisin
How large was the admixture of Homo Sapience genes to the population of Neanderthals for which your conclusions were formulated (I ask this the second time as I forgot to give my name the first time)

3:10
Harold L. Dibble: Not being an expert on Neandertal genetics, I'm a little hesitant to say with certainty what this evidence means. First, I think that the genetic evidence that we now have represents a major breakthrough in methodology for understanding many aspects of Neandertals -- whether they were or were not different species, the extent to which we may have mated with them in the past, etc. But like a lot of early research, we're now going to be moving into a period of fairly intense debate on these subjects as new labs try to replicate these studies. We'll have to wait a few years to see how it all shakes out.

3:10
Comment From Santiago Flores
Could you comment on the presence of the Neandertal gene in modern humans? I would be interested in the social implications of Neandertal/homo sapien mixing. Thanks!

3:11
Michael Balter: I see Rob Gargett, one of the original skeptics about Neandertal burial, has joined us and asked Harold a question. He is working on his response right now!

3:12
Michael Balter: We've got some very illustrious visitors: John Shea is an expert on hominin projectile technology, and Lyn Wadley led the excavations at the fantastic MSA site of Sibudu in South Africa for many years.

3:13
Michael Balter: We welcome questions from Neandertals, ie if you have language!

3:15
Comment From John Higgins
Did Neanderthals teach each other? If so, how effective were they in transmitting culture to successive generations?

3:15
John Speth: Hi John, Intriguing issue. Difficult to answer in concrete terms but there are many things that would suggest lots of interaction and LOTS of cultural transmission. As a non-lithics (stone tool) specialist, this is made on the basis of how things appear to me. The stone tools from the MSA, the time period more or less equivalent to the Eurasia Middle Paleolithic, look amazingly similar and working with 4th graders they notice the same thing. They share an amazing amount in common and striking differences from what comes before or after. And as we've gotten better at dating the record prior to the range of radiocarbon we are finding that the MSA and MP are roughly contemporary. How is it possible that similarities of that nature and degree can emerge more or less simultaneously from South Africa to England? To me that implies a huge amount of interaction, presumably both cultural and genetic, both requisites when we are dealiong with small, mobile, dispersed populations who have to maintain viable breeding networks to survive and persist. That requires LOTS of interaction.

3:15
Comment From Rob Gargett
Hi, All. Harold: Pachyderms of one sort of another have demonstrated similar adaptive plasticity and specific longevity to that of the Neanderthals. Would you say the same about their intelligence?

3:15
Harold L. Dibble: Hi Rob -- sure, a lot of species have very flexible behaviors. But, assuming that Neandertals did have a behavioral pattern different from ours, yet obviously quite big-brained (and I'll take that as a reflection of intelligence) the question becomes: how did they use that intelligence? Following cultural anthropologists like Goodenough, I've quite a believer in culture as supplying us with rules, or guidelines, for appropriate behavior, which is reflected in a high degree of patterning in the archaeological record. Neandertal occupations don't seem to show that -- rather, their behavior changes quickly to varying conditions. So, what I'm saying is that their big brains suggest intelligence, and the archaeological record is showing how they used it.

3:18
Michael Balter: As many of you know, Neandertals or their ancestors appear in Eurasia beginning about 250,000 years ago, while modern humans don't arrive until somewhere around 50,000 years ago--at least according to current evidence.

3:19
Comment From Cinda Coggins Mosher
(I should preface this by saying I am in English/Rhetoric and not science or anthropology, so bear with me...) To what extent do you believe that Homo sapiens and Neanderthals socially intemingled? There was the recent study that suggested interbreeding, but do you think that they lived closely with each other on a daily basis?

3:19
Harold L. Dibble: This is a question that is going to have to wait until our dating becomes more precise. It is roughly assumed that Neandertals and moderns both inhabited Western Europe over a 5,000 year period, and there is some genetic evidence that they may have exchanged some genes. However, remember that populations of both Neandertals and modern humans were pretty small and the chance of them running into each was still pretty low.

3:21
Comment From Guest
Should burials really be considered a marker for 'humanness'? The underlying reason for burying the deade is still unknown.

3:21
Harold L. Dibble: The question of burials works one way, but not the other. That is, since lots of peoples today do not bury their dead, not engaging in the practice does not make them any less human. However, the real issue is not what Neandertals were doing with their dead, but whether or not they had religion, use of symbols, etc. If we find a deliberate burial, then, it gives evidence that they did.

3:22
Comment From Dick Cavallaro
Would you comment on their clothing and shelter?

3:22
John Speth: Hi Dick. Clothing and shelter don't often preserve, all the more so when they are temporary and flimsy and made of perishables, whether leather or brush. But we have indirect indicators. The evolution of hair and body lice is being studied genetically and suggests that clothing has been around for quite awhile (I don't remember off hand what the published dates are). That's an interesting line of research however and has the potential of telling us about when clothing might have become a regular part of human adaptations. The stone tools offer insights. The Neanderthal period (Middle Paleolithic) has zillions of what we call "scrapers" and many of these preserve use-wear traces that do indeed suggest they were used for scraping skins. That of course doesn't tell us what they made but it is certainly suggestive. There's also a lot of use-wear evidence for woodworking and I suspect they were doing a lot more than just making spears. There are also some putative traces of actual shelters, some possibly using mammoth bones, others perhaps involving mostly hide covering, but that sort of evidence tends so far to be late and not completely compelling. On the other side of the coin, humans are incredibly adaptable to cold, with the development of brown (shivering) fat, as demonstrated by military studies and the cold tolerance of the hunter-gatherers of Tierra del Fuego.

3:25
Michael Balter: Neandertals were first discovered in Gibraltar in the 1800s, but researchers didn't know what they were. They only got clued in when specimens were found in the Neander Valley of Germany. Had things turned out differently, they might have been called Gibraltarians instead; but people there say that is just as well.

3:25
Comment From Angus
Would Neanderthals consider it important to have recognizable human traits? Do we believe that it benefits them as a species?

3:25
Harold L. Dibble: You know, I sometimes wonder why some people argue so strongly that Neandertals have to be considered to be just like us, as if to say otherwise is some kind of insult to them. Considerting our current condition, and our very uncertain future, I tend to think that pushing our brand of humanity on them could be the bigger insult.

3:27
Comment From Grmay H. Lilay
Just for curiosity:) How do you spell NeandertHals?

3:27
Harold L. Dibble: The change in common spelling, from Neanderthals to Neandertals took place as a result in German orthography. Note that the scientific name for them -- if you consider them to be a seperate species -- is Homo neanderthalensis. But among specialists, there are some who use the H and those who don't. So, either way is fine.

3:29
Michael Balter: The very last Neandertals lived in Spain, Portugal, and Gibraltar, at least as far as we know.

3:29
Comment From Beth Skwarecki
What's the current thinking on the Neandertals' diet? Especially how much they hunted vs. ate plant foods. Was their diet likely different from Homo sapiens of the time?

3:30
John Speth: Hi Beth, a topic dear to my heart! Here I recognize that my views as they are evolving may be more than three standard deviations from the current mean, but here goes anyway. Generally bones are what preserve, big bones are more visible and seemingly of more interest to a lot of people, and reflect a long bias in our own traditions. So since Darwin, and probably long before we have seen big-game hunting as what we as humans are all about and it is what largely drove our evolution. But a close look at modern hunter-gatherers like the Hadza and San (Bushmen) suggests that men do most of their big-game hunting at the time when other foods, gathered mostly by women, are at their peak (baobab, mopane worms, various seeds, nuts and fruit, etc.). Also men's hunting is notoriously unreliable, they fail most of the time, the spend inordinate amounts of time tracking, etc, not a very reliable and effective way of provisioning on a per capita daily basis. Social/political dimensions such as "costly signaling" are now being looked at very closely by behavioral ecologists (same for chimpanzees) and it looks increasingly like male hunting of big game is largely underwritten by women and serves social/political functions first and foremost and provisioning second. In many hunter-gatherers, men would do better in return rates and reliability by doing what women did. There's another entire issue with the nitrogen values in Neanderthals, but I better leave that one alone here. There's also alot of work going on now showing from microfossils in Neanderthal teeth that they were indeed exploiting plant foods. We don't know how much.

3:31
Comment From Guest
That's a bit ridiculous. The 5,000 year overlap and the genetic evidence suggests that 'modern' humans and Neandertals must have overlapped socially. The archaeological record suggests slightly more than a casual interaction between the two species.

3:31
Harold L. Dibble: Well, I really don't know of any clear examples in the archaeological record for interactions. We have assemblages with Middle Paleolithic artifacts, with Neandertals. We have what most consider to be a derivative of Middle Paleolithic -- the Chatelperronian -- with Neandertals (or that's the evidence to date). And we have Upper Paleolithic assemblages with modern H. sapiens. While you may think that they must have interacted -- and they did if the genetics are correct -- the archaeological evidence doesn't give any evidence of how, or how often, they did.

3:36
Michael Balter: Paul Mellars at the University of Cambridge has argued that modern humans outcompeted Neandertals by outnumbering them 10 to 1 in Europe; but other researchers contend that they never directly competed with each other.

3:37
Comment From Gunes Duru
Hi MichaelHow can you describe symbolic or/and behavioral similarities between the Homo sapiens and Neanderthals, neurology or some kind of interaction? what have we learned from the Neanderthals?

3:38
Harold L. Dibble: At this point, I'm still skeptical of the degree to which Neandertals used symbols, which for me would include language. There is no unequivocal evidence for art or ritual, for example. To me, this kind of behavior is one of the defining characteristics for modern behavior, which so far seems to be confined to modern H. sapiens. The second part of your question is what we have (or can) learn from Neandertals. My answer is that they represent a form of big-brained hominin whose behavioral pattern is now extinct. To me, then, it's a fascinating problem to try to figure out what that behavior was.

3:42
Michael Balter: Our guys are about to post more words of wisdom, stand by!

3:43
John Speth: Just by way of some general comments, I have been concerned about what seems to be a double standard in the way we interpret Neanderthal behavior, capacities, and so forth. Neanderthals have for generations been viewed as something inferior. Our standard is largely what we see or infer from the French Upper Paleolithic sequence of tools. We also bring in a lot of assumptions that may be in need of considerably scrutiny. First, we lpook at the French UP record as evidence of a kind of technological progress that we assume somehow translates into these foragers being more efficient in whatever they were doing (mostly hunting in most peoples' view)/. If one looks at the East Asia record for the same time period, or the early Australian record, we see very little of that sport of supposed "progress." They seem to have done adequately without all the burins, endscrapers, body ornaments and so forth. We can see something roughly analogous even in the North American archaeological record. The first humans well documented in N Amer are no more than 12000-14000 years old. Aside from "pretty points", there is incredibly little that smacks of symbolism (painted caves, ornaments, etc.). That elaboration doesn't come to a mere 5000 or so years ago with the Middle to Late Archaic. Nobody would question that we are dealing with modern humans. So what drives the elaboration? To me demography is a key variable. Archaeologists are now beginning to seriously consider demography with Neanderthals. Up till recently their demography was dismissed as "tiny mobile groups widely scattered over the landscape" End of story. How then did they manage to people a huge chunk of Eurasia? Something is missing in all of this. I see the first hints of this growth in places like the Middle East where we begin to get multiple burials in the same site, which to me suggests some kind of emerging corporateness, which in turn suggests to me that populations are growing. Also there are many more sites, bigger sites, deeper sites, stratified hearths and ash layers, etc. Something is going on demographically and I think it sets the stage for the Upper Paleolithic. Not all that long ago when most accepted Neanderthals as a separate species that sort of view didn't float. But now that we are seeing evidence of interbreeding, this sort of scenario becomes far more plausible. I suspect with Neanderthals we are seeing populations going extinct, not species, and population extinctions have always been going on.

3:45
Comment From Santiago Flores
I am unfamiliar with the burial debate. What are the main points of the debate, and what evidence is being used?

3:45
Harold L. Dibble: There are only a half dozen or so finds from Western Europe that people have interpreted as evidence for deliberate burial. The problem, for almost all of them, is either that they were excavated long ago (meaning close to 100 years ago) with methods that were not as rigorous as today's, or by amateurs, and again there is a lack of documentation. When we recently re-excavated one such site, Roc de Marsal, we found that there was little evidence that definitely pointed to any kind of ritual burial -- the skeleton was deposited in a natural pit (not a freshly dug grave), there was nothing that could be interepreted as grave goods associated with the skeleton, and because the skull itself spanned two archaeological layers, it suggests that it was not even completely covered. Now, that's one site, but it is important to take a fresh look at some of the other claims to see if they hold up to further scrutiny. One argument that is often used is the completeness of the skeleton (the argument being that they could only be complete if they were buried). But there are many purely paleontological sites that also have articulated skeletons, showing that such a criterion is not definite proof.

3:47
Michael Balter: A team recently claimed that Neandertals might have made cave art in Spain dated to at least 41,000 years ago, but other researchers are withholding judgement.

3:49
Comment From David Valentine
Neanderthals in the Iberian Penisula appear to be gathering the wing feathers of birds of prey. Would you recognise this as symbolic behaviour?

3:49
John Speth: HI David, The Neanderthal feathers are really interesting. There's other data emerging now showing similar patterns. For example work recently published by Eugene Morin and others and at Fumane Cave in Italy (I'm sorry I don't have full refs at hand). Yes, I think it is symbolic although I have no idea what the symbolism might be. I do wonder why one gets cutmarks at points of feather attachment. Although I haven't plucked all that many chickens in my life, I don't think you'd find any cutmarks when I finished. But that to me doesn't rule out the possibility that birds were being used in some symbolic context. But why not cannibalism? Who eats conspecifics for dinner? In the modern (ethnohistoric) world it is one of the most highly charged symbolic acts we can think of, including communion. Conspecifics are skinny, and dangerous as a regular food source and worse yet as a starvation food. I can't prove Paleolithic cannibalism was symbolic, but how many out there have even put the idea on the table?

3:51
Michael Balter: Neandertals and modern humans shared a common ancestor that probably lived in Africa about 500,000 years ago. But Neandertals evolved from hominins that moved in Europe and Asia, while modern humans from those that stayed in Africa--at least according to the thinking of most researchers.

3:52
Comment From Kristen Grace
I recently read a hypothesis that the reason modern Homo Sapiens survived and developed as opposed to other tribes, such as the Neanderthal, was pure luck (timing, location, weather etc.) and not mere ability and intelligence. What are your thoughts on this?

3:52
Harold L. Dibble: When we try to explain what happened in evolution -- whether we looking at human evolution or evolution in any species -- the argument comes down to showing how a new set of traits had some adaptive significance -- that is, allowed the new species to continue and perhaps fill different niches. There are evolutionary changes that take palce more or less randomly, but it is unlikely that luck or random events could explain something like the spread of modern H. sapiens across the entire globe. So, the problem is to isolate what characteristics of modern H. sapiens allowed for this. The simple answer is we don't yet know, but the major hypotheses out there by and large count on language and symbolism, that in turn allowed them to build larger social networks. My own opinion is that it probably was not a technological advance that was responsible for it.

3:54
Comment From Diwiyana
What is the extent of the Neanderthals' range? I know they lived in Spain, and some were found in European Russia. How far east have they been found?

3:54
John Speth: Hi Diwiyana, Neanderthals per se, based on skeletal materials and presumed associations with certain types of Middle Paleolithic stone tools, extended from Western Europe certainly into Central Asia. How far beyond that right now hinges much more on genetic data, which is not my forte, but based on recent finds and genetic studies at the site of Denisova in Siberia, there were "archaic" (a term as slippery as "modern") humans more or less contemporary with Neanderthals but who apparently represent a different (or several different) populations.

3:57
Comment From Huma Shah
Do you think one day, when most humans are enhanced, we will be asking 'How human were unenhanced humans?

3:57
John Speth: Hi Huma, Fun question. I wish we had a geneticist online as well. Work by John Haws, Henry Harpending and many others suggests that the rate of evolution has increased substantially in the last 20,000 years. Evolution is NOT over. Reasons behind this stem from massive population growth, incredible changes in habitats, incredible expansion of diet and techniques of food processing. Along with that comes lots of new diseases. Are we enhanced....? Who knows....

3:58
Comment From Fulco Scherjon
Is it possible to comment on likely colonization speed comparing Neandertals to modern humans (who are capable of very quickly covering large territories)?

3:58
Harold L. Dibble: Most people today would argue that Neandertals evolved from an earlier ancesor that had left Africa some hundreds of thousands of years ealier. In fact, Neandertals as a group did not have that large a range -- from Western Europe through to parts of Central Asia. Modern humans, on the contrary, spread throughout the world in just over 100,000 years.

3:59
Michael Balter: Okay, we're out of time, and did the best we could to answer as many questions as possible. Thanks to everyone for tuning in! But be sure to tune in next Thursday, when we will have a live chat about science and the upcoming election.

3:59
Writer: Michael Balter How Human Were Neandertals?



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