A new study finds that some peculiarities of adult Neanderthal skeletons may be the product from repetitive scrapping:
Colin N. Shaw et al., Neandertal Humeri May Reflect Adaptation to Scraping Tasks, but Not Spear Thrusting. PLoS ONE 2012. Open access.
AbstractUnique compared with recent and prehistoric Homo sapiens, Neandertal humeri are characterised by a pronounced right-dominant bilateral strength asymmetry and an anteroposteriorly strengthened diaphyseal shape. Remodeling in response to asymmetric forces imposed during regular underhanded spear thrusting is the most influential explanatory hypothesis. The core tenet of the “Spear Thrusting Hypothesis”, that underhand thrusting requires greater muscle activity on the right side of the body compared to the left, remains untested. It is unclear whether alternative subsistence behaviours, such as hide processing, might better explain this morphology. To test this, electromyography was used to measure muscle activity at the primary movers of the humerus (pectoralis major (PM), anterior (AD) and posterior deltoid (PD)) during three distinct spear-thrusting tasks and four separate scraping tasks. Contrary to predictions, maximum muscle activity (MAX) and total muscle activity (TOT) were significantly higher (all values, p<.05) at the left (non-dominant) AD, PD and PM compared to the right side of the body during spear thrusting tasks. Thus, the muscle activity required during underhanded spearing tasks does not lend itself to explaining the pronounced right dominant strength asymmetry found in Neandertal humeri. In contrast, during the performance of all three unimanual scraping tasks, right side MAX and TOT were significantly greater at the AD (all values, p<.01) and PM (all values, p<.02) compared to the left. The consistency of the results provides evidence that scraping activities, such as hide preparation, may be a key behaviour in determining the unusual pattern of Neandertal arm morphology. Overall, these results yield important insight into the Neandertal behavioural repertoire that aided survival throughout Pleistocene Eurasia.
The tasks that experimentally cause the same kind of asymmetry are hacking, pushing and pulling, while actions related to spear thrusting actually seem to reinforce the left side. The authors think that the repetitive nature of the task, which takes a very important work time investment in modern studied populations from Africa and the Arctic, may have been decisive in the development of the deformations.
Scrapers are incidentally the most common tools found in Neanderthal sites all across West Eurasia.
Of course it could well be that Neanderthals were mostly left handed for some odd founder effect of their species or even cultural bias. This possibility is also considered by the authors although it is not their primary hypothesis.
|Some Mousterian scrapers (source)|
"Neanderthals were mostly left handed" incorrectReplyDelete
"Neanderthals were mostly right handed" correct
But the point of the article is that the right humerii were unusually dominant compared to AMH, perhaps for fire starting?
Sorry, rushed. Authors suggest habitual hide scraping as cause for pronounced right forelimb dominance. I would add plant processing (bark/root scraping) and fire starting (right hand rubs an angled stick on another held horizontally by static left hand like a plough, as opposed to AMH spinning a stick between both hands like a drill while mouthpiece keeps it in vertical position). BTW, scraper, not scrapper.ReplyDelete
BTW, scraper, not scrapper.Delete
Ah, the auto-correction did not detect it but now I see that the two words mean slightly different things. Thanks.
"I would add plant processing (bark/root scraping) and fire starting"...
Not sure about plant processing but I just watched Bear Grills on TV and fire starting is so easy when you know how... No sticks: flint and proper tinder (like birch bark, which has enough oils to light even if wet). I love fire-making made easy... people think it's horribly hard but normally not if you know how and have the proper materials at hand.
Yes, i agree with Maju on his apreciattions about fire starting. And i dont agree with DDeden. I cant even imagine wich evidence supports the idea of a division of 1 technique of fire-making for AMH and a different one for Neanderthals (being both broadly extended and exclusive). I find that idea quite arbitrary. I can point many etnographic examples of human groups (we can agree they are AMH, i supposse)that they've never used a drill for fire-making. And, also, i dont really think there's direct evidence of those drills either on Neandertal associated MP/EUP or AMH associated EUP.ReplyDelete
On the paper's subject: I think it is a good starting point, and i also could suggest other activities, both extenuating and lateralised. like wood working, or carcass processing of big game.
I also thought about wood working, notably because some facets of Mousterian are rich in saw-like implements.Delete
I feel that if Neanderthals had to work so hard with leather, so should H. sapiens, right? Although I do not know if intensive spear thrusting might have compensated.
It seems to me a beginning of something but not at all conclusive. Not yet.
Possibly, specific populations/chronology should be brought to the equation,not just the taxon proxie. But yes, it is an start.Delete
Both Neanderthals and AMH worked hard with leather, woodcraft, food processing etc. but neanderthals used their right hand dynamically (scraping) and left hand statically (to hold item still), while AMH pinned item and used L & R hands in force symmetrically, similarly neanderthals wore a cloak/shawl/fur over the left shoulder and held it over breast (and suckling baby inside) with left hand, while AMH wore it similarly but pinned/sewn/belted together above waist allowing both hands to work dynamically.Delete
DDeden. I'm sorry, but your assumptions about what Neanders and AMH did are not based on evidence.Delete
My impression as well.Delete
The same parsimonious logic applies to neanderthal hunting, clearly such upper body asymmetry rules out habitual endurance running/persistence hunting, compare to the Kalahari bushmen who actually do endurance running/persistence hunting, they have much higher degree of upper body symmetry.Delete
wow, DDeden i think you're deep in what we sometimes call "ontologia de la ausencia" in spanish academia.Delete
Please cite some evidence, because i cant see your parsimonious logic.
In fact, where you say "parsimonious logic" i'll say "wild especulation with no reasonable basis".
Your "clearly such upper body asymmetry rules out...", from my point of view should be:
"clearly such upper body asymmetry means nothing significant to explain...".
Not to speak of the dare assumptions you wrote on july 23 9:32 PM comment ^^
"Deep" into prehistory? Yes indeed, the tracks and traces reveal themselves in anatomy, language, genomes, stones, sherds, etc.Delete
Alas, though I live on the banks of Biscayne Bay, I'm not an academic Spaniard; would you care to translate your signatory phrase into English or Malay?
He means "ontology of absence". It's a very linear translation but I'm not sure of what it means (I'm never sure what "ontology" means: it's a blurry, imprecise word).Delete
What I know is that you are making claims that are not clearly supported by the data of this study, which only covers Neanderthal anatomy and not really that of H. sapiens.
Different studies of H. sapiens do suggest that our kin had, in the Gravettian at least (your usual Crô-Magnon type), some different asymmetry which has been used to claim a life of projectile thrusting.
So I'd say you need a clear comparison and less just writing on the dust.
Ontology is a difficult term indeed. I used it in the "theory of knowledge building" sense, meaning that DDeden was using a "theory of knowledge building of the absence (of data, of evidence...). Its a typical pun from prehistoric academia, sorry.Delete
What I know is: in the absence of data, DDeden assertions about Neanders & AMH might seem plausible...
But the archaeological evidence that i've studied about pleistocene human populations (AMH, Neander & others) strongly suggests that there's no case for DDeden's assertions.
From my point of view, a broad range of behavioural variability of both Neandertals & Early UP AMH has been clearly documented, in different areas, ecological conditions, and chronologies. That huge behavioural variability, related to cultural adaptations, social organization & subsistence strategies, completely invalidades the oversimplification that DDeden did about "What Neanders do", and "what AMH do". Using hunting as an example: In some places the Neandertals hunted steppe big game, in other places they really went for middle sized high/medium-mountain bovids, and yet in some areas of southern Europe they had a strong preference for medium/small game (rabbits, birds, turtles, even molluscs and fish). Also, different strategies of wood, herbs & vegetal foods gathering and processing have recently been documented in different areas. We could go on with camp disposition, lithic & hard tissue raw material procurement, hearts & fireplace distribution, etc.
On the other hand, as Maju suggested, there are other studies whose data show strong trends of bilateral asymmetry on nowadays/recent/historical populations, both H-G and industrial-capitalist samples. While i dont support Churchill and Rhodes final conclusions, the raw data of several of their papers can be a good example of what i'm saying here.
Finally, I dislike the logical breaks & jumps between different concepts that are NOT equivalent: i. e. 1 - Moderns humans as a whole & broad concept; 2 - nowadays very specific H-G groups like bushmen; 3 - Early UP AMH.
Those concepts are not the same nor interchangeable, and jumping from one notion to another without justification is logical fallacy.
"i also could suggest other activities, both extenuating and lateralised. like wood working"ReplyDelete
I remember reading some years ago that Neanderthals worked wood, and that was my first thought on reading this post. The woodworking seems to have been at least partly as a method of sharpening wooden spears.
"I feel that if Neanderthals had to work so hard with leather, so should H. sapiens, right?"
Scraping meat and fat of a hide is not so strenuous. Any sharp rock would be sufficient. Skinning the animal in the first place is what takes the effort. I speak from experience as I've often done both for any number of animals during my life.
The authors have factored actual hide-scraping and leather-working from a number of tribes from North America and Africa.Delete