Somedays, it's just awful to have the mind of a 12 year old boy. So I'm reading this serious and interesting paper on Neandertals, and learn something new.
Two particular characteristics have received considerable attention; pronounced humeral diaphysis strength asymmetry and anteroposteriorly strengthened humeral diaphyseal shape. In particular, humeral bilateral asymmetry for cross-sectional area, and torsional and average bending rigidity, appear exceptionally high in Neandertals (averaging 24–57%) compared to skeletal samples of modern Holocene H. sapiens (averaging 5–14%).
That's science-speak for "Neandertals had massively muscular right arms compared to their left." And my mind went right into the gutter.
Anthropologists had their own less juvenile explanations: their strong right arms were a response to extreme muscular activity of repetitive thrusting (ack, back into the gutter) with long, heavy spears (slap me hard.) The paper, though, analyzed muscular activity in experimental subjects who made spear thrusts while hooked up to loads of instrumentation, and discovered that, contrary to their expectations, it was the left arm, the off hand, that carried the largest load in stabilizing the thrust. So that hypothesis simply doesn't work.
So they tested an alternative explanation, and it wasn't the first one that leapt to my mind. One of the most common kinds of tools found at Neandertal sites are scrapers —if you're using hides for clothing and shelter, there is a lot of processing involved — prolonged, repetitive scraping motions while stripping excess flesh from the underside of skins. I imagine scraping a mammoth skin is a huge endeavor that does involve a lot of work. They reviewed ethnographic studies, and discovered that processing a single cow hide, for instance, takes 6-10 hours of work. So they hooked up their test subjects to instruments and measured muscle activity during scraping…and it matches, generating forces that could lead to a build-up of muscle and bone in the right arm.
Unfortunately for my adolescent Neandertal wanking hypothesis, though, the comparison probably doesn't hold up. Even the most obsessive individual is going to be hard up to maintain 6-10 hours of constant activity. Rats, I guess I'm not going to be making a novel contribution to anthropology. Besides, I imagine this guess was made many times before, and for some reason never made it into print.
Shaw CN, Hofmann CL, Petraglia MD, Stock JT, Gottschall JS (2012) Neandertal Humeri May Reflect Adaptation to Scraping Tasks, but Not Spear Thrusting. PLoS ONE 7(7): e40349. doi:10.1371/journal.pone.0040349.
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Um, what if Neandertals were left handed?
" Even the most obsessive individual is going to be hard up to maintain 6-10 hours of constant activity."
This assertion is easily shown to be untrue by simply noticing that the majority of humanity (especially in pre-modern times) worked long and difficult hours each day, frequently without breaks for week-ends and vacations. Prior to the 20th Century in the USA, the standard work week was comprised of 12-hour days, six or seven days weekly. Constant activity is absolutely required of assembly-line workers if they want to keep their jobs. Is that an obsession or simple acknowledgement of physical reality?
Before you say that I don't know what I'm talking about, my own life includes similar jobs. The most physically demanding took place over three years working 12 hours daily, seven days a week, in an environment that justified the description "hellish". There were no breaks for lunch or coffee, such things were expected to be done without interruption of the work flow. I was paid very well for the work based on my production, as such it was in my own selfish interest to work without breaks because of company rules that forbade more than 12 hours of work in one day.
Obsession, or just doing what needs to be done?
By the way, the only profound effects on my body during all this was almost total elimination of body fat and the development of a splendidly responsive body which stood me in good stead during later years at different occupations, and even today fifty years later.
^the 6-10 hours referred to spending that much time wanking. i honestly doubt your job involved choking the chicken for 12 hours a day 7 days a week
don't give up on the Neandertal wanking hypothesis just yet, it could explain their eventual extinction? okay, maybe not the thought did cross my mind.
I may have read pharyngula in seed. but if neanderthalians were like us but robust, then the occurance of specialized left-handed dimorphism would have been selective to the heterozygote? not on them though, where is the mitochondrial DNA?
Much has been made lately about the evident interbreeding between modern humans and Neanderthal that is evidenced by DNA sequencing. How did they eliminate retroviral transduction (if that is the right term) as a possibility for the common genetic material. Is it the quantity of common sequences?