The Khvalynsk Neanderthal Humerus

I meant to write about this yesterday but got sidetracked and Hawks beat me to it. Except –

Hawks didn’t track down the original article that the press release and news stories were based on. The humerus was found in the osteological collections at the Vernadsky Geological Museum in Moscow and was originally from Khoroshevsky Island. It lacks the proximal and distal ends. The authors of the paper analyzed the find using x-rays, CT, and histological analysis. At this point the bone is undated. What they were trying to address is this:

The striking hypertrophy of the cortical layer in Neanderthals is often attributed exclusively to huge physical stress mostly affecting the right arm. In one of the most suggestive studies, the asymmetry of Neanderthal humeri was addressed in a comparative context (Trinkaus, Churchill, Ruff, 1994). In modern athletes (tennis players) displaying a hypertrophy of one arm, the asymmetry of shaft measurements is considerable and similar to that seen in the Neanderthals.

They go on to say that:

The results of our X-ray analysis of the Khvalynsk and Bronze Age specimens suggests that while the degree of mechanical stress was probably the same, the response to this stress was quite different. Similar processes, caused by inter-specific variation in plasticity versus mineralization of bone tissue, led to another, more often discussed morphological difference: the presence of a prominent pilaster on the femora of anatomically modern humans, and the absence of this feature in Neanderthal femora despite their general robusticity.

As the vast comparative material demonstrates, similar features of endosteal structure and muscular relief are present in all Neanderthal humeri, implying that the entire combination is indeed a species-specific characteristic. The task for the future is to assess the morpho-physiological nature of the bone response which was adaptive for this group of fossil hominids.

The authors then attempt to provide that explanation, which is where the popeye arms and being hopped up on androgen – although this last is a one line sentence in the paper referring one to the literature.

Therefore, despite living in rather similar environments, archaic and modern arctic populations developed radically different physiological adaptations, mostly owing to two variously directed types of mineral metabolism. The archaic type was based on a regular and intense accumulation of minerals and of proteins, specifically of collagen, which is the principal protein of the bone. This type of metabolism must include an intense absorption of lipid soluble vitamin D, and the intense functioning of the thyroid gland, secreting calcitonin, and of the liver, as well as the suppression of parathyroid hormone synthesis or reduced sensitivity to it.

A number of factors could account for this, one of which is the aforementioned androgen:

Because a reduced mineralization rate can also be caused by glucocorticoids, Neanderthals were either insensitive to these hormones or their secretion was reduced. At the same time, as repeatedly noted by E.N. Khrisanfova (1971, 1974, 1984, 1990), Neanderthals demonstrate a markedly “androgenic” constitution. High secretion of androgens results in a general intensification of anabolic processes, specifically of osteogenesis. In modern humans it normally increases the secretion of glucocorticoids, specifically of cortisol.

I’m not sure if I agree or not, I’ll have to think about it somemore. It is an interesting paper and deserves a lot better than the goofy stories in the press.

About these ads

One Response

  1. thx for the link, they make a point about dimorphism, interesting i think this find has sometime been refered to indeed for the perceived gracility of endemic european early neanderthal, i wonder if that ancient reference also told sth about the skullcap originally with it.

    some of the clue may be in that neanderthal are so far supposed to have lived in way smaller groups, so as to have to perform a more athletic hunting style (unlike hawks assumed mainly by the males), otoh there is ‘patho’gen (a gen) that causes elephantiasis (? i think there is a modern name for it) in modern humans that was supposedly common as a (counterbalance for the bigger injury’s in smaller groups) genetically healthy expression in neanderthal, so some extreme hormonal discrepancy’s are not farfetched to expect or presume at this point. in modern humans this gen expresses as an overdose of growth hormone from the hypofyse (wich they surgically curb to cope)

Comments are closed.

Follow

Get every new post delivered to your Inbox.

Join 57 other followers

%d bloggers like this: