Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: wannabe on 25/07/2009 16:35:28
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Researching the question "why do Africans show, on average, such white coloured teeth, I only get 2 directions to further my thinking: 1) the contrast with the darkness of the skin colour, which I think holds no validity and 2) the thickness of the enamel.
There surely is reason to have the enamel thicker, but the reason most often cited: Western style diet does not seem to hold up very well as there are many generations of Africans exposed to western style diets who seem to not show the effects of such.
Could the answer lie more in Darwinian selection, i.e. could the far more recent emergence out of 'primitive' societal organization/lifestyle have conferred survival benefits on the healthier and more capable tooth owners? And the propagation of less capable teeth have occurred through advances in medicine and general support of the cultural advances into agricultural & urban societies and have lessened the effects of poor(er) teeth?
I am trying to arrive at an answer to my question following the same type of reasoning applied to the incidence of disorders like deficienteye sight, diabetes mellitus etc.
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An interesting question. I'm not sure of the mechanics of the answer but what I will point out is that white teeth aren't necessarily healthy teeth. The near-luminescent tooth shade favoured by Hollywood at the moment, which makes celebrities look like they've had lights installed in their mouths, is an effect of bleaching or tooth veneers.
But the "healthiest" teeth from the perspective of decay risk are actually those that have flouride in the enamel matrix (flouroapatite); this makes the enamel slightly darker in hue; people who live in high-flouride water areas (like Maldon in Essex, UK) therefore have browner teeth but far fewer black ones (ie decayed or filled!).
Chris
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Ah Chris, how excellent an idea to further explore.
There is a further corollary to the question under the loupe, the question of normalcy of teeth as seen from the perspective of regularity, spacing and otherwise utilizing the available jaw space most efficiently.
My boxer dog BB shows a very crowded, uneven and poorly arranged set of teeth whereas her offspring Chico has his father's perfection. His dad is a local 'hound' of various mix used for hog hunting and is the product of selection for qualities related to competencies vs appearance (the Boxer criteria for selection).
So inbreeding seems to lead to much of the imperfectly developed teeth seen in many a human population. If data exist showing that correlation that would steer the thinking further in that direction.
Thus whiteness of teeth relates to local mineral variations, crowded uneven teeth to inbreeding. If I translate that to indigenous populations I think I see much potential for the inbreeding postulation to be plausible. The exposure to minerals is more tenuous in that a great number of Africans have lived for quite a few generations in cities, exposed to the common diet variations, mineral supplementations found in western societies. I just don't know if tooth whiteness is on the decline in those places.
Your thoughts.........
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Researching the question "why do Africans show, on average, such white coloured teeth,
I only get 2 directions to further my thinking: 1) the contrast with the darkness of the skin colour, which I think holds no validity
The context of a tone can make it appear different shade ...
[ Invalid Attachment ]
image source (http://www.psy.ritsumei.ac.jp/~akitaoka/gilchrist2006mytalke.html)
The squares are both the same shade, but the one on the right, (surrounded by a darker tone than the one on the left), appears lighter.
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Thanks for that RD. It seems to invalidate my initial invalidating that direction of evidencing the reasons. This visual demonstration is rather powerful and I will give it the proper value.
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Researching the question "why do Africans show, on average, such white coloured teeth,
I only get 2 directions to further my thinking: 1) the contrast with the darkness of the skin colour, which I think holds no validity
The context of a tone can make it appear different shade ...
[ Invalid Attachment ]
image source (http://www.psy.ritsumei.ac.jp/~akitaoka/gilchrist2006mytalke.html)
The squares are both the same shade, but the one on the right, (surrounded by a darker tone than the one on the left), appears lighter.
This is what I feel is the correct answer.. Exactly my thoughts RD.. Nice demonstration!