Re: Article: Human 'dental chaos' linked to evolution of cooking
From: James Michael Howard (jmhoward_at_anthropogeny.com)
Date: 02/23/05
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Date: Wed, 23 Feb 2005 18:18:06 GMT
On Wed, 23 Feb 2005 10:14:27 -0700, Rich Travsky
<traRvEsky@hotmMOVEail.com> wrote:
>
> http://www.newscientist.com/article.ns?id=dn7035
>
> Crooked and disordered teeth may be the result of people having evolved
> to eat relatively mushy cooked food, suggests new research.
>
> The disarray may have developed because evolutionary pressures affecting
> the size and shape of both the front teeth and jaw conflict with those
> influencing the back teeth. This means that there is often not enough
> space in the human jaw to accommodate all our teeth.
>
> By animal standards, human dentition is extraordinarily disordered, says
> anthropologist Peter Lucas of George Washington University in Washington
> DC, US.
>
> "The only body parts requiring regular surgery are the teeth," says Lucas.
> "It is extraordinary that the normal development of human teeth routinely
> fails to produce 'ideal' dentition," he says - and no one has yet been
> able to offer an explanation for this phenomenon.
>
> Human teeth are often spatially disarrayed or "maloccluded", accounting for
> the huge number of people who seek treatment from orthodontists. This
> disarray can lead to periodontal and gum disease, because it becomes more
> difficult to clear food particles from the mouth.
>
> Teeth can also be missing - wisdom teeth simply do not have enough space to
> fit into the jaw, and sometimes do not form at all. In contrast most other
> mammals - including our close relatives, the great apes - have very low
> frequencies of malocclusion, Lucas told New Scientist.
>
> Lucas's theory is that human dentition began to go haywire soon after our
> early Homo ancestors learnt to chop and process food with simple tools and,
> later, to cook it. These processes greatly decrease the size and toughness
> of food. Lucas estimates, for example, that molars can be between 56% and
> 82% smaller when eating cooked potato rather than raw.
>
> The front teeth and jaws are primarily occupied with reducing food to a
> small enough size to consume, whereas the molars and premolars at the back
> of the mouth are used to grind down tough particles.
>
> Lucas, speaking on Saturday at the American Association for the Advancement of
> Science meeting in Washington, DC, US, argued that since the advent of cooking
> these two processes have fallen out of sync.
>
> "The size of particles has reduced more rapidly than the rate at which the
> [toughness] of food has changed," he says. In response the human jaw may have
> shrunk beyond the point where it can hold all the molars required to
> successfully chew tough food. Lucas will now test the idea by measuring the
> particle size and toughness of food eaten by different animals and correlating
> these with tooth and jaw measurements.
> ...
> Anthropologists have not been able to agree on when our earliest ancestors
> started to prepare food. Current estimates place the advent of cooking anywhere
> between 2 million and 300,000 years ago.
asinine
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