Sunday, February 20, 2005

Human 'dental chaos' linked to evolution of cooking



The NewScientist reports "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.

Mess of a mouth

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.

Read the rest here.

You are what you eat!

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