烹飪進化與牙齒的關係
簡單來說, 現在的人比較多牙齒問題, 是與進化有關聯的. 古代人的jaw都比較大, 因為他們需要把肉咬碎. 後來人類學會煮東西來吃. 食物變比較軟了, 就不需要那麼大的jaw去用力把食物咬碎. 所以人類進化, jaw size 慢慢的變小. 人也不需要智齒了. 因為小的jaw根本沒位置讓智齒長出來. 沒長智齒的朋友….. 恭喜你! 因為你比其他人 more evolved 才會沒智齒….. XD
Related link: dos’s blog 的 “現代人美齒7大準則”
(from NewScientist.com)
Human ‘dental chaos’ linked to evolution of cooking
14:25 19 February 2005
John Pickrell, Washington DC
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.
Out of sync
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.
“We’ve evolved to eat mush,” agrees paleoanthropologist Bernard Wood also of George Washington University, but not involved in this study.
“We’re a pretty puny bunch, really, with small teeth and small jaws,” he says. “If we couldn’t get the foods we like, and we ever had to adapt quickly, we might be in a terrible mess because our teeth aren’t equipped to cope with anything very substantial.”
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.
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