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Subject: [DNA] a dentist comments on shovel teeth and genetic heritage
Date: Wed, 16 Jan 2002 08:48:13 EST


Please forgive if this topic has been banned by now ... I am behind on
reading the list.

I forwarded a description of this phenomenum from the list to a dentist
friend who used to be a biologist and has studied evolution ... and asked for
her comments.

What I sent her and her response are at the end of this message. I think
the main point with respect to the discussion here is the following. With
traits such as this where frequencies of a trait may be higher in one
population than another, but that there is no one-to-one correspondence
between the trait and membership in a population ..... that one should not
try to conclude too much from any one person possessing such a trait.

David Hamill

> There is also a ridge on the back of the first four teeth - two front
teeth
> and the ones on
> either side (upper and lower) of some descendants. If you place your
> fingernail at the gum
> line and gently draw (up or down) you can feel it and it makes a slight
> clicking sound.
> The back of the teeth also curve outward rather than straight as the
> descendants of
> anglo-saxon parentage do. Teeth like these are called Asian Shovel Teeth.
> Many Indian
> descendants also have this type of teeth. The back of the first four
teeth
> of Northern
> European descendants are straight and flat.

Within a broad generality, this is true. However, human variation being as
it is, there is plenty of overlap even in populations that are not mingling.
Asians do tend to have some shovel incisors, but not all and to widely
varying degrees. Native north Americans as well as some of the native south
Americans. Of course there is much evidence that these populations are
related to the Japanese (not Chinese, as originally thought!).


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