Someone writes:

Susan Stockwell <[log in to unmask]>
Subject: dentists

>his teeth would have enough room in the jaw (a great rarity in my
> >generation and younger) because the jaw would have developed properly
> >through suckling.

European populations, especially north and western European populations,
from which many "white" Americans are descended, tend to have small faces,
tucked under their skulls, as do many Asian populations.  In contrast, many
Eastern European, African, and Australian Aborigine populations have big
faces, which project farther forward.  Imagine looking at a profile of
someone's face.  Now imagine a line drawn straight down from the eyebrows,
perpendicular to the floor/ground.  Most north/west European-descended
people will have only a bit of the bony root of their nose, plus the
cartilaginous bridge and tip of their nose projecting beyond this line, and
none of their teeth, or perhaps just the incisor teeth in the front.  Most
Africans, many Eastern Europeans, and most Australian Aborigines, will have
browridges, the entire bony root of their nose (plus the rest of the nose)
and many of their teeth projecting in the front of this line, perhaps as far
back as their premolars.  This is known as 'facial prognathism.'  It is a
genetic difference between various populations of humans from different
parts of the world.  For an amazing example of this, rent the video "Speed"
from the video store and check out the original bus driver.  He is an
African-American, I assume, and he has huge brow ridges, and a very
projecting face.  Now contrast him to Keanu Reeves, also in the film, who is
of Asian and western European ancestry, and who has a very flat face, not
projecting much at all, with none of his teeth projecting beyond a line
drawn down from his browridges.

All of which is to say that it is isn't *just* the lack of breastfeeding
that contributes to people of north/west European descent having small
mouths and dental overcrowding.  Certainly, the lack of breastfeeding
contributes, but even in breastfed children of this population, even those
breastfed for years, you will still see problems with overcrowding and lack
of 3rd molar (wisdom teeth) development (they will be missing or impacted,
or rudimentary).  There is often not space behind the 2nd molars for the 3rd
molars to erupt.  In contract, if you look in the mouth of an adult from
most African or Australian Aboriginal populations you will see not only full
and normal eruption and occlusion of the 3rd molars, but even 'retro-molar'
space, meaning more space in the mandible for teeth behind the 3rd molars
(which humans don't have).

Thus, we cannot attribute orthodontic problems in the modern US "white"
population only to formula-feeding.  We have many thousands of years of
population differentiation between our ancestors and those of people from
other parts of the world.


>I have heard a dentist attribute this overcrowding to evolution,
> >presumably on the basis that people in breastfeeding cultures are less
> >evolved than formula fed societies. Another thing to make me dubious
> >about the theory of evolution but that's off topic!

You misunderstood what the dentist said/meant.  It is true that the
overcrowding is due to evolutionary changes in some human populations --
this doesn't make them adaptive.  Evolution refers to a change in the gene
frequencies in a population over time.  It can occur by many processes other
than "natural selection for the most adaptive choice at any given time."  I
don't think the dentist meant to imply that people in breastfeeding cultures
are less evolved than those in formula-fed societies.  He was more likely
referring to the fact that north/west Europeans and their descendant
cultures are most likely to be formula-fed today, while many African and
Aboriginal cultures are still breastfeeding for several years.

End of anthropology lesson for today.

Kathy Dettwyler


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