the aetiology of dental crowding

One cause is sleeping on your stomach.  Dr. Hal Huggins goes into the
subject in depth in his book "Why Have Ugly Children."  I got an out
of print copy on the internet.  Dr. Huggins is a man spearheading the
future of dentistry.  His methods lead a person not to have any
dentistry done that is not compatable with the human body.  Modern
dentistry can run havoc with everything from the nervous system to the
DNA.  For a short course...nickle braces damage the DNA and root
canals create disease and mercury in dental amalgams causes birth
defects.  For more see his website    http://www.drhuggins.com/.

The main aetiology of dental crowding is the smaller size of the jaw
bone as compared to the number and size of the teeth. Early man had
large jaws to help him eat raw food. As man evolved, learnt the use of
fire, of cooking, and hto, he began to need his jaws less and less to
tear off large and hard pieces of food. As a result, the size of his
jaws decreased. But the nunber of teeth remained the same.Hence for
those children with a smaller jaw, teeth tend to crowd together.

Dr. Weston Price attributes it to diet.

"He observed that crowded, crooked teeth were becoming more and more
common, along with what Price called "facial deformities"--overbites,
narrowed faces, underdevelopment of the nose, lack of well-defined
cheekbones and pinched nostrils. Such children invariably suffered
from one or more complaints that sound all too familiar to mothers of
the 1990s: frequent infections, allergies, anemia, asthma, poor
vision, lack of coordination, fatigue and behavioral problems."

http://www.westonaprice.org/traditional_diets/ancient_dietary_wisdom.html