Joe Navarro also gives us insight into body language in What Every BODY is Saying:
''The writer and zoologist Desmond Morris observed that our feet
communicate exactly what we think and feel more honestly than any
other part of our bodies (Morris, 1985, 244). Why are the feet and legs
such accurate reflectors of our sentiments? For millions of years, long
before humans spoke, our legs and feet reacted to environmental threats
(e.g., hot sand, meandering snakes, ill-tempered lions) instantaneously,
without the need for conscious thought. Our limbic brains made sure
that our feet and legs reacted as needed by either ceasing motion, running
away, or kicking at a potential threat. This survival regimen, retained
from our ancestral heritage, has served us well and continues to
do so today. In fact, these age-old reactions are still so hardwired in us
that when we are presented with something dangerous or even disagreeable,
our feet and legs still react as they did in prehistoric times.
First they freeze, then they attempt to distance, and finally, if no other
alternative is available, they prepare to fight and kick.''