Evening star., 1933-07-23
Man Walks Erect, Not
Because ofPrActice in
Using His Legs, but as a
Resnlt Of Millions Of
Years Of Using His
Hands and Arms.

ners of the limbs of land-living vertebrates.
Indeed. the first land visiting, as distinguished
from later land-lving, backboned animal
was probably fish, or half-hsh half
amphibian, that tipped its way from puddle 10
puddle with fins that may have fringed out into
something like fingers These were SUCCEEDED
by true amphibians like salamanders and mud
puppies, and these in turn by reptiles.
The original groups Of four-legged animals
stuck pretty conservatively to the limb position
set by the fishes; with legs sticking straight out
from the sides of the body, and feet sticking out
straight from the ends of the legs These
primitive amphibians remained as fiat on their
bellies as did the adventurous fish.
A few of the more progressive ones did in
time bend down their forearms and lower leg
joints to raise their bodies clear of the ground.
but even these left the legs still sticking straight
out sidewise
The first real progress came when, with the
DEVELOPMENT of reptilian life the next stage,
the limbs of these lowly creatures became bet
ter adapted to lift their heavy bodies against
the pull of gravity. They brought their thighs
and upper armbones around more or less paral-
lei with the body. and used both upper and
lower joints to raise themselves clear of the
ground.
THIS, of course brought the toes in parallel
to the body, instead Of at q right angle
projection, as In the lower orders. All this
made for tremendously greater efficiency in get
ting about
It was from the quadrupedal reptihan stage
that the earliest forms of mammalian life ap-
peared Certain groups of these original
mammals (very opossumlike in appearance)
learned to climb the trees, probably as a means
Of protection from the great carnivorous dino
saurs which lived at the same period, or IN
seeking food; and there started the line OF
descent that eventuated in the primate family
(Which includes the monkeys and apes) and
finally in the physical ancestry Of man.
In the trees the emphasis shifted from hind
legs to forelegs, as means for getting about
On the ground quadrupeds tend to give
more and more Of the job Of getting along to
their hindlegs. The posterior limbs in q major
ity Of them have become more muscular, longer
and more stoutly boned than the foreltmbs.
But among tree-dwelling primates the
cestral ape-group due to its increasing size, de-
veloped the habit of swinging by the hands like
. tzapese performer, and letting the hindlegs
be used chiefly as . means Of reaching for
support when coming to q rest So powerful
arm, shoulder and chest muscles were progress
xively developed and the hindlegs became ex-
tended in line with the body.
ONE group Of the monkey family, the
~ baboons and drills, either came down out
Of the trees too soon, while they still employed
the ancestral quadrupedal habit, or else re-
adopted it after they found themselves on the
ground. At any rate, they are now Is COM
pletely our-footed as dogs or bears though,
like bears, they can and do stand On their
hindlegs and use their forelegs rs arms occa-
sonally
Thus 1t was the ancient anthropoid group