Yoga Anatomy

26 Yoga anatomY

When creatures began to use their forelimbs to interact with their environment, the
ability to bear weight on the lower extremities became more necessary, and this signaled
the beginning of the uniquely human second lordotic curve—the lumbar. At first, it was
just a flattening out of the primary curve at the base of the spine, in order to allow animals
such as the yellow-bellied marmots pictured in figure 2.8 to support their center of gravity
above their base of support for longer periods of time.
The presence of a tail also helped in that feat of balance, but as the tail gradually disap-
peared, the shape of the spine had to change in order to bring the center of gravity fully
above the base of support. When this occurred in human evolution, the hip, sacral, and
leg structures essentially remained stationary in their quadruped relationship to the earth,
and the torso pushed its way up and back, forming the lumbar curve.
Figure 2.9a illustrates the difference in shape between a chimpanzee spine and a human
spine. Notice the absence of a lumbar curve in the chimp. This is why in order to move
across the ground, primates walk on their knuckles (figure 2.9b), and when they run on
their hind legs, they must throw their long arms back. Without a lumbar curve, that is the
only way they can get their weight over their feet.
The human spine is unique among all mammals in that it exhibits a full complement of
both primary (thoracic and sacral) and secondary (cervical and lumbar) curves (figure 2.10).

E5267/Kaminoff/fig2.9/417584/alw/pulled-r2

E5267/Kaminoff/fig2.10a/417585/alw/pulled-r2 E5267/Kaminoff/fig2.10b/421803/alw/pulled-r2

Figure 2.8 Flattening the primary curve to get the forelimbs off the ground.

Figure 2.9 (a) Only humans have lumbar curves, so (b) our primate cousins cannot be considered
true bipeds.

a b