Interesting paper discussing scoliosis in the context of human evolution... (emphasis added)

A Homo erectus skeleton was found to have substantial scoliosis. "KNM-WT15000 H. erectus" is Turkana Boy which is 1.6 million years old.

4.4. Clinical implications afforded by the fossil record of
our spine: scoliosis

The above conclusion is of interest with respect to the
incidence of a modern human malady, idiopathic scoliosis.
In a recent survey of a large sample of great ape skeletons
by B.M. Latimer of the Cleveland Museum of Natural History,
no cases of scoliosis were observed in several hundred
chimpanzee and gorilla spines.

Such a finding is in accord with the observations of Lowe
and colleagues [46]. “Naturally occurring scoliosis in vertebrates
is seen almost exclusively in humans. . . .[I]t has been
difficult to distinguish causative factors from those that may
result from the condition. . . . The current thinking is that
there is a defect of central control or processing by the central
nervous system that affects a growing spine. . . and that
the spine’s susceptibility to deformation varies from one individual
to another” ([46], p. 1165). However, “[a]ny hypothesis
that proposes a neurological defect must account
for the impression that many patients with idiopathic scoliosis
have above-average ability in sports.
These observations
have been largely anecdotal, but a study of girls attending
ballet school showed that the prevalence of scoliosis may be
as high as 20 percent” ([46], p. 1162).

These conclusions are fully concordant with the highly
unusual “situation” that characterizes modern humans, viz.,
a re-elongated lower spine with what can only be described,
compared to other primates with long lower spines, as a
“semi-competent” erector spinae.
Significant lumbar deviation
is prevented in apes by their precipitous lumbar reduction,
lumbar vertebra “capture” by their ilia, and in Old
World monkeys by their massive erector spinae (Fig. 7).
While this may not account for idiopathic thoracic manifestations
of the disorder in humans, subtle imbalances in
the elongated human lumbar spine might possibly play an
initiating role even though they would remain subclinical
until downstream and more cranial effects became more

At a minimum lumbar scoliosis is seriously debilitating
and should have long been a target of strong selection. Why
is it still prevalent in humans? The logical response is that
selection for effective bipedality must have been so vigorous
in the ancestors of A. afarensis that functional lordosis was
facilitated despite the increased risk of scoliotic deviations
and flexion-induced injury permitted by a semi-competent
erector spinae.
The functionally elongated lumbar column
of Australopithecus and its descendants must have predisposed
them to even greater rates of spinal pathology than
occur in modern humans. It is important in this regard that
the spine of KNM-WT15000 H. erectus skeleton displays
substantial evidence of scoliosis, including both thoracic
asymmetry and vertebral fracture (J.C. Ohman, B.M. Latimer,
personal communication; observations by the author).
Risk of scoliosis may have served as the most prominent selection
factor favoring reduction in the length of the human
lumbar column over the course of the Plio-Pleistocene.