The lumbar curve forms later from twelve to eighteen months, when the child begins to walk.
2.
The cervical and lumbar curves are " compensatory " or " secondary ", and are developed after birth.
3.
The fossils are sufficient to indicate that there was a lumbar curve, implying some adaptation to upright walking, in distinction to otherwise similar species known from the same period.
4.
The lumbar curve is more marked in the female than in the male; it begins at the middle of the last thoracic vertebra, and ends at the sacrovertebral angle.
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