Numerical variation of the presacral vertebral column in three population groups in North America

Abstract

A total of 1,239 skeletons from among Mongoloid, Caucasoid and Negroid population groups in North America was examined for variations in the number of presacral vertebrae. The overall incidence of variation was 11%; 6% with 23 and 5% with 25 presacral vertebrae. Differences in total variation among the three groups were not significant, but differences in the incidence of 23 and 25 presacral vertebrae among the groups were highly significant.Numerical vertebral variation occurred in 11% of both sexes, but with males having a higher frequency of 25 presacral vertebrae and females having a higher frequency of 23 presacral vertebrae. The incidence of the specific variation of 23 or 25 presacral vertebrae was not significantly different among the males of the three groups studied, whereas 23 presacral vertebrae were found significantly more often in the Negroid females. Numerical variation of vertebrae was not associated with age.The data strongly support the conclusion that the total frequency of variation in the number of presacral vertebrae is a specific characteristic of any particular population group and that there is a tendency in all population groups toward an increase in number in males and a decrease in number in females.

The new framework for understanding placental mammal evolution

“…As previously discussed, (89,90) cervical formula is extremely conservative among mammals; however, thoracolumbar count is less so. For example, a large sample of humans (98) shows median values of 7 cervicals, 12…”

Numerical Variations in Human Vertebral Column

“…The incidence of such variations was reported by Nishi (1928), Bornstein and Peterson (1966), Pineau and Delmas (1969), and Kaufman (1974) to be as 8.2% (in 9 out of 158 Japanese skeletons, where 6 were male and 3 were female), 2.2% (in 19 out of 647 male skeletons (2.9%), and in 9 out 592 female skeletons (1.9%), 7.2 (in 8 out of 110 skeletons), and 7.5% (in 35 out of 321 male skeletons (10.9%), and in 7 out of 169 female skeletons (4.1%), respectively.…”

“…Thus, 25 PSV was grouped, for example, as C7, T13, and L5. The incidence of such kind of variations was determined to be 2% (in 2 out of 100 skeletons), 2.6% (in 33 out of 1239 skeletons), 2.8% (in 13 of 462 skeletons) and 6.3% (in 7 out of 110 skeletons) by Staderini (1894), Bornstein and Peterson (1966), Kaufman (1974), and Pineau and Delmas (1969), respectively. On the other hand, Steinbach (1889) named the added vertebra between the thoracic and lumbar regions as thoraco-lumbar vertebra.…”

“…Bardeen (1904) has expressed that the incidences of numerical increase with 25 PSV (4.3%) and numerical decrease with 23 PSV (4.7%) were approximately close to each other. However when sex is taken into consideration, 25 PSV is frequent in males whereas 23 PSV is common in females (Hasebe, 1913;Nishi, 1928;Bornstein and Peterson, 1966;Kaufman, 1974). The incidence of 25 PSV was found to be 6.8% in males and 3% in females by Bornstein and Peterson (1966), and the incidence of 23 PSV was determiend to be 7.9% in females, which was nearly two folds of males (4.2%).…”

“…However when sex is taken into consideration, 25 PSV is frequent in males whereas 23 PSV is common in females (Hasebe, 1913;Nishi, 1928;Bornstein and Peterson, 1966;Kaufman, 1974). The incidence of 25 PSV was found to be 6.8% in males and 3% in females by Bornstein and Peterson (1966), and the incidence of 23 PSV was determiend to be 7.9% in females, which was nearly two folds of males (4.2%). According to some researchers (Lanier, 1939;Bornstein and Peterson, 1966;Kaufman, 1974), a vertebra with costal facets was thought to be contributed to the thorax, and this vertebra, bearing cervical or lumbar ribs was classified as a thoracal vertebra without taking into consideration other morphological characteristics.…”