Racial differences in vaginal dimensions: strike one more against Rushton

J.P. Rushton in Race, Evolution, Behavior (pdf) claims black > white > Asian. What do we actually see?

Gynecol Obstet Invest 2000;50:54–59

Comparison of Vaginal Shapes in Afro-American, Caucasian and Hispanic Women as Seen with Vinyl Polysiloxane Casting

Paula B. Pendergrass Cornelia A. Reeves Meyer W. Belovicz Darron J. Molter Janet H. White

Abstract

Full vinyl polysiloxane casts of the vagina were obtained from 23 Afro-American, 39 Caucasian and 15 Hispanic women in lying, sitting and standing positions. A new shape, the pumpkin seed, was found in 40% of Afro-American women, but not in Caucasians or Hispanics. Analyses of cast and introital measurements revealed: (1) posterior cast length is significantly longer, anterior cast length is significantly shorter and cast width is significantly larger in Hispanics than in the other two groups and (2) the Caucasian introitus is significantly greater than that of the Afro-American subject.

[. . .]

In addition to the three molds, vaginal length and introital distensibility were obtained. With the subject in the supine position, length was taken by having the subject insert a 7-inch polished acrylic rod as far back into her vagina as possible without causing discomfort; introital distensibility was determined by having the subject insert a lubricated 125-ml polypropylene Erlenmeyer flask as far back as possible into her vagina without causing discomfort. The circumference at the point of entry was marked and measured, and a diameter was calculated.

[. . .]

Comparisons of the length of anterior and posterior cast walls as measured with calipers for all three study groups are given in table 2. For the posterior measurements, Hispanics showed a much narrower range than either Afro-Americans or Caucasians, and, importantly, they exhibited no posterior lengths less than 8 cm. Consequently the mean for Hispanic casts was significantly greater (p = 0.01). The mean anterior length for Hispanics was also significantly different (p = 0.01) but was shorter than those of the Afro-Americans and Caucasians. Consequently, the overall picture of the Hispanic cast is one that is relatively short along the anterior wall, but considerably longer along the posterior wall. The longer posterior measurements are reflected in deeper posterior fornices among the Hispanic subjects which, interestingly, all showed a full cervical imprint in the cast; this suggests that the cervix in Hispanics consistently lies in a deeper position within the vaginal vault.

Comparisons of the length of anterior and posterior cast walls as measured with strings for all three study groups are shown in table 3. These measurements directly reflect the caliper measurements. Hispanic casts are significantly longer posteriorly (p = 0.01) and shorter anteriorly (p = 0.01), with anterior lengths being shifted downward 1–1.5 cm.

Maximum widths (side-to-side) and depths (anteriorposterior) are given in table 4. Hispanic casts are significantly wider than either Afro-American or Caucasian casts (p = 0.01), with the mean being over 2 cm greater than Caucasians, and over 1 cm greater than Afro-Americans. Also, the range of widths is noticeably narrower among Hispanics indicating a more homogeneous group.

The mean depth is somewhat greater among Hispanics but is not significantly different from that of Afro-Americans and Caucasians. The variability among Hispanics is smaller with a narrower range and a smaller standard deviation.

Average rod lengths for Caucasians and Afro-Americans were 11.51 and 11.18 cm, respectively, and introital diameters were 4.66 and 3.14 cm, respectively. Both measurements were significantly different as measured by t test (table 5). Because rod and introital measurements were obtained from only 5 Hispanic subjects, no statistical comparisons can be made. Hispanic rod lengths ranged from 8.2 to 12.5 cm, and the introital measurements ranged from 1.9 to 3.2 cm.

A summary of t tests for comparison of Caucasian, Afro-American and Hispanic subjects is presented in table 5. These results show statistically significant differences among the three groups in the following areas: (1) the posterior cast length as measured with both calipers and strings is significantly longer for Hispanics than for Caucasians and Afro-Americans; (2) the anterior cast length as measured with both calipers and strings is significantly shorter for Hispanics than for Caucasians and Afro-Americans; (3) the width of casts in the lying position is significantly greater for Hispanics than for Caucasians and Afro-Americans; (4) the Caucasian introitus is significantly greater than that of the Afro-American. From this we conclude that there are differing distributions of shapes and much greater homogeneity among Hispanics than among Afro-Americans or Caucasians.

Trivial, perhaps, but these things add up. Racial differences exist, but--contrary to the impression one might get reading REB--they don't always neatly align with Rushton's "r-K" framework. Much of his work has value, but Rushton is far from infallible.

Previously, I've taken issue with some of Rushton's claims concerning testosterone (low in sub-Saharan Africans compared to Westerners; minimal black-white differences in America; hardly a good candidate to explain black social pathology), fundamental vocal frequency, penis size (what evidence exists suggests minimal black-white differences), and testis mass (greater in whites compared to Asians and blacks, according to the available autopsy studies).