Dataset Information

Differential Placing of Flexion Creases Contributes to Sex Differences in the Second-to-Fourth Digit Ratio (2D:4D).

ABSTRACT: The present research examined whether differential placing of the basal flexion creases contributes to the occurrence of sex differences in digit ratio (2D:4D) derived from palmar digit lengths. The ratio of palmar-to-dorsal digit length, a measure of the placing of the basal flexion crease in the finger, was derived for the digits 2 and 4 of the right hand in two independent samples (Study I: N = 100; Study II: N = 200), in accordance with discovery-replication sample approach. The results show that men have lower palmar-to-dorsal digit ratios than women, and this effect is significantly stronger for digit 2 than for digit 4. Thus, the present study supports the likelihood that differential placing of flexion creases in the digits contributes to the occurrence of sex differences in palmar 2D:4D. In addition (Study II), the measurement procedure assessing the placing of flexion creases was validated. In conclusion, this evidence highlights potential conceptual shortcomings and technical limitations in the measurement conventions and methods currently employed in the field of 2D:4D research.

SUBMITTER: Kumar S

PROVIDER: S-EPMC6688535 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

Differential Placing of Flexion Creases Contributes to Sex Differences in the Second-to-Fourth Digit Ratio (2D:4D).

Kumar Sanjay S Voracek Martin M Singh Maharaj M

Frontiers in endocrinology 20190802

The present research examined whether differential placing of the basal flexion creases contributes to the occurrence of sex differences in digit ratio (2D:4D) derived from palmar digit lengths. The ratio of palmar-to-dorsal digit length, a measure of the placing of the basal flexion crease in the finger, was derived for the digits 2 and 4 of the right hand in two independent samples (Study I: <i>N</i> = 100; Study II: <i>N</i> = 200), in accordance with discovery-replication sample approach. Th ...[more]

PMID: 31428058

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Project description:ObjectivesTo explore whether random chance, weak research methodology, or inappropriate reporting can lead to claims of statistically significant (yet, biologically meaningless) biomarker associations, using as a model the relation between a common surrogate of prenatal testosterone exposure, second-to-fourth digit ratio (2D:4D), and a random indicator of good luck.DesignCross sectional study.SettingUniversity sports performance laboratory in the United States. Data were collected from May 2015 to February 2017.Participants176 adults (74 women, 102 men), including university students, faculty, and staff with no history of injuries, disease, or medical conditions that would affect digit length.Main outcome measures2D:4D, body composition parameters potentially influenced by androgens (bone mineral content, bone mineral density, body fat percentage), and good luck (using poker hands from randomly selected playing cards as a surrogate).Results2D:4D significantly correlated with select body composition parameters (Spearman's r s range -0.26 to 0.23; P<0.05), but the correlations varied by sex, participant hand measured, and the method of measuring 2D:4D (by photocopy or radiography). However, the strongest correlation observed was between right hand 2D:4D in men measured by radiograph and poker hand rank (r s=0.28, P=0.004).ConclusionsGreater prenatal exposure to testosterone, as estimated by a lower 2D:4D, significantly increases good luck in adulthood, and also modulates body composition (albeit to a lesser degree). While these findings are consistent with a wealth of research reporting that 2D:4D is related to many seemingly disparate outcomes, they are not meant to provide confirmatory evidence that 2D:4D is a universal biomarker of nearly everything. Instead, the associations between 2D:4D and good luck are simply due to chance, and provide a "handy" example of the reproducibility crisis within medical and scientific research. Biologically sound hypotheses, pre-registration of trials, strong methodological and statistical analyses, transparent reporting of negative results, and unbiased interpretation of data are all necessary for biomarker studies and other areas of clinical research.

Dataset Information

Differential Placing of Flexion Creases Contributes to Sex Differences in the Second-to-Fourth Digit Ratio (2D:4D).

Publications

Differential Placing of Flexion Creases Contributes to Sex Differences in the Second-to-Fourth Digit Ratio (2D:4D).

Similar Datasets

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