Comparison of External Measurement Methods of the 2D:4D Digit Ratio

IF 1.9 4区医学 Q1 ANTHROPOLOGY

American Journal of Human Biology Pub Date : 2026-09-20 DOI:10.1002/ajhb.70337

İlknur Çöllü, Mehmet Ali Malas

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引用次数: 0

Abstract

Objectives

External methods for measuring digit length differ in the hand surface and anatomical landmarks used, but the comparability of resulting 2D:4D ratios is unclear. This study compared 2D:4D ratios obtained using four external measurement methods and evaluated between-method differences, correlations, and reliability.

Methods

Digit lengths were measured in 231 Turkish university students (103 males, 128 females). Measurements were obtained directly with calipers from the dorsal and ventral surfaces and indirectly from photocopies and photographs. The 2D:4D ratio was calculated as second-digit length divided by fourth-digit length. Right and left hands were analyzed separately for effects of measurement method, sex, and hand side.

Results

Males had lower 2D:4D ratios than females for all methods and hand sides except direct dorsal measurement of the left hand. Mean ratios were lowest with direct dorsal measurement and highest with direct ventral measurement. Differences among methods were significant for both hands (p < 0.001). Between-method correlations ranged from r = 0.529–0.771 for the right hand and r = 0.440–0.776 for the left hand (all p < 0.001). Intraobserver and interobserver reliability in the pilot sample was high (ICC = 0.85–0.95).

Conclusions

The 2D:4D ratio varies systematically according to the external measurement method used. Measurement protocols should therefore be reported explicitly, and absolute 2D:4D values obtained using different methods should be compared cautiously. These findings highlight the importance of standardizing measurement methods in 2D:4D research and suggest that the detection of sex differences may vary according to both the measurement method and hand side.

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二维：四维数字比外部测量方法的比较。

目的：测量手指长度的外部方法在手部表面和使用的解剖标志上有所不同，但所得到的2D:4D比率的可比性尚不清楚。本研究比较了使用四种外部测量方法获得的2D:4D比率，并评估了方法间差异、相关性和可靠性。方法：对231名土耳其大学生（男103名，女128名）进行手指长度测量。测量直接用卡尺从背和腹表面获得，间接从复印件和照片获得。二维：四维比例计算为第二位数字长度除以第四位数字长度。分别分析右手和左手的测量方法、性别和手侧的影响。结果：除直接测量左手背侧外，男性各测量方法的2D:4D比值均低于女性。直接背侧测量的平均比值最低，直接腹侧测量的平均比值最高。结论：采用不同的外部测量方法，2D:4D比值存在系统性差异。因此，测量方案应明确报告，使用不同方法获得的2D:4D绝对值应谨慎比较。这些发现强调了标准化测量方法在二维：四维研究中的重要性，并表明性别差异的检测可能因测量方法和手侧而异。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

American Journal of Human Biology 生物-生物学

CiteScore

4.80

自引率

13.80%

发文量

124

审稿时长

4-8 weeks

期刊介绍： The American Journal of Human Biology is the Official Journal of the Human Biology Association. The American Journal of Human Biology is a bimonthly, peer-reviewed, internationally circulated journal that publishes reports of original research, theoretical articles and timely reviews, and brief communications in the interdisciplinary field of human biology. As the official journal of the Human Biology Association, the Journal also publishes abstracts of research presented at its annual scientific meeting and book reviews relevant to the field. The Journal seeks scholarly manuscripts that address all aspects of human biology, health, and disease, particularly those that stress comparative, developmental, ecological, or evolutionary perspectives. The transdisciplinary areas covered in the Journal include, but are not limited to, epidemiology, genetic variation, population biology and demography, physiology, anatomy, nutrition, growth and aging, physical performance, physical activity and fitness, ecology, and evolution, along with their interactions. The Journal publishes basic, applied, and methodologically oriented research from all areas, including measurement, analytical techniques and strategies, and computer applications in human biology. Like many other biologically oriented disciplines, the field of human biology has undergone considerable growth and diversification in recent years, and the expansion of the aims and scope of the Journal is a reflection of this growth and membership diversification. The Journal is committed to prompt review, and priority publication is given to manuscripts with novel or timely findings, and to manuscripts of unusual interest.