The digit ratio (2D:4D) in China: A meta-analysis

Area of Science:

• Anthropometry
• Human biology
• Behavioral endocrinology

Background:

• The 2D:4D ratio, a marker of prenatal androgen exposure, varies across populations.
• Understanding factors influencing 2D:4D in diverse ethnic groups is crucial for human behavior research.

Purpose of the Study:

• To investigate digit ratio (2D:4D) patterns in China (mainland and Taiwan).
• To analyze the impact of ethnicity, digit measurement techniques, age, and latitude on Chinese 2D:4D.

Main Methods:

• A comprehensive meta-analysis of 28 studies.
• Inclusion of 112 independent samples and 19,093 participants.

Main Results:

• Right-hand 2D:4D was significantly lower in males than females; left-hand differences approached significance.
• No significant 2D:4D variations were observed between Han Chinese and ethnic minorities.
• Indirect digit measurement methods yielded lower 2D:4D ratios compared to direct methods; age and latitude showed no effect.

Conclusions:

• Chinese 2D:4D sex differences align with Western studies, suggesting genetic factors over environmental influences like latitude.
• Digit measurement methodologies significantly impact 2D:4D findings, precluding combined analysis of different techniques.