Second to fourth digit ratio: ethnic differences and family size in English, Indian and South African populations.
Manning JT, Henzi P, Venkatramana P, Martin S, Singh D.
School of Biological Sciences, The University of Liverpool, Liverpool, UK. email@example.com
BACKGROUND: The second to fourth digit ratio (2D:4D) is lower in men than in women. 2D:4D may be established in utero and is negatively correlated with sperm counts and testosterone in men and positively correlated with oestrogen in men and women. Negative associations between male 2D:4D and family size and positive associations between female 2D:4D and family size have been found in some European populations. AIM: The study seeks to investigate the relationship between 2D:4D and family size in samples from Europe, Asia and Africa. SUBJECTS AND METHODS: Measurements of right hand 2D:4D were made in English (Merseyside, n = 403), Indian (Sugali and Yanadi, n= 160) and South African (Zulu,n = 258) populations. RESULTS: 2D:4D was weakly sexually dimorphic and showed strong ethnic differences. There were significant associations between 2D:4D and family size. For males these included negative associations in English and South African samples, and in the total sample. In females there was a positive association in the English sample, a negative association in the South African sample, and the total female sample showed a positive relationship between 2D:4D and family size. CONCLUSIONS: 2D:4D showed weak sex and strong ethnic differences. Low values of 2D:4D were associated with large family size in men. The situation was less clear in women but on balance there was evidence to support a relationship between high values of 2D:4D and large family size.
Source: Ann Hum Biol. 2003 Sep-Oct;30(5):579-88.
PMID: 12959899 [PubMed - in process]