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Emma Nelson,

Department Archaeology                         

University of Liverpool

 

Using digit ratios (2D:4D) to investigate social systems in anthropoids; implications for the study of the evolution of hominin sociality.                                       Questions    References

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Questions
  • Does 2D:4D reflect changes in social system across anthropoids? Are these results inline with what we expect from different levels of PAE across species? For example is low 2D:4D (high PAE) associated with high levels of sexual selection? How can this inform us about the evolutionary changes of sociality through primate evolution? 
  • Does 2D:4D correlate with other traits associated with sexual selection such as canine and body size dimorphism and secondary sex ratio?  
  • Does 2D:4D correlate with measures of social complexity such as brain size and group size?
  • Does 2D:4D reflect differences in sexually selected traits and behaviours at different taxonomic levels (genus, species, and population)? 
  • Do ratios calculated from the hard tissues, such as the length of the 2nd to 4th proximal phalanges (2PP:4PP), correlate with soft-tissue 2D:4D? Can formulae be developed to mathematically replace the soft-tissue component of bone derived ratios?
  • Finally, in the light of what is found by this study and what we already know from human 2D:4D research, will it be possibly to use bone ratios taken from fossil samples to understand the evolution of social systems in the hominin lineage?
References

1 Manning, J.T., Scutt, D. and Lewis-Jones, D.I. 1998. The ratio of the 2nd to 4th digit length: a predictor of sperm numbers and the concentration of testosterone, luteinizing hormones and oestrogen. Human Reproduction,13 (11): 3000-3004

2 Lutchmaya, S., Baron-Cohen, S.,  Raggatt, P. Knickmeyer, R. and Manning, J.T. 2004. 2nd to 4th digit ratios, fetal testosterone and estradiol. Early Human Development, 77:23 – 28

3 Manning, J.T. 2002. Digit Ratio. A pointer to fertility, behavior, and health. Rutgers University Press. New Brunswick, New Jersey, and London

4 McIntyre, M.H., Cohn, B.A. and Ellison, P.T. 2006. Sex dimorphism in digital formulae of children. American Journal of Physical Anthropology, 129:143-150

5 Kondo, T., Zakany, J. Innis, J.W. and Duboule, D.1997. Of fingers, toes and penises. Nature, 390:29

6 Manning, J.T., Churchill, A.JG. and Peters, M. 2007. The effects of sex, ethnicity, and sexual orientation on self-measured digit ratio (2D:4D). Archives of Sexual Behavior, 36(2):223-233 [recent overview]

7 Manning, J.T., Barley, L., Walton, J., Lewis-Jones, D.I., Trivers, R.L., Singh, D., Thornhill, R., Rohde, P., Henzi, P., Soler, M. and Szwed, A. 2000. The 2nd to 4th digit ratio, sexual dimorphism, population differences, and reproductive success: evidence for sexually antagonistic genes? Evolution and Human Behaviour, 21:163-183

8 Bailey, A.A. and Hurd, P.L. 2005. Finger length ratio (2D:4D) correlates with physical aggression in men but not women. Biological Psychology, 68(3):215-222

9 Benderlioglu, Z. and Nelson, R.J. 2004. Digit length ratios predict reactive aggression in women, but not in men. Hormones and Behavior, 35(5):558-564

10 Manning, J.T. and Taylor, R.P. 2001. The 2nd to 4th digit ratio (2D:4D) and male ability in sports: implications for sexual selection in humans. Evolution and Human Behavior, 22:66-69

11. Paul, S N; Kato, B S; Hunkin, J L; Vivekanandan, S; Spector, T D. 2006 The Big Finger: the second to fourth digit ratio is a predictor of sporting ability in women. British Journal of Sports Medicine. 40(12):981-983

12 Roney, J.R. and Maestripieri, D. 2004. Relative digit lengths predict men’s behavior and attractiveness during social interactions with women. Human Nature, 15 (3):271-182

13 Van den Bergh, B. and Dewitte, S. 2006. Digit ratio (2D:4D) moderates the impact of sexual cues on men’s decisions in ultimatum games. Proceedings of the Royal Society B: Biological Sciences, 273:2091-2095

14 Clark, A.P. 2004. Self-percived attractiness and masculinization predict women’s scoiosexuality. Evolution and Human Behavior, 25:113-124

15 Van Anders, S.M., Vernon, P.A. and Wilbur, C.J. 2006. Finger-length ratios show evidence of prenatal hormone-transfer between opposite-sex twins. Hormones and Behavior, 49 (3):315-319

16 Malas, A.M., Dorgon, S., Evcil, E.H. and Desdicioglu, K. 2006. Fetal development of the hand digits and digit ratio (2D:4D). Early Human Development, 82(7):469-475

17 Manning, J.T., Bundred, P.E., Newton, D. J. and Flanagan, B.F. 2003. The second to fourth digit ratio and variation in the androgen receptor gene. Evolution and Human Behavior, 24: 399-405

 

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