Study of Aggressive Behavior of an Individual from Ratio of Index and Ring Fingers’ Length

Lecturer, Department of Anatomy, Kathmandu University School of Medical Sciences, Chaukot, Nepal Assistant Professor, Department of Anatomy, Kathmandu University School of Medical Sciences, Chaukot, Nepal Associate Professor, Department of Anatomy, Kathmandu University School of Medical Sciences, Chaukot, Nepal Post Graduate Student, Department of Anatomy, Kathmandu University School of Medical Sciences, Chaukot, Nepal Lecturer, Department of Physiology, Tribhuwan University, Universal College of Medical Sciences, Bhairahwa, Nepal Post Graduate Student, College of Nursing, B. P. Koirala Institute of Health Sciences (BPKIHS), Dharan, Nepal


Introduction
Human aggression is defined as any behavior directed toward another individual that is carried out with the proximate (immediate) intent to cause harm. In addition, the perpetrator must believe that the behavior will harm the target, and that the target is motivated to avoid the behavior [1][2][3][4] . Aggressive behavior in society is a serious social problem. Between 1998 and 1999, the number of violent offences in England and Wales rose by 6.3%, the majority of which was violence against the person (83%) 5 .
The ring finger is the fourth digit of the human hand and the second most ulnar finger located between the middle finger and the little finger while the index finger is the first finger and the second digit of a human 6,7 . The index finger is located between the thumb and the middle finger and usually the most dexterous and sensitive finger of the hand 6,8 . Digit ratio commonly known as 2D:4D is the ratio of the index finger (2D) to ring finger (4D) 9 . Finger length ratio (2D:4D) is a sexually dimorphic trait. The ratio of second digit (index finger) to fourth digit (ring finger) is smaller for males than females in humans, mice and baboons [10][11][12][13][14][15] . Males develop a lower 2D:4D than the females by the end of the first trimester of gestation or by the 14 th week of gestation 16-IJBR (2014) 05 (11) www.ssjournals.com

Participants
Subjects for the present study were recruited from Kathmandu University School of Medical Sciences (KUSMS), Chaukot, Nepal. Two hundred students (77 boys and 123 girls) with no congenital anomalies of finger were randomly selected as participants from KUSMS, Chaukot, Nepal. Age ranged from 19 years to 25 years. The study was approved by the Institutional Review Committee of Kathmandu University School of Medical Sciences (IRC-KUSMS). On obtaining the written consent from participants after explaining the purpose of the present study, Buss and Perry Aggression Questionnaires 41 were distributed. The questionnaires were collected after completion by the participants.

Measurement of 2D:4D Ratio:
The dorsum of the both hand was kept on smooth surfaced table with fingers fully extended. Then length of index finger (2D) and ring finger (4D) of both hands was measured on ventral surface of hand from the midpoint of most proximal crease of each digit to fingertip [8,9], using digital vernier calipers. The length was taken in millimeter (mm) and ratio was calculated by dividing index finger length by ring finger length. Mean of right and left hand ratio was taken as mean 2D:4D ratio for each participant.

Statistical Analysis
Data was analyzed using SPSS version 17.00 and Microsoft Office Excel 2010. The analysis was performed to derive mean, median, mode, standard deviation, minimum and maximum values. Two sample t -test was done for average digit ratio and different aggressions. P value of less than 0.01 was considered as significant. The present study shows physical aggression more in male than in female while verbal aggression, anger and hostility are more in female than in male. But total aggression of male (83.52) is more than that of female (80.23) {Table 1}.   (11) www.ssjournals.com  0.073 P value = 0.073 Pearson correlation between average 2D-4D ratio of male and female is 0.073 which is not statistically significant (table 3). In male physical aggression is correlated with verbal aggression, anger and hostility but there is no correlation between verbal aggression and anger (table 4). In Nepalese female population studied, physical aggression is correlated with verbal aggression and anger but it did not show correlation with hostility (table 5).

Results
Anger significantly correlated with physical aggression and hostility both in male and female (table 4 and 5). Average 2D-4D ratio is neither correlated with any form of aggression in male nor correlated with any form of aggression in female (table 4 and 5).

Discussion
Human beings have emotions throughout their life. Every emotion is related to the achievement of personal goals; therefore, happiness is linked to the progress towards the goal whereas sadness is linked to the failure or non-achievement of a goal. Anger arises when a plan goes away or is blocked and anxiety emerges when a goal is threatened, and so on 42 .
From the present study aggression showed a reliable sex difference with males being on average, more aggressive than females. This study agrees with the study done by Daly 47 .
The present study showed the aggression more in male than in female while verbal aggression, anger and hostility were more in female than in male [table 1]. These results are different than those Bailey et al and Virupaxi et al. In their results physical, verbal and anger were more in male; and only hostility was more in female.
We found significant correlation of anger with physical aggression and hostility in male. In the study done by Bailey et al anger significantly correlated with all three sub-scales of aggression (physical aggression, verbal aggression and hostility) in male. In the present study all form of aggression were correlated in female, except verbal aggression with hostility and anger. In the study of Bailey et al all form of aggression were correlated in female, except in case of verbal aggression and hostility.
We did not find any correlation between digit ratio and any form of aggression either in males or in females. These results agree with the results obtained by Virupaxi et al.
We found from the present study that index finger length in males was shorter than ring finger length and significantly different as compared with females. These results confirms that digit ratio (2D:4D) is sexually dimorphic. These findings show similarity with earlier findings of George 48 47 who found that index fingers in males tend to be shorter than ring fingers. These fingers lengths are affected by testosterone and estrogen in intrauterine life 12 .
We also found that females had higher digit ratio in comparison with males. These result agree with earlier results of Phelps, George, Manning et al 24  IJBR (2014) 05 (11) www.ssjournals.com

Conclusion
On average, males are more aggressive than females. The physical aggression is more in males but verbal aggression, anger and hostility are more in females. The ratio of index finger and ring finger (2D:4D) is higher in male than in female. Males have shorter index finger than the ring finger but females have equal length of index and ring fingers. This information is useful in forensic science and anthropology. Therefore, large Nepalese population in other parts of Nepal should be studied.