Effects of hand preference on digit lengths and digit ratios among children and adults

Kumar, Sanjay; Singh, Maharaj; Voracek, Martin

doi:10.1016/j.earlhumdev.2020.105204

Cited by 5 publications

(2 citation statements)

References 84 publications

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“…This explicitly indicates that the same mechanism is not mediating the effects of different variables (which may not be clear in a single‐digit ratio study). Thus, the present study adds support to the significance of multiple digit ratios study design (Kumar et al, 2017; Kumar, Singh, & Voracek, 2020; Loehlin et al, 2009; Stolten et al, 2016; Voracek, 2009).…”

Section: Discussionsupporting

confidence: 74%

Effects of caste, birth season, and family income on digit ratios

Kumar

Voracek

2022

American J Hum Biol

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Objectives: The contributions of latitude and ethnicity in the determination of cross-society differences in digit ratios are unclear. In India, different castes (endogamous groups) have been living in the same areas (villages or towns) for the last 1500 years and, therefore, these groups may have different gene pools without a latitude-related difference component. Thus, in the present study, we studied the effect of caste on digit ratios. We also studied the effects of sex, birth season, and family income on digit ratios. Methods:We selected a sample of 301 college students (age: M = 19.9 years, SD = 2.63) in Muzaffarnagar city of western Uttar Pradesh, India, and asked participants for information regarding their birth month, religion, caste, and monthly family income. We measured participants' dorsal and palmar digit lengths (of all fingers, except the thumb, in both hands) using vernier calipers of 0.01 mm accuracy. Results: Other backward castes (intermediate castes) had longer digit lengths than general castes (upper castes), scheduled castes (lower castes), and Muslims. However, there was no difference in digit ratios of caste groups (scheduled castes vs. other backward castes vs. general castes vs. Muslims) or specific castes (Chamar-Jatav vs. Jat vs. Pandit-Tyagi). Winter-born women had lower left dorsal 2D:4D and 3D:4D ratios than summer-born women. Family income was related to higher dorsal 2D:4D and 3D:4D ratios among women. Moreover, in dorsal digit ratios, sex difference (men < women) occurred in digit ratios constituting digit 5, whereas, in palmar digit ratios, sex difference occurred in digit ratios constituting digit 2. Conclusions:The present study suggests that endogamy-led genetic difference in ethnic/caste groups is not a determinant, whereas birth season (i.e., the exposure to sunlight) and family income might be determinants of digit ratios.In addition, compared to palmar digit ratios, dorsal digit ratios are better markers of sexual dimorphism.

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Section: Discussionsupporting

confidence: 74%

Effects of caste, birth season, and family income on digit ratios

Kumar

Voracek

2022

American J Hum Biol

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“…It was found that the right 2D:4D ratio correlates with the duration of bipolar disorder in manic patients. It is known that the 2D:4D ratio is more sensitive in the right hand compared to the left [20]. We believe that the right hand 2D:4D ratio can be used to determine the chronicity of the disease in cases where su cient medical history cannot be obtained in manic patients.…”

Section: Discussionmentioning

confidence: 93%

Could the shortness in the digit ratio (2D:4D) of manic people with bipolar disorder be directly associated with criminal behavior?

Emre,

Yıldız,

Aydin

et al. 2024

Preprint

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The purpose of this study was to examine the relationship between 2D:4D digit ratio and aggression and impulsivity in manic patients (BP) with and without a history of criminal behavior. The study included a total of 106 participants, which encompassed 41 healthy individuals, 34 BP with a history of criminal behavior (CBP), and 31 BP who had not engaged in criminal activity (NCBP). All participants were administered a socio-demographic data form, the Buss-Perry Aggression Scale (BAQ), Barratt Impulsiveness Scale-11 (BIS-11), and the Young Mania Rating Scale (YMRS) for those with bipolar manic disorder and 2D:4D digit ratio measurement. The right hand 2D:4D finger ratios of BP included in the study were significantly lower compared to the control group, and that the right hand 2D:4D finger ratio was correlated with the duration of the illness. Moreover the BAQ scores of BP were higher compared to the control group. In CBP, both the right hand 2D:4D and left hand 2D:4D were significantly lower compared to the control group. Furthermore, the BIS-11 score and YMRS of CBP were significantly higher compared to NCBP.

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