Random deviation from perfect symmetry of organisms is defined as fluctuating asymmetry. Fluctuating asymmetry is widely considered to be a marker of developmental instability, developmental noise and phenotypic quality at the population level. In this study, we investigated hypothesized relationship between 2D:4D digit ratios as a proxy measure of prenatal sex hormones and developmental instability levels in young adult humans. Materials and Methods:In the study, seven bilateral traits were measured for fluctuating asymmetry, as well as second and fourth digit lengths on both hands of 185 individuals, 87 men (mean age: 22.42 ± 3.37) and 97 women (mean age: 22.88 ± 3.87). The second digit length was divided by the fourth digit length and the resulting value was used as the digit ratio (2D:4D). Composite fluctuating asymmetry was calculated using five bilateral traits displaying fluctuating asymmetry.Results: Only the right hand 2D:4D ratio is lower in men than in women. However, this difference disappears when the effect of digit lengths is controlled. Composite fluctuating asymmetry results reveal that men are more asymmetrical than women. There was no significant relationship between digit ratios and composite fluctuating asymmetry. Conclusion:In this study, the 2D:4D digit ratios appear to be influenced (at least in humans) by different digit lengths. This study also confirms previous studies that digit ratios as a proxy measure of exposure to either high testosterone or estrogen levels during early development does not appear to affect levels of developmental instability.

Handgrip strength is a quick way to assess overall muscle strength. Low handgrip strength is an indicator of poor health. While handgrip strength is related with mortality and morbidity, for some parameters, handgrip strength is even a stronger predictor of health than chronological age alone. Handgrip strength is highly sexually dimorphic and has a high heritability. It is thought that this is an outcome of sexual selection and intrasexual competition in our evolutionary history. Some anthropological studies confirm this view, and it is claimed that there are relationships between grip strength and aggression, athletic performance and attractiveness, especially in men. The aim of this study is to review the relationship of diseases with handgrip strength in anthropological perspective and examine the idea that handgrip strength being a marker of biological fitness.

Some research in the field of anthropology provides some evidence that high hand grip strength and a symmetrical body are reliable indicators of health and fitness. In this study, we consider the relationship between these two indicators in healthy young individuals. In the study, 185 university students (87 males and 97 females) were examined. In addition to the weight and height of the students, eight bilateral traits were measured with an accuracy of 0.01 mm to evaluate their bodily symmetry, and their hand grip strength was determined with a hand dynamometer by applying the Southampton protocol. The composite fluctuating asymmetry formula was used to standardize the bodily symmetries of individuals. Analyzes show that women have a more symmetrical body structure and lower hand grip strength scores than men. When the effect of weight and body mass index was controlled, no correlation was observed between composite fluctuating asymmetry and hand grip strength in both sexes. As conclusion, although hand grip strength and body symmetry are accepted as reliable indicators of health and fitness, it is seen that there is no significant relationship between the two indicators in both sexes in our study. In addition, our findings support the view that fluctuating asymmetry is not a reliable indicator to predict an individual's physical fitness and developmental quality.