Many theories have been advanced to explain human hairlessness, however, there is no consensus. This study of 76 males observed that skin reflectance measuring skin colouration and melanin pigmentation correlated with hair size and follicle density. Individuals with a greater concentration of melanin within the superficial layer of the skin had a lower follicle density and smaller sizes of hairs. In contrast, individuals with a lower melanin concentration and lighter skin colour had a full range of hairiness. This leads to the suggestion that over the course of human evolution, high concentrations of melanin in consistently exposed to ultraviolet radiation areas developed first and that hair loss was a consequence of competition in the skin between melanin production and hair growth. Darker pigmented skin and lower follicle density are significantly correlated (R2=0.283; p<0.05). Individuals with darker skin had a mean of 4.91 follicles per cm2 whereas those with lighter skin reflectance had 11.20 follicles per cm2. This suggests that increased concentrations of melanin in the basal layer of the epidermis may limit hairiness by negatively influencing the skin's ability to produce hair.

Palmistry or Chiromancy is the art of reading lines on the palm of the hands. Today, many researchers believe that the lines on the palms of the hands can predict the individual’s future. Computer programs are being designed which can automatically read the lines on the palm of the hand. One popular theory is that the length of the line of life will indicate lifespan. This theory was investigated in 1974 by Wilson and Mather who found no significant correlation between life expectancy and the length of the line of life. In 1990 Newrick and colleagues found a significant correlation as measured on 100 cadavers. These conflicting investigations are the only existing studies which have explored the relationship between palmistry and longevity. Since then no other study has validated nor disproven these claims. A total of 60 cadavers donated to The University of Adelaide were used in this study. Total hand length and the line of life length were measured on all cadavers. The age at and cause of death were also recorded. Linear regressions were used to establish any correlations between longevity and the length of the line of life. No significant correlations were found. There was also no significant difference between males and females or the right or left hands. As no significant correlations were found between longevity and the line of life all efforts at producing more reliable and automatic ways to read the lines are futile. This study puts to rest any debate surrounding the use of the line of life in palmistry as introduced by Newrick and colleagues.