The Origin of Personality types developed under selective pressures: Introducing Climatic-Adaptation Theory

Abstract

Classification of different char - acteristics of individuals is a longstand- ing debate in the study of personality type. Although classified personality types among temperament theories in Western and Oriental medicine share similar char- acteristics, understanding their relation- ship is limited both by difficulty in scientif- ic approach and by a lack of explanation for the personality types that can encom- pass these theories. In this study, we sug- gest inherent personal traits and individual differences based on selective pressures. Personality types adapted to different cli- mate zones are proposed and are com- pared to temperament theories. INTRODUCTION Traditional Western and Oriental medicine have attempted to cat- egorize people into different personality types through theoretical concepts such as Ayurveda, traditional Chinese medi- cine, the four temperaments theory, and four-constitution medicine 1-3 . Although various theories have been proposed over the centuries, they share a similar fundamental attitude that humans have a connection to nature. In addition, the characteristics of each personality type have many commonalities among theo- ries regardless of culture 4-5 . Studies us- ing psychological assessments have also shown similarities between catego- rized individuals and personality types through temperament theories 3,6 . These facts suggest that traditional tempera- ment theories do not provide arbitrary categorizations of personality character- istics; rather, they may provide specific conditions for differentiating personality types. Since Charles Darwin's theory of evolu- tion by natural selection, modern humans have been understood as the result of evolution from a common ancestor 7 . Genetic and archaeological evidence has shed light on the history of human settlement in the Late Pleistocene 8-9 . As modern humans spread over the globe from Africa, adaptation due to natural selection in different environments, es- pecially climate conditions, played an important role in human survival 10 . Therefore, different personality types can be understood as resulting from adap- tations to different environmental con- ditions throughout the history of human settlement. In this study, we introduce a theory of the origin of personality types. This theory is based on the hypothesis that the migra- tion of humans and their adaptation to various climate zones led to the forma- tion of different personality types. This study aims to explain the traits of person- ality types based on adaptation to differ- ent climate zones and to compare these adaptive traits with the personality char- acteristics of temperament theories. In the next section, we explain the theory of climate adaptation. We then compare it with the temperament theories and lastly discuss the present work.