The Evolutionary Life History Model of Externalizing Personality: Bridging Human and Animal Personality Science to Connect Ultimate and Proximate Mechanisms Underlying Aggressive Dominance, Hostility, and Impulsive Sensation Seeking

Abstract

The present work proposes an evolutionary model of externalizing personality that defines variation in this broad psychobiological phenotype resulting from genetic influences and a conditional adaptation to high-risk environments with high extrinsic morbidity-mortality. Due to shared selection pressure, externalizing personality is coadapted to fast life history strategies and maximizes inclusive fitness under adverse environmental conditions by governing the major trade-offs between reproductive versus somatic functions, current versus future reproduction, and mating versus parenting efforts. According to this model, externalizing personality is a regulatory device at the interface between the individual and its environment that is mediated by 2 overlapping psychobiological systems, that is, the attachment and the stress-response system. The attachment system coordinates interpersonal behavior and intimacy in close relationships and the stress-response system regulates the responsivity to environmental challenge and both physiological and behavioral reactions to stress. These proximate mechanisms allow for the integration of neuroendocrinological processes underlying interindividual differences in externalizing personality. Hereinafter I further discuss the model's major implications for personality psychology, psychiatry, and public health policy.

Why and how the early-life environment affects development of coping behaviours

“…From an evolutionary perspective, there is therefore a distinct benefit to maintaining developmental processes that facilitate fast and targeted learning in the very first stages of life, as well as processes that fine-tune coping behaviours to existing environmental conditions. As the early-life environment can be almost indistinguishable from life history, an additional advantage is a closer match to life-history aspects such as birth weight and number of offspring (Wolf et al 2007 ; Edenbrow and Croft 2011 ; Niemelä et al 2012 ; Hengartner 2017 ). Developmental processes that are sensitive to input from the immediate surroundings allow organisms a degree of flexibility and adaptability across generations, and increase the chances that young are capable of responding quickly and appropriately to surroundings that they do not yet have the personal experience with.…”

“…Even though some of the evolutionary factors underlying coping are becoming clear (see “ Why the early-life environment affects the development of coping ” section (Øverli et al 2007 ; Wolf et al 2008 ; Hengartner 2017 )), the developmental processes through which coping behaviours emerge have been studied to a much lesser degree (Stamps and Groothuis 2010 ; Groothuis and Trillmich 2011 ), and the mechanisms leading to coping behaviours later in life are largely unexplored (Haun et al 2013 ; Miranda 2017 ). Here, we review the literature to shed light on the way coping behaviours develop, by categorising the developmental processes impacted by environmental factors.…”

“…A great deal of developmental research has been devoted to understanding whether and how experiences in ontogeny shape behavioural development later in life, yet insufficient attention has been paid to why and how such cross-time influences should characterise animal (Skinner and Zimmer-Gembeck 2007 ; Groothuis and Trillmich 2011 ; Trillmich and Hudson 2011 ) or even human (Belsky 2007 ; Ellis and Boyce 2008 ; Haun et al 2013 ) development, or how natural selection structures the early-life effects on development (Ellis and Boyce 2008 ). Despite extensive study on specific stressors and behaviours, no overarching developmental framework currently exists to explain why or how animals develop the strategies with which they respond to their environment (Skinner and Zimmer-Gembeck 2007 ; Hengartner 2017 ).…”

Establishing the Substantive Interpretation of the GFP by Considering Evidence from Research on Personality Disorders and Animal Personality

“…As detailed by two evolutionary models, selection for fast vs. slow LHS results in correlated personality traits due to trade-offs between somatic and reproductive efforts (Stamps, 2007 ; Wolf et al, 2007 ). That is, individuals who invest heavily in early reproduction (fast LHS) must be bold and aggressive in order to outcompete rivals and attract mates, whereas individuals who delay reproduction (slow LHS) must be risk-averse, sociable, and docile, otherwise they would not survive long enough to benefit from future fitness returns (Hengartner, in press ). Boldness-aggressiveness thus constitutes a behavioral syndrome, also termed proactive personality profile, whereas sociability-docility forms another syndrome, coined reactive personality profile (Groothuis and Carere, 2005 ; Koolhaas et al, 2010 ).…”

“…Both syndromes are supposed to be extreme poles along a common GFP-like personality dimension that is co-adapted to LHS (Reale et al, 2010 ). That is, proactive personalities reflect low GFP scores (asocial, irritable, aggressive, and impulsive), while reactive personalities reflect high GFP scores (sociable, cautious, empathic, and self-controlled) (Hengartner, in press ). Mounting evidence from different animal species now supports these personality profiles as correlates of LH traits (Biro and Stamps, 2008 ; Careau et al, 2009 , 2010 ; Le Galliard et al, 2013 ; Niemela et al, 2013 ; Montiglio et al, 2014 ; Schuett et al, 2015 ; Binder et al, 2016 ; but see also Debecker et al, 2016 ).…”