Behavioural defences in animals against pathogens and parasites: parallels with the pillars of medicine in humans

Abstract

No other theme in animal biology seems to be more central than the concept of employing strategies to survive and successfully reproduce. In nature, controlling or avoiding pathogens and parasites is an essential fitness strategy because of the ever-present disease-causing organisms. The diseasecontrol strategies discussed here are: physical avoidance and removal of pathogens and parasites; quarantine or peripheralization of conspecifics that could be carrying potential pathogens; herbal medicine, animal style, to prevent or treat an infection; potentiation of the immune system; and care of sick or injured group members. These strategies are seen as also encompassing the pillars of human medicine: (i) quarantine; (ii) immune-boosting vaccinations; (iii) use of medicinal products; and (iv) caring or nursing. In contrast to animals, in humans, the disease-control strategies have been consolidated into a consistent and extensive medical system. A hypothesis that explains some of this difference between animals and humans is that humans are sick more often than animals. This increase in sickness in humans leading to an extensive, cognitively driven medical system is attributed to an evolutionary dietary transition from mostly natural vegetation to a meat-based diet, with an increase in health-eroding free radicals and a dietary reduction of free-radical-scavenging antioxidants.

Infectious disease, behavioural flexibility and the evolution of culture in primates

“…Some of these anti-parasite strategies may themselves be facilitated by social processes (such as ectoparasite removal during allogrooming) or be socially learned [20]. Comparisons have previously been made between animal self-medication behaviours and human medicine [61], and further study of animal behavioural responses to disease may shed light on the evolution of human medical practices. Additionally, we only investigated one aspect of parasitism; other measures such as prevalence, intensity or virulence of parasites could provide further insights to the hypotheses that we tested [20].…”

Introversion and human-contaminant disgust sensitivity predict personal space

“…Indeed, recent research has demonstrated that the first line of defense against infectious disease is located in the nervous system-what has been referred to as the "behavioral immune system" (Schaller & Park, 2011). Like many other animals (Hart, 2011), humans are endowed with a suite of psychological mechanisms that facilitate the detection and avoidance of sources of contaminants, including conspecifics.…”

Hygienic tendencies correlate with low geohelminth infection in free-ranging macaques

“…Animals have thus developed behavioural strategies to avoid infection [1][2][3], akin to the suite of behaviours we collectively refer to as 'hygiene' among humans [4]. Some well-known behavioural defences against parasites include their direct removal via grooming or weeding [5,6], the avoidance of infected conspecifics [7] and strategies for waste management [8], all of which function to mitigate fitness losses associated with infection.…”