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Why Do We Feel Sick When Infected--Can Altruism Play a Role?

Shakhar K, Shakhar G - PLoS Biol. (2015)

Bottom Line: Nonetheless, SB seems evolutionarily costly: it promotes starvation and predation and reduces reproductive opportunities.Former explanations focused on individual fitness, invoking improved resistance to pathogens.Could prevention of disease transmission, propagating in populations through kin selection, also contribute to SB?

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, College of Management Academic Studies, Rishon LeZion, Israel.

ABSTRACT
When we contract an infection, we typically feel sick and behave accordingly. Symptoms of sickness behavior (SB) include anorexia, hypersomnia, depression, and reduced social interactions. SB affects species spanning from arthropods to vertebrates, is triggered nonspecifically by viruses, bacteria, and parasites, and is orchestrated by a complex network of cytokines and neuroendocrine pathways; clearly, it has been naturally selected. Nonetheless, SB seems evolutionarily costly: it promotes starvation and predation and reduces reproductive opportunities. How could SB persist? Former explanations focused on individual fitness, invoking improved resistance to pathogens. Could prevention of disease transmission, propagating in populations through kin selection, also contribute to SB?

No MeSH data available.


Related in: MedlinePlus

The costs of SB to direct fitness.Behavioral (pink) and physiological (green) symptoms of SB can, either directly or indirectly, lead to maladaptive consequences (orange) that reduce individual fitness.
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pbio.1002276.g002: The costs of SB to direct fitness.Behavioral (pink) and physiological (green) symptoms of SB can, either directly or indirectly, lead to maladaptive consequences (orange) that reduce individual fitness.

Mentions: Unlike physiological symptoms of sickness, such as fever and hypoferremia, which likely boost resistance to pathogens (Box 1), behavioral symptoms remain poorly explained. Clearly, all of these symptoms impose significant costs to host fitness (Fig 2) [11,12]. Anorexia and adipsia increase the risk of starvation, loss of essential nutrients, and dehydration, particularly in the context of fever. Lethargy can lead to predation by slowing down prey and singling it out for predators [13,14]. Social disinterest decreases parental care [15,16], limits mating opportunities [17], and, together with fatigue, can lead to loss of territory and social status [7,18]. For SB to evolve, these costs must be offset by benefits—what can these benefits be?


Why Do We Feel Sick When Infected--Can Altruism Play a Role?

Shakhar K, Shakhar G - PLoS Biol. (2015)

The costs of SB to direct fitness.Behavioral (pink) and physiological (green) symptoms of SB can, either directly or indirectly, lead to maladaptive consequences (orange) that reduce individual fitness.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608734&req=5

pbio.1002276.g002: The costs of SB to direct fitness.Behavioral (pink) and physiological (green) symptoms of SB can, either directly or indirectly, lead to maladaptive consequences (orange) that reduce individual fitness.
Mentions: Unlike physiological symptoms of sickness, such as fever and hypoferremia, which likely boost resistance to pathogens (Box 1), behavioral symptoms remain poorly explained. Clearly, all of these symptoms impose significant costs to host fitness (Fig 2) [11,12]. Anorexia and adipsia increase the risk of starvation, loss of essential nutrients, and dehydration, particularly in the context of fever. Lethargy can lead to predation by slowing down prey and singling it out for predators [13,14]. Social disinterest decreases parental care [15,16], limits mating opportunities [17], and, together with fatigue, can lead to loss of territory and social status [7,18]. For SB to evolve, these costs must be offset by benefits—what can these benefits be?

Bottom Line: Nonetheless, SB seems evolutionarily costly: it promotes starvation and predation and reduces reproductive opportunities.Former explanations focused on individual fitness, invoking improved resistance to pathogens.Could prevention of disease transmission, propagating in populations through kin selection, also contribute to SB?

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, College of Management Academic Studies, Rishon LeZion, Israel.

ABSTRACT
When we contract an infection, we typically feel sick and behave accordingly. Symptoms of sickness behavior (SB) include anorexia, hypersomnia, depression, and reduced social interactions. SB affects species spanning from arthropods to vertebrates, is triggered nonspecifically by viruses, bacteria, and parasites, and is orchestrated by a complex network of cytokines and neuroendocrine pathways; clearly, it has been naturally selected. Nonetheless, SB seems evolutionarily costly: it promotes starvation and predation and reduces reproductive opportunities. How could SB persist? Former explanations focused on individual fitness, invoking improved resistance to pathogens. Could prevention of disease transmission, propagating in populations through kin selection, also contribute to SB?

No MeSH data available.


Related in: MedlinePlus