Shakar & Shakar on Sickness Behavior, 2015

Manganus

Manganus

Established Member (Voting Rights)
How to explain the evolutionary advantages of Sickness Behavior.
This article is from 2015. Maybe the scientific frontier has advanced since. Anyone knows?

Anyway: I'm a bit impressed. :)

Source: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002276

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PLOS Biology: Why Do We Feel Sick When Infected—Can Altruism Play a Role?Keren Shakhar, Guy Shakhar, Published: October 16, 2015

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?
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I don't believe a word of it. All those things on the left can be seen as self-protection, not herd protection. Also it is worth remembering that sickness behaviour is a microbe strategy as much as a host strategy.

To me this diagram is exactly the sort of pseudoscience that psychologists get up to.
 
Sickness behaviour could be seen as conserving energy to use to fight infection. If you don't feel like eating you don't have to go and hunt. Hiding away until you can outrun a predator is a good strategy so you can survive to pass on your genes.

Or sickness behaviours could be a side effect of the body's way of fighting infection.
 
Manganus said:
How to explain the evolutionary advantages of Sickness Behavior.
This article is from 2015. Maybe the scientific frontier has advanced since. Anyone knows?

Anyway: I'm a bit impressed. :)

Source: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002276

image
Click to expand...

WTAF? The level of delusion is something to behold.

Humans have existed for 300K years. 95% of our species' existence has been as hunter-gatherers. "Sickness behavior" meant death for most of that history. If you cannot follow the tribe, the tribe cannot sustain you. Not "will not", but "can not".

If there is any evolutionary advantage it's in culling the herd, but considering how high infant mortality was until the 20th century, that's a horribly flawed hypothesis.

Who broke these people's brains?
 
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rvallee said:
"Sickness behavior" meant death for most of that history. If you cannot follow the tribe, the tribe cannot sustain you. Not "will not", but "can not".
Click to expand...

That assumes all tribal hunter gatherer communities moved on every day. Some had seasonal home bases such as caves or huts for some of the time with hunters going out to hunt and bringing food back to base. Anyone with a short term infection could retreat to a dark corner of the cave and rest for a few days while recovering. I agree people with potentially long term debilitating conditions might lag behind when the tribe moved and be less able to run from predators, hence 'survival of the fittest'.
 
Trish said:
That assumes all tribal hunter gatherer communities moved on every day. Some had seasonal home bases such as caves or huts for some of the time with hunters going out to hunt and bringing food back to base. Anyone with a short term infection could retreat to a dark corner of the cave and rest for a few days while recovering. I agree people with potentially long term debilitating conditions might lag behind when the tribe moved and be less able to run from predators, hence 'survival of the fittest'.
Click to expand...

Oh that's definitely the big difference: acute vs. chronic. Acute response is manageable when resources are scarce.

But this goes beyond chronic illness mediated by the immune system. Someone falling from high enough and breaking both legs is unlikely to survive those circumstances. Technically that's an acute medical problem but it has lasting impact that turn it into a chronic problem, since without proper care broken legs don't heal themselves well enough to enable hunting or walking long distances. Outcome is likely to remain the same as the local food reserves get depleted and the tribe has to move on or starve.
 
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