Your symptoms? Evolution's way of telling you to stay home

January 7, 2016
Your symptoms? Evolution's way of telling you to stay home

When you have a fever, your nose is stuffed and your headache is spreading to your toes, your body is telling you to stay home in bed. Feeling sick is an evolutionary adaptation according to a hypothesis put forward by Prof. Guy Shakhar of the Weizmann Institute's Immunology Department and Dr. Keren Shakhar of the Psychology Department of the College of Management Academic Studies, in a recent paper published in PLoS Biology.

We tend to take it for granted that infection is what causes the symptoms of illness, assuming that the microbial invasion directly impinges on our well-being. In truth, many of our body's systems are involved in being sick: the immune system and endocrine systems, as well as our nervous system. Moreover, the behavior we associate with sickness is not limited to humans. Anyone who has a pet knows that animals act differently when they are ill. Some of the most extreme "sickness behavior" is found in such social insects as bees, which typically abandon the hive to die elsewhere when they are sick. In other words, such behavior seems to have been preserved over millennia of evolution.

The symptoms that accompany illness appear to negatively affect one's chance of survival and reproduction. So why would this phenomenon persist? Symptoms, say the scientists, are not an adaptation that works on the level of the individual. Rather, they suggest, evolution is functioning on the level of the "selfish gene." Even though the individual organism may not survive the illness, isolating itself from its social environment will reduce the overall rate of infection in the group. "From the point of view of the individual, this behavior may seem overly altruistic," says Dr. Keren Shakhar, "but from the perspective of the gene, its odds of being passed down are improved."

In the paper, the scientists go through a list of common symptoms, and each seems to support the hypothesis. Appetite loss, for example, hinders the disease from spreading by communal food or water resources. Fatigue and weakness can lessen the mobility of the infected individual, reducing the radius of possible infection. Along with the symptoms, the sick individual can become depressed and lose interest in social and sexual contact, again limiting opportunities to transmit pathogens. Lapses in personal grooming and changes in body language say: I'm sick! Don't come near!

"We know that isolation is the most efficient way to stop a transmissible disease from spreading," says Prof. Guy Shakhar. "The problem is that today, for example, with flu, many do not realize how deadly it can be. So they go against their natural instincts, take a pill to reduce pain and fever and go to work, where the chance of infecting others is much higher."

The scientists have proposed several ways of testing this hypothesis, but they also hope its message sinks in: When you feel sick, it's a sign you need to stay home. Millions of years of evolution are not wrong.

Explore further: Immune response affects sleep and memory

More information: Keren Shakhar et al. Why Do We Feel Sick When Infected—Can Altruism Play a Role?, PLOS Biology (2015). DOI: 10.1371/journal.pbio.1002276

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17 comments

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BartV
1.4 / 5 (10) Jan 07, 2016
So crazy that a non-proven theory as evolution can generate so many topics as this one.

Perhaps it is atheists' way of replacing "God" with "Evolution". As you can try to do in the title.

Whatever the case, "Evolution" has all of the traits of a man's-thought-up religion.

RobertKarlStonjek
not rated yet Jan 07, 2016
If you do not stop all activity and get bed rest then you are far more likely to die from your disease, so becoming depressed and weary vastly increases your chances of survival. As many doctors know and as their advice often reflects, bed rest can cure a vast array of minor maladies that could easily turn nasty and even deadly if the person did not take to the bed.

The hypothesis given above ignores centuries of medical practice in which advising people to do what they feel like doing, to go to bed and rest, greatly enhances survival.

When this survival mechanism is triggered off without a physical trigger it is known as 'clinical depression'. People lose interest in pleasurable activity, feel physically weak and sick and frequently see the doctor not for the depression but the physical symptoms which they blame for their condition.
Vietvet
3 / 5 (4) Jan 07, 2016
So crazy that a non-proven theory as evolution can generate so many topics as this one.

Perhaps it is atheists' way of replacing "God" with "Evolution". As you can try to do in the title.

Whatever the case, "Evolution" has all of the traits of a man's-thought-up religion.


TogetherinParis
1 / 5 (2) Jan 07, 2016
And sneezes? Coughing? Diarrhea? This paper is a first thought load.
jsdarkdestruction
5 / 5 (2) Jan 07, 2016
Interesting idea, but then why do different diseases and infections cause different symptoms and different levels of severity? If it was just your bodies responding to warn others/keep you home then shouldnt symptoms and severities and lethalities all be the same?
jsdarkdestruction
4.4 / 5 (7) Jan 07, 2016
So crazy that a non-proven theory as evolution can generate so many topics as this one.

Perhaps it is atheists' way of replacing "God" with "Evolution". As you can try to do in the title.

Whatever the case, "Evolution" has all of the traits of a man's-thought-up religion.

What evidence would you require to consider evolution "proven"?

No ones trying to replace your God. You could easily view evolution as one of gods rules and laws that dictate the universe and everything in it through the laws of physics he set. Stop being paranoid.
It is rich to see a creationist accusing science of being like the made up religions of the world and then still blindly believe they are the only ones who's God is real. Apply the same thought process that make you believe evolution is like mans dreamt up religions to your own religious beliefs once.

FredJose
1 / 5 (5) Jan 08, 2016
In other words, such behavior seems to have been preserved over millennia of evolution.

This is an unscientific statement. Period. There is no observational evidence of such supposed "evolution". No one has or is able to go back into the past and to observe and record it, it cannot be repeated, cannot be confirmed or falsified, it's simply a faith statement made by a disciple of the evolutionary religion.

@jsdarkdestruction
You could easily view evolution as one of gods rules and laws that dictate the universe and everything in it through the laws of physics he set.

NO, it cannot. If you believe in the Christian God then His word clearly states that everything was created in 6 normal 24 hour, human understandable days.
If in doubt go read Ex 20:8-11. The context is clear about the days referring to God's creation being exactly the same as those referring to man's required response to work for 6 days and then rest on the 7th.
FredJose
1 / 5 (4) Jan 08, 2016
@jsdarkdestruction
You could easily view evolution as one of gods rules and laws that dictate the universe and everything in it through the laws of physics he set.

The problem with this kind of thinking is that it requires life to arise spontaneously from purely random physical and chemical processes.
Currently we do not observe such happenings. On the contrary, we ONLY observe that life comes from life as a continuing confirmation of Louis Pasteur's original postulates.
In view of the impossibility of spontaneous life one cannot then make the God-of-the-gaps assumption that God intervened conveniently to create the first life and then left it to "evolve".
gkam
2.6 / 5 (5) Jan 08, 2016
Fred, how could we have "days" without a Sun and an Earth? These words were spoken for generations in the Age of Ignorance before they were put down on parchment. Surely, you cannot "believe" them.
DavidTheShepherd
1 / 5 (3) Jan 09, 2016
@Gkam -
how could we have "days" without a Sun and an Earth?

This is an elementary thing, dear gkam. There's actually great significance in exactly that fact.
God said "Let there be light and there was light". If you read Revelation 21:23 you'll see that God HIMSELF is more than capable of providing the light.

The significance is this - that no one human being can then claim that the sun is more important and required for life. This actually therefore prevents people from worshiping the sun as if it is the thing that gave life on earth. In fact this is exactly what the current paradigm is - namely that we are children of the stars, i.e. that we/life are the product of processes that occurred in the stars[sun] long ago. The bible forestalled such "sun""-worshiping and idolatry. with precisely the wording that it has.
The sun and moon were only created on day 4.
DavidTheShepherd
1 / 5 (4) Jan 09, 2016
These words were spoken for generations in the Age of Ignorance before they were put down on parchment. Surely, you cannot "believe" them.

Strange then that you believe that life can erupt spontaneously from random physical and chemical processes, in total contradiction of what we actually observe, namely that once living things die they cannot rise again from the dead all by themselves. In fact even with the most sophisticated tech we cannot bring the dead back to life!!
Essentially you belief that life can rise from the dead[materials] all by itself with no outside help required. Perhaps you are the one believing in fairy tales????
gkam
3 / 5 (6) Jan 09, 2016
I have a great idea: We can divide into groups, each group inventing an Imaginary Being. We can endow those Imaginary Beings with ridiculous power, and then create entire legends around them.

Then, we can kill each other over whose Imaginary Being is the "real" one.
TheGhostofOtto1923
2.3 / 5 (3) Jan 09, 2016
I have a great idea: We can divide into groups, each group inventing an Imaginary Being. We can endow those Imaginary Beings with ridiculous power, and then create entire legends around them.

Then, we can kill each other over whose Imaginary Being is the "real" one.
I have a better idea. Lets divide into groups - psychopaths and everybody else - and let the larger group kill the smaller group for all the damage and suffering and ruination and insanity the smaller group has caused.
gkam
2 / 5 (4) Jan 09, 2016
Your fixation on psychopathy is telling, as is your malice.

Is it the only you can get the attention you seem to need?
jsdarkdestruction
5 / 5 (2) Jan 09, 2016
Fredjose, depends on which form of Christianity you subscribe to. Not all versions take genesis or the bible in general literally and consider it metaphoric.
PhotonX
5 / 5 (3) Jan 12, 2016
If you believe in the Christian God then His word clearly states that everything was created in 6 normal 24 hour, human understandable day
How do you know? Were you there? Has anyone ever gone back into the past to see if this fairy tale could even be remotely true? Have you gone back in time to see Christ crucified? You're just taking other people's word for it. Sorry, FredJose, but you can't have it both ways. Your willful ignorance and logical fallacies are laughable.
.
.
animah
5 / 5 (2) Jan 13, 2016
let the larger group kill the smaller group

That would make the larger group psychopaths by definition.

even with the most sophisticated tech we cannot bring the dead back to life
There are many, many things we can't do even with the most sophisticated tech.

For example, we can't do fusion energy. That doesn't prove it doesn't occur in nature - it does inside every star in the universe! So your "proof" is just you jumping to conclusions.

Worse, your statement indicates that if tech could one day make life out of dead materials, God's existence would be disproven.

Well, that tech is coming fast:
http://spectrum.i...oduction
"DNA Manufacturing Enters the Age of Mass Production"

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