Our bodies or infection: What actually kills us?
A growing body of evidence suggests that our immune systems may be responsible for the deaths of others from infectious diseases such as COVID-19.
Since a virus doesn’t “want” to kill the host - us - and has a sole goal of surviving and reproducing, it might be that our bodies are the cause of death following infection.
In an effort to stop the virus in its tracks, the body can harm major organs that include the lungs and heart. This has led some doctors to focus on reducing the immune response of infected patients in order to save them.
But, the question still remains: what’s the point of having an immune system if it kills us?
The answer may be to do with our evolutionary history and require us to think about immunity in terms of communication and behaviour alongside biology. And, the more that researchers can understand how our immune system originated, the more likely they are to develop better ways of dealing with it.
What does behaviour have to do with immune systems?
This ties into the concept of the behavioural immune system. Feeling disgusted or repulsed by something because it makes us feel like it poses a threat to our health is just one example.
Animals do this too, with research showing that some animals avoid others that show signs of illness.
But, unlike other animals, humans are likely to be compassionate towards those with symptoms of illness or injury, according to more recent theoretical research.
According to this theory, that is why people tend to exclaim when feeling pain, rather than silently moving away.
Some psychologists argue that this is because immune responses involve communication just as much as they do self-maintenance, since people who have received care in the past have probably tended to do better than those trying to survive on their own.
In evolutionary literature, these kinds of displays of pain are referred to as kinds of “signals”, which can be faked to exploit the world around us.
Faking it is an evolutionary thing
How many times have you faked being in pain or sick to avoid an obligation? If your answer is ‘all the time’, you’re not alone. People feign these signals frequently to get support from others, avoid obligations or give themselves more time to complete a task. And this is an important part of any signalling system, where the response to a particular signal will start to dictate how and why that signal is used.
People aren’t the only ones looking to benefit
Germs also use immune signals for their own gain.
While some viruses hijack human immune responses such as coughs and sneezes to get passed on to new hosts, germs like SARS-COV-2 - which causes COVID-19 - can prevent our signalling to others that we are sick so it can spread without anyone realising.
Viewing immunity as more than just a biological system could help us understand and even predict how particular infections will interact with a patient’s immune system, where future research could help us sort the immunity hijackers from other germs.