How people can tell by their face whether someone is sick – knowledge

Do people recognize whether a stranger is sick? To find out, researchers intentionally infected test participants. And shown: one look is enough.

People can tell from the face of sick people that they are not healthy. Even peoples who barely or not at all know western faces can identify sick western Europeans with great certainty. This comes to the conclusion one in the trade journal Proceedings of the Royal Society B. published study of the Karolinska Institute in Stockholm.

It is known that mammals have the ability to recognize sick conspecifics. This is crucial in order to reduce contagion and increase your own chances of survival. An international team of researchers led by Artin Arshamian has now looked to what extent people can do this and, above all, whether they can do this when people from other cultures suffer from illnesses with whom they have had little or no contact. Ultimately, they investigated whether the ability to recognize sick people is a universal human quality.

For their study, the researchers injected their test subjects with unpleasant intestinal bacteria

For this study, researchers from the institute injected the 13 test subjects with either a placebo substance or fragments of E. coli bacteria, against which the human immune system reacts with defense measures and symptoms such as tiredness and headaches. Two hours later, the faces of the participants were photographed. At this point in time, the complaints were not yet fully developed, the researchers write. Body temperature and breathing rate would have peaked around four hours after the injection. These recordings were eventually shown to other participants from Sweden as well as to people from five other populations around the world. You should indicate which of the faces hid sick people and behind which healthy people.

Three groups were small hunter-gatherer peoples from Thailand, Malaysia and Mexico. According to this, they live in rainforests and the desert and have little or no access to television or the Internet. The other participants were city dwellers from Thailand and Mexico.

All groups were able to identify a sick person with a high probability of being hit. Nevertheless, the test result is surprising, as Arshamian explains. It was assumed that those who were more used to Western European faces had an advantage over the other groups. “But that was not the case at all,” says Arshamian. The Swedish test group did not do better than the other groups.

In further projects, the scientists now want to investigate, among other things, whether sick and healthy people can also be differentiated based on their movements.