Social distancing is a natural instinct in both humans and animals, yet the need to socialize often wins over safety, according to a study from the University of Pittsburgh. The researchers say that we are evolutionarily inclined to avoid people with a contagious infection, but we do not always use our good common sense.
“Recent decades have been characterized by an increase in the emergence of novel pathogens and the spread of existing ones, driven by factors such as human population growth, global commerce and travel, anthropogenic environmental change and interactions between humans, wildlife and domestic animals,” wrote the study authors.
“Because the reproductive rate of directly transmitted pathogens increases with the availability of hosts and their rate of contact, social animals that live at high local densities of closely interacting conspecifics may be particular vulnerable to the threats posed by some of these emerging infectious diseases (EIDs).”
“Reducing the degree of sociality (i.e. the tendency to congregate in groups with conspecifics) might therefore be an important strategy by which social animals can ameliorate the impacts of directly transmitted EIDs.”
The researchers set out to investigate how social behaviors change in response to infectious diseases. Led by Jessica Stephenson, the team observed guppies as they were placed in a tank next to members of their species with infectious diseases.
Many of the guppies made their way to the side of the tank near the other guppies, regardless of the contagion risk, which is expected behavior among a social species.
However, certain male guppies strongly avoided the side of the tank close to infectious fish. It turned out that these guppies were the most susceptible to parasitic worms.
Stephenson said that overall, human beings are normal social animals in many of our behavioral responses to infectious disease. But choosing our social inclinations over the evolutionary instinct to keep our distance counteracts the efforts of public health measures to control disease transmission. Without social distancing, benefits such as “global disease surveillance” are wasted, explained Stephenson.
“That the vast majority of our species has largely squandered the potential payoffs of these benefits is again consistent with other social animals: the cost of social distancing itself can outweigh the cost of contracting the disease,” said Stephenson.
“For some, no amount of Zoom and FaceTime can make up for the lost benefits of social interactions. These frustrating, if wholly natural, behavioral decisions will result in the persistence of COVID-19 until the advent of perhaps our greatest advantage over other species facing emerging infectious diseases: vaccination.”
The study is published in the journal Proceedings of the Royal Society B: Biological Sciences.