Back when humans clustered in close-knit family groups and had only rare interactions with strangers along their vast migratory paths (pretty much exclusively to trade or to kill), ostracizing the diseased had clear evolutionary payoffs. A member of the group suffering from an infectious illness could be identified and isolated on the basis of symptoms, or even altogether abandoned in a remote stretch of wilderness. The loners would probably succumb to the elements or die of starvation, but if not, they'd have a difficult time joining or capturing the attention of a new group. Isolation halted the transmission of infection, and entire groups were spared from the scourge of the disease.
At the end of the day, the most callous were the most evolutionarily fit.
In a densely packed civilization where human contact is common and advanced medical care available, the motivation to stigmatize infectious diseases no longer provides any societal benefit.
But we don't live in caves anymore. In a densely packed civilization where human contact is common and advanced medical care available, the motivation to stigmatize infectious diseases no longer provides any societal benefit. The natural inclination can even amplify transmission and increase the risk of a dangerous epidemic, according to a new paper published in Communication Studies by Penn State University communications professor Rachel Smith and biology professor David Hughes, both researchers at the institution's Center of Infectious Disease Dynamics.
In modern times, the stigmatized will often come into contact with strangers and might even find an ostracized group to connect with instead of seeking treatment, leading to a cascading effect. "If infected persons shift their interactions to spend more time with each other, they may infect each other with different strains of a disease," the authors write. "Co-infections can lead to new strains that are more lethal and/or more infectious." Additionally, anxieties about their impending excommunication may trigger rises in cortisol levels, weakening the immune system and potentially producing more dangerous strains.
Stigmas against infectious diseases may also create a major lag time between the outbreak and the discovery of the cause. Public health officials and the media may frame messaging about the outbreak around an infected subset of the population, which squanders time that could be spent containing transmission. Back in 1993, the Four Corners region saw "a lethal respiratory infection," which was branded as the Navajo flu. Investigators later found that it was actually the hanta virus, which is transmitted by mice.
Recent research indicates that it's "extremely difficult" to kill existing stigmas, according to Smith, but some of her
indicates that stigma avoidance for new diseases can be achieved by focusing alerts on general health rather than specific people.
But will people really go against a strong evolutionary inclination? "
Evolution is an important force in human behavior, but by no means a deciding one," Hughes, the co-author, explains in an email. "Just think of contraception or adoption. Both healthy choices driven by cultural rules and not the response of behavior to evolutionary pressures to maximize reproduction. So, although stigmas might have played a positive role ancestrally, they do not now and so we can culturally jettison them."