1.  Introduction

Paranoia, which is an excessive and illogical fear that other people are planning to hurt them, is frequently associated with psychiatric disorders like schizophrenia and delusional disorders. Recent ideas in evolutionary psychology say that paranoia may be an adaptive trait that has evolved to help people survive in dangerous situations. This theory says that being more skeptical can help people cope with social situations and keep them safe from people who might hurt them. Saalfeld et al. [1]and Green and Phillips [2] suggest that this point of view says that paranoia is a necessary part of a larger way of thinking that has grown up to spot threats in the environment and in social situations.

During their evolution, early humans had to deal with many dangers, like being hunted, hostile members of their own species, and not having enough resources. In these situations, the price of a false positive is usually much lower than the price of not finding a real threat. This risk imbalance may have caused cognitive processes that are overly vigilant, like paranoia, to develop. These processes put finding threats ahead of getting things right [3]. This bias may enhance survival in ancestral environments by enabling individuals to anticipate and evade social exclusion, deceit, or hostility. However, paranoia seems to be a social defense mechanism instead of a mental illness. Thereby, modern paranoia can be categorized as a pathological manifestation of once benign mechanisms, but the high-threat environment in which these systems evolved is no longer suitable for the present day.

Modern paranoia may therefore be the result of the maladaptive expression of once adaptive mechanisms in circumstances that no longer resemble the high-threat environments in which these systems evolved. Crucially, paranoia may not be consistently maladaptive; rather, it seems to manifest in a multifaceted manner in the population, with many people exhibiting subclinical suspicion that does not fit diagnostic standards. This implies that paranoia, particularly mild to moderate forms, can be beneficial by enhancing vigilance in physically and socially unpredictable situations.

Early human tribes may have relied primarily on social threat detection to maintain their hierarchy and community. Recognizing dishonesty or social betrayal would have been beneficial in both cooperative and competitive settings. Over time, these benefits may have produced a cognitive bias that made people think that ambiguous cues could be detrimental. In this context, paranoia is more of a defensive social strategy than a mental illness.

This study seeks to understand paranoia from an evolutionary perspective by examining the brain's reaction to stimuli that mimic threats to ancestral survival. We utilized functional magnetic resonance imaging (fMRI) to examine the cerebral activity of individuals exhibiting heightened and diminished paranoia while they observed images of secure and perilous ancient environments. We investigate the prefrontal cortex and amygdala, brain regions associated with threat detection and emotional regulation. We examine whether individuals with higher levels of paranoia exhibit neural patterns of a more intense threat-response system.

We are attempting to reframe our understanding of paranoia as a potential adaptive mechanism with evolutionary significance, rather than merely a symptom of illness.

2.  Theoretical framework

Evolutionary psychology aids us in resolving problems resulting from the difficulties our ancestors faced by explaining how our cognitive and emotional processes have changed over time. This theory posits that individuals have historically employed paranoia as a threat management strategy to safeguard themselves from social perils such as betrayal and natural hazards like wild animals. The Error Management Theory [4] posits that natural selection engenders biases that reduce the likelihood of critical errors, such as the inability to recognize a genuine threat in ambiguous situations.

Anxiety is connected to the way humans have evolved. For instance, the state of perpetually concerning oneself with the impression one creates on others in professional or quotidian contexts may be associated with a "paranoid tendency" (in this context, "paranoia" signifies not a severe mental disorder but a predisposition towards excessive vigilance). From an evolutionary standpoint, in historical competitive contexts, individuals exhibiting excessive naivety were susceptible to deception and exclusion from social groups. However, today's paranoia is more of an excessive watchfulness than the useful protective mechanism it once was.

3.  Participants

We chose students who were studying psychology to take part in our paranoia experiment. They were put into two groups: one group had a high chance of being paranoid, and the other group had a low chance. We chose 200 people from a larger group (100 men and 100 women, ages 18 to 25 on average) based on their paranoia scores. None of the people who took part had ever had a neurological or psychiatric condition before, and all of them gave their informed consent in accordance with the ethical standards of the institution.

4.  Materials for experiments

A set of pictures showing possible threats and neutral situations in a prehistoric setting were made to mimic the conditions in which our ancestors lived. The pictures showed hostile people, dangerous animals, and environmental cues that weren't clear. Twenty individuals, not part of the study, evaluated the emotional intensity and perceived threat of each image utilizing a Likert scale from 1 (not threatening) to 7 (extremely threatening). The final set of stimuli only included images that had the same ratings (standard deviation < 1.2).

Functional magnetic resonance imaging (fMRI) was used to measure neural activation during the presentation of images. The main areas of focus were the amygdala, the anterior cingulate cortex, and the prefrontal cortex. All these areas of the brain are involved in processing emotions and seeing threats.

5.  Methodology

The Green Paranoid Thoughts Scale (GPTS) was used to figure out how paranoid the participants were at first. They were put into groups based on how anxious they were. Seven participants did not belong to either the low-paranoid or paranoid groups.

During an fMRI session with neural recordings, participants were scanned while viewing the stimuli (pictures) in a random order. Each image was shown for three seconds, followed by a fixation cross for two seconds to reduce the carryover effects. They were instructed to simply gaze at the images without taking any particular action. After scanning, participants completed a test to gauge their individual perceptions of each image's level of threat.

6.  Result

Our research indicates that participants with elevated paranoia scores exhibited significantly greater activation in the amygdala and anterior cingulate cortex when exposed to threatening stimuli rather than neutral ones. The group with low paranoia, on the other hand, didn't respond as strongly in these areas.

There was also a big difference in the threat level ratings between the groups. Perceptual bias significantly influences people. People who are very paranoid tend to think that dark forests and shadowy figures are more dangerous than people who are less paranoid.

These results are consistent with prior research indicating that heightened threat perception correlates with increased activity in these cerebral regions [4,5].

7.  Discussion

It is intended to find out if there is an association between paranoia and evolutionary psychology. Our findings support the idea that paranoia is a defense mechanism that helps people see threats in situations that could be dangerous. The data clearly shows a link: people with higher levels of paranoia show more activity in brain areas linked to regulating emotions and recognizing threats.

These results support evolutionary theories that say people use paranoia to confront perceived threats. This system was probably made to help people stay safe when things become dangerous and to make them more aware of what's going on around them. The study indicated that people who are very paranoid have more brain activity and heightened subjective perceptions. This result is in line with a system that finds threats no matter how likely or unclear they are.

This study indicates how complicated paranoia is. Paranoid subclinical symptoms suggest that paranoia is a spectrum disorder rather than a distinct clinical entity, potentially beneficial in contexts where social norms are ambiguous. For example, being a little more careful could help people handle tough social situations or keep them from being taken advantage of.

This heightened sensitivity may be less advantageous in contemporary settings, which significantly diverge from those of our forebears. People who are prone to paranoia may become more cautious because cities are crowded, politics and society are unpredictable, and there are many unclear social cues that come up when people talk to each other online.

8.  Limitations

Social desirability effects may distort or influence the self-reported paranoia metrics in our study. To examine the temporal and contextual variations in paranoia, future research ought to employ longitudinal methodologies. fMRI can identify localized brain activity; however, it cannot establish a causal relationship.

In subsequent research, scholars may examine the cultural and developmental disparities in paranoia, as well as its interaction with other traits such as anxiety or personality. It would also be beneficial to examine how environmental stressors, such as social isolation or discrimination, can intensify or alleviate paranoia among diverse demographics.

9.  Conclusion

The functional magnetic resonance imaging (fMRI) technique was utilized in this study to investigate the brain responses of psychology students between the ages of 18 and 25 to ancestral threat-mimicking stimuli. The findings indicated that those with higher levels of paranoid had more activity in the amygdala and anterior cingulate cortex, as well as a greater perception of threat in ambiguous cues. This lends credence to the idea that paranoia represents an ancestral adaptive threat-detection system. The fact that it is maladaptive in modern surroundings, which broadens its scope beyond that of a psychiatric illness, is a spectrum. Subclinical forms may be helpful in maintaining vigilance.

Ethical consideration

Before taking part, each person signed a form giving their permission. Steps were taken to ensure that the people taking part in the fMRI scan were safe and comfortable. After the session, participants were given the chance to take their data out of the experiment and were given a full debriefing. We also gave out the contact information for mental health resources in case the experiment made anyone upset.