Dreams contain information on how humans evolved to become apex predators and cement their position at the top of the food chain.
The reason why many of us have dreams in which we are under attack or thrown into a highly stressful situation is that dreams function to help us learn and develop real-world skills that improve both our cognitive and physical performance under stress. In this sense, dreams have played a central part in the evolution of our species and its ability to problem solve. Anttio Revonsuo developed 'Simulation Theory' in which he suggests dreams have an evolutionary function by allowing living organisms to improve their responses to threats.
Dreams have a biological function. They are designed to simulate real life, in particular, to expose us to potential problems and threats in order to provide a better understanding of how to avoid them and overcome them. Early humans would have dreamt of scenarios which were likely to cause them harm in the prehistoric world. These dreams would have helped prepare them for these problems in the real world, equipping them with the mental and physical skills to guarantee their survival. The same function applies to dreams today. There is a reason why many of our dreams are stress related. We dream of public speaking events, exam stress, work and family feuds. This is endorsed by research. Anxiety is the most frequent emotion we experience in our dreams, with negative emotions making up two-thirds of our dreaming experiences. This fits with Revonsuo’s Simulation Theory, which argues the anxiety-inducing situations in dreams are honing our ‘fight or flight’ response. Anttio Revonsuo and Katja Valli also spent a lot of time comparing dreams of children who had experienced trauma in their early life with those who had not. They found that those who had experienced trauma had dreams with more threats in them. This is because the child’s mind is trying to keep it safe. It is trying to replay the traumatic events to build an effective response. The brain wants to be sure that if the situation happens again, it will respond more effectively to avoid the danger.
Dreams are Not Realistic Dreams cannot hold an evolutionary function because they are not realistic. Most recurrent dreams offer scenarios that have limited real-world application. Dreaming that you are in naked in public may be anxiety-inducing, but it does not hold much value for improving our threat perception and motor skills because the scenario is so utterly implausible. Do We Need to Rehearse Instinct? Why would humans and other organisms need to ‘rehearse’ instinctual behaviours like our ‘fight or flight’ response? The definition of instinct is that it is an innate knowledge or response to danger. The idea that we need to ‘rehearse’ or sharpen our instincts through dream simulations would mean we have to reassess the meaning and function of instinct. On the Matter of Sex Finally, if dreams had an evolutionary function, surely more of our dreams would be about reproduction and contain sexual themes. In humans, around 6% of dreams contain sexual imagery and themes. If dreams functioned to improve the evolution and preservation of our species, surely sex would play a much more prominent role in our dreaming.
[P1] Dreaming is not random but organised. [P2] Dreams simulate threatening real-life events. [P3] The simulation of threats in dreams improves an organism's motor and perceptual performance when confronted with the threat in real life.
[Rejecting P2] Most recurring dreams do not mimic real-life scenarios but implausible situations. [Rejecting P3] This performance is dictated by instinct. By definition, instinct is not something that needs improving or rehearsing. It is innate knowledge.