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Blog 16: The evolutionary origins of dreams?

2nd November 2020

Can we explain the differences between waking and dreaming through my proposal on the evolutionary origins of dreams? I summarised this in Blog 13 when I compared my theory to Freud’s. Across evolutionary time, we lived in a much more dangerous world. When we were threatened by predators or competed with others for food and water, we needed to use our past experience to make fast, unconscious decisions to fight, freeze or flee. Or ignore the threat and carry on. Dreams associations drove these actions through identifying patterns in the behaviour of predators and competitors.  For example, lions generally sleep during the day.

Daytime is sleep time


They tend to hunt and visit the waterhole at night. But, during the dry season, lions can get so thirsty that they drink at the waterhole during the day. In our early, pre-linguistic days, visualising such behavioural patterns in dreams and, retaining the images unconsciously, enabled us to evaluate the likelihood of sensory input during the day, for example, a flash of yellow (lion or harmless yellow butterfly?) in the undergrowth on approach to a waterhole. We dreamed to avoid dangers and stay alive. We dreamed to survive!

We saw in the last blog that dreams almost always happen somewhere- at a place- and tend to portray movement, particularly approaches, going somewhere or towards something. Early humans would have walked to a waterhole or dependable food site and the approach would have been the most dangerous time because of the danger of “sit and wait” predators, like a lion, being hidden in the undergrowth.

I can see this phenomenon in our garden. We have several fruit trees, we fight a losing battle with squirrels who compete with us for the fruit. Next door’s cat (a sit and wait predator) sometimes hides in the cover of our hydrangea bush,

Pussy the predator


in the hope of capturing one of the squirrels. But I haven’t seen any evidence of a squirrel kill so far. Do the squirrels dream of the associations which predict the likelihood of the cat being present? I think they do! Hence they have managed to avoid it.

The common dream themes of being chased, engaging in sex and of falling (and, thus, becoming vulnerable to predation) would clearly have been of immense  significance in our evolutionary context. Early death was a constant possibility for our ancient ancestors so reproduction had to happen in early adulthood. Life expectancy only began to increase about 30,000 years ago, up until then it was unusual to live past the age of 30. Consequently, the dream theme of a person alive as dead was unsurprising because death wouldn’t have been an unusual event.

Dreams take elements of past experience, sometimes from years ago and associate them in a dream narrative. Consequently, the theme of a person now dead as alive makes sense in that context because they were alive when the association took place. Early humans would have experienced the deaths of significant others more often than we do now, consequently it’s likely that dead people would have made frequent appearances in their dreams- whenever the dead person was associated with the dream theme.

In contrast, our ancestors didn’t read, calculate, write or watch TV.

What early humans didn’t do


This may explain why these activities still don’t usually feature in our dreams. But another explanation, probably more telling,  is that we do these activities everyday- making them mundane. As we saw in Blog 15 everyday, routine activities don’t tend to feature in dreams.

Although early humans faced many perils, they would have had humdrum routines too. Most days, there wouldn’t have been a flash of yellow or other possible indication of a predator on approach to the waterhole, a few birds in the air, maybe a couple of zebra already drinking, along with a few warthogs. No elements that were worth remembering as indicative of the presence of a predator or an aggressive human competitor. In other words, mundane things which happened at a typical, uneventful waterhole visit weren’t likely to feature. We constructed dreams to avoid possible threats and take advantage of new opportunities, like a glimpse of an attractive potential mate just leaving the waterhole. Threats and opportunities didn’t arise on a daily basis. Everyday events which weren’t associated with threats and opportunities didn’t tend to appear in dreams.

On the other hand, Blog 15 pointed out that our emotional concerns, activities and interests in waking life also appear in dreams. Contemporarily, these concepts may better capture the nature of dream content than threats and opportunities.  Across evolutionary time, a key emotional concern was not getting eaten by a predator.  This would have been a more or less constant, albeit underlying, concern but may only have featured in a dream when an event triggered relevant associations. Nowadays our emotional concerns are more likely to be around work and intimate relationships but, as in our evolutionary past, concerns may only appear in dreams when a relevant associated event offers new insight into them.

This evolutionary context of threats, opportunities for rewards and emotional concerns may also explain the intense emotionality of dreams, with the prevalence of primary emotions, like fear, anxiety, anger and elation. In dreams our fear is sometimes provoked by bizarre, threatening images of the type we wouldn’t encounter everyday.

What the hell?


Social emotions, like embarrassment, shame, guilt, sympathy, jealousy, envy and pride would have developed later in our evolutionary history. Such emotions don’t feature as often in our dreams.

Dreams are always visual, we sometimes hear sound, contemporarily, usually speech, but this is sporadic rather than an extended conversation. Our other senses, taste, smell and touch, are overwhelmingly absent from dreams. Again this may reflect the archetypical predator-associated dream in our evolutionary past. If you had got near enough to a fearsome predator to touch, smell or taste it- you would have been eaten. Hence you wouldn’t have dreamed that night of predator-associated touch, smell or taste experiences.

Finally, I’m a different person in my dreams because if our dreams still bear the imprint of those of our early ancestors, many facets of the dreaming me would differ.  If I’d lived, as an early human, I certainly wouldn’t have been an academic. I may have formed a pair bond but I wouldn’t have had marital status. And, given that I would, in all probability, have died before reaching the age of 30, my dreaming age wouldn’t have matured past young adult.

Scientists have discovered an early human habitat in the Olduvai Gorge, Tanzania, despite access to water, food and shelter, living 1.8 million years ago  exposed early humans to the risk of meat-eating predators. In such an environment, to meet my needs for food , water and shelter, I would have had to be much more active than I am now.  Also, in such conditions, I’d probably be less restrained, less compassionate, more conflictual, more sexually transactional and my encounters with others would be more aggressive.

But what about other dream characteristics: sparsity; single-mindedness; bizarreness; lack of insight; absence of a past and a future; bizarreness and hyper-associativity? To explain these I, first, return to my proposal of dreams as patterns in experience.

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