Threat 21)Simulation Theory
This clever evolutionary theory holds that dreaming serves a biologically adaptive function because it allowed our ancestors to simulate problem-solving strategies for genuine, waking life threats. Antonio Zadra, Sophie Desjardins, and Eric Marcotte of the University of Montreal neatly summarize the central argument of the theory this way: “By giving rise to a full-scale22)hallucinatory world of subjective experience during sleep, the dream production mechanism provides an ideal and safe environment for such sustained practice by selecting threatening waking events and simulating them repeatedly in various combinations.”
Costly Signaling Theory
Boston University neuroscientist Patrick McNamara's theory draws from the well-known “23)handicapping principle” in evolutionary biology, where some organisms have been observed to display behavioral traits or physical characteristics that seem 24)ostensibly to disadvantage them but in fact simply reflect their genetic value. The classic example of this is “25)stotting” behavior in healthy young gazelles, where these animals jump up and down in front of a 26)predatory leopard rather than immediately run away. Stotting is a “costly signal,” but it works, because the leopards take this stotting display as evidence that this particular gazelle is so healthy and fit that it can afford to handicap itself and is therefore unlikely to be an easy target. McNamara argues that dreaming can best be understood also as a type of costly signal. He points out that REM sleep is associated with increased 27)mortality, particularly with respect to the irregular activity of the 28)cardiovascular system.
Dreaming as Problem-Solving
Barrett's preferred evolutionary explanation for dreaming, and the one she's best known for, is that29)dreamscapes provided our ancestors (and therefore us) with a sort of creative 30)canvas for solving real-world problems. In support of this, Barrett describes the work of Stanford University psychologist William Dement, who in the early 1970s instructed hundreds of undergraduate students to work on a set of challenging 31)brainteasers before bedtime, so that they'd fall asleep with the problems still on their mind. For example, “The letters O, T, T, F, F…form the beginnings of an infinite sequence. Find a simple rule for determining any or all successive letters.” [The correct sequence is the first letter of each number, so the next one would be “S” for “six.”] One participant who went to bed frustrated by this brainteaser dreamed:
I was walking down the hall of an art gallery. I began to count the paintings—one, two, three, four, five. But as I came to the sixth and seventh, the paintings had been ripped from their frames! I stared at the empty frames with a peculiar feeling that some mystery was about to be solved. Suddenly I realized that the sixth and seventh spaces were the solution to the problem.
Personally, I think each of these major evolutionary theories of dreaming has some currency. And speaking of bizarre and surreal, there's of course the curious case of 32)erotic dreams. And the exploration still has a long way to go.