Dreams and Evolution

What is the current hypothesis regarding how dreams evolved? I remember reading that without dreams we would start to go insane, which means that they’re required for us to survive. Also, other animals dream (like my dog); however, I don’t know if they need them to survive.

So at what point in the evolutionary tree did humans gain the ability to dream and at what point did they become a necessity for us to survive? At what point did other animal acquire the ability to dream and why?

I’m skeptical that without dreams we’d start to go insane, and that we need dreams to survive.

I have no doubt that somebody has claimed it as fact, but one has to wonder how they would know.

I don’t know anything about how dreams evolved.

AFAIK- Dogs do dream and will exhibit similar reactions to humans if they don’t get their required sleep.

I’m not positive though.

I recall reading somewhere (I think in my Psych class years ago), that an experiment was undertaken where subjects where woken just as the began REM sleep, thus preventing them from dreaming. As the experiment continued, the subjects began to go insane.

I couldn’t find a link in a quick Google search, sorry.

Shit, I’d go crazy if a bunch of asshole researchers kept waking me up. :slight_smile:

Seriously, there’s a lot going on when you sleep other than dreaming. Could be something else entirely going on.

I’m also somewhat skeptical of the claim, though of course I’m in no such place to make judgements on it.

I wonder if dreams are an intentional evolutionary development or more a natural “symptom” of having an advanced brain?

This site supports Bup’s skepticism and Skott’s recollection. Without REM sleep, says the author, you’ll get cranky but won’t necessarily go crazy. link

More info, written for the regular joe, here: link

This next site, not really written for the regular joe, talks about why we need to dream. I’m not qualified to tell you whether this is a good site or a bunch of BS. Among other things I read at this site is this: “It is now believed that many memory circuits of the brain are reinforced during sleep, a process in which synaptic strengths are maintained at dedicated levels. Synaptic strength maintenance occurs largely through the action of self-generated, spontaneously occurring, slow brain waves (waves at frequencies less than about 14 cycles per second). This occurs both during rapid-eye-movement (REM) and nonREM sleep, though there are significant differences in function between the two phases. Maintenance is necessary since all synaptic strengths weaken with time due to “turnover” of essential molecules. Without remedial action during sleep, all memory circuits that were not being regularly ‘exercised’ by frequent use while awake, would gradually deteriorate and their encoded memories be lost.” I removed a number of hyper-text citations while copying this. The site can be found here: link.

I tried to Google up a site that dealt with animals, evolution, and dreams. “dream REM evolution” turned up this site: link. It doesn’t look very scientific, but it does have, in addition to pretty colors and a picture of a unicorn, a list of animals that do and do not have REM sleep and/or dreams (evidently REM sleep and dreams don’t always require each other). By this point I grew tired and chose not to exam the other 7,939 websites.

Hope this was somewhat helpful. Have a great day!

Well, actually, it looks like the partial paragraph I quoted is about why we need to sleep, not why we need to dream. Aw well. You can go to the website in question and puzzle it out for yourself, I guess. :slight_smile: Lots of info about dreaming and craziness and stuff to be found there.


I read a study once about a group of lab rats that scientists derived of sleep. They kept shocking the rats to keep them awake and after less then a week they had all died. Not exactly about dreaming but interesting all the same.

Well, I haven’t found a link to the research I recall, but this is interesting. From http://www.sas.upenn.edu/~danielgz/dreams07.html:

Here’s something that somewhat refutes and confirms my earlier postilization from http://www.sleepmedservices.com/101questions/dreams.html:

However, that’s kind of off the main question I was hoping to find out, which is how and why dreams evolved. Or at least the hypotheses :slight_smile:

From the same page I quoted above, a similar experiment was done with rats and REM deprivation. They lasted a little longer though…

In his The Cerebral Symphony, William Calvin discusses the nature of consciousness, touching on dreams briefly. The research he cites indicates that the main purpose of the subconscious mind is to throw together concepts at random. The filter between the conscious and unconscious minds throws out the bad ones. If the filter is too strong, a lack of creativity results. Too weak, and insanity occurs.

During sleep, the filter is inactive, and all the random juxtapositions of images, ideas, and imagination can make it to the conscious brain. Hence the truly bizarre nature of dreams.

Woohoo! I get to contribute! Yay!

I am getting all my information from Scientific American’s “The Hidden Mind” special edition issue (Vol. 12 No. 1), specifically out of the article entitled “The Meaning of Dreams” by Jonathan Winson.

According to Winson, REM sleep appeared in mammals around the same time as live birth. The echidna doesn’t show REM while sleeping, whereas the marsupials and placentals do. Where it gets interesting is the size of the prefontal cortex. “The echidna … has a larger prefrontal cortex compared with the rest of its brain than does any animal, even humans.”

Winson says that basically dreams are useful for processing and storing memories that are important for an animal’s survival. Instead of having to perform all its memory processing while everything happens, the animal can handle the processing when nothing else is going on. Handling everything realtime is more expensive, leading to a larger prefrontal cortex (hence the echidna’s big brain).

With the advent of dreams, brains became much more efficient, allowing for increased intellectual power with a reduced size. Hence, more adaptability with fewer resources needed, and natural selection took it from there.

So to answer the OP more succinctly, humans inherited dreaming from their forebears. Dreaming developed somewhere between egg-laying mammals and live-birth mammals, and has been a vital part of the process ever since. Whether or not a kangaroo (fer instance) can survive without dreaming, I don’t know.

If you find this interesting, I’d recommend the article I mentioned above. The author does a much better job than I in describing what’s going on, and the rest of the issue is very interesting as well.

I seem to recall reports of one gentleman who had a piece of shrapnel in his brain and either hadn’t slept or hadn’t dreamt in several years, without apparent ill effect.

Ahh - here’s a cite - the relevant part:

So - I’d say it’s not required for survival, but you’d have to be re-wired some first in order to cope.

Since many animals can dream, I had assumed that dreaming came about in some forebearer that we and say, my dog, share in common. However, as mentioned in a link above, not all mammals dream and mammals are not the only animals that dream. Based on these two facts, it would almost seem that dreaming evolved either before the first mammals came about (i.e. at a point where mammals and other dreaming animals have a common ancestor) or after (i.e. where the dreaming and non-dreaming animals branch off).

I also try and think of why dreaming came about and why it became a required part of some animals lives. I’m not an expert in evolutionary theory, but I have a hard time understanding how dreaming started as a mutation that was able to be inheirited and then became a necessity for survival.