By "dream", I mean:
- Dreaming while sleeping.
- Dreaming about their future life while being awake.
Thank you in advance.
According to this Psychology Today blogpost, it is quite likely that animals can dream. Particularly mammals that according to the blogpost:
All mammals share the same neural structures that are important in sleeping and dreaming.
However, for your second question, I do not think it is at all possible to know what they are dreaming about (if they indeed do dream).
Dreams are simulations created by the brain in order to train us to cope with challenging situations. Most of the dreams present situations where the individual is confronted with challenges or risks he/she might face during the life. Evolutionary concept of dream suggests that its a way by which brain try to notify some risks and train us to invade through it. The evolutionary acceptance of dreams is due to the "threat simulation" feature it possess. By which an individual can gain advantage of several situations he/she confronts in life.
Finnish psychologist Antti Revonsuo posits that dreams have evolved for "threat simulation" exclusively. According to the Threat Simulation Theory he proposes, during much of human evolution physical and interpersonal threats were serious, giving reproductive advantage to those who survived them. Therefore dreaming evolved to replicate these threats and continually practice dealing with them. In support of this theory, Revonsuo shows that contemporary dreams comprise much more threatening events than people meet in daily non-dream life, and the dreamer usually engages appropriately with them. It is suggested by this theory that dreams serve the purpose of allowing for the rehearsal of threatening scenarios in order to better prepare an individual for real-life threats.
Yes they do. Studies suggests that animals can dream while sleeping, entire human dreams occur during the REM sleep period. Most of the mammals do have the REM sleep period and it suggests that they do dream in this time of sleep.
Dreams occur during REM sleep. We typically have 3 to 5 periods of REM sleep per night. They occur at intervals of 1-2 hours and are quite variable in length. An episode of REM sleep may last 5 minutes or over an hour. About 20% of sleep is REM sleep. If you sleep 7-8 hours a night, perhaps an hour and half of that time, 90 minutes, is REM sleep.
REM sleep is characterized by a number of other features including rapid, low-voltage brain waves detectable on the electroencephalographic (EEG) recording, irregular breathing and heart rate and involuntary muscle jerks. Reference
This link provides much more examples.
According to the studies of MIT,
Wilson, associate professor of brain and cognitive sciences at MIT, and biology graduate student Kenway Louie trained rats to run along a circular track for a food reward.
They monitored the animals' brain activity during the task and while they were asleep. While the animal ran, its brain created a distinctive pattern of neurons firing in the hippocampus, a brain area known to be involved in memory.
Like us, rats go through multiple stages of sleep, from slow-wave sleep to REM sleep. In humans, it is during REM sleep that most dreaming occurs.
The researchers then examined more than 40 REM episodes recorded while the rats slept. About half repeated the unique signature of brain activity that was created as the animal ran. The correlation was so close that the researchers found that as the animal dreamed, they could reconstruct where it would be in the maze if it were awake and whether the animal was dreaming of running or standing still.
These memories were replayed at about the same speed that the animal had experienced them while awake. Reference
Dreaming about their future life while being awake, good question. If they do so then it will be a contradiction to our long held view of animal thought process. Most of the animal thought process that we try to reveal is through the firing of particular areas in their brain with the association of certain hormones. By this process we can find that which all neural pathways are used while dreaming and which are not.
As we can find that animals also have dreams, then it is obvious that they could recollect it (some what vague) and can prepare mentally to face those particular situations. This doesn't mean that they do have plans about events coming for them in future, but researchers states that dreams are their only offline experience with those events. The memory of those dreams help them to ensure little advantage over those future events. While in the case of humans, we have a highly complex brain which is so good at simulating events by which we can plan our future, but other animals lack this complex structure(complex but not as much as ours), so they entirely rely on dreams for that purpose.
Why do animals dream about one experience and not another? "This work allows us to evaluate the content of dreams and create tests to see which awake patterns create patterns when the animal is asleep," Wilson said. "If we are able to evaluate the content of the dreaming state, we may be able to find out why certain events get replayed and others don't."
This work also raises questions about long-held assumptions about animals' thought processes. Only a handful of species — among them chimps and dolphins — were thought to have any ability at all to recall and evaluate detailed sequences of events after they occurred. Wilson points out that "dreams are the ultimate off-line experience. This work demonstrates that animals are capable of re-evaluating their experiences when they are not in the midst of them." Reference
From the ScientificAmerican
Yet, given the vast documentation of realistic aspects to human dreaming as well as indirect experimental evidence that other mammals such as cats also dream, evolutionary psychologists have theorized that dreaming really does serve a purpose.
Although the linked article doesn't look like they were talking about animals. But I wont purchase the article to check that...
As for your second question, I would say yes, when you would say, making a plan is equivalent to dream of the future. Crows are smarter than you think...