I think it would be fairly shocking to find that something like dreaming would evolve in two species whose most recent common ancestor didn't dream.
To have two non-closely related species implement sophisticated cognition in a way that overlaps so much suggests that intelligence and consciousness, or at least the kinds that we experience, doesn't or can't take a wide variety of forms.
It's not surprising that a dog dreams; there's a dog analogue for most human things, right down to the eyebrows. But an octopus? Wow.
Emerging evidence suggests that basically everything has a "sleep-like" state (lowered activity, periodic, homeostatically regulated, increased arousal threshold, necessary for good health).
In most things with good experimental models for learning and memory, this sleep-like state supports formation of long term memories, e.g. [0] in nematode worms and [1] in honeybees.
So really the rate limiting step is the discovery of how to interrogate/characterize behavior, learning and memory in weird little critters that don't sense or behave like mammals.
Of course there is also the philosophical question re: qualia of memory-reconsolidation-associated processes in sleep and whether they feels the same to a human or nematode - Probably not, as everything else probably feels pretty different to them too! But from a behavioralist perspective they're pretty much the same modulo the behavioral range of a human or a worm.
I fully admit that I didn't read the first line of the article because I need a nap, but I stand by the fact that I think all things that sleep dream. I would not be surprised if we find out one day if we are around for a bit longer that trees dream. They definitely sleep and I've heard them say they make plans.
In all seriousness though, I like Douglas Hofstadter's consciousness cone. If it is life, it has a mirage of consciousness. I think his term "mirage" doesn't fully illustrate the holographic nature of it, but I don't quite have a better grip on it than that myself. If it has a rest period likely where it sorts what it's done and turns that into new patterns... well, that's a dream to me. I think we will see dreaming things anywhere we find life in the cosmos. I think it goes all the way down and is fundamental.
The results from this paper are very exciting to me in that context. They illustrate my assumptions. I think it's important research for sure. I watched octopus sleep and change color in person at an aquarium in Seattle. A great pacific octopus. I've also been there when they were awake just before feeding and had one all wadded up watching me through the glass waiting for their feeder. They are incredible.
While I agree that it's silly to pretend like dreams are something exclusive to humans (especially considering that our prefrontal cortex is largely deactivated during them anyway), I think it can be misleading to categorise all animals as having similar experiences to humans in their dreams.
Take Dolphins for example. They need to keep one hemisphere active at all times to keep themselves swimming and breathing while the other rests so at some point in their sleep, the hemisphere that's resting swaps over. This is going to give their dreams a very different feel to ours, possibly something in between a lucid and regular dream, and those are fellow mammals!
Imagine how different the experience of even birds must be never mind Octopuses which are 600 million years removed from us in terms of evolution and have a neural structure that is far more distributed than our own. Perhaps individual octopi legs have their own separate stream of consciousness distinct from the animal as a whole.
Do trees actually 'sleep'? Like they don't have neural centers that we consider to be brain-like, that I know of. Further, just defining the concept of sleep is a little tricky and I'm not aware of anything like sleep-ish brain waves, or not moving for a long period of time that we consider sleep-like in trees.
So this idea of sleep evolving in two different species whose ancestor didn't sleep is very interesting.
Trees definitely sleep nightly and hibernate in winter [0]. Their root system and the mycelial network that interoperates with them is astoundingly complex and looks very similar to a brain as we faster moving life are blessed with on top.
Here is a lady talking about some of Paul Stamets' research. [1] I also recommend this talk by him. [2]
Mushrooms interacting with plant roots look similar to a brain and we are just beginning to grok how deep that goes.
I don't necessarily buy that this is equivocating anything. How else would you define sleep scientifically other than as a nightly cycle that follows a circadian rhythm and propagates metabolic and hormonal changes throughout the body?
If you're trying to argue that it needs to have a "rest" component to it, I would remind you that during night time, trees do not photosynthesise and also the human brain is not at all at rest during sleep in terms of objective neurochemical activity. Consciousness is lost (except even this is a hazy cut off thanks to dreams) but there is a lot going on still in the brain and body.
That's a fair rebuttal, my bad. However, one thing that plants do more during the night without any bio-mechanical necessity attached to it is the release of auxin which is the flora analogue to growth hormone, just like animals do during sleep.
> So this idea of sleep evolving in two different species
You're assuming sleep comes after consciousness. Whatever sleep and dreams are, it's entirely possible they are the precursor to consciousness, not an evolutionary step off of consciousness.
I’ve heard it said that trees are upside down people, with a “head” buried in the earth. It’s a flawed metaphor of course but it gets people thinking.
There’s been some interesting experimental research on how certain plants respond to stimuli and taproot lobotomies. These seem to be evidence for the equivalent of a brain-like computational center in plants. https://en.m.wikipedia.org/wiki/Plant_cognition is a good jumping-off point.
For a long time, people thought that applying terms like cognition and intelligence to plants and mold was anthropomorphizing, but nowadays it might be seen as animal-centrism, to proclaim that cognition and intelligence are exclusively within the domain of the animal kingdom.
Similar to what you find interesting here, plants seem to have evolved computational structures that are similar to our neural system, in that they have stimuli responses that are biased genetically, but that can also adapt to lived experience via hormonal feedback loops that serve as a kind of memory.
> I think it would be fairly shocking to find that something like dreaming would evolve in two species whose most recent common ancestor didn't dream.
I don't see why.
Our most recent common ancestor with wasps very likely had neither eyes nor legs, but we and wasps both have both of those. Perhaps it's more obvious why eyes and legs are of use to terrestrial animals who hunt by sight, than it is why dreams are of use to anyone - but why should the null hypothesis not be that a convergently evolved trait is adaptive and thus likely to be conserved?
I can't find the article saying that the most recent common ancestor between humans and octopi doesn't dream. I think that'd be quite hard to prove, since that species is likely extinct.
From what I remember Our common ancestor lived 500 milion years ago. It was rather a realy simple creature. With not many neurons and I think this is some kind of estimation. Of course we can't be sure but we never can be sure.
I hope you can understand me my english isn't very good
Cephalopods are protostomes (https://en.wikipedia.org/wiki/Protostome), vertebrates are deuterostomes (https://en.wikipedia.org/wiki/Deuterostome). I'd think with our current understanding of bilaterian evolution, one would expect the last common ancestor to be something relatively simple (a worm-like animal?) with a rudimentary nervous system.
The protostomes are a monophyletic group, i.e. they include all the descendants of some animal that lived a short time before the beginning of Cambrian, probably around 550 million years ago.
On the other hand the deuterostomes might be or might not be a monophyletic group, it is not known yet with certainty, so it is still possible that the word "deuterostomes" might be invalid, if there exists no such group.
The name "deuterostomes" is used for the ensemble of 2 groups, the chordates (including us) and a group composed of echinoderms and hemichordates (Ambulacralia).
These 2 groups share one character present in their ancestors, the existence of some openings that connect the pharynx with the exterior (e.g. the ears in humans or the gills in fish).
However, there is a chance that this character also existed in the ancestor of the protostomes, but it was then lost, in which case it would not be a proof of a closer relation between chordates and echinoderms+hemichordates.
The ancestor of the protostomes and the ancestor of the chordates both had a rather complex nervous system, while the ancestor of the echinoderms+hemichordates had a much simpler nervous system, similar to that of many of the cnidarians (but even some jellyfish have a more complex nervous system than that).
If it will be proven in the future that in fact the protostomes are more closely related to the chordates than the echinoderms(+hemichordates), then their common ancestor would already have had a complex nervous system.
In this case, the similarities between octopuses and mammals, while still greatly increased by convergent evolution, would be far less surprising, because there would be much more features of the nervous system that would be inherited from the common ancestor.
While there are many genetic similarities between echinoderms+hemichordates and chordates (i.e. us), most of those are also present in cnidarians, so they must be older than the separation between chordates and protostomes. The chordates retained them but the protostomes lost those features, so they are not a definitive proof of relationship.
Which is the closest relative of the chordates is one of the most important questions of the animal phylogeny and there are chances that the answer that was believed true for more than a century is in fact wrong.
The correct answer to that question has consequences mainly for understanding the evolution of the nervous system and for the applicability of some things that we can learn about the brains of protostomes (like the octopuses) to our own brain.
Yes, this last common ancestor has humans and octopi among its descendants, but also limpets, clams, and sea squirts. If it also dreamed, if dreaming isn't a product of convergent evolution, that is also amazing.
Your English is excellent, by the way, what little of it I've read.
To have two non-closely related species implement sophisticated cognition in a way that overlaps so much suggests that intelligence and consciousness, or at least the kinds that we experience, doesn't or can't take a wide variety of forms.
It's not surprising that a dog dreams; there's a dog analogue for most human things, right down to the eyebrows. But an octopus? Wow.