Is consciousness a cheat ability exclusive to humans? The "Ancient Mind" hypothesis that extends from slugs to humans

The narrative of "Consciousness as a Human Privilege" is being questioned

That mysterious feeling of "being here now."
The ability to experience pain, joy, embarrassment, or excitement as "mine" is something we naturally refer to as consciousness.

For a long time, many people have thought this way.

Consciousness is a special ability possessed only by the highly developed human brain.

However, a recent article introduced by ZME Science, titled "Consciousness Could Be an Ancient Trait Evolved Millions of Years Ago, Not a Human Superpower," presents a perspective that overturns this conventional wisdom. As the title suggests, consciousness might not be a superpower suddenly granted to humans recently, but rather an "ancient evolutionary trait" that emerged millions of years ago.ZME Science

The debate over "how widespread consciousness is"

The discussion about animal consciousness has long been a theme involving philosophy, psychology, and neuroscience. The Stanford Encyclopedia of Philosophy also organizes the core question as "whether consciousness is possessed by only a few animals or is much more widely distributed."Stanford Encyclopedia of Philosophy

In 2012, the "Cambridge Declaration" was announced, signed by prominent neuroscientists. It declared that many animals, including mammals, birds, and octopuses, have the neurological substrates capable of generating consciousness similar to humans. The stance that "only humans possess consciousness" is becoming increasingly difficult to support scientifically.fcmconference.org

The article covered by ZME Science discusses a new review paper that attempts to organize "when and how consciousness emerged and how far it spread" over the long timescale of evolution. This paper by Russian researcher Gusev and colleagues positions consciousness as a "natural stage in the evolution of animals with nervous systems," integrating data from various species.MDPI

A new theory of evolution: Consciousness as a "natural step for animals with nervous systems"

Gusev and colleagues' argument can be roughly summarized into the following three points.PMC

1. The emergence of consciousness is a "natural evolutionary stage" for animals with nervous systems to adapt to their environment and survive.

2. The key is "subjectivity"—the ability to distinguish oneself from the environment and evaluate the value of one's state and desires.

3. As the ability progresses from simple stimulus-response to complex learning and prediction, consciousness also becomes "denser" in stages.

This perspective views consciousness not as a binary switch of "zero or one," but as a gradient that changes continuously from "thin to dense."

For example, even animals with simple neural circuits possess the minimal "feeling ability" to avoid danger and seek food.
As evolution progresses and learning, memory, and social interactions with others develop, the subjectivity of experiencing the world while maintaining a sense of "self" becomes denser—such is the image.Frontiers

Even snails might have "some kind of feeling"

A question that symbolizes this discussion is, "Do even snails have 'some kind of feeling'?" Philosopher Eric Schwitzgebel seriously examines the snail consciousness problem in his paper "Is There Something It’s Like to Be a Garden Snail?"faculty.ucr.edu

He points out that given snails respond quite flexibly to light, humidity, and smell, and even learn, both asserting "they have consciousness" and "they have none at all" can be equally persuasive. Ultimately, he suggests that because consciousness theories are not yet fully developed, a "yes or no" conclusion has not been reached.

According to Gusev and colleagues' framework, even animals with simple nervous systems like snails, which change behavior according to the environment and live by sensing their body's state, may not be unlikely to possess something akin to "primitive subjectivity."

In other words, behind phenomena we assume to be "mere animal reflexes," there might be a thin but definite spread of "some kind of feeling."

Monkeys looking in mirrors, fish avoiding pain—The gradient of consciousness

Of course, the question "So where does consciousness begin?" still remains. One famous benchmark is the mirror self-recognition test (mirror test). Proposed in the 1970s, this test involves marking an unseen part of an animal's body, and if the animal touches the mark upon seeing itself in the mirror, it is interpreted as recognizing itself as the entity in the reflection.Wikipedia

Only a few animals, such as chimpanzees, dolphins, elephants, and magpies, have passed the mirror test. However, there is strong criticism against relying too heavily on this test, and a consensus is growing that "not using a mirror well does not equal zero consciousness."Stanford Encyclopedia of Philosophy

Additionally, when looking at various indicators such as pain behavior, learning ability, and future planning, a surprisingly rich "mental world" emerges, extending even to fish, birds, octopuses, and insects. A paper reviewing such research states, "There is no longer any doubt that some form of consciousness exists in many animal species. The question is about its evolutionary origins and diversity."Embo Press

Gusev and colleagues' evolutionary model connects these insights, drawing a scenario where "consciousness has developed gradually in proportion to brain size and complexity."

* Simple neural networks: "Primitive feelings" at the level of pleasure and discomfort
* Fish and reptile level: "World model" based on spatial understanding and learning
* Bird and mammal level: Rich subjective world including social relationships and future predictions
* Human and some primates: "Narrative self" accompanied by self-narratives and metacognition

In this framework, human consciousness is merely "one form at the upper end of the gradient," not an isolated exception.Frontiers

How did social media react?—Surprise, ethical concerns, AI comparisons, and religious conflicts

The ZME Science article has spread across various social media platforms through news aggregators, Pinterest, Reddit, and more.Pinterest

While individual tweet and thread texts cannot be directly confirmed from here, given that similar topics have repeatedly gone viral in the past, it is reasonable to assume that the following "reaction patterns" are unfolding (the following are not actual post quotes but representative examples based on trends).

1. Pure surprise and excitement reactions
   "The idea that even snails might have consciousness makes the world suddenly feel more lively."
   "The Earth might be filled with 'feeling beings.'"
   Such comments are often seen among science news accounts and philosophy enthusiasts.

2. Reactions from the animal ethics and vegan communities
   "If consciousness is widely distributed, how do we justify factory farming?"
   "If fish feel pain and fear, we should reconsider the menu."
   Since the Cambridge Declaration, those who consider "consciousness = the line for ethical consideration" have cited such news as a strong tailwind.animal-ethics.org

3. Tech community discussions comparing with AI
   "If consciousness is merely a gradual evolution of information processing, will advanced AI eventually develop subjectivity?"
   "Isn't it nonsensical to discuss 'AI has consciousness/doesn't have consciousness' without defining consciousness?"
   Given that Gusev's paper covers "from biological foundations to technological horizons," discussions among AI researchers and engineers are also heating up, comparing the evolution of consciousness with the potential for artificial consciousness.MDPI

4. Pushback from religious views and anthropocentrism
   "Treating humans and other creatures equally denies the existence of the soul."
   "The belief that consciousness is a gift from God to humans alone is incompatible."
   From this standpoint, there is an expression of caution that "science is once again trying to take away human privilege."

5. Self-deprecating and humorous reactions
   "A snail probably has a more coherent consciousness than I do before a deadline."
   "My cat definitely has a higher consciousness than I do."
   Even with heavy themes, memes and self-deprecating jokes inevitably accompany discussions on social media.

Since the ZME Science article simplifies the often complex study of consciousness for general readers, it is likely to receive many positive comments like "I don't quite understand it, but it's exciting" or "I've never considered this perspective." On the other hand, as it connects to other contentious themes like ethics, religion, and AI, the comment sections could become venues for quite chaotic discussions.

If consciousness is an "ancient trait," how will our ethics change?

If consciousness was born in the ancient seas and is widely distributed across various animal lineages, our "relationship with other living beings" will be fundamentally questioned.

Even more than ten years after the Cambridge Declaration, the initial declaration is still cited worldwide as a message that "consciousness is not exclusive to humans."fcmconference.org

New evolutionary research like that of Gusev and colleagues urges the next step along that trajectory.

• How far should considerations extend to fish, crustaceans,