Clones may be dead on arrival—consciousness debate shifts

subcortex consciousness – A plan to grow “unfeeling” clone bodies without a conscious brain is drawing attention to a deeper scientific fight: whether consciousness is rooted in the cortex—or can arise from the brain’s older, more primitive subcortex.

Heavily marketed immortality fantasies are nothing new. But one recent idea coming out of Silicon Valley carries a chill of its own: growing human clones as spare parts—grown without a conscious brain, intended to become “body transplants,” and hypothetically, a path to living longer.

The premise is simple enough to be unsettling. If these clones are wholly unconscious—no awareness of the world, no faint sense of themselves—then the ethical barrier supposedly collapses. The hard part is proving what consciousness requires.

It isn’t clear how much—or how little—brain these clones would have. But the concept rests on a key prediction: the clones would lack a cerebral cortex. the wrinkled outer layer linked to sophisticated cognitive functions such as language. self-reflection. and abstract thought. Most theorists have long assumed that the cortex is where consciousness, or subjective experience, arises. If that’s right, an organism without it would have no thoughts, sensations, or emotions—no inner life at all.

Yet a growing group of consciousness researchers is pushing back. insisting that this way of looking at the mind may be as mistaken as the old geocentric model once was for astronomy. They argue that consciousness could originate deep within the brain’s most evolutionarily ancient realm: the subcortex.

Mark Solms, a neuropsychologist at the University of Cape Town in South Africa, describes the corticocentric framework as foundational. “It’s a foundational theory about where the mind is. ” he says—adding that it’s “as old as any attempt to relate brain to mind” in neuroscience. For him and others aligned with the subcortical view, the disagreement isn’t academic. If the subcortex can support experience on its own, then the field’s definition—and measurement—of consciousness changes. And so does who (or what) deserves moral concern.

The cortex and the subcortex are tightly interconnected. When most sensory information enters the brain. it flows through deep-brain relay points in the subcortex on its way up to the cortex. The cortex then responds with feedback signals in an ongoing communication loop. “It’s been clear for nearly a century that if certain parts of the subcortical brain stem get damaged. ‘the lights go out. ’” Solms says.

That’s the disagreement in miniature: is the subcortex simply a power supply keeping cortical consciousness running, as “corticalists” hold? Or can it sustain basic consciousness by itself?

For subcorticalists, the evidence they cite is almost painfully human.

Children born with hydranencephaly are frequently categorized as being in an unconscious vegetative state because they are born without a cortex. Yet in 2004. Bjorn Merker. a Swedish neuroscientist. joined five families at Disney World and spent a week observing the children’s behavior. They giggled. played with toys. and showed “responsiveness to their surroundings in the form of emotional or orienting reactions to environmental events. ” Merker later wrote. Merker says he couldn’t believe he was seeing philosophical zombies—beings that act normal while lacking felt experience. Solms later followed Merker’s example and spent time around children with hydranencephaly. “The evidence that they are not ‘zombies’ is exactly the same evidence that your dog and your cat are not zombies. ” he says. “They’re reporting by their behavior that they’re feeling things.”.

The catch is brutal. The appearance of consciousness and consciousness itself are not the same thing. Strictly speaking. researchers can’t determine whether an organism is conscious unless it can narrate its experience. which forces scientists into inference when language isn’t available. That leaves room for an impasse: how can nonverbal life-forms prove they aren’t mindless automatons?.

That’s why other researchers lean on the structure of the brain itself. Matthias Michel. a philosopher at the Massachusetts Institute of Technology. is prepared to attribute consciousness to other mammals with a cortex and to birds with a functional equivalent in the pallium—but not to fish or insects that lack a cortex.

Michel’s conviction is shaped partly by studies focused on vision and the path visual information takes. Visual input travels from the eye to subcortical structures and then on to the primary visual cortex at the back of the brain. From there, neural activity ripples across higher cortical areas. Michel argues that this initial pass unfolds unconsciously. beneath the threshold of awareness. and that only later—when feedback loops start reverberating within the cortex—do people report conscious awareness of what they’re seeing.

But another set of observations undercuts any simple “watch the cortex and you’ll find consciousness” story. “Consciousness is just the tip of the iceberg,” Michel says. “The large part of your behavior is driven by unconscious processes.” In blindsight. for example. people whose visual cortex has been damaged appear to respond to visual stimuli while insisting they see nothing.

From that perspective, hydranencephaly children could be reacting without having subjective experience—subcortical activity might drive behavior, without necessarily creating an inner world.

Solms counters by shifting where researchers aim their attention.

Most consciousness research has leaned heavily on vision, but Solms argues that investigators should start with feeling. He takes feelings to be intrinsically conscious, saying that “If [we] had started with feeling rather than vision, there would have been no mystery to begin with.”

He advances an evolutionary case: feelings show up once organisms become complex enough to juggle competing needs—eating. sleeping. finding mates. evading predators. Such organisms must reprioritize constantly. In Solms’s view, feelings give direction to action. “We feel,” Solms says, “so that we can transcend instinct.”.

Tim Bayne, a philosopher at Monash University in Australia, finds the argument compelling even without committing fully to subcortical ideas. “You’ve got to integrate all of that stuff, and you’ve got to act in real time,” Bayne says. “Maybe that’s what consciousness is all about, and pretty simple animals have that.”.

If consciousness is tied to this kind of real-time balancing. it might not be limited to species with massive cortical expansion. Subcortical architecture. Solms and others argue. evolved during the Cambrian explosion—more than 500 million years ago—while the cortex in mammals began to coalesce around 300 million years ago. Drawing that line forward would include reptiles, amphibians, and fish. Some researchers also suggest analogous brain structures may support consciousness in insects and cephalopods, including octopuses.

Even subcorticalists concede the cortex enriches human experience. Merker puts it bluntly: “Everything that makes our world rich is a gift of the cortex. And by the same token, without the cortex, there is no such richness.” The dispute is about what creates consciousness at the most basic level.

Subcorticalists argue that the cortex distills and expands—but experience itself emerges from deeper circuitry. Daniel Freeman. a neurophysiologist at M.I.T. describes the mismatch between the brain’s torrent of information and what people actually perceive. “Our experience is so simple by comparison,” Freeman says. “Somehow. the thinking goes. cortical information must be distilled into a single stream of awareness.” In that model. cortical activity funnels diffuse electrical signals downward toward a neural bottleneck in the brain’s nether regions. where the chaos becomes something suited to consciousness.

Solms argues that in children with hydranencephaly and in primitive animals. the subcortex alone might yield only “the most rudimentary form of consciousness.” He points to deep-brain stimulation that can summon basic but powerful emotions such as severe depression and fear. Michel pushes back. For him, even that may be explained by higher brain activity downstream. “Even experiencing a dim light, the most boring experience,” Michel insists, “would require something like the cortex.”.

That standoff is now meeting a new technical challenge.

Anil Seth. a neuroscientist at the University of Sussex in England. says there isn’t enough evidence to fully support either cortex-origin or subcortex-origin versions of consciousness. Seth agrees with Michel that there’s “a wealth of evidence” linking cortical processing to consciousness. but says the precise brain activity tied to experience—the neural correlates of consciousness—has remained elusive. He adds that the lack of consensus could stem from how little is known about what goes on in the subcortex during experience.

Enter transcranial focused ultrasound. or tFUS. a technique that may let researchers probe subcortical structures directly—“the terra incognita lurking beneath a relatively well-mapped cortex.” Freeman and Michel. despite holding opposite views on where consciousness lies. have co-authored a paper suggesting that tFUS offers “an exciting opportunity for breakthroughs in consciousness research.”.

Seth frames it as a chance to test the theory in a concrete way. Michel says that if stimulation of subcortical regions led to a person regaining the sensation of pain after losing it due to cortical damage, he would be “blown away.”

While the cortex-centered view still dominates, the debate appears to be shifting.

Bayne and Seth wrote an influential review of consciousness theories in 2022 that relegated subcortical considerations to one sentence in a sidebar. reflecting how little these ideas appeared in the broader discourse. Bayne says the debate has opened up since then: “I think the debate has opened up a little bit.”.

A notable sign arrived in 2024 with the New York Declaration on Animal Consciousness, released and signed by nearly 600 scientists. The declaration notes that other mammals and birds are almost certainly conscious. It states that “the empirical evidence indicates at least a realistic possibility of conscious experience in all vertebrates … and many invertebrates” and argues that researchers must consider their welfare. Solms and other confirmed subcorticalists have signed alongside Seth, who still leans cortical but says he’s open. “I wouldn’t be terribly surprised if we look at the book of truth. ” Seth says. “and the answer is that some basic forms of consciousness are completely supported by the subcortex.”.

That’s where the Silicon Valley clone scheme bumps into the science.

If the subcortex can support basic consciousness. then “unfeeling meat sacks” may not be as ethically effortless as the scheme suggests. If the cortex is necessary for experience, then the plan could be exactly what it claims to be. Either way, the question goes beyond philosophy and tech marketing. It presses directly on how we decide what counts as a mind.

In a field where researchers still lack certainty about the neural correlates of consciousness, the subcortex is no longer a footnote. It’s becoming a potential frontier—one that could force the world to look for consciousness in the place it least expects.

And for anyone imagining cloning bodies without inner life, that shift won’t just change how scientists measure experience. It could determine whether the project creates less harm—or simply uses the wrong definition to avoid accountability.

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