The xenomorph has been on screen for nearly half a century, and the films that introduced it remain cinematic and cultural milestones: Alien (1979) is a masterpiece of claustrophobic horror; Aliens (1986) reimagines the same creatures as the centrepiece of an action epic without ever softening the claustrophobic, all enveloping, terror.
And Ellen Ripley is the perfect match to the Alien Queen. What a movie. Surely one of the greatest and thematically deepest action adventure movies of all times.
Sigourney Weaver’s performance is utterly iconic, and Aliens is still analysed for themes ranging from survival and perseverance; to the powerful bonds of motherhood and the maternal instinct through Ripley's protective relationship with Newt; to corporate greed and exploitation; to the reversing of traditional gender roles with a strong female protagonist combating another female – the Alien Queen. There are even themes revolving around trust in AI systems: the robot Bishop (who prefers the term ‘artificial person’ to ‘synth’), and whether he can be trusted or not.
And the movie itself is utterly edge-of-the-seat, hands-over-eyes, terrifying, non-CGI movie making.
The crew are attacked by xenomorphs - creatures almost beyond human experience: utterly pitiless, ravenous, predatory hunters, combining the worst things that hunt you in your nightmares with all-too-real characteristics drawn from numerous species here on earth.
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The later sequels stumble: Alien³ and Resurrection offer fragments of cinematic brilliance but in the end just aren’t in the same league as first two movies. The prequels aspire to myth-making, but theological digressions leave the alien itself strangely diminished, and the experience just tiresome. I thought they just weren't that good (undergoing that transformation that befell The Terminator series as well: diminishing returns because if an unwillingness to really reimagine the the storyline).
The new Disney series - Alien: Earth - is so different, astonishing:- unsettling, eerie, and brilliant, restoring what was most disturbing about the original films - not cheap blood-spattered spectacle but a foreboding and unsettling atmosphere; not cheap body horror, but the uncanny sense of encountering something that is at once alien and all too biologically plausible. And there’s lots more - identity, consciousness, family, and much more. And there are other aliens too - a weird multi-eyed, multi-legged, sort of parasite thingy with an eerie intelligence.
Honestly - the biosecurity protocols, safety handling, and security around these off-Earth beasties leaves a lot to be desired.
So, lets think about the xenomorph as a counterfactual organism.
What if we treated it seriously? What would its nervous system look like, its metabolism, its forms of learning and memory? What kind of world would such a creature inhabit — and what kind of mind would it have?
What follows is an attempt to answer those questions: a plausible cognitive neurobiology of the alien.
sensory systems and the alien umwelt
Umwelt, introduced by Jakob von Uexküll, describes the subjective world of an organism: the way its senses and actions shape reality. A tick inhabits a world of heat, butyric acid, and gravity. A bat lives in a world of echoes and flight at night, whereas we humans move through a deeply social world of colour, speech, and symbols.
The xenomorph’s umwelt is stranger still: a fused sensory landscape built from chemical gradients, vibration, and heat, with predatory targets a reflexive must. Everything must die - this is its prime motive force.
Chemosensation predominates their world. The disarticulatable inner jaw is weapon and probe, functioning like the vomeronasal organ of snakes, sampling airborne molecules and surface residues, detecting prey identity, hormonal state, injury, and even emotional arousal.
Acoustic and vibrational mapping provide the sensory framework for its perceptual world. The seeming lack of eyes suggests some form of bioecholocation or biosonar: maybe cranial sweeps scan an environment actively, with low frequencies mapping structure and high frequencies resolving detail. Mechanoreceptors in limbs and tail detect microvibrations: a footstep on steel plate, the pulse of a heart behind a wall, low-frequency, fear-inhibited breathing from a hiding target.
Dermal photoreceptors scattered along dorsal ridges may allow crude light detection, useful for orientation in mixed illumination or zero gravity.
All of these inputs fuse in a multisensory hub, result in a dense three-dimensional cognitive map, continuously updated. A corridor is not seen in perspective lines but felt as resonance and odour. A prey animal is not a body in space but a plume of carbon dioxide, stress hormones, and heat pulses, a target to be attacked and killed.
motor systems and predatory precision
Perception is only half the story; action is the other half, for predation also demands precise and lethal motor control directed to the vulnerabilities of the target.
The xenomorph exhibits both centralised planning and peripheral autonomy. A basal ganglia-like system switches actions: stalking, sprinting, striking. A cerebellar analogue provides predictive timing of leaps, tail sweeps, and inner-jaw strikes, based on models of prey trajectory. Peripheral ganglia embedded in limbs and tail manage reflex arcs, enabling instantaneous grips or blows without delay (think scorpions).
This architecture combines the grace of vertebrates with the efficiency of invertebrates.
cognition and planning
The xenomorph is more than a reflexive predator, for it displays planning, memory, and even restraint.
Working memory and spatial learning are evident in their rapid mastery of ship layouts. Hippocampal-like structures likely bind events to spaces, generating cognitive maps.
Queens show counterfactual and foresight oriented reasoning: in Aliens, the queen restrains drones when Ripley threatens her eggs. That moment reveals foresight: simulating futures and choosing strategically, choosing the future of her brood over immediate attack. And the drones obey her - so they have some sort of representation of social hierarchy.
Such behaviour implies prefrontal-like circuits capable of inhibiting immediate impulses in favour of long-term outcomes.
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learning and memory
Their repertoire spans every major form of learning: they show habituation to irrelevant noise and sensitisation after combat encounters.
They form also classical conditioning associations, as in Alien: Resurrection, when drones respond to cues predicting pain. Briefly: in the Calibos Caging/Testing scene, in this sequence, which takes place early in the film on the military research vessel Auriga, scientists are seen observing the captured Xenomorphs in their containment cells.
A light flashes or an alarm/sound is triggered (the Conditioned Stimulus or CS).
Immediately following the cue, a blast of flame or an electric shock is administered to the cage floor, which causes the Xenomorphs extreme pain (the Unconditioned Stimulus - UCS).
The Xenomorphs instinctively recoil from the pain (the Unconditioned Response or UCR).
After repetition, the Xenomorphs begin to recoil or become agitated when they see the light or hear the sound before the pain is administered. This learned anticipation is the Conditioned Response (CR).
They also show intrumental learning: in Resurrection, two drones kill a third to use its acid blood as a solvent to escape from captivity - this is action–consequence reasoning at its cruellest and most utilitarian, not just action based on instinct.
They adjust tactics after failure, which suggests episodic-like recall. They consolidate procedural memories in their mastery of climbing, duct navigation, and zero-gravity locomotion.
hive organisation and cognitive stratification
Xenomorph society is cognitively layered:
Drones operate tactically: they are stimulus-driven yet flexible, capable of silent coordination and probing defences.
Queens act strategically: they integrate sensory streams, weigh risk against brood survival, and direct drones through pheromonal and bioelectric cues.
recognition and vitality detection
Hive survival depends on identifying conspecifics and assessing prey vitality.
Pheromonal signatures, movement patterns, and acoustic cues support recognition. Mechanoreceptors register heart tremors. Chemosensors detect exhaled carbon dioxide. Dermal receptors map heat profiles.
This ensures drones target living hosts and coordinate without confusion.
heart–brain coupling
Cardiovascular state and neural control are tightly linked.
Baro- and chemo-receptors send signals to central hubs; descending autonomic fibres adjust heart rate and contractility.
Different behavioural modes emerge: stealth mode involves low heart rate and vasoconstriction. Strike mode brings a sympathetic surge, attacks timed to cardiac phases. Wound mode raises vascular resistance to contain haemolymph leaks.
Queen pheromones likely entrain drone heart rhythms, synchronising the hive into shared physiological states: a creeping rhythm for silent approach; an assault rhythm for swarming.
Dormancy employs punctuated pacemaker rhythms, sustaining perfusion at minimal cost.
respiratory physiology
Xenomorphs breathe oxygen, but not as vertebrates do.
They switch between aerobic metabolism for endurance, anaerobic bursts in low oxygen, and hibernation states where demand falls close to zero.
Valved air sacs permit silent respiration and oxygen storage, supporting stealth attacks.
nutrition and energy
Their energy requirements are enormous. Explosive locomotion, neural integration, acid blood homeostasis, and rapid growth demand a hyper-efficient digestive system.
The gut is likely short but highly absorptive, lined with folds maximising nutritional uptake. A foregut chamber dissolves prey tissues in an ultra-acidic bath, much like spider digestion. Storage sacs act as reservoirs, sustaining drones through long intervals and permitting regurgitation to nourish brood or queen.
They consume animal biomass: muscle, organs, marrow, blood. They may recycle waste products and extract minerals to reinforce their armour.
They may also harvest molecules from the atmosphere during stasis. Atmospheric harvesting is maintenance rather than growth. It is trickle charge; biomass feeding is fast charge.
This dual system explains their persistence: eggs seemingly remain viable for centuries.
predator–prey imbalance
A population of xenomorphs is ecologically unstable: predator density rises too quickly to be sustained by available prey. Without restraint, collapse through starvation necessarily follows.
Hibernation provides the solution: eggs in stasis, drones in torpor, queens in diapause. The species survives in boom–bust cycles.
dual-mode nervous system
Such a life cycle requires flexible neural control. Active mode sustains learning, memory, and predation. Dormant mode reduces firing rates but preserves engrams; minimal watchdog circuits monitor for prey cues.
nervous system architecture
Their neuroanatomy shows convergences and novelties: they may combine insect-like ganglia, cephalopod-like autonomy, and vertebrate-like centralisation. A tri-axial neural axis, with rapid synaptic remodelling, could explain their speed and plasticity.
comparative cognition
Placed on an Earth scale, drones easily surpass dogs: they resemble wolves, dolphins, corvids, or octopuses: tactical hunters, socially coordinated, but not symbolic cognisers.
Queens approach apes, elephants, or orcas: they display foresight and anticipation, inhibitory control, and colony-level command.
The hive as a whole is greater than its parts: a predator society with hierarchy and synchrony.
what it is like to be a xenomorph
Their umwelt provides hints: to be a drone is to inhabit a world of chemical plumes, vibrations, and thermal gradients, coupled with intense prey-focused activity. Time flows in pulses linked to heartbeat and respiration. The drone experiences itself as a vector of the queen’s will; consciousness is flow-like, action-driven, stripped of narrative.
To be a queen is to experience the hive as part of the self. Drones are extensions of her agency. Her consciousness includes anticipation, brood-centred valuation, and inhibitory control. It resembles elephant or ape awareness: strategic and long-horizon, though without symbolic thought.
reproduction and variation
Variation arises through horizontal gene transfer. Facehuggers integrate host DNA into embryos, producing hybrid traits. Queens maintain genetic libraries that recombine across generations. Drones may carry host-derived elements back to the queen.
This mechanism ensures adaptability and cumulative selection across time.
Several evolutionary paths could converge on such a form. They may have evolved as parasitoid predators, eusocial ambushers, or deep-sea opportunists adapted to darkness and vibration.
Alternatively, they may have been engineered as bioweapons. Their ecological instability would then be a feature rather than a flaw.
conclusions
The xenomorph terrifies because it kills without and because it adapts quickly. It learns, anticipates, and organises. It can stalk silently for days, erupt into explosive violence, hibernate for centuries, or direct a hive with strategic foresight.
Its flaw is ecological unsustainability: a predator so efficient it collapses its own food base. Such perfection makes sense less as a stable species than as a weapon.
Its true horror lies in its alien umwelt. The world of the xenomorph is gradients of chemical signatures, echoes, and heartbeats. And predation - always attacking. Its consciousness is hive-linked, brood-centred, and future-oriented. It is a predator that perceives life in signals we barely understand, and acts with an intelligence that, while not human, is all the more frightening for being realisable.
I haven't enjoyed a scientific validation of sci-fi this much since I read Max Brooks' World War Z! Thanks for this Shane, a great read.