Posthuman Genetic Modifications (IF)

Hard Science-Fiction Setting

Posthuman genetic modifications go far beyond cosmetics or regrav facilitation; these are invasive changes that take months to master. Posthumans are humans who have undergone extensive modification. Two main paths exist: genetic rewrites, formally called Morphs, and mechanical augmentations, known as Cyborgs. Both exceed medical correction and create visibly distinct forms of humanity.

Lesser Morphs usually keep the base human form and give specific abilities: degrav resistance, vision enhancement, optimization for specific actions. Extensive Morphs are invasive genetic programs that alter the body into specialized phenotypes, such as the ones below. They are optimized combinations that create a consistent whole, but this makes them incompatible with each other; you cannot be both an Angel and a Lemure at the same time.

Morph changes do not breed true and must be applied per individual. The Earthforce Medical Service (EMS) strictly forbids creating new human subspecies that breed true; control of the creation of Morphs loosened during the Fall but is formally still there. Lineages that breed true may exist in secret, but cannot pass routine security inspection.

Cyborgs follow the opposite route, replacing or supplementing flesh with machinery. The two approaches do not combine well; a person is either a Morph or a Cyborg, very rarely both.

Changing phenotype is technically straightforward. A skilled subject can go from Baseline to a chosen Morph in about a week of treatment — feasible during an interplanetary voyage. Reversing to Baseline is just as simple, and Morph-to-Morph conversion is possible if the subject already has experience with both types. The bottleneck is training: an unfamiliar Morph requires months of practice, typically completed in virtual reality before the change. A familiar phenotype can be resumed quickly; adopting a new one demands planning and preparation.

Social acceptance varies. Baselines often lump all Morphs together as mods, whether the changes are subtle tweaks or major rewrites. Those with minor upgrades may distance themselves from the visibly altered, while full programs are seen as useful yet alien. In many habitats Morphs are respected specialists; in others they are stigmatized as insidious or monstrous. A community open to posthumans benefits from their presence; a prejudiced one will have none, and an indifferent habitat only a few.

Angel

A low-gravity hexapedal, flight-capable human variant with three limb pairs: manipulator arms, legs, and mid-torso wings. Wings hinge from a reinforced scapulo-pelvic girdle and a keeled sternum; they fold flat along back and flanks for confined spaces. Skeleton is light with selective hollows; musculature favors endurance; lungs use avian-like flow with air-sac analogs; a shortened gut prioritizes dense fuels.

Angels function well in spin gravity and can stow wings for ladders, shafts, and suit work. Angels can hover in the middle air of spin habitats and quickly descend the gravity gradient using a compact round brake chute in a waist pack; the chute bleeds speed while the wings handle steering, flare, and landing. Faster and lighter, Angels are superlative “middle-air supervisors” for open-volume patrol and response.

Socially, Angels read as different without feeling odd: human face and hands, graceful posture, and a name that softens first impressions. Crews adapt quickly; etiquette centers on wing sheaths in tight spaces.

Operating envelope: Below ~0.15 g, partial wing deployment provides excellent body control; the wings act as control/brake surfaces only. In 0.15–0.30 g Angels can ground-launch, climb, cruise, and soar, requiring more effort toward the upper end of this range. Above ~0.30 g the wings assist steering and flares but cannot sustain takeoff; use a brake chute for landings. Around Earth Standard Gravity (1 g) Angels can steer if they have a chute; on land they move well but tire quickly. In water, they perform poorly, with more drag and less power than Baseline. In a vacuum the wings are inert; Angels fly only in standard density atmospheres; no natural atmospheres sufficient for flight exist.

Costs and limitations: High-energy diet; poor tolerance for bulky/low-quality foods; light bones increase fracture risk under 1 g impacts; prolonged 1 g work raises fatigue and overuse injuries; unsheathed wings tear in clutter; flight performance depends on adequate air density and drops sharply in thin, turbulent, or contaminated atmospheres.

Kobold

A high-gravity/standard-gravity Morph optimized for endurance, load-bearing, and impact tolerance. Compact and low-slung, with dense bone, heavy musculature, and a supporting tail that acts as a stabilizer rather than a grasping organ. The tail widens stance in gravity, provides a third anchor under shock or load, and serves as a counterweight; in microgravity it works as a reaction tail for orientation and bracing.

Kobolds exhibit reptilian traits: scaled integument resistant to abrasion, heat, and solvents; thickened nails and broad hands for traction and tool grip; skull ridges that mitigate impacts. Facial expressivity is muted by the integument — a social handicap rather than a threat cue — so Kobolds rely on posture and deliberate gestures to emote. They are shorter and more compact than Baseline (~85% height), but denser and heavier (~120% mass). This build eases circulation in high gravity, improves stability, and makes their strength immediately apparent.

Kobold feet are short and broad, with an opposable spur and grasping, locking toes that wrap around rungs and mesh. This lets them brace on steep spokes and hull surfaces, holding position with minimal strain. Specialized hull shoes integrate with the toe structure for vacuum work, combining natural grip with mag plates and mechanical spines for ice.

In habitats Kobolds gravitate to the lower decks and steep-gradient spokes where others tire or grow disoriented. Their dense build, vertigo tolerance, and cardiovascular reinforcement let them work comfortably in high-g sectors. On the outer hulls of spin habitats (effectively neutral g) they clamp to structure and translate hand-over-hand/foot-over-foot.

Culturally, Kobolds are seen as dependable but alien. Baselines accept them as essential but dull, the opposite of the glamorous Angels of the middle air, and association with underdecks reinforces this prejudice. In Jovian polities their superior high-g tolerance in cockpits and assault roles provokes prestige anxiety and gatekeeping from Baseline elites, feeding prejudice despite their utility.

Operating envelope: In microgravity Kobolds use tail-assisted attitude control and locking toes to work at near-Baseline efficiency despite stocky builds. Low gravity is their worst interval; heavy bodies jump and balance poorly. Kobolds thrive from ~0.8 g to 1.4–1.6 g, with heavy shifts to ~1.8 g, short tasks at 2.2–2.5 g, and brief harnessed bursts to ~4–5 g without injury; negative-g tolerance is comparable when properly supported. They sink in water, but while moving can operate just under Baseline. As pilots they enjoy a modest g-tolerance edge that is offset by their higher mass.

Costs and limitations: High metabolic demand; reduced sprint speed and agility; poor swimmer. Low facial expressivity can impede social rapport. Tail and scales pose snag/abrasion risks in cluttered spaces.

Lemure

A microgravity Morph built for spacecraft and freefall habitats. The body is light and long-limbed, with grasping hands and feet and a prehensile tail for anchoring and maneuver. Lemures are smaller than Baseline overall, averaging about 75% of typical human height and weight, with a short torso and proportionally longer limbs and tail. Reduced mass helps in microgravity and lessens strain at 1 g, while long reach and the tail make them fast and precise in freefall. Hands and feet are similar, though hand–eye coordination is markedly better with the hands. Short, dark, curly fur covers much of the body, providing abrasion protection without snagging; some Lemures minimize clothing, which is generally frowned upon in shared spaces.

Large forward-facing eyes and a tuned vestibular system give precise orientation in three dimensions; fine tactile filaments on the skin provide contact feedback. Appearance reads as slim, big-eyed, and tailed—some call it goblinlike.

Lemures excel at clambering, bracing, and rapid translation in microgravity, and remain competent in low gravity (0.15–0.35 g). In Earth Standard Gravity (1 g) they fatigue quickly and are poor at load-bearing. Vision is low-light biased and rod-heavy; color discrimination is reduced compared to Baseline. Bright sunlight or a glowing spin axis causes glare and delayed adaptation; visors and baffled lighting are routine kit. Specialized space suits include both disposable monofilament anchors that disintegrate after use and micro-thrusters for navigating empty space.

In habitats the Lemure is the master of the central axis; quick leaps and rail-to-rail translations let them avoid spin-drift and do tasks quickly and efficiently. They can work down the gravity gradient along scaffolds and ladders but avoid deck-level and especially underdecks. They sortie well with prospectors and salvage teams, but avoid the outer hulls of spin habitats.

Socially, Lemures are perceived as very alien but generally nonthreatening. Most humans socialize at 1 g, where Lemures are slow and awkward; this, combined with small stature, makes them seem harmless despite clear superiority in freefall. In microgravity environments they present as highly capable, but often out of sight.

Operating envelope: In microgravity Lemures use prehensile tail, handlike feet, and brachiation-like movement to best advantage, making them fast and precise. Low gravity strains endurance but preserves agility; with sufficient clutter they can brachiate. At 1 g they tire quickly — still limber, but unable to brachiate like their much smaller namesake animal. In water they are near-Baseline: buoyant and comfortable at the surface, but inefficient at depth.

Costs and limitations: Reduced 1 g endurance; light sensitivity in unbaffled illumination; snag risk for tail and tactile filaments in cluttered spaces.

Melusine

An aquatic Morph for long-duration work in high-pressure oceans, including Earth’s abyssal zones and alien seas like those on Jovian Europa and Saturn's Enceladus and Titan. Retaining separate legs, Melusines use fin-like feet for propulsion and control. Oxygen is extracted from water via trailing branchial fans — vascularized, skirt-like arrays that grow continuously and expand under hypoxia; in dry or hazardous conditions they remain short or retracted.

To survive extreme pressure, Melusines employ collapsible lungs that are deflated before submersion, eliminating internal air volume and shifting respiration to the external fans. Residual gases are absorbed via a high-perfusion pulmonary interface, preventing nitrogen narcosis and decompression sickness (no pressurized gas is breathed at depth). Internal air cavities (e.g., sinuses) are filled with fluid.

Melusines excel in deep-sea mobility, temperature/pressure tolerance, and sustained submersion—making them suited to subsurface exploration and aquatic colonization. They operate near-Baseline in low gravity and have a slight advantage in microgravity due to low inertia and stabilizing control surfaces.

Melusines belong on worlds with oceans, not on habitats. Most habitats don't have much use for them, some have lakes on the inner surface and others use water rather than ice in the outer shell, but these are special cases.

Operating envelope: In microgravity Melusines benefit from the three-dimensional orientation they use underwater, but tend to oversteer when using fins. At low gravity they are hindered by fins and their branchial fans, but they carry their weight well. At 1 g, they are more seriously hindered, struggling to carry their weight unsupported by water. They thrive in water, maneuvering readily and resistant to pressure and cold.

Costs and limitations: High-energy diet and high ambient moisture requirements; reduced mobility and fatigue risk in 1 g; respiratory fans are vulnerable to desiccation and abrasion when exposed; bones are light and somewhat fragile. Standard environments remain usable via lungs and protective gear, but prolonged dry exposure without hydration/sheathing degrades performance.

Satyr

A low-gravity surface specialist for airless worlds. Satyrs keep near-human stature and proportions but carry strengthened lower limbs and goat-like split hooves for traction on rock and cut faces. Long elastic tendons store and return energy for efficient bounding; ankles and knees are reinforced for repeated ballistic hops. A short, non-prehensile tail and tuned vestibular system stabilize attitude in flight; dense hoof keratin and pads shed abrasive dust. Soft, curly, close leg hair insulates joints without snagging suits; small horn buds and slightly pointed ears mark them as posthuman without drifting into the uncanny. Official designation: Satyr; polite colloquial: faun; derogatory: devil, goat.

Built for low-g operations (~0.15–0.40 g), Satyrs clear rubble fields in long, controlled arcs, plant tools with sure footing, and climb steep cuts like goats. Hands are fully dexterous; torso mass sits low for balance and fall safety. Socially they blend into mixed crews; “faun” styling shows up as personal fashion, not a separate culture. Their legs enable stationary vaults and rhythm hops even in 1 g.

Satyr field gear is built around the feet. Satyr-spec vacuum boots complement the natural hoof on regolith, ice, and broken ground—widened dust-shedding soles with tunable stiffness, microspines/sipes, inflatable pads for regolith, and spikes for ice. These boots can be worn without a suit, but the bare hoof handles most habitat terrains on its own. Vac suits also integrate microthrusters at the center of mass for mid-arc trim and landings, with seals, gaiters, and anti-static coatings as standard.

Operating envelope: Excels on airless low-g surfaces and in dust-choked cuts; adequate in microgravity (prefers tethers/rails for translation); serviceable in 1 g but slower and knee-limited for sprints and long treks; slightly below Baseline in aquatic settings.

Costs and limitations: Terrain surprises can injure on landing; knee/ankle overuse risk in 1 g; poor swimmer; continuous dust management; bounding is unsafe in dense atmospheres with crosswinds.