Summary of our technical strategy
At a glance
Our grand aim is to develop all necessary techniques for a complete anthropomorphic bodily modification procedure to be available to patients well within the next three decades. To accomplish this, the core of our research strategy is our continued work on in-house, applied research on the areas we understand as being most important to a successful procedure. We are using an engineering mindset, cutting problems into smaller pieces that can be individually understood and resolved. Moreover, several of our projects – research into tails and eye modifications, for example – are promising to be directly useful to people in their own right.
In this document, we introduce some of the reasoning and technical decisions underlying our research strategy. We narrow in on what we believe are the four most crucial and difficult regions of anatomy for modification: the head, integument, tail, and eyes. We explain why those regions present unique difficulties, and why other regions are potentially less difficult. Candidate technologies, including cellular and gene therapies, surgical approaches, and neuroprosthetics, are discussed alongside the respective anatomical regions.
From this analysis, we are able to propose an estimated overall timeline for how our projects will proceed, and we are actively using this timeline for internal project management purposes. This document will help you follow along with some of our rationale and decisions represented in the timeline shown below. Note that this document is opinionated and is not intended to be comprehensive.
Illustration of how we will be prioritizing our research projects according to region of anatomy. Each of 8 anatomical regions will have an iterative series of projects, proceeding from foundational research, through preclinical development, to clinical testing and any relevant regulatory approvals.
Order of operations: feasibility and anatomical detail, then other decisions
When you think of the form you want, where do you start? You might intuitively start by listing some of the physically apparent qualities, like a particular height and body shape, facial shape, and dermal characteristics. Maybe these qualities are close to what you have now, or maybe there’s a larger gap to cover. Regardless, they should feel like part of you, they should be sufficiently robust so that you don’t have to worry about hurting them (and heal predictably if you somehow do), and they shouldn’t get in the way of how you live.
This is how we have organized our goals, as well. We started by imagining the goals we actually wanted: a variety of identity-affirming forms, ranging from more to less human-like, including humans with animal characteristics such as “neko” forms, furry anthropomorphic forms, quadrupedal forms, and creatures with more (or less!) than the usual set of four limbs. We deconstructed each, considering the sorts of demands each one would incur. Demands in physics and biomechanics, physiology, technological implementation, and the degree of confidence in our ability to achieve an excellent, fulfilling result in a reasonable span of time.
Based on our analysis, anthropomorphic forms appear tractable within the above mentioned span of time. Lower targets underrepresent the advancements possible with realistically-obtained research – and setting our sights lower would risk creating a set of technologies that are incapable of coming together into a unified, satisfying whole. Higher targets, while we believe they are achievable in many cases, would risk stretching our resources too thin, create overly ambitious expectations for stakeholders, and delay success for people who could start benefitting earlier.
While a detailed discussion of overall feasibility is beyond the scope of this document, at the end, we include links to a few more detailed discussions for certain anatomical additions and related projects.
With complete and practical anthropomorphic forms being set as the general long-term goal, we next started to divide those forms into anatomical areas of interest. Starting from a comprehensive list of anatomical regions, we collapsed them into 8 key types. We have: craniofacial, eyes, ears, gender affirmation, integument, appendages, digitigrade stance, and the tail. We considered other anatomical and physiological regions as well, but lowered their priority due to relevance (e.g., minimal changes to pectoral girdle or internal organs needed), deleteriousness to expected or normal biological functioning, or expectation to be relatively trivial (such as dentition changes).
In ranking the eight anatomical regions for project management purposes, four appear to be the most demanding and rate-limiting: the head, integument, eyes, and tail. We have prioritized research to these areas as described in more detail below. We expect the remaining anatomical regions will benefit from technologies developed and easily re-deployed from other areas.
The specific choices of technology used – whether genetic, cellular, surgical, neuroprosthetic, or a combination – depends greatly on the specific challenges posed by the anatomical site of interest. Specific technical choices in some cases – such as whether or not to use synthetic actuator materials when implementing a permanent tail – might not need to be made until years from now. On the other hand, other technical choices need to be made relatively quickly, based on informed opinions of a technique’s likelihood to work, as compared to alternative technologies. This should be balanced by the the length of timeline it would take to develop. Our current, general lean towards genetic or cellular approaches for the integument is a choice we are likely to make within the next few years.
Another set of decisions that will depend greatly on the specifics in question are regulatory in nature. Regulations, generally speaking, have the lowest burden on the use of drugs and therapies off-label, followed by surgical procedures, and the development of new medical devices. Finally, regulations are the most stringent for the development of new drugs, biologicals, and cellular and genetic therapies. It is impossible to give an exact timeline at this stage, due to needing to find the best therapy or combination of therapies, and considering that no decisions on regulatory/legal jurisdictions have been made. Still, we anticipate that regulatory approvals might take less time for craniofacial and tail changes, and more time for eye and integument changes, based on the technologies being considered for each.
Anatomy-driven discussion
Craniofacial anatomy
After detailed background research into head anatomy and physiology, we reason that excellent results in quality, appearance, and physiological function are tractable with the following features:
- Emotive, muscular snouts
- Eye placement compatible with bilateral vision
- Head shape compatible with physiological function and not impinging upon the braincase
- It is tractable for ears to either appear on top of, or on the side of, the head
Head models of an anthropomorphic wolf and dragon, both made with overlaid CT cranial models and careful preservation of features near the braincase or otherwise expected to be difficult to modify.
Critically, and fortunately, it appears that the braincase does not need to be modified for at least some anthropomorphic forms. In our own models, using real patient CT scans (n=2), braincase modifications appear geometrically compatible with muzzle shapes that conform to what artists would illustrate, even if they didn’t have to worry about braincase constraints (https://freedomofform.org/4613/june-2022-newsletter/). More stringent modeling, for more patients and for more anthro species target outcomes, is necessary to explore how wide the acceptable parameter space is.
Importantly, most craniofacial modifications are not expected to require any new sensorimotor information. While sizes of features obviously differ between anthros and humans, the existing topology of innervation with sensory structures and muscles will be sufficient. In other words, we do not need to change how various features within the craniofacial region relate to each other.
In terms of project management, we expect relatively routine techniques such as distraction osteogenesis, and otherwise changing the shape of existing or patient-derived tissues without needing to change their gene expression, will be sufficient. However, further research is required to determine effective therapies that achieve desirable results.
Significant modeling and planning will be required to ensure practical and effective results. For instance, how do you plan and coordinate substantial shape changes in a part of the body with dozens of irregularly shaped bones – many of them tiny – along with the matching musculature? How do you ensure that breathing, vocalization, ingestion, non-vocal communication cues, and so on are preserved? How do you make everything else look and function correctly while preserving the braincase? We expect that craniofacial modeling and planning will be one of the most essential uses for computer-aided design software we are developing, the Anatomy Reengineering Framework (ARF). This software should greatly enhance and offer insights into developing anatomical changes while simplifying design.
(Note that eyes and ears require different discussions from the craniofacial modifications in this section. See later sections for details.)
Integumentary modifications
The skin is one of the most visible areas that will be affected by our modifications. Our Integument Review Project is taking a detailed look at how to create fur, scales, and feathers. It appears that fur will be most easily implemented, followed by scales, then feathers. Follow-up research, including wet-lab research, is already in progress.
We have no major concerns about overall feasibility for any of the above integumentary coverings. While there are and will always be details to work out (such as how thick a fur coat can be before someone overheats, integration of sweat glands and other ancillary structures, or developing alternative ways of heat management), there are no major limitations that would risk taking options off the table (contrasting with, for example, constraints on braincase shape, or the physics of flying).
There are several possible ways of accomplishing integumentary changes, and the possible methods somewhat differ based on whether we’re talking about fur, scales, or feathers. In general, the technologies will involve manipulating a small unit of living tissue, easily reached on the surface of the body, repeatedly over a large area.
For example, fur modifications might involve injecting new hair follicles grown in-vitro from patient-derived cells. Or, it might involve injection of genetic vectors (whether transient or long-lasting) to transdifferentiate existing cells in-situ. It’s even possible that non-genetic therapies could be useful, such as signaling proteins or small molecules, that would modulate the regulatory pathways that already exist in skin cells. Skin is already good at growing hairs, and it is possible that the biochemical equivalent of “asking nicely” might get us close to a solution.
Needless to say, existing skin in humans is not as good at growing scales or feathers, suggesting that the application of signaling proteins or small molecules will not be not sufficient in these applications. However, the creation of tissues grown from patient-derived cells, and the injection of genetic vectors, present platforms that can enable up to tens of hypothetical genetic changes, and an arbitrary degree of control over the shape of cells via bioprinting or other in-vitro assembly method.
A proposed system of creating and maintaining the textured pattern of scales. Scale boundaries are maintained through long-range inhibition and short-range activation. In nature, this leads to so-called ‘Turing patterns’, which is the process in which hair follicles, scales, and feather follicles are distributed on the skin during embryogenesis. From the Integument Review project’s May 2022 update.
By its nature, the skin is the most accessible anatomical site for modification, which counterbalances the more difficult demands on manipulating biological mechanisms. While controlling the tissue microstructures that cells assemble into (e.g. follicles), or the structural molecules they extrude, might be tricky to optimize, these will be far lower demands than, say, axon guidance, or asking cells to assemble new tissues as if they were undergoing embryonic development.
In project management terms, we are allowing time for continued literature research and planning, as well as many years of wet-lab experiments. We also expect a lengthier regulatory approval timeline than most other anatomical modifications, due to the reliance on novel genetic and cellular therapies.
Making a tail possible
The tail is challenging in ways that are unique compared to the other anatomical sites we are looking at. Most important is the challenge of completely new demands for neurological information: humans have little existing neurological ability to control or sense a tail. Secondarily, the tailbase will involve meaningful changes to the shapes and topology of bones and muscles in one of the most biomechanically demanding (in force magnitude as well as in complexity) parts of the body.
So far, we have mostly been working on the neurological ability to interface with a tail. In our Enhanced Tail project so far, we have been developing devices and software that can detect and interpret muscle signals, to move a tail appropriately in response. As our research matures in the coming years, we will apply what we learn from electromyographic readings to permanently embedded, bidirectional interfaces that allow both motor control and sensing.
Concept drawing of an early, temporarily-attached tail neuroprosthetic, using an electrode array.
In biomechanical terms, it appears tractable to exchange the existing, fused coccyx and related tissues in humans for a longer, integrated tail. Coccyx removal is surgically possible today, though is associated with significant risks of side-effects and complications. We are hopeful that replacement of, rather than simple removal of, the coccyx would ameliorate the side-effects and complications, but more research is clearly needed.
Bones around the tailbase. Panel A: Human model with hips, lumbar vertebrae L4 and L5, the sacrum, and the coccyx visible. Panel B: Model with thick, muscular tail, with the hips, lumbar vertebrae L4 and L5, the sacrum, and caudal vertebrae Ca1 and Ca2 visible.
Finally, a tail – regardless of how it’s controlled and mechanically attached – might be composed of biological materials, synthetic materials, or a combination thereof. While we have many ideas for implementation, ranging from bioprinting, to gradual tissue reshaping, to neuroprosthetics embedded within living tissue, we do not see this as rate-limiting for the creation of functional, permanently integrated tails. We’ll start finalizing implementation ideas and testing them after we are close to getting satisfactory answers for neural interfacing and biomechanical integration.
In project management terms, we are prioritizing neurological control of tails, and will improve neural integration in both temporarily attached and permanently attached prosthetics/modifications as we grow and evolve. The first 1-2 versions of our tail prosthetic will not require patient testing or regulatory approvals, whereas latter versions, moving towards greater capabilities and permanent integrations, will require patient testing and appropriate regulatory approvals.
Ocular systems
The eyes are complex, delicate, and sensitive, and as you might predict, also present unique challenges compared to the other anatomical sites under consideration. Among the most important sensory organs, they allow us to interact with our world. As such, maintaining what these organs can provide is of paramount of importance. Not to mention their importance in day to day conversations through non-verbal communication.
In discussions so far, we have largely been settling on the idea of modifications to the sclera, iris, and pupil as being most feasible. Less feasible, and therefore not in immediate consideration, might be modifications to the eye’s size, since such changes would imply enlarging the retina (though, at least, not asking for a higher information capacity of the retina). Finally, modifications to light perception would be most complex – such as perception of new colors or greater visual resolution. These would involve manipulating the retina’s neural connectivity, and potentially that of subsequent neural pathways leading towards the visual cortex, depending on specifics.
While some cosmetic eye modifications are currently performed by body artists, such as scleral or iris pigmentation, information available to us suggests that these are rarely performed, risky, and unlikely to satisfactorily meet the level of quality we are demanding in our anatomical goals.
Broadly speaking, technologies that appear useful include gene and cell therapies, as well as structured cell assembly i.e. bioprinting. Some synthetic materials or devices, ranging from permanent implants to scaffolds to guide gradual tissue shape change, could also be employed. These techniques are somewhat similar to those used in the integument: focused on biological mechanisms, and working on a superficial tissue. Generally, techniques used on the eyes would have lower complexity than their integumentary equivalents, but higher demands on precision and safety towards nearby tissues.
For example, a hypothesis we are currently investigating is that gene therapies involving melanin could be sufficient for changing iris and/or scleral color. In other words, instead of thinking about tens of genes, we might only need to modify a handful at most. However, any therapies applied can be expected to need the precision afforded by a manually-controlled micromanipulator or equivalent. While we have ideas about how to accomplish precise manipulations more easily and cost-effectively, these would need research.
Our eye project is still at an early stage and doesn’t have its own research page yet. You can read a first look at the project description in our March 2023 newsletter.
Other anatomical sites
Contrasting with craniofacial modifications, the integument, the tail, and eye changes, we expect that ear modifications, paws and claws, digitigrade stance, and gender affirmation can be deferred until later in the research schedule.
For ears – ear modifications are commonly performed by body modification artists already, and clinical advances in bioprinting are also relevant. While muscular control of ears would be beneficial, we see it as less challenging than tail muscular control – and therefore not requiring focused research. Finally, even though canines and other creatures appear to have ears on the top of their head, sound is actually routed downwards through a vertical external ear canal to a position very similar to that in humans. So, no movement of the middle or inner ears would be required in patients; mimicking the vertical external ear canal will be dramatically simpler.
For paws and claws, musculoskeletal changes, as well as the creation or implantation of claws, would be required. However, musculoskeletal changes would be simpler than craniofacial ones. Similarly, claws would use similar techniques to those we develop elsewhere.
Digitigrade stance is scheduled later, because we anticipate that a tail would be very important for balance for people walking in a digitigrade fashion. In addition, it would use similar musculoskeletal techniques to those we develop elsewhere.
Gender affirmation is scheduled later because it is an active area of research by multiple third parties, and several desirable affirmation goals may not need our direct involvement. Still, we will actively monitor the field’s progress against our goals and adjust as needed.
Bringing it all together
Let’s return to the research schedule first shown at the top of the page.
Spanning over approximately thirty years, this plan separates an anthropomorphic procedure into several anatomical regions: the tail, craniofacial changes, ears, paws and claws, digitigrade stance, integument, eye changes, and gender affirmation. Proceeding from left to right, the research for each anatomical region goes through a foundational research and model-building phase, followed by preclinical development, and finishing with testing and relevant regulatory approvals.
We will use an iterative approach: while final testing and regulatory approvals are being obtained for earlier versions, we will keep working on the next version. For each anatomical region, the first two iterations that will be used in full-body procedures are illustrated. Subsequent iterations can be assumed.
While regulatory approvals may be easier for certain devices and surgical procedures, the development of genetic or cell therapies, e.g. needed for integument, may involve a longer approval process. Fortunately, while preclinical development and especially testing and regulatory approvals will be expensive, preliminary research and model-building are relatively inexpensive. This schedule allows our research expenses to scale with our organization’s resources.
General resources
General feasibility discussions
Anatomical Studies whitepaper (2018)
Candidate technologies overview whitepaper (2018)
Overview of Craniofacial Bone Implant Materials and Techniques (Aegaeon Galefang, 2024)
