What would it look like to build a human?

Question

I am writing a book where organ printing has advanced such that humans can grow full hands, arms, legs, and every inside organ. This process is used to "make" soldiers in Earth's future because cloning full troops is too expensive and time consuming.

Assuming that surgical knowledge is advanced enough to attach human segments, how might I describe a team of surgeons assembling a full body?

• The organs are grown in segments (kinda like the song "Dem Bones" but with skin and organs too).
• Ignore the costs. This question is about describing what it would look like.

Answer 1

You could think of it like building a house or a car. You got to start with the framework. A home needs the wood frames to be up before anything else. A car needs it's steel frame to be laid out first before anything else, so too would a body or those organs wouldn't really get too far. So describe the process, First you need the bones to be in place which you take ligaments and attach the bones to each other. Then you would apply muscle tissue to the bones so that the bones are set in place. You would want to put the brain in too so that as things start being piled on you don't have to pull off the skull to add in a brain. You will also need to attach the eyes before the skin goes on so that you can work into the skull to attach the eyes and other pieces.

I won't continue as this post would become a bit long but I think you understand the gist of what I am trying to say. Think about how it would be done logically. You can't start adding organs when they have nothing to attach to. You can't keep bones together without ligaments and muscles. You can't keep the innards from becoming outards without the skin layer and muscle that has yet to be added (like abdominal muscles for example would probably be one of the last muscle groups to be added).

Answer 2

It would look like an assembly line where a larger thing is made of smaller things.

I think for this endeavor it would also look like a temple. If you can build a soldier organism from the ground up, the only reason I can imagine that you would want it to have a human form is that you have nonrational religious beliefs about it. It is sort of like the people building cars being dead set that they look like horses. Presumably the religious aspect of this endeavor would manifest itself in the typical ways: incantations, incense, tall hats etc.

Answer 3

Step 1: Build a template library

Well, this part might be a tad morally controversial, since it basically involves taking a few hundred soldiers and ... uh... slicing them up into really thin, 10nm wide slices. Obviously this presents interesting technical challenges, including non-destructive tissue vitrification (forgot to mention, you gotta turn your soldiers to glass first), nanometer resolution scanning and feature resolution across the slices. Basically you have to figure out how to freeze a human into a glassy substrate mid-breath and then scan them and reassemble the giant 3-D jigsaw puzzle into a meaningful whole again. This is, needless to say, many orders of magnitude beyond our current computational and matter-control capabilities, but nothing (besides maybe the near-instant non-destructive vitrification bit) is physically impossible.

Once these few near-impossible steps have been achieved, you have your template library. At first you'll want to rebuild exact clones, but as the cost per build decreases (practical, hands-on experience with doing stuff almost always brings the per unit cost down), your engineers can start playing around with chimeras, combining the best features extracted from across specimens.

Step 2: Full in-silico instantiation

Build an in-silico model of the complete build. With realistic physics and some significant supercomputing muscle, a "build" could be tested in virtual reality for seconds (or if the funding is particularly generous maybe even weeks or months) before it is judged fit for a fleshbuild.

This is particularly used for testing blended builds, or daring tweaks to an existing model. Particular parameters can be altered (let's up aggro to 17/25, and test if it can still obey orders, or just going on bloody indiscriminate rampages). Depending on the battlefield purpose, certain features that would prove lethal in days or socially undesirable in human soldiers that would have to function in a society could be baked into the vatgrown. Think replacing the digestive system with a glycogen store, if the specimen has an expected lifetime measured in days.

Step 3: Good old-fashioned 3D printing

Again, depending on the per-unit cost and the expected durability, certain shortcuts and digital workarounds can be made. If the per unit cost is in the tens of millions of dollars and durability in years, you can build many redundant systems (2 hearts, advanced stop-bleed tech, etc), whereas if the cost can be brought down to roughly the current price to produce a calf in the West (about $1000) and the expected life-time is in days or hours, you can skip many life-maintenance systems that would be needed in a longer-lived or more valuable specimen (I already mentioned replacing the digestive system with an energy storage as a possible example).

The most complex parts will probably be the wiring diagrams of the brains. Human neurons usually take years or even decades to wire themselves into a useful network, with slow dendritic and axonic growth and pruning of synaptic connections. Presumably, with proper chemical prodding the neurons can be coaxed into linking much faster and along predetermined paths. The amount of information stored in this will be truly enormous. The human wiring diagram relies on a few tens of megabytes stored in DNA (nowhere near enough to specify the cross-wiring of billions of neurons), and makes up the rest with chaotic growth followed by aggressive pruning. Presumably, your builders can rely on a version of this on metaphorical steroids. Explosive dendritic growth followed by ruthless pruning. Nanomachinery, directed microwave activity, lasers ... there are many options here. Alternatively, you can skip the whole wetbrain and go for bionic options, with in-silico (computer)-ran versions, which may often be faster and more capable than the biological versions.