I have a robotic species on a distant planet (not necessarily similar to Earth, but it is indeed rich in metals and other materials necessary for making robots). They are born in a factory (duh!), made by "hand" from other robot(s).

They are programmed (by an ancient civilization that perished a long time ago) to preserve themselves as a species. Each individual is born with the identical program, which is slowly altered to suit the current need of the society. Note that there is no centralized program that tells them what to do; they are all autonomous, but prioritize their species as a whole.

The interesting part is that they are manufactured as a small robot, analogous to a 5 years old kid, and grow up to adult human size. This is always the case for all robots, although the actual process differs for each robot: some may grow slowly, some may have a longer arm, but all of them will always grow into a humanoid shape - always bipedal, with two arms, and a head, and a body.

How does this process of "growing up" work in robots?

The answer should address two things:

  1. Their limbs physically slowly grow larger over time.
  2. All robots only reach adult human size.

I'm not asking why (they are programmed to do so, just like our DNA influences our appearances), but how would this process actually work? They don't have cells like we do. They are composed of metals and wires just like our robots - but in a far more sophisticated way. So, no nanobot - they just don't reach that technological level since their idea of a robot is always macroscopic (based on their creator program), and all robots on the planet are always humanoid.

And yes, they are sentient. And no, they don't obey Asimov's Law. But don't worry, they don't know planet Earth. Yet.

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    $\begingroup$ Maybe each one is made of nanobots? $\endgroup$ – Mark Gardner Jul 5 '17 at 13:18
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    $\begingroup$ Don't railroad the answers. Show what you have already done, state your problem. You can't cater answers. that is the XY problem. I can answer your requirements with one word. "nanites". Also your tags are incompatible. Read the tag wikis. $\endgroup$ – Mindwin Jul 5 '17 at 14:11
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    $\begingroup$ One of the things we do here at worldbuilding is to challenge the question's assumptions to see if they are solid. Flimsy assumptions will reduce the value of the fictional work/world and make it less believable, so these challenges help improve overall world quality. - - - - Maybe you need to rethink your design. Also you need to explain why those factories dont CQ their product and/or the robots don't have a self-repair or integrity routines. $\endgroup$ – Mindwin Jul 5 '17 at 14:42
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    $\begingroup$ I think you should leave this question laying still for a while, and begin fleshing out your mechanical lifeforms bit by bit. Also, you can use the meta sandbox to test questions before bringing them to the site. And remember, ask about problems, not about possible solutions. google "xy problem" on stackexchange.com to learn more. $\endgroup$ – Mindwin Jul 5 '17 at 14:56
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    $\begingroup$ I think a key question to answering this question is why do the robots grow up like this? Typically when we talk of "robots" in contrast to "living things" one of the major tenants is that the robots are built with a purpose from day 1, while living things consist of the mismosh of whatever happened to work and they kept it. If we understand more of what the robots are supposed to gain from this growing up process, we'd be able to better shape answers to suit because we could get into the minds of the robot designers. $\endgroup$ – Cort Ammon Jul 5 '17 at 16:59

What is initially created is a really basic unit which is capable of:

  • produce energy to self sustain
  • gather resources
  • move
  • self optimize its behavior

when it happens that the unity has gathered enough resources, the self optmization can plan an "expansion" (e.g. realizing a better arm for resource gathering, or a more efficient energy generation). Expansion over expansion the robot actually grows and can also develop new abilities (e.g. swim to gather sea sunk resources).

The expansion can be done either by the robot itself (assuming it is able to assemble the expansion) or by a factory upon exchange of resources.

  • $\begingroup$ I like how it already address my next question "Why they need to be manufactured as child robot?". $\endgroup$ – Vylix Jul 5 '17 at 13:56
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    $\begingroup$ @Vylix To be more efficient. Why spend time and energy on making a larger robot when it can grow itself? $\endgroup$ – Cees Timmerman Jul 6 '17 at 17:48

Mirroring Mental adulthood

Even though a machine is created, or built, it does not necessarily mean that whatever program is operating the construct is not an "adult" from beginning.

In humans, adulthood is not only the (mostly) completed growth, but also development of knowledge, character, empathy and, possibly most importantly, responsibility.

The same could be true for your synths operating system. Since they are modeled after some kind of human psyche, they desire a similar progress as humans do. There may even be rare deviations that defy this imperative.
In essence, they acquire the parts themselves and integrate them as they develop their operating system into "adulthood", which doesn't necessarily mean that everything needs to be perfectly streamlined.

It also explains why some individuals have slightly longer appendices on a single side, as they cannot upgrade both sides simultaneously, due to not having more tool-bearing arms.

Scheduled inspections and upgrades

Maybe there is some kind of "development progress measuring" in regular intervals, much like regular inspections in machines today, where robots assess the mental development of an individual, and upgrade the chassis accordingly.

In this case, irregularities could be reflections of irregularities in the mental development process of that entity of which the entity has no influence upon, as changes are imposed by its peers.

  • $\begingroup$ I like the scheduled inspection that allows the part exchange (or upgrade). This eliminates the need for "parent". Coupled with your "already mature" program, this is a very solid answer. $\endgroup$ – Vylix Jul 5 '17 at 13:50

I would make it a cultural thing. Having the robot mature in a smaller less powerful body makes sense both in terms of resource conservation and to minimize damage caused by individuals who do not conform to the societal norms.

A new, and more powerful, body is earned piece by piece as you mature into your role in the greater good. Once you've passed a certain threshold your guardians will either install new body parts or activate parts of your programming which allows your nanobot maintenance system (analogous to our immune system I would hazard) to reconfigure your existing body to new specifications.

The benefit would be that robots who can't cooperate with other robots will just stay small obnoxious machines which can be easily contained. (Unless they evolve the skills to to hack their own configuration.) While the largest and most powerful robots would usually be the ones who contribute best to society.

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    $\begingroup$ I realize this is the second time today I've suggested what essentially becomes a caste system. For the record I'm not a big fan of them in the real world ;) $\endgroup$ – Doomfrost Jul 5 '17 at 13:26
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    $\begingroup$ I like the cultural approach indirectly dealing with the growing up. $\endgroup$ – Vylix Jul 5 '17 at 13:47

The body parts are passed down/recycled

The mature robots doing specialized work require and manufacture high-performance body parts and replace pairs of limbs/parts if one of them gets damaged or degrades. These are then obtained by younger/less essential robots who refurbish them and use them, again discarding their own old parts.

Servos and other components are reused in smaller parts when their performance drops, so the newly manufactured robots have to make do with those while they are "growing up" into their role in robot society.

This results in immature robots having varying sizes, types and functionalities in their limbs, depending on their assignments, status, "friends" and the dumb luck of finding an awesome part. The robots also make different choices. Some may keep a matching pair of crappy limbs while others take any bigger/better limb individually, compensating for the imbalance as much as they can.

Finally, the mature robots all end up human-sized with the same body plan because to deviate from compatibility would be a huge efficiency loss. So new robots are made able to use existing parts, while the mature robots do not modify themselves or manufacture parts that would be unusable for the next generation. Incremental improvements do happen, but slowly, over generations of robots.

  • $\begingroup$ Maybe there are "dungeons" where they can loot the most awesome body parts. $\endgroup$ – Vylix Jul 5 '17 at 13:52

Easy. They are analog so have very little memory. So their command are very simple and short. As they are expanding their calculating capability they add memory to accommodate that and learn new commands and programming languages.
In human terms their brain grow.

At some point they decide to go beyond "enough" zone. Some of them go past that, as our bodybuilders or scientists, but majority stay in the zone.
By exceeding the "enough" I mean they can work on their new limbs and make them from different materials. Maybe instead of using "github" for coding they write the code by themselves so it may take longer to create it but they save milliseconds in decision making.


Robots are manufactured small to reduce the amount of raw materials which need to be present at one locality. Since artificial Neural Networks takes times to map themselves, as the cybernetic mind is programming itself, the robot consumes raw material, and grows.

This is accomplished by a swarm of nanites (microscopic robots) which reside inside the robot. These nanites take care of repair and replacement of defective parts, reconfiguration, and growth. These microscopic robots take raw material (metal, silicone, etc.) and grow the robot. The speed of growth, size, and shape of the robot depends upon the purpose of the robot.


I have a similar idea to "Culture" and "Power consumption"

These robots just have to learn how to use their bodies during some machine-learning process. It is easier for the first time to learn using smaller parts but when an unit progresses in learning, its parts are to be continuously replaced by slightly larger step by step. (The algorithm is not scalable and there is a risk to fall in a local optimum)

Of course the process have to stop, when robot size is sufficient for task he is "born" for: exploiting mineral resources, building other machines etc..

The process needs to be repeated for each unit separately because each unit is programmed to have different target dimensions (there is a diversity). The reason is, that the whole robot swarm (let call it "society") tries to learn optimal robot sizes to perform general tasks by experimenting on "real-life" examples (and by the time, optimal ways of doing things). Maybe they use some kind of evolutionary algorithm -each unit has its own genetic code determining its body dimensions.


Evolution just like meat robots

Meat robot (humans) are self-repairing. A damaged limb will repair itself continuously.

Metal robots are also self-repairing. However their limbs must repaired all at once.

The ore-gatherer who lives in the mountains waits for her pickaxe-arm to wear down before crafting a new one and attaching the replacement. The new arm is bigger and stronger. Clearly there is enough ore around to wear down the first one. So she can afford to specialise to the task.

The ore gatherer who lives in the ocean has no ore to gather. His pickaxe arm remains unused and unreplaced. He is unsuited for his environment. He cannot gather whatever fuel he needs. He starves.

Repeat until the robot in question either starves; or they specialise and enlarge each part of their anatomy until every part is replaced by an adult sized part. They are all grown up!

Why stop there?

You have to ask yourself why humans did not evolve to be bigger. Environmental pressure. We were the right size for the jobs we did. Smaller makes us vulnerable; bigger makes us need to much food. Evolution ensured we were not too big or too small.

The robots grow according to 'evolution on steroids'. So what's to stop the Ore-gatherer building itself into a Bagger 228? Well ask yourself what ability the humanoid robot has but the bagger does not. Then design the environment so that ability is vital.

For example the Bagger is largely immobile. The ore gatherer has to navigate steep slopes and caves. It cannot afford to grow so big. The human shape is great for climbing like a monkey though.

Still perhaps some robots do evolve into Baggers, tractors, submarines and war machines. But I imagine these guys living in fairly remote areas. Open caste mines, farms, deep oceans and in space. They would serve pretty much the same function as their non-sentient equivalents do in the real world. Consider Brian Aldiss' "Who can replace a man?"


Well, outside of nanotechnology, I’d assume the only way for the physical growth to be possible would be to replace the limbs with longer limbs over time until they reach adulthood. As for the mental aspect, I’d imagine it’d be similar to people in real life, their programming reshaping itself based on its environment.


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