Radio Thinkers

Creatures that communicate by biological radio pops up in science fiction occasionally and it's a fun idea. However, there are some practical concerns with regards to evolving a radio in a creature's head.

I'm looking for a discrete sequence of evolutionary pressures that would encourage a species to develop radio communication without any external tools or equipment. The radio must be embedded in their bodies in order to be considered. Why would they evolve radios in their heads and what evolutionary steps would get them there?

Evolutionary Environment

Let's use a cooperative hunter species on an Earth like planet for a start. The planet can have any features you'd like in terms of atmospheric or crust composition, as long as a normal Earth human can survive there without a space suit (ignoring any pathogenic concerns).

This is a question so fanciful giant leaps or large amounts of handwaving are discouraged.

Note: There is this question about how a hive-mind might communicate. I believe this question is distinct in that it asks for an evolutionary process instead of just how it might work after evolving.

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    $\begingroup$ Love the question, can think of lots of ways to use this in a story! $\endgroup$ – Serban Tanasa Oct 7 '15 at 3:37
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    $\begingroup$ very strong radiowave can induce high current in cells altering/damaging the DNA btw if biological radio is even possible the sensor (antenna/dish) would probably be super large to pick up feeble signal or unless the animal invest in their super effective metabolism rate to rev up the power. $\endgroup$ – user6760 Oct 7 '15 at 3:52
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    $\begingroup$ Voice of skepticism, here. The wattage required for any kind of distance could be severe, and to exist within safe limits it may have to be directional. Omnidirectional broadcast spreads thin very quickly indeed, requiring currents several times that needed to kill any known lifeform. This organ would have to be be highly specialized and carefully isolated from ordinary tissues. If someone is playing with this idea, the back of the human skull forms a reasonable resonant cavity/parabolic dish that could create the necessary directionality for persons facing each other. $\endgroup$ – Sean Boddy Oct 7 '15 at 5:58
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    $\begingroup$ @SeanBoddy, Never before have I thought of the back of the skull as a parabolic dish support... The fact that said skull part does not necessarily have to remain attached to the rest of the body creates further interesting possibilities... $\endgroup$ – Serban Tanasa Oct 7 '15 at 14:12
  • $\begingroup$ @SeanBoddy - Bluetooth devices require very little power to run and can reach distances of a couple hundred feet. This would require receivers to be very closely spaced, but would satisfy the need for a large transmitter. Also, the device might be inside the head, but the transmitter could be located on the epidermis of the skull ... doesn't have to be in contact with brain matter. This would be much like the proximity of hearing aids with the connectivity or ear pieces which connect to phones. $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Oct 31 '15 at 23:09

As I stated in my answer to the linked question, the evolutionary prerequisites for radio communication is in a species that is able to precipitate a variety of metals in a variety of forms and an environment high in metals.

Initially, a precursor species would evolve to use metal to enhance its neural transmission rates as electrical transmission is vastly faster than human nerves' sodium-gate depolarization system, in itself a highly advantageous strategy in evolutionary terms.

It is likely that creatures using metal as a nerve conduction rate booster would have found that unshielded nerves would cause radiation detectable not only within a creature's own body, but in other creatures too. As faster nerve conduction is too great an advantage to give up, shielding would have evolved, quite possibly by running nerves through the centres of metal bones, or perhaps by sheathing the individual neurons in metal.

However, the possibilities of transmission and detection of EM radiation means that not all metal nerves would have evolved to be completely shielded, some could be partially shielded and be used to detect EM radiation.

So, we have evolved creatures that emit RF energy as a by-product of their neural activity. From there, once shielding has evolved to reduce cross-talk between nerve fibres, detection of RF leakage requires more sensitive receiver organs. Along with this, any deliberately unshielded neurons would emit RF energy detectable at greater range.

As there is almost always an advantage in being able to communicate at longer distances, the evolution of a stacked pile of depolarising cells (as occurs in electric eels) allows higher transmitter voltages, and hence higher power and range.

We then get to the point of bandwidth. EM radiation emission will most likely begin at lower radio frequencies, but it is entirely possible that mechanisms could evolve to increase the frequency of emitted radiation. Since a system of this type could have practically each neuron driving an EM transmitter of a different frequency, high bandwidth can be achieved by rapid changes in signal amplitude and frequency that is allowed by using high-frequency EM radiation, and also by multiplexing - using many frequencies simultaneously. This could ultimately allow an evolved bandwidth many times greater than our own Wi-Fi communication, which could also be somewhat directional. Another argument for higher radio frequencies and microwaves is that smaller antennas are required.

Since all this bandwidth is relatively easily achieved in evolutionary terms - simply by duplicating the relevant organs - there is no reason why the beings would not evolve to make use of this bandwidth. Since the highest intelligences of species on earth are found in those creatures with an active social life (and this ability makes for a great social life), the evolution of intelligence is pretty much a given.

Considering that a sentient, tool-using species that can communicate via RF at what are probably high bandwidths, it is unlikely that humans could easily develop an interpreter for this alien language, especially given that it would most likely be multiplexed, and both frequency- and amplitude-modulated, as well as rapid and idiosyncratic rather than following any simple grammar as in human-manufactured RF communication. It is far more likely that these creatures - should it occur to them that audio is being used to communicate ideas, a not-unlikely proposition given their inherent ability to share processing - would learn to understand and communicate with humans using human language, given its likely lower bandwidth and complexity.

Of course, since we're talking about evolution, an evolutionary feature such as metal-enhanced neurology would have to occur at a very early point in the species' evolutionary history. This means that - thanks to evolutionary divergence - there would most likely be a great number of species on this world which emit RF energy to a greater or lesser extent.

We can anticipate that in the groups of creatures with unshielded neurology, the 'noisiness' of their neurons would be a beacon to the RF senses of predators, particularly those who have shielded neurons themselves, and thus have a lower background noise over which they can 'hear' their prey. From this, we can anticipate that these may be easy prey to such predators, and would hence be prone to adopting an r-strategy.

Other species would have evolved to communicate via RF to a greater or lesser extent; we can anticipate a wide variety of such creatures occupying multiple niches, though as the communication range of RF is such that it can be anticipated that many would be at least a bit smarter than a terrestrial-equivalent species mainly due to the greater opportunities for social interaction.

As to the environment, there is practically a necessity for more metals to be accessible. This does not preclude an oxygen atmosphere, but there may be levels of atmospheric dust containing heavy metals that would have toxic effects on humans not protected by respiratory filters or who eat the local life forms. This would make face mask filters highly advisable rather than essential, and we could have a human living for quite some time without one before they might start to experience symptoms of heavy metal poisoning.

A potential reason for humans to be interested in such a world is that with the biological precipitation of metals, mining metals would be an almost trivial exercise of picking up the carcasses of dead creatures, whether recently dead or fossilised. Some very interesting alloys are likely to have evolved, as is foam-metal which is both light and strong due to its internal voids.

  • $\begingroup$ The thing about bandwidth is that it requires you to be selective in what frequencies you use as a carrier. If you receive and amplify too wide a band, you also amplify the noise floor with it, ultimately requiring a narrower band. The creature without an effective filter would essentially be able to detect all communication, but not retrieve the original messages. Conversely, the creature with an adjustable filtering mechanism could listen to anything 1 at a time, and maybe/not understand its intent. $\endgroup$ – Sean Boddy Oct 7 '15 at 17:49
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    $\begingroup$ The most wildly successful organism, though, would have a fairly wide filter, excluding the most useless bands, and have a section of brain performing software radio calculations. This isn't all that daft considering that human hearing is already, essentially, an ongoing Fourier analysis. $\endgroup$ – Sean Boddy Oct 7 '15 at 17:53
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    $\begingroup$ @MontyWild I just came back to this question and your answer is exceptional. Thank you Monty. $\endgroup$ – Green Aug 10 '16 at 12:41
  • $\begingroup$ Boddy just defined your predators and prey too ;-) $\endgroup$ – Giu Piete Dec 2 '18 at 3:07
  • $\begingroup$ 1. I like most of your answer. 2. I understand why people think metal nerves are a huge improvement, but they're really not. People forget the synapses, which are important not only for their transfer, but also modulation of the signal. Metaphor: a highschool raly race the kids will run 1 minute and then do an hour of administration before the next can run. Replacing the runners with the fastest sprinter alive to 10 seconds might seem impressive, but overall it's nothing. The metal also has a ton of disadvantages. It is harder to maintain. (...) $\endgroup$ – Trioxidane May 24 at 4:59

A complete answer would require a full transceiver, with a means for sending and receiving radio signals. This answer presumes that a receiver evolves first, then later a transmitter, and finally the link is made for social communications.

Suppose our planet has birds that have an ability to sense magnetic field, evolved for long range navigation. Further suppose that this bird's prey decides to live near deposits of magnetic ore. Our predator eventually notices that rapidly changing field direction, although disorienting, means something yummy is near. So the birds evolve to enjoy the sensation, and see how quickly they can fly back and forth. Their sensing organ grows, more neurons are dedicated to it, etc.

Now suppose some of these birds branch off and become mammals, and some mammals branch off and live underwater, like dolphins, in search of a niche. They evolve an electrical discharge mechanism like eels, to protect themselves from larger predators.

Et voilà! One dolphin notices when the others discharge, enjoying the sensation, and joins in. To conserve energy, they gradually boost the frequency to MHz range. Eventually, they develop different modulations to signal danger, satisfaction, food, rhetoric, and ultimately sarcasm. Nothing more remains for these creatures on this world. They leave, saying only "So long, and thanks for all the fish."


It would be difficult. But I would guess that an organ to sense the radio waves would be first. Like how we see light, to help us navigate more effectively in our environment.

So I would think an environment where radio waves are prevalent but not overwhelming and can be used just like sonar. Having an organ more like an ear than an eye for radio wave detection would 'encourage' another organ to generate radio waves, like bats and dolphins use echolocation.

However, echolocation really seems more likely to have occurred by generating a sound and getting better and better reception to understand the feedback. In this case having a radio generator. So how do you get a radio generator?

All mammals produce infrared radiation and on humans if we could see this we would be able to know much more about each other as we converse. So in a low light environment, instead of our visible light we might shift the more toward infrared. If we could 'see' our body heat patterns we would could learn to control them more into what is being 'said'.

Organs might develop that are more a 'mouth' for more direct and form of communication. Slowly shifting both the transmitter and the receptor (though I expect this would begin to require 2 different receptors, one for Infrared and the other for Microwaves, moving on down to radio waves) to different bandwidths maybe for less interference or a way to be 'silent' for prey.


Slow and steady growth to radio signals

Monty Wild gave a great answer, but unfortunately there is one thing that is a flight of fancy. The metal nerves. See my comments why they are actually unpractical. This answer is improving on the answer of Monty Wild.

Metal and bones

Most animals that get metals in their body see that most metal ends up in the bones. This is for most harmful, but some creatures like spiders and scorpions use tiny amounts in their claws and teeth to strengthen them. They are arranged singularly though, so no connected weave to make a good transponder. A creature could conceivably increase the amount, trying to store excess as a fixed core inside the bones, like a metal wire. This doesn't need to be much and can be build on the outside of the bones. This will be the start of the antenna. It'll greatly reduce the amount of metal needed compared to metal nerves, making it much more believable. The lesser amount of metal also prevents a lot of difficulty with the creature, as many metals aren't good for animals in larger dosis. They interfere with many normal processes of the body, binding and unbinding important things.

Radio and social

With metal in place, it can resonate thanks to nerves. Especially if they have nodes of Ranvier the electrical signal could jump to the metal a bit, giving it a resonance and a small RF signal. This can be picked up by someone close, probably touching at the start. That means they can feel it, as well as that the interference with the nerve can start signals to the brain. This can be seen as positive, which can lead to evolutionary reinforcement. Just like eyes, this communication can start to develop slowly. The signals are increased with dedicated nerves, stacked like those of electric eels. Together with a straight connection to the brain it'll be the basis from which it can expand to the complexity of communication.

First it'll get more range and allow for more feelings, at a very, very rudimentary level, to be transferred. It helps with telling each others location at (really) short distances, helping people not bumping into each other as well.

It'll evolve to greater ranges, possibly more tiny antenna for directionality (both for communication as well as feeling the direction someone is present, like your ears can tell the direction of a sound), and attune to more clear signal transfer. This is just a long evolutionary process that increases itself. Like sound replacing sign language, it'll slowly become more important the more range and differentiation they get. Eventually they can transmit emotion and meaning at the same time, clear over distance.


The RF signals will change with the creatures growth. Young creatures will have shorter antennae than older ones, with likely less powerful nerve cells. That would mean a different band and less range, making it feel like a childrens voice to them. Similarly older people are likely to have bigger antennae, but the age of the nerves could make them "sound" different as well.

The creatures can have an "always on" band of RF signals to know exactly where someone is closeby. It is likely only used for short times or intermittently, as it uses a lot of energy to keep it on (you're nit going to talk non-stop), as well as it becomes difficult to understand the signals with many people there (again, the same as talking).

The range can be modulated like talking, allowing people to scream or whisper.

Talking with RF can be much more efficient, as it can be used two-way at the same time, especially if you have separate receiver antennae, while much more clear on the meanings and feelings. Only problem is processing, as the brain mimics your own thoughts and emotions, meaning the return signals might mix up or can't be processed. The speed and amount of information can be much higher though.

Seeing a face also becomes less important, as emotion can be embedded or have it's own frequency. No visual signals needed. This can lead to much better communication, as you don't miss out on many subtleties while not able to see the other. You can continue crawling under your car and talk unaffected for example.


The visible light band is a special case of the EM Radio Wave spectrum so evolution of vision might be a guide. It started with just detection and seeking the heat from light. So radio evolution would start with just the detection of the magnitude of an existing signal.

Creatures have evolved to detect EM waves outside the so called visible frequency band, to detect infrared, some examples are some species of snakes.. Again this likely started as detection of heat. The difference with vision is that any material denser than air blocks infrared. Lenses are important in evolution of vision. Creatures which detect infrared have external sensors on their skin. They can detect presence of infrared but cannot focus it into an image as with the visible light spectrum can be focused with a lense.

Further into the radio spectrum, gain from a metal antenna would have the corresponding significance.

Birds and bees detect the earth's magnetic field as they fly through it. Motion through a magnetic field produces EM waves. This might also be guidance.

You have to consider where the original signal occurred to be detected. Reception would evolve first, because transmission without reception would not have any effect for adaptation. So the transmission has to be present when the creatures first evolved reception.

For light and infrared it was heat. It might be motion through a magnetic field. Maybe there is some other natural source of radio transmission. If naturally occuring it might not be a signal interpreted as communication but would just be a constant source of EM waves or pulses. Creatures might evolve to approach to distance themselves in regard to the location of this radio source.


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