Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

We use electromagnetic communication everywhere these days. Cell phones, wifi, old-school radio transmissions, television, deep space communication, etc.

I'm curious about some of the possible reasons we have never seen biological systems having evolved to use electromagnetic, i.e. radio, for communication. The one obvious exception to this are organisms that generate their own light, i.e. bioluminescence. Cuttlefish are masters of this, and many other species as well.

It seems like bio-radio could have offered all kinds of evolutionary advantages for animals capable of using it.

Are their basic physical limits in chemistry, or excess energy requirements or something that would basically have made this impossible? Or was this perhaps just something that life never evolved to use, but would otherwise be possible in evolution?

share|improve this question
    
Also, don't forget magnetotactic bacteria –  nico Aug 15 '12 at 8:07
2  
Light is an electromagnetic wave. The only difference is wave length and energy. –  Konrad Rudolph Aug 15 '12 at 21:03
    
What about Sharks? –  Armatus Aug 16 '12 at 8:17
4  
Life did evolve to use radio, we use it all the time. –  Hermann Ingjaldsson Aug 19 '12 at 8:58
1  
See electrocommunication, weakly electric fish and Mormyridae. They use 500 Hz electric sine signals (however, AFAIK using conductance of water, not - electromagnetic waves). –  Piotr Migdal Aug 21 '12 at 20:06
add comment

5 Answers 5

up vote 18 down vote accepted

There is a very different mechanism for generation (and detection) of ultraviolet, visible and infrared light vs radio waves.

For the first, it is possible to generate it using chemical reactions (that is, chemiluminescence, bioluminescence) with a typical energy of order of 2 eV (electronovolts). Also, it is easy to detect with similar means - coupling to a bond (e.g. using opsins).

For much longer electromagnetic waves, and much lower energies per photon, such mechanism does not work. There are two reasons:

  • typical energy levels for molecules (but it can be worked around),
  • thermal noise has energies (0.025 eV) which are higher than radio wave photon energies (<0.001 eV) (it rules out both controlled creation and detection using molecules).

In other words - radiation which is less energetic than thermal radiation (far infrared) is not suitable for communication using molecular mechanisms, as thermal noise jams transmission (making the sender firing at random and making the receiver being blind by noise way stronger than the signal).

However, one can both transmit, and detect it, using wires. In principle it is possible; however, without good conductors (like metals, not - salt solutions) it is not an easy task (not impossible though).

share|improve this answer
1  
Why is the thermal noise not a problem in mechanical devices then? Is the only reason the better conductivity of the material? –  Konrad Rudolph Aug 15 '12 at 21:05
2  
Thermal noise is devastating for molecular devices, as detectors/emitters (two-level systems) are all the time saturated (so e.g. a photon has the same probability of being absorber and to steal excitation). For macroscopic currents there is no such mechanism and one can easily go beyond the thermal noise (so for animals its only a technical problem of getting good enough conductors and generators of high frequencies). Moreover, AFAIK water absorbs most of radio waves (it's why submarines use sonars, not - radars), so radio communication would work only for land animals. –  Piotr Migdal Aug 16 '12 at 12:07
add comment

A quick comparison between light and sound vs. Radio

  • Light: Wavelength 380 nm -740 nm
  • Sound: 17 mm - 17 m
  • Radio: 1mm - 10e5 km

EM spectrum

From the Planck relation, the energy of a wave is inversely proportional to the wavelength. As a result light is stronger than sound which is stronger than FM radio which is stronger than AM radio. Very likely, the energy density provided by radio is far too weak to have meaningful signal processing.

However, there are some uses in the radio frequency. Bat echolocation occurs at a frequency of 14,000 to 100,000 Hz which is well within the radio frequency.

share|improve this answer
    
You don't need a lot of energy to communicate anything. Anyway, radio and wifi works, so it's not a good argument. –  Piotr Migdal Aug 15 '12 at 12:15
2  
@PiotrMigdal, I agree with that counterargument. However, electronic forms of communication via Radio and wifi have the luxury of being amplified. Yes, signaling cascades exists but certainly are not optimal compared to higher frequency channels. Your answer is certainly better. –  bobthejoe Aug 16 '12 at 5:43
1  
A good point with amplification. For radio you want sine-wave amplifiers, not cascade amplifiers, so here there may be a problem as well. However, the first step is to have good wires... –  Piotr Migdal Aug 17 '12 at 10:12
add comment

We cannot know if evolution succeeded or not, because we haven't visited all places where evolution happens, like, other planets.

share|improve this answer
    
We do not use it in biological systems, as the question reads. –  Daniel Standage Aug 15 '12 at 15:00
    
You can continue to downvote my answer if you must but I haven't seen a single refutation of this argument. There is no way we can know what evolution is capable of, except by looking everywhere it possibly acts. So we can never know. Every downvote of this shows you have no argument but a personal axe to grind. –  rwst Aug 20 '12 at 14:11
add comment

Actually, electromagnetic communication is used by certain fish, the mormyrids and the gymnotids. Pulse modulated in the former and amplitude modulated in the latter.

However, the frequencies used are not much greater than 1Khz, which is not what we ordinarily consider to be in the radio frequency spectrum.

There is, too, another biological species in which the use of the full RF spectrum has evolved. Its activities even extend to the use of the UV and X-ray frequencies.

That species is our own. I am not being flippant here. We must not fall into the trap of considering ourselves as apart from nature. Contrary to our usual intuitions, technologies have evolved autonomously within the collective imagination of our species.

The broader evolutionary model which supports this contention is outlined, very informally, in "The Goldilocks Effect: What Has Serendipity Ever Done For Us?" , a free download in e-book formats from the "Unusual Perspectives" website.

share|improve this answer
    
Thanks for the info about mormyrids and gymnotids. I'll do some further reading on them. I am only interested in biologically-generated radio communication, which was where my question was directed. One of the key differences between technology and biology is that the former is not inherently inheritable. A flock of birds that communicate via radio will pass that ability to their young and is innate. Human speech capability is passed innately to our young. The knowledge to build technology is sociological, not biological. –  Geuis Aug 18 '12 at 22:13
    
You miss my point. The evolution of technology cannot be dismissed as "sociological". If examined carefully is ti an inevitable outcome of biology. It is so very easy to fall into that anthropocentric trap. The mechanisms of transmission are, of course, not identical for the various phases of the overall life process. –  Peter Kinnon Aug 19 '12 at 4:24
    
this is a good answer - adaptation could, given proper conditions, create radiosensitive organisms I'm sure. –  shigeta Aug 19 '12 at 9:49
add comment

Because the intermediate stages are not evolutionarily favoured. That's why.

Sound and light perception are useful without any generative capability. An organism with a tiny amount of perception for either of these things has an advantage over those without; and an organism with a tiny amount more has an advantage over those with a tiny bit less. This advantage forms the basis for selection and thus improved sensory capabilities (balanced, of course, by the cost of those capabilities).

Being able to perceive radio on the other hand provides no useful information about the world at low level perception so even if an organism was to randomly mutate so as to detect radiowaves* there would be no selection for this ability, and thus no mechanism to drive the evolution of advanced radio reception. Without the ability to perceive radiowaves there is no possibility of evolving the ability to generate radio signals in a controlled manner.

*-In fact, since radiowaves generally interact very little with organic materials unlike heat, light and sound even this first step of random mutation is much less likely than for sense that have evolved.

share|improve this answer
    
I find the "intermediate stages" along with "no useful information about the world" argument more satisfactory than thermal noise argument. Terrestrial animals preferred visible light to be visible because of Sunlight spectrum. en.wikipedia.org/wiki/File:Solar_Spectrum.png Sound has high attenuation, so it is more fit for local communication without attracting predators from long distance. –  Vikas Jan 22 at 17:56
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.