Have we ever observed a new functional biological structure arising spontaneously such as a new functional organ (sensory or otherwise. such as tracing some creature in the past few hundred years which had no electroreception organ and now has evolved this organ)

Or has what we observed been limited to changes in existing structures.

(Lenski's E. coli bacteria is not what i am looking for since it is a change in an existing metabolic system (not a new functional structure) and furthermore e-coli already had some ability to use citrate as an energy source )

Looking for a completely new functional organ (such as a new sensory organ) that we have actually observed - not deduced from fossil record.

Also not looking for something trivial such as a new/modified enzyme or protein molecule but rather a new organ in a species at least the size of an insect.

  • 2
    $\begingroup$ Can you define "functional biological structure"? As it is now, this is a good question which is not very clearly defined. For example, would a single new enzyme count as a "new function"? $\endgroup$
    – March Ho
    Commented Apr 26, 2015 at 5:57
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    $\begingroup$ @MarchHo looking for a new organ, such as an electroreception probe or a poison gland with delivery system. i.e. a new working functional system of non trivial complexity $\endgroup$
    – r2d2
    Commented Apr 26, 2015 at 6:03
  • $\begingroup$ @MarchHo new enzyme is not a sensor or organ. looking for a new functional system like a new organ or a new sense. I updated the question to reflect your point. thanks $\endgroup$
    – r2d2
    Commented Apr 26, 2015 at 10:35
  • $\begingroup$ how about story of epigenetic inheritance of fear? nature.com/news/… Although it wasn't spontaneous $\endgroup$ Commented Apr 26, 2015 at 10:59
  • 1
    $\begingroup$ @r2d2 And what do you exactly mean by "trivial complexity arguments"? $\endgroup$
    Commented Jun 29, 2015 at 11:19

4 Answers 4


It seems like you are attempting to frame this as a question about current evolutionary theory. However, current evolutionary theory doesn't expect anything as complex as an organ to arise spontaneously without any precursors. You suggest a new claw in an insect would be something "spontaneous" enough for you. This again shows that your question and the answer you are looking for are not related to evolutionary theory. The insect organs you are talking about are all modified appendages. This includes claws, mandibles, antennae, legs, fangs. These appendages all share a common genetic and developmental framework that has been slightly modified over long periods of time to give raise to the variety of insect appendages that we see today.

The idea that evolutionary theory supports the spontaneous creation of organs is a willful ignorance of evolutionary theory. The molecular mechanisms that generate novelty (e.g. genome duplication, gene duplication, de novo genes, mutation, gene regulation) for natural selection to work on are relatively well understood. Since we have an understanding of how novelty is created it is known that spontaneous organ generation has never happened or is expected to happen under evolutionary theory.

Here is link to the University of California, Berkeley's webpage designed to teach the public about evolution.

  • $\begingroup$ Welcome to Biology. Great answer to a controversial question. +1. If you could add a reference to the evolutionary theory to allow people to read about it more that would really help. $\endgroup$
    – AliceD
    Commented Jun 29, 2015 at 0:09
  • $\begingroup$ nice dodge. of course it is not expected to happen because then random evolution would need to be observable and that would be the end of theory. and we cant allow that to happen, right $\endgroup$
    – r2d2
    Commented Jun 29, 2015 at 6:26
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    $\begingroup$ @r2d2 You may continue your efforts to associate these false hypotheses with Evolutionary Theory. However, I believe your time will be better spent reading and understanding Evolutionary Theory than parroting old and disproved creationist miseducation literature. At the very least, a better understanding of evolution will allow you to form coherent arguments against it. $\endgroup$
    – Darwin
    Commented Jun 29, 2015 at 6:30
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    $\begingroup$ this "answer" should be changed to a comment. show me please some real empirical evidence or admit that none exists. i dont want to waste this question on pitiful dodges whose stregnth of argument is only that the creationist alternative cannot be true $\endgroup$
    – r2d2
    Commented Jun 29, 2015 at 11:00
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    $\begingroup$ @r2d2 You should check your condescending attitude. "i dont want to waste this question": really!!? Stop behaving as if you are some kind of supreme being. Provide details in your question if you expect an answer with "empirical evidence". $\endgroup$
    Commented Jun 29, 2015 at 11:17

How about the Italian wall lizards that evolved new muscles around their intestines after being introduced to an island? (other article, actual paper). The paper reports that these cecal valves are "a structure previously unreported for this species and rare in this family and scleroglossan lizards in general"; indeed, "The fact that <1% of all currently known species of squamates have cecal valves ... illustrates the unusual nature of these structures in this population.".

It is possible that these values are an ancestral structure that was reactivated by natural selection; however, we know that natural selection can act very quickly to change the size of morphological structures, so it's also possible that existing muscles quickly changed size in response to selective pressure. Figuring out the developmental mechanism of cecal valves would sort that out.

  • $\begingroup$ comment there: "I’m assuming this is a predominance of one possible phenotype, not a change in the genetic structure of the lizards, and that the genes for this phenotype were already present in these lizards..." answered there: "it’s still just the phenotypic expression of a bunch of stupid base pairs... There are other herbivorous lizards with cecal valves" makes sense given that took only 30 generations. i.e. sounds like this was already built into the lizards and was waiting to come out when needed $\endgroup$
    – r2d2
    Commented May 29, 2015 at 10:31
  • $\begingroup$ Do you have EVIDENCE that it was "built into the lizards"? Or did you just make that up so you can deny that the example you asked for was given to you? Why ask the question if you are prepared to say that EVERY possible answer "was always built in" with no evidence to support your claim? $\endgroup$
    – swbarnes2
    Commented May 29, 2015 at 17:10
  • $\begingroup$ @r2d2 I've updated my answer to reflect your point. Don't forget that for most (all?) animals, every individual starts as a single cell, so everything is "just the phenotypic expression of a bunch of stupid base pairs", plus whatever else was contained in that cell. $\endgroup$
    – Gaurav
    Commented May 29, 2015 at 20:47
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    $\begingroup$ morphological changes not what i am asking. the "new valve" they found between the small and large intestine is simply an enlargement of muscles already present in the gut wall at this juncture. looking for completely new functional structure. like a new primitive claw in insects or new antenna. also, just curious how do you know the changes were from random mutations/NS? given that 30 generations is nothing for genetic algorithms (have worked with some) it seems far more likely those changes were built in responses/activations of existing DNA - not new genetic info from random mutations $\endgroup$
    – r2d2
    Commented May 31, 2015 at 18:24
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    $\begingroup$ @swbarnes2 you are the one jumping to conclusions here without evidence. arent you a scientist? given that it was <30 generations. it was either a very lucky dice roll or pre-existing phenotype expression. let's wait and see. secondly, it was not a new organ or limb as that link explains $\endgroup$
    – r2d2
    Commented Jun 1, 2015 at 11:09

To be sure a new trait actually evolved before our very eyes and wasn't simply mistaken for a wild trait we never noticed, you probably want to look at domestic animals. We have directly observed, through animal husbandry, the evolution of new fingers in cats, new ribs in pigs (wild pigs have 14, some breeds now have 17), new fins in fish (here I'm talking about the double tail mutation in golfish).

These new structures act, for the most part, like the old ones. I assume because of this you might be interested too, in the observed evolution of completely new functions from old parts:

The Norwegian Lundehund (dog breed) has evolved the ability to seal its ears shut with muscles that other dogs/wolves use to simply move their ears.

As someone else mentioned, In an island population of Podarcis sicula (lizard species), muscles in the digestive tract which normally function to squeeze food through the intestines, have bunched up to form a new valve, thus creating a fermentation chamber.

Off the top of my head, I can't think of other directly observed changes in function but there are MANY super solid inferred changes in function:

Bee stingers are modified ovipositors (egg-laying organ). We know this because they are nearly identical to the ovipositors of other insects, and because the queen uses hers as a stinger and as an ovipostor.

Snake venom is modified saliva and snake fangs are simply a merger of tooth and saliva duct.

Bird wings are modified arms with 3 fingered claws. I could go on but I'll call that good.

  • $\begingroup$ just curious is there any evidence that these changes occurred by random mutations? i could think of other possibilities such as inherent mechanism within the organism which changes itself. after all, we are far from fully understanding even the most simple bacteria $\endgroup$
    – r2d2
    Commented Mar 27, 2018 at 5:35

There are two main issues in your question that make it hard or fundamentally impossible to answer. The two issues are

  • What you would accept being an 'observation'
  • What you would accept being significant enough to be an example of interest.

A big issue in your question is based upon what you call an observation!

When you say

observed - not deduced

, you highlight the whole issue of what you would consider being an observation.

In science, observations often take complex form. It is not only direct visual observation recorded on a standard camera. It is like asking for, recorded-on-camera evidence that quartz exist. Such evidence don't exist (and cannot exist), yet we know of their existence through other means of observation. It would make no sense for someone to only consider camera recording as valid mean of observation.

Of course, We have never recorded on a camera the evolution of an entire new organ because it takes a lot of time. Yet, evidences are numerous.

This technic of limiting arbitrarily the field of methods that one accepts to recognize as bringing evidence and call "observation" is a common technic from science denier (e.g. flat earth society, creationist). I made a similar point as the one I made here on this post if you want.

How to solve this "What is an observation" problem?

There is only one way to go. It will be for you to be able to understand the forms that observation can take. For this, you will have to learn a little bit about evolutionary biology and evolutionary genetics. For a very short introduction to evolutionary biology, you can have a look at Evo101 by UC Berkeley.

You may have hoped for someone to give an entire course on evolutionary biology to fill up this gap of knowledge of yours but I am afraid it would be way too much work for a single post. If this was your position, then it would be like refusing to accept that earth is a sphere without having yourself explain how GPS data work. We just can't give you an entire course here.

So you have two solutions; rely on authority or understand by yourself. If you rely on authority you have two main options; Rely on those that rely on evidence (science) or those that don't rely on evidence and either rely on other forms of justification (justification theory;such as a religious book for example). (either those that work through observations, scientists). You second solution is to understand the field by yourself and therefore start studying for it.

A second issue is that it is unclear to know what you would accept being "not trivial"

When you say

Also not looking for something trivial such as a new/modified enzyme or protein molecule but rather a new organ in a species at least the size of an insect

It is hard to know what you would call a significant enough evolutionary event to be accepted. The risk is that you may define it large enough so that it fundamentally cannot be observed by a mean that you would accept.

For your curiosity, this post talks about evolution of lactose digestion in humans and this post about the evolution of cardio-vascular system.

Somewhat related post

You might want to have a look at post Is evolution a fact? and the link posts in the top voted answer.

Just another comment

random evolution

In the scientific literature, "evolution" is never said to be "random". The fact that you're using this expression shows what kind of literature you are used to.

For all reasons explained above, the question cannot be answered, not by lack of evidence, but because the question is unclear. I am therefore voting to close as unclear. Good luck in your investigation of the question.

  • $\begingroup$ listen to your words. then it sounds like the whole area is not at all scientific. yet it is taught as science $\endgroup$
    – r2d2
    Commented Mar 21, 2018 at 19:16
  • $\begingroup$ My answer is more of an explanation for the philosophical difficulties behind the question. My answer is more of a long comment to explain why I think the question is unclear and deserves to be closed as such. $\endgroup$
    – Remi.b
    Commented Mar 21, 2018 at 19:25
  • $\begingroup$ its not my question thats unclear. its the whole theory of random evolution thats unclear $\endgroup$
    – r2d2
    Commented Mar 27, 2018 at 5:33
  • $\begingroup$ @r2d2 I am quite convince there is no way to change your mind, so I won't try too hard. If you wanted to learn something you would have by the time (and would have stopped to stop to call this field of knowledge the "theory of random evolution" as creationist do; nobody call it that way in science). I am a researcher in the field of evolutionary biology and I know a thing or two about this theory and it is always a bit funny to face someone who knows nothing about it but thinks he knows best. $\endgroup$
    – Remi.b
    Commented Mar 27, 2018 at 15:05
  • $\begingroup$ that was not me. it was a random computer glitch. i;ve studied the theory extensively. but it boils down to taking seriously something which is foolish and stupid. the scientists cannot reject it though, because it's the only explanation that "fits" the way they view the world $\endgroup$
    – r2d2
    Commented May 5, 2018 at 19:44

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