Aristotle on the mayfly

A paper I recently saw in EMBO Reports made the following assertion:

Ancient Greek philosophers laid the groundwork for the scientific tradition of critical inquiry, but they nevertheless missed out on one aspect important to modern science. Many philosophers obtained their results through a tradition of contemplation and thought rather than experimental procedure, which, not surprisingly, led to errors. Aristotle’s belief that the brain is a cooling organ for the blood was definitely not based on anything that scientists today would consider scientific evidence. He also thought that in humans, goats and pigs, males have more teeth than females, a notion easy enough to correct. His statement that flies have four legs was repeated in natural history texts for more than a thousand years despite the fact that a little counting would have proven otherwise.

Say what? Aristotle was not an observer? He had no evidence for his views? That sounds wrong... and it is.

The thing about brains is often repeated because Harvey made a lot of it. But in point of fact brains do cool the blood - at least, in humans. They also do one or two other things, but we should beware simplistic functional ascriptions the way we should beware simplistic historical myths. Aristotle was not wrong so much as insufficiently right. There's a difference.

The thing about teeth is also instructive. Robert Mayhew, in chapter 5 of his book The Female in Aristotle's Biology, points out that observation need not have changed Aristotle's mind. Despite there being other texts that support the equality of tooth number, Aristotle's observations, assuming he made them, may have been on individuals who had poor diet, lacking in vitamin C, leading to tooth loss throughout their lives. Or it may have been that his theoretical commitments to teeth being instruments not only of nutrition but of defense, led to the conclusion that women do not engage in defense and thus lack the teeth needed. Either way, it was not something that could be resolved by a few simple observations.

But I want to focus on the mayfly. Here is the offending text, from History of Animals 490a–b:

All creatures that are capable of motion move with four or more points of motion; the blooded animals with four only: as, for instance, man with two hands and two feet, birds with two wings and two feet, quadrupeds and fishes severally with four feet and four fins. Creatures that have two winglets or fins, or that have none at all like serpents, move all the same with not less than four points of motion; for there are four bends in their bodies as they move, or two bends together with their fins. Bloodless and many footed animals, whether furnished with wings or feet, move with more than four points of motion; as, for instance, the dayfly (ephémeron) moves with four feet and four wings: and, I may observe in passing, this creature is exceptional not only in regard to the duration of its existence, whence it receives its name, but also because though a quadruped it has wings also.

All animals move alike, four-footed and many-footed; in other words, they all move cross-corner-wise. And animals in general have two feet in advance; the crab alone has four.

Now several things should be noted: he doesn't say all flies have four legs; he mentions a particular animal, the "ephemeron", which is most likely a species of mayfly, or Ephemeroptera, of which there are over 2000 species. Go look at the left hand photograph of the Hexagenia species shown here:


How many legs does it have? Well, it is standing on four, because the forelegs are specialised simply to hold onto the female during mating in flight (the sole task of the adult mayfly). Aristotle, who counts legs based on their functionality, is in fact correct, if that is the kind of species he was observing. We say it has six legs because the forelegs are homologous with the hindlegs. He said four because the forelegs aren't used for walking.

Secondly, note that Aristotle mentions the ephemeron in the context of *walking*, where he makes the point that motion requires four points of contact with the ground, even if the animal has no legs. Moreover, it is "not less" than four. So he may be excused for not using modern concepts and criteria, but he is not guilty of misobservation, as so many want to make out. In fact, Aristotle was a damned good naturalist observer. For example, he observed and reported live birth among dogfish some 2200 years before that observation was made by modern scientists. If Aristotle wasn't a scientist and a good observer, nobody ever has been. William Macgillivray, in 1834, wrote:

Natural history, considered as a science or body of doctrine, commenced with Aristotle, the founder of the Peripatetic School, and one of the most illustrious philosophers of antiquity. His writings were held in the highest estimation by his own countrymen the Greeks, as well as by the Romans: they were considered as the most authentic sources of knowledge, after the revival of learning in Europe; and even at the present day their influence may be traced in the works of many who have not so much as bestowed upon them a cursory glance.

Moreover, Aristotle knew that insects had six legs. In the Parts of Animals he wrote:

The anterior legs [of insects] are in some cases longer than the others, that they may serve to wipe away any foreign matter that may lodge on the insect's eyes and obstruct its sight, which already is not very distinct owing to the eyes being made of a hard substance. Flies and bees and the like may be constantly seen thus dressing themselves with crossed forelegs. Of the other legs, the hinder are bigger than the middle pair, both to aid in running and also that the insect, when it takes flight, may spring more easily from the ground. This difference is still more marked in such insects as leap, in locusts for instance, and in the various kinds of fleas. For these first bend and then extend the legs, and, by doing so, are necessarily shot up from the ground. It is only the. hind legs of locusts, and not the front ones, that resemble the steering oars of a ship. For this requires that the joint shall be deflected inwards, and such is never the case with the anterior limbs. The whole number of legs, including those used in leaping, is six in all these insects.

Who is responsible for this long standing canard? It is worth noting that in general those of the seventeenth century tended to deprecate Aristotle (many being motivated by the neo-Platonist revival of the time) in order to enlarge their own novelty or stature. Jan Swammerdam for example consistently deprecated Aristotle's achievements. However, I cannot find anyone who actually repeats in, on a search though In fact in a late nineteenth century text I found someone who mentioned the mayfly, but correctly restricted it to that one organism. Moreover a search through several histories of biology, from Nordenskiöld to Magner, failed to find that canard. So I wonder if this is in fact something invented in the last 50 years or so. Anyone have any ideas?

At any rate, the more I read Aristotle, and the more I understand both where things stood at his time and what he actually said, I find him to be an amazing natural historian, a good observer, and generally not a bad theoretician. Sure, his theories are wrong, and his overall philosophy of teleology in biological cases (not, I hasten to add, in his physics) is unnecessary now we have teleosemantic explanations (i.e., natural selection), but he is not the moron of popular history of biology; far from it.

Funnily enough, the EMBOR author of the canard, Katrin Weigmann, is trying to make the case that science is not infallible, while ignoring the very real actual achievements of the people she denigrates. Nobody thought science was infallible anyway, but trying to make out that errors were made where they weren't doesn't give one much confidence in any subsequent argument. And of course this is another case of scientists doing bad history for [scientific] political reasons.

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Looking through Ms. Weigmann's bibliography at the end of her article the only possible source for her Aristotle claims must be Zankl H (2004) Der grosse Irrtum-Wo Wissenschaft sich tauschte. Darmstadt, Germany: Primus that is assuming she got them from a book at all. As this is a piece of popular science writing I strongly suspect that many of its Irrtumer (mistakes/ errors for those that don't read German) are based on inaccurate anecdotes. Should I manage to get my hands on Zankl's book I'll let you know but I don't intend to buy it!

I shall confess immediately that I am the current assistant editor of EMBO reports (though not at the time this article was published in 2005).

While I cannot give you greater insight into Katrin Weigmann's sources, I can tell you that we've given more recent, if brief, coverage to some of Aristotle's remarkable ideas and achievements (and errors) in taxonomy as part of this Viewpoint here (hopefully you have access):

Anyhow, I just stumbled on your blog and wanted thank you for reading EMBO reports and to say that I hope you will continue to discuss our content as and when it peaks your interest (though hopefully not just our errors!).

Kind regards,

Sam Caddick

By Samuel Caddick (not verified) on 16 Sep 2008 #permalink


Aristotle's observations, assuming he made them, may have been on individuals who had poor diet, lacking in vitamin C, leading to tooth loss throughout their lives.

What the.... ?!

Hang on: People lose teeth... It's not like Aristotle didn't know this! Examine more than one person. Use symmetry. Ask them if they've lost teeth. For somebody who can apparently so carefully examine mayflies would so badly botch identifying/counting teeth defies parody.

If he had *actually* done any inspections, he should have concluded that the numbers of teeth varies among men and women both (i.e. wisdom teeth)!. Ergo, he almost certainly did no inspection at all.

Lastly, (and maybe you're having a bad day), on what grounds are you making the Vitamin C remark? The ancient Greek diet featured olives, olives, olives, wine and olives, and guess what olives contain?

Sorry for mauling you, but...

By Lurker #753 (not verified) on 16 Sep 2008 #permalink

Fun with punctuation:

"Nordenskjöld" means "Northern Shield", while "Nördenskjold" translates into "Shield of the Nerd".

Sam, thanks for dropping in. This was not an attack upon EMBOR, but a general comment upon the way scientists (and science journalists) misuse history. It's something of a crusade of mine.

Lurker: it's easy to be wise after the event, but the fact is that Aristotle was sensitive to the sorts of variations one actually finds in the field (go look it up - tooth number is not necessarily constant) before he would make a general claim. Moreover, his functionalist perspective may have made him give more weight to the variation than others like Hippocrates did. As to diet, I am repeating Mayhew's comments. He said that women got lower quality food in the main. Hence they may have had tooth development problems. It's the kind of whiggism you show here that exhibits the problem scientists have with history.

Song: I like my version. But I'll correct it. Damn.

With Ernst Mayr [What Evolution Is] and George Gaylord Simpson ,I note as Paul Draper told me, that the weight of evidence shows no cosmic teleology. With that fact, I note the atelic argument that therefore no god has any intention and thus natural selection's bosses are other natural causes [William Provine].
I note that Weisz in "The Science of Biology" shows that any teleological process would be backwards causation while the fact is causalism is at work.

By Morgan-LynnTGr… (not verified) on 16 Sep 2008 #permalink

There's a source a lot older than 2004 (which will surely not surprise Thony). In my youth I read and took too seriously a whole lot of Bertrand Russell, and I'm pretty sure that's where I got the "Aristotle didn't count his wife's teeth" etc. I could probably dig out a citation if I were at home with my books.

But it may also be in the works of Bergen Evans, a mid-20th-century iconoclast of some worthiness but no infallibility.

In any case the idea of Aristotle as a non-observer was well established by the 1950s, and in my meager experience looked like received opinion among people who were skeptical of the ancient heavy thinkers. Skeptical, and in this case wrong.

By Porlock Junior (not verified) on 16 Sep 2008 #permalink

John, I don't know when the mayfly story started. But I have a collection of essays by Will Cuppy called "How To Become Extinct" -- the collection was published in 1941; the essays, mostly in the New Yorker, well before that -- that makes some snarky comments on the 4-legs bit. The essay is called "Aristotle, indeed!" and includes such lines as: "I don't doubt that Aristotle thought more in actual footage during his life than any other person thought in the same elapsed time of 62 years. I do say, however, that any prize he deserves for doing so should be for quantity, not quality, as a great deal of it was spinach."

Here's the most relevant part:

Take what he says about the snake's legs -- or lack of legs, rather. He says snakes have no legs because, if the had any, they would only have two or four, and that wouldn't be nearly enough. You can stay up all night figuring that one, snatch a few winks of sleep, and fly at it again the next morning. And you'll be little the wiser. All you'll be is a wreck.

How, you may wonder, did Aristotle arrive at this goofy bit of natural history? Well, he had a theory that "no sanguineous creature [by which he meant red-blooded] can move itself at more than 4 points." "Granting this", says he, and I'll grant it, merely to see what happens -- "Granting this, it is evident that sanguineous animals like snakes, whose length is out of all proportion to the rest of their dimensions, cannot possibly have limbs; for they cannot have more than four (or they would be bloodless) and of they had two or four they would be practically stationary; so slow and unprofitable would their movements be."

Honestly, if I made a practice of promulgating such drivel,m where would I be today? In Ward 8.

So, nothing specifically about mayflies, but the rest of the story is there. I wonder if Cuppy was part of an early 19th-century trend, scoffing at Aristotle, or whether he might even have started a trend.

Ian, it sounds like Cuppy had Twain-envy. But you mean early 20th, not 19th century, don't you?

On Aristotle; while it's great that his texts have survived, I find it disappointing that his illustrations (e.g. dissection drawings referred to in the animal books) did not survive the chain of copyists. It's their absence - and the study of the works mostly by philosophers (usually more or less theologians) rather than biologists - that leads to these sort of misconceptions arising (this reminds me of missionary anthropology).

By John Scanlon FCD (not verified) on 16 Sep 2008 #permalink

Oops, yeah,of course I meant early 20th, not 19th. I wrote in a hurry because it took me a while to find the book and it was my bedtime ...

Maybe this discussion is dead, but....
The motivation to post was that the remarks on Vitamin C and "assuming he made [such observations]" look like idle speculation. The analogous case that comes to mind is Darwin's did-whales-come-from-bears remark in the first edition of OoS. He wrote that line as though no available evidence bore upon the subject, whereas it actually did and he got hauled up short by those in command of it.

I studied archaeology in college (not that long ago), and in all the discussions of what is known about standards of life, diet, etc., including discussion of tooth wear/loss, I don't recall any evidence that supports what Aristotle said. There was heavy tooth wear and tooth loss, yes, but I don't recall a male/female distinction.
So, perfectly aware that you may be about to hoist me on my own evidential petard, can you show me what the basis is for saying that Aristotle was reporting accurately, when my (limited) archaeological knowledge suggests he must have been reporting hearsay?

By Lurker #753 (not verified) on 17 Sep 2008 #permalink

forelegs are homologous with the hindlegs.

Serially homologous, not homologous! :-P

(Sorry. Some people find it fun to invent terminology.)

Zankl H (2004) Der grosse Irrtum-Wo Wissenschaft sich t[ä]uschte. Darmstadt, Germany: Primus [...] Irrt[ü]mer (mistakes/ errors for those that don't read German)

Not mistakes -- errors, erroneous reasoning.

How, you may wonder, did Aristotle arrive at this goofy bit of natural history? Well, he had a theory that "no sanguineous creature [by which he meant red-blooded] can move itself at more than 4 points." "Granting this", says he, and I'll grant it, merely to see what happens -- "Granting this, it is evident that sanguineous animals like snakes, whose length is out of all proportion to the rest of their dimensions, cannot possibly have limbs; for they cannot have more than four (or they would be bloodless) and of they had two or four they would be practically stationary; so slow and unprofitable would their movements be."

That's actually correct, even though for reasons quite different from any Aristotle can have imagined.

his illustrations (e.g. dissection drawings referred to in the animal books)

<weep> <wail> <lament>

By David Marjanović (not verified) on 17 Sep 2008 #permalink

On homology, I knew that. But IIRC serial homology was invented by Owen, who defined homology in the first place, based on Goethe's serial repetition notion of the vert skeleton.

On illustrations, I too lament. If only some Greek had invented lithography...

Is it fair to say that the internet has become the Nördenskjold?

Another impressive observation from Aristotle: Tim Birkhead notes in Promiscuity that he was first to describe what we now know as sperm competition (in chickens)

People don't just LOSE teeth-- sometimes they never get them (I'm thinking unerupted wisdom teeth here). Are therre any statistics on how common this is, and whether it is more common in women than men? I'm guessing, but I suspect women's facial skeltons (incl. jaw length) are slightly smaller than men's proportional to overall body and overall head size, so it wouldn't be an UTTER surprise if they had a higher frequency of third molar noneruption. But this is just a guess.

By Allen Hazen (not verified) on 18 Sep 2008 #permalink

Not mistakes -- errors, erroneous reasoning.

David, you are in error or to put it another way you are mistaken oder auf Deutsch, du irrst dich!

Schoeffler/Weis, Deutsch-Englisch Woerterbuch, 5.Auflage, Ernst Klett Verlag, Stuttgart, 1978 p. 501

Irrtum (schuldhafter - -) error; (Missverstaendnis) mistake; (Versagen, Versehen) fault...

Leo: Irrtum

With regard to how many teeth a person may have had in life, is it apparent from the tooth sockets in human jawbones that the number of teeth does not vary between the sexes?

By grasshopper (not verified) on 19 Sep 2008 #permalink