Jim Moore's "AAT Sink or Swim?" Web Site
AAT Claims and Facts: Tears & the AAH


The AAH argument for tears has always been, at best, a peripheral one. Hardy never even mentioned it and Morgan's early attention to it perhaps was misguided. She all but withdrew her support for the idea in her latest book.

Moore does make some, rather slight, kind of concession to this fact early in the page, writing "some proponents of the AAT have moved away from the idea that the aquatic phase was in a salt water environment" but, nonetheless goes on to make the unsupported claim that "but most still claim humans' sweat and tears systems evolved as an aquatic feature, as an excretory system for salt." In fact he all but ignores his own admission that this is really a non-topic because he goes onto to write nearly 5,000 words and 84 paragraphs on the subject. This is roughly twice as much as two of the major pillars of the AAH were afforded. Moore wrote about 2,000 words and 30 paragraphs on hairlessness; about 3,000 words and 33 paragraphs on fat (actually only about 1,800 words and 15 paragraphs if you take away the copious quotations from Pond); and 0 on wading bipedalism.

On this page, Moore makes two major claims about the AAH on the subject of tears. One is wrong in its factual basis as it does not take into account Morgan's clear renouncement of the idea in 1997 (see point 2) and one is clearly correct, although Morgan has clearly backed away from her earlier position on this too (point 1).

Moore is correct to argue that the evidence in tears does not appear to support the AAH. However, as Morgan has pretty much conceded that herself in her last book, and most other proponents of the theory have never claimed tears did support there case, it is rather a mute point.

Perhaps the most significant aspect of this page is the fact that Moore continues to maintain it as a major part of his AAH refutation, seven years after the fact that Morgan all but withdrew her support for the arguments it contains.

Moore's initial point on this page seems to be an attempt to ridicule supporters of the hypothesis, claiming that they still consider salt tears would have evolved as an excretory mechanism even if they lived in fresh water habitats. Without a citation to back this claim up, however, this really should be seen as just gossip.

Tears and the AAT
Moore starts with a quote from William Frey in which he basically says that he thinks only humans (my emphasis) have ever been observed to exhibit emotional tears. Moore probably wants to draw attention to the fact that Frey doesn't mention aquatic mammals here, only humans. Morgan quotes the same authority in her books (Moore even gives a reference to one such citation, but not to any of her claims) on this subject but Moore suggests that her citing of his work is misleading. He writes "Dr. Frey has done studies of emotional tears and Morgan feels support they her theory. Why she feels they support her is rather inexplicable, once you look at the evidence, including the evidence in the book which Morgan cites."

Moore says the two AAH claims here are that:

1) "this particular AAT idea, initially promoted by Morgan and since repeated many times by AATers, is that emotional tears are seen only in humans and aquatic animals"

2) tears "...(and our sweat glands) evolved as system to excrete salt."
 and he deals with the two claims separately on the page

But before we follow his arguments, perhaps we should question his starting point. Are these actually the claims made by Morgan or other AAH proponents?

In 'Scars of Evolution' Morgan introduces the idea of weeping salt tears thus: "Marine reptiles, and some marine mammals, encountering the same problem [the need to excrete excess salt], deal with it not by nasal dripping [as with marine birds] but by weeping salt tears, for example, marine iguanas and turtles, marine crocodiles, sea snakes, seals and sea otters." Morgan (1990:96.) No mention of emotional tears there but on the next page she does imply it when she wrote "The connection between weeping to excrete salt and weeping from emotion is not easy to understand, but it an ancient one. There are accounts of copious nasal dripping in seagulls in situations of aggressive confrontation, and weeping in sea otters when distressed or frustrated. The stimulating hormone prolactin, which appears to be involved in human weeping is released in response to emotional stress"  (Morgan 1990:97).
In her latest book, Morgan clearly backs away from this salt tears argument and it could be argued that Moore should therefore have withdrawn it too. However Morgan did write "But humans also weep tears which have nothing to do with local irritation of the eyeball. Darwin called them, rather picturesquely, 'psychic' tears. A more neutral term would be simply 'non-reflex' or 'emotional' or 'non-irritant', and it seemed to me that they were not without analogues in the animal world." (Morgan 1997:103.) She quotes from Schmidt-Nielsen's (1959) paper that, like marine birds that excrete salt from nasal glands "there are similar salt-excreting organs in marine crocodiles, marine iguanas, sea snakes and marine turtles. In all of these cases the brine is excreted from the eyes in the form of salt tears. If the creatures are induced to ingest salt water, the tears are activated." Morgan (1997:104.)
So, perhaps we should give Moore the benefit of the doubt here. Morgan does seem to still be arguing that there is something rather unique about human tears which tends to be shared by more aquatic animals.

The second claim, that tears evolved as a system to excrete excess salt, is less ambiguous.
Morgan clearly withdrew her support for that hypothesis in 1997. She wrote "I made the suggestion [In Scars..] that both the tears and the sweat might have been at one time more concentrated than they are now, and evolved originally for the excretion of salt. I was almost certainly wrong about that..." Morgan (1997:102). And "On balance, then, I am inclined to concede that the excretory hypothesis of tears was misconceived." (Morgan 1997:108). She concludes "Despite the lump in the throat, the original AAT theory of tears has flaws in it. If there were any other theory available that had no flaws in it it, then that would settle the matter" Morgan (1997:108.)
Moore's site was last updated early 2004 but he has not yet amended this page accordingly. Instead it remains, at the time of writing (March 21st 2004) seven years after Morgan published those statements, as a critical indictment on her work and the AAH itself.

Do animals shed emotional tears?
Moore begins this section by drawing upon Frey's Chapter 14, basically to show that Morgan was economical with the facts that she chose to report in her 'Scars of Evolution' account.
Specifically, Moore claims that Morgan omitted dogs, wolves, lab rats and gorillas from her citation. It's true that she did specifically list certain aquatic animals, which Frey referred to, without mentioning the others and this might be interpreted as being somewhat economical with the truth. but it should be noted that her point was made before the Frey reference.
However, this is impossible to defend. It does taint her work with the feeling that on this occasion she valued getting over her argument more than the accuracy of the content she was using to back that argument up.
I think, however, that this was an isolated case of misrepresentation. It's a great pity that she did so but it does not make all of her ideas wrong and, should, at least, be judged alongside some of the misrepresentations Moore has made himself on his web site.

Moore summarises the section thus: "So we can see that there is every bit as much, and as little, evidence for non-aquatic animals shedding emotional tears as there is for aquatic animals. This is contrary to Morgan's claims in print, as well as the claims Morgan and others have made repeatedly in the sci.anthropology.paleo newsgroup and other online forums." and it appears he may be right.
However, for many proponents of some kind of AAH this is no problem to the hypothesis as a whole.

The excretory abilities of the lacrimal (tear) glands
The second part of this web page is almost irrelevant, since Morgan has clearly withdrawn her support for the idea that salt tears in humans could be a remnant of salt excretion from an earlier aquatic phase.

However, for completion's sake, Moore's criticisms will nevertheless be evaluated.

Moore introduces the subject by claiming that Morgan's understanding of classification of tears into two  distinct types was confused. She claimed that the two types were 'psychic' or emotional tears and 'reflex' tears whereas, actually, the two types are 'basal' and 'reflex' tears. Apparently 'psychogenic' tears are classified under the 'reflex' type. Perhaps Morgan did get the minutia of the  taxonomy wrong but the important question remains: Is there any difference between the composition of 'psychogenic' tears and the composition of other types of reflex tears? It was that difference that Morgan was arguing might provide a clue to a more aquatic ancestry in humans. And it was that difference which Morgan claimed Frey demonstrated.

Moore's first point argues that as human lacrimal glands cannot actively excrete sodium today it is unparsimonious that they should have evolved this ability in the past for a period and then lost that ability again. Nobody could argue with that.

Secretions in tears
In the next section Moore goes on to provide several quotes which show that human lacrimal glands are capable of active excretion of potassium (4x serum levels) and manganese (30x). There's also a quote from Frey showing no significant difference between 'phsychogenic' and other 'reflex' tears in mangansese levels but nothing regarding the other ions.

The next section, entitled 'innervation of tear secretion', argues that the active excretion of potassium by human lacrimal glands actually more closely parallels terrestrial animals such as ostriches

Moore finishes the page with a section on homeostasis where he outlines that the main principle of salt excretion is that a hypertonic solution has to be generated for it to work. He makes some good points, for example, arguing that the main organ of homeostasis is the kidney and this organ has developed further in mammals than other animals. He goes to great lengths to argue that as human tears and sweat cannot do not have this property it cannot be a plausible mechanism for salt excretion.
He ends by writing "By the way, all this info was available long before even Hardy wrote up his AAT paper; even longer before Morgan did her first book on the subject. Was Morgan aware of it? I got the reference to Weiner and Hellman's research from her; she quoted them. So she had the info in her hand that proved her contention to be wrong even as she wrote it up." This is a rather disingenuous point as Morgan made it clear that she was arguing that the use of lacrimal glands for some types of excretion today may have been indicative of a slightly different use in the past.

Moore ends the page with several references emphasising the use of kidneys in marine mammals in osmoregulation.
It should be noted that, once again, the comparisons that matter should be with chimpanzees and gorillas and not with seals and dolphins. If human kidneys turned out to have a better excretory function than our nearest ape ancestors then that should be an observation which is explicable by some parsimonious storyline. If their function was not significantly different it would suggest that there is really nothing to explain.

Moore makes a rather good case that as the human lacrimal glands are not capable of the excretion of sodium then it is rather unparsimonious to suggest that they would have evolved the ability to do so for a period of our evolution only to revert back again afterwards. He also makes some very good points that even marine mammals which, like desert animals, are most concerned with salt excretion have evolved very efficient lobulated kidneys, to perform this excretion, and not done so through either sweating or the shedding of tears.
These would be winning arguments in this debate if Morgan had not already conceded to them in 1997.


Denton, Derek; Weisinger, R; Mundy, NI; Wickings, E J; Dixson, A; Moisson, P; Pingard, AM; Shade, R; Carey, D; Ardaillou, R; Paillard, F; Chapman, J; Thillet, J; Michel, J B (1995).

Morgan, Elaine (1990). The Scars of Evolution. Oxford University Press (Oxford)

Morgan, Elaine (1997). The Aquatic Ape Hypothesis. Souvenir Press (London)

Schmidt-Neilsen, Kurt (1959) Salt Glands, Scientific American, 200 (1), 109-116.

 William H. Frey and Langseth, Muriel  (1985): Crying: The Mystery of Tears   Minneapolis: Winston Press.