email - May 2014

Non-mammalian Milk

John J. Emerson claims some non-mammals produce milk.

Teb ran across an interesting website, and sent us this email telling us about it.

Subject Fish milk???


I am a little frustrated here. Whilst you publish many seemingly incontrovertible arguments, I can always find something on the internet which seems to invalidate (some of) your posits.

A case in point is your assertion that "lizards did not grow breasts", which at first I thought was gospel. The problem is, I think I have found cases of lactating lizards and "milk"-bearing fish ( Surely it is not too far-fetched to think that a lactating lizard might grow (evolve?!) breasts?

The thing is, I am looking to distil the argument against the theory of macro evolution down to a certain number of incontrovertible statements, as evolutionists will latch onto the slightest doubt or misstatement and play it for all its worth.

I hope you can shed some light on this.

Kind regards,


The link he sent us goes to a website posted by John J. Emerson. Emerson claims that some birds, fish, and lizards produce milk. He writes,

It’s moderately well known that several families of birds (pigeons and doves, flamingos, and penguins) secrete a kind of milk (called “crop milk”, though penguins don’t have crops) for their young. This is real milk, secreted by a special gland – not regurgitated, half-digested food from the parent’s stomach. (Regurgitators put their bills into the chick’s mouth to deliver food, whereas in milk-providing species the chicks put their bills inside the parent’s mouth to nurse.) The three families evolved this capacity independently, for three different reasons. With penguins it seems to be an emergency food substitute in case the feeding parent (usually the female) doesn’t return to the nesting parent in time. With flamingos it’s apparently because the chicks aren’t able to handle normal food, and perhaps because the flamingo’s bill makes the regurgitation method awkward.  In the case of pigeons, it allows them to raise several small broods per season (only one or two eggs each), since their well-fed squabs grow extraordinarily quickly. (This is probably also why squabs are so fat, juicy and tasty.)

It's less well known that at least one species of fish, the discusfish, feeds its young with a secretion that might as well be called milk. (Mammary glands are skin glands too, in the big picture of things). The tiny fry live off their egg-sacs for several days, and then migrate and attach themselves to one of the parents, where they feed off the fish-milk.

The capacity to produce milk is thought to trace back to the therapsids -- Triassic links between reptiles and the mammals and birds. (The discus-fish are [a] different, unrelated story.) But regardless of everything, mammals will continue to be called mammals, and pigeons ain't mammals. Don't let your biology teacher fool you with a trick question. 1

Let’s address his claims one at a time. First, let’s talk about birds.

Bird Milk

It is commonly known that baby birds are typically fed by one parent or another. That parent leaves the nest to eat food, then returns and vomits the half-digested food into the open mouths of the newly hatched baby birds. Yes, it’s gross—but that’s why kids remember it.

From an evolutionary perspective, this seems hard to understand. How does a bird know to feed its babies this way? Maybe it remembers being fed this way when it was a baby. But how did its parent know to do this? Did its parent accidentally vomit into its mouth? If this accident didn’t happen, then the baby bird would have starved to death, and not remembered being saved by its parent so it could save its offspring the same way. That doesn’t seem to be a plausible scenario for how such a strange behavior would evolve accidentally.

Birds seem to be instinctively programmed to feed their chicks this way. This kind of programming depends upon the existence of a programmer; but students aren’t allowed to consider that possibility.

Unlike other birds, pigeons feed their young with “crop milk,” just as Emmerson says—but he doesn’t quite tell the whole story.

Crop milk bears little resemblance to mammalian milk, the former being a semi-solid substance somewhat like pale yellow cottage cheese. It is extremely high in protein and fat, containing higher levels than cow or human milk. It has also been shown to contain anti-oxidants and immune-enhancing factors. Like mammalian milk, crop milk contains IgA antibodies. It also contains some bacteria. Unlike mammalian milk, which is an emulsion, pigeon crop milk consists of a suspension of protein rich and fat rich cells that proliferate and detach from the lining of the crop. In pigeons and flamingoes, both the male and female adult produce crop milk and share in the feeding and care of the young. 2

So, the “milk” produced by pigeons isn’t really milk. It isn’t produced by mammary glands. It is just called milk because it nourishes infants. The false notion that pigeons produce milk is a result of confusing terminology.

But since we are on the subject, here’s something to ponder. If pigeons and robins evolved from a common ancestor, why don’t robins produce crop milk? Are pigeons more closely related to flamingos than they are to robins because pigeons and flamingos had a common ancestor that produced crop milk, but robins didn’t? (This is the kind of subjective analysis that cladistics is based upon. That is, a scientist doing the analysis has to decide, “Which characteristic is most important when constructing an evolutionary tree—crop milk or body style?”) Did the mythical ancient ancestral bird produce crop milk, but nearly all modern birds lose that functionality through devolution? If they did lose that functionality, what survival disadvantage was there to producing crop milk? These are all philosophical questions, not scientific questions, because they can’t be answered by a laboratory experiment. The answers are just speculative opinion—not science.

Emerson’s explanations for why penguins, flamingos, and pigeons independently evolved different kinds of “milk” are simply speculative philosophical stories, not scientific facts.

In summary, “bird milk” is not really milk. It doesn’t prove that birds evolved mammary glands; but it does raise some questions that evolutionists can’t answer.

Fish Milk

Emerson’s page has four links to Discus Milk pages. Two of the links are broken, and the third one goes to a page written in Romanian.

The only useful link on Emerson’s page is It is a personal page posted in 2001 by Sam Chng. His page is an excellent example of what real science is (or used to be). He has posted a series of photographs documenting the breeding of his pet discus fish, with dated comments describing what happened each day. These are real, scientific observations—not philosophical speculation.

Like crop milk, the discus “milk” isn’t really milk. It is more like mucus.

[August] 14th [2001] - Discus Milk Feeding:: It was cool that they hatched. Today they were starting to feed on the parent's mucus. It's called Discus milk. Hehe... It has the nourishment needed by the fries to grow quickly. The parents take turns to feed the young. To do that they have to transfer the fries across to each other. In order to transfer, they make a graceful turn away from the other parent fish. The fries would always go to the nearest body they can feed on. You can then see the fries hurrying to the other parent. So cute! 3

Again, the “milk” isn’t milk. And, again, it raises interesting questions about instinctive behavior. How do the fish know to transfer the fries from one to the other? Does that happen by accident? or are they programmed to do that?

Reptile Milk

Emerson quotes three links about Therapsids, the so-called mammal-like reptiles. Here is the first.

“Lactation appears to be an ancient reproductive trait that predates the origin of mammals. ….. Mammary patch secretions were co-opted to provide nutrients to hatchlings, but some constituents including lactose may have been secreted by ancestral apocrine-like glands in early synapsids. Advanced Triassic therapsids, such as cynodonts, almost certainly secreted complex, nutrient-rich milk, allowing a progressive decline in egg size and an increasingly altricial state of the young at hatching. This is indicated by the very small body size, presence of epipubic bones, and limited tooth replacement in advanced cynodonts and early mammaliaforms. Nipples that arose from the mammary patch rendered mammary hairs obsolete, while placental structures have allowed lactation to be truncated in living eutherians.”

The link is not very helpful because it goes to a Dutch portal called Kluwer. Unfortunately, you have to know enough Dutch to subscribe to it in order to read the articles. It’s been about 30 years since I worked in the Netherlands, so my Dutch is pretty rusty; but it seems to me to be a collection of legal, financial, and governmental articles, not biology. So, the quotation of a biology article written in English attributed to this website is surprising, to say the least.

Here’s the second link:

“The secretion of nutrient rich milk probably began in therapsids, such as cynodonts”:

Like the previous link, this link goes to a home page of a journal. In this case, it is the home page of The International Journal of Developmental Biology. You have to subscribe to it to read the article.

The third link goes to an obsolete web page.

Therapsids as a missing link between reptiles and mammals:

Because the links on Emerson’s page were not helpful, we did our own literature search. Our search of the professional literature for therapsids turned up little more information about therapsids than a search for scientific articles on Bigfoot because there is so little evidence for either one. Both creatures are based on the assumption that there must be missing links (between reptiles and mammals in one case, and apes and man in the other).

The Missing Reptile/Mammal Link

Evolutionists believe that reptiles evolved into mammals at a certain time in their mythological evolutionary history, and looked for a missing link in rocks they believe to be that old. In those rocks they found some teeth that look like the ones from saber-toothed cats (mammals) found in the La Brea Tar Pits, but could not have come from a mammal because mammals had not evolved yet (according to their belief). Therefore, they “must” have come from reptiles.

Furthermore, there were some partial skulls which had jaw bones that looked somewhat like the bones in mammalian ears, “proving” that mammalian ears evolved from reptile jaws. The official tall tail about therapsids can be read in Wikipedia, 4 so we won’t bother to repeat it here.

Since mammal-like reptiles supposedly went extinct 100 million years ago, one might wonder, “How do they know they gave milk?” Nobody has ever seen one nurse her young. Nobody has ever found a mummified one with breasts. Our depiction of Boobzilla in our award-losing video 5 is simply an artist’s depiction.

Seriously, how do they “know” therapsids evolved into mammals? Here’s what the peer-reviewed scientific literature says:

Over time, therapsids show an increasing development of mammalian characters. These include the evolution of the mammalian middle ear, a bony secondary palate, and a mammalian “phalangeal formula” (the number of phalangeal bones in each digit). 6

The phalangeal bones are the bones in your fingers and toes. The reason you can bend your fingers is because there isn’t just one bone in your finger, there are three obvious ones, and a tiny fourth one on the tip of each finger, except the thumb.

But it isn’t just the number of finger and toe bones that “prove” these reptiles were evolving into mammals! Oh, no! They can tell they were starting to give milk because of their teeth and ears! Just three years ago we read this in a respected scientific journal:

Editor's summary
The lower jaw of reptiles is made up of several bones. In mammals, however, it consists of just one, the tooth-bearing dentary. Most of the rest have become the ossicles that transmit sound through the middle ear. This transformation is an iconic example of evolutionary change, but direct fossil evidence of the transition has been hard to find. That's why a fossil described by Jin et al. is so important. It is from a triconodont (a type of extinct mammal) from the Cretaceous period in China. In it, the lower-jaw elements have started to resemble middle-ear ossicles, but are still joined to the lower jaw by a sliver of ossified cartilage. This element, Meckel's cartilage, is an important part of the inner surface of the lower jaw; the new fossil shows that it was a vital piece in the evolutionary jigsaw that led to the formation of the mammalian middle ear. 7

They “know” therapsids evolved mammary glands by studying their teeth, their mouths, their fingers and toes, and because their jaw bones became their ear bones. We know—it’s udderly ridiculous to infer mammary glands from jaw bones that look like ear bones, which is why I wrote the song, “I Heard it Through My Jaw Bones” 8 two years ago.

In our search of the professional literature, we came across this paragraph:

Studies of fossil vertebrates belonging to the group Synapsida are central to understanding mammalian origins. Synapsida includes mammals and is one of the two major clades of amniotes (all fully terrestrial vertebrates). The other is Reptilia, which includes modern turtles, snakes, lizards, crocodiles, and birds. The therapsids, one major group of nonmammalian synapsids (historically but erroneously known as “mammal-like reptiles”) have been particularly important to understanding the acquisition of mammalian characteristics. One of the key features within the evolutionary history of synapsids is the morphological differentation [sic] of their dentition (teeth) over time. 9

Although we agree that therapsids are erroneously called “mammal-like reptiles,” we would like to know why Fröbisch admits it. We could not find the basis for his statement.

The concept of mammal-like reptiles is simply a result of the belief that there must be some missing link between reptiles and mammals. The “evidence” for their existence is that some skulls (which came from an extinct species that presumably was a reptile because mammals had not evolved yet) have teeth that look more like mammalian teeth than reptilian teeth, and they have jaw bones that look like ear bones, and pieces of fingers that look like they came from a mammal. They never found Boobzilla’s bra, or any other evidence that she nursed her reptilian offspring.

Remember, Teb said,

The thing is, I am looking to distil the argument against the theory of macro evolution down to a certain number of incontrovertible statements, as evolutionists will latch onto the slightest doubt or misstatement and play it for all its worth.

Unfortunately, Teb will never find these incontrovertible statements because evolutionists will controvert them no matter how incontrovertible they are. They will claim that birds, fish, and extinct lizards give milk, even though they don’t.

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6 Jörg Fröbisch, Science, 25 March 2011, “On Dental Occlusion and Saber Teeth”, pp. 1525-1528,
7 Jin Meng, Yuanqing Wang & Chuankui Li, Nature, 14 April 2011, “Transitional mammalian middle ear from a new Cretaceous Jehol eutriconodont”,
8 Disclosure, April 2012, “I Heard it Through My Jaw Bones”,
9 Jörg Fröbisch, Science, 25 March 2011, “On Dental Occlusion and Saber Teeth”, pp. 1525-1528,