Natural History

I’m about to quote from book that contains a description of a Japanese chin, which is called a “Japanese pug,” that some might find offensive.

Please note that I am not anti-Japanese chin.  This is a brachycephalic breed, and unlike many other breeds of this type, the Japanese chin has had this morphology for a long time.  They arrived in the West with these particular features, and among toy breeds, they haven’t changed as much as some others.

That said, this breed was not exactly well-received among male naturalists of the nineteenth century.

And the text I’m about to quote comes from a naturalist of that time period and demographic.

I quote this text for two simple reasons:

First of all, it how extreme brachycephalic dogs actually are.

And secondly, it shows the pitfalls of using morphology alone to determine taxonomic status.

The text I quote mentions an analysis by a scientist named Cope. I am assuming that this “Cope” is Edward Drinker Cope, a nineteenth century American comparative anatomist.

Cope apparently thought that the “Japanese pug” was so morphologically dstinct that we would have to call it a distinct species.

In fact, Cope thought that this animal deserved its own genus!

Cope’s classification of this animal is mentioned in The Standard Natural History, Volume 5 (1884) by Friedrich von Hellwald, an Austrian geographer and historian.

Some breeds of dogs are by many regarded as abnormalities or monstrosities, as the bulldog, pug dog, and Japanese pug, which have the bones of the muzzle defective; the turnspit, again, is remarkable for its short legs. In the Japanese pug the characters of degradation are so extensive and so numerous that, were the breed wild, it would unhesitatingly be placed in a distinct genus, and Cope has described it as such under the name of Dysodes pravus. The teeth of this pug differ from those of ordinary dogs in the constant absence of the first inferior premolar and of the last inferior true molar, the false grinders ranging in various individuals from four above and three below on each side to two above and two below, while the molars are either one above and two below, or two above and one below. The incisors, which at birth are normal, are shed at the age of six months, the last tubercular molar of the upper jaw disappears with age, and the first superior premolar is rarely present, and doubtless shed before maturity….

The hair of this variety is long and not curled, the color usually black and white, and the size that of a rather small black and tan terrier. Many examples of this singular dog have been brought to this country, and it has recently become fashionable in England to possess one of these pets, which even in Japan are said to be uncommon and expensive. Cope says of it: “It does not appear to possess the senses of sight and smell in the same degree as the species of Canis. It cannot follow its master through a crowded street, and is readily lost, even on open ground where opportunities for sight are good. As house-dogs they are cleanly, and intelligent in certain directions.” They do not learn tricks easily, but seem to understand their master’s disposition and wishes; are vivacious, and are not disinclined to bite those they do not like. The very large eyes, excessively short muzzle, and inflated forehead give this dog a look of intelligence which its habits do not bear out — it has, in fact, been degraded by an artificial life and fed upon vegetable food until it has almost ceased to be a carnivore (pg.  428-429).

Some of these “degradations” may have been the result of the predominantly rice-based diet that these dogs were fed. They may not have been fed good quality protein, which would affect mental development and the sensory abilities.

However, I don’t think that’s really what’s most interesting.

Using morphology alone, at least one well-educated comparative anatomist thought that that Japanese pugs, which we call Japanese chin, were more than their own species.

They belonged to their own genus!

In the von Hellwald text, other dog breeds are listed as distinct species, but all are listed as being members of Canis.

Today, we’d find such classification bizarre, for now it is clear enough to see that all dogs belong to same species. And they all descend from the wolf.

For a variety of reasons, domestic dogs have been able to produce a variety of bizarre phenotypes. Indeed, the skulls of domestic dogs vary more than one will find across the whole rest of the order Carnivora!

At one time, it was assumed that dogs were derived from multiple ancestral species.  It was assumed that such diversity in phenotype could only be created by crossing different species.

Today we know that domestic dogs have the wolf as their primary– and perhaps sole– ancestor. With the exception of dogs that are known hybrids, no one has yet found golden jackal or coyote genes in domestic dogs.

So in the nineteenth century, it was possible that a dog with such extremely different morphological features could be classified in such a way.

We now know that Japanese chin are fully domestic dogs in their ancestry and lineage. They readily bred with toy spaniels and pugs in Europe, and they also were crossed with pekingese dogs.

There is nothing about them that would require one to list them as a different species.

And to place them in their own genus– well– that’s quite absurd.

But at the time, it was acceptable to think of them this way.

So if morphological methodologies could lead people into such errors, we should be careful about relying upon morphology to determine taxonomy and phylogeny.

If all we have are bones or fossils, then we have to make educated guesses.

But if we have the DNA, it’s better to use molecular analyses in order to avoid such bizarre classifications.

Yes. Japanese chin are dogs.

But at one time, they were were not only their own species, they were their own genus:

Dysodes pravus.

The name means “stinking evil.”

Not a nice name for any dog.

Especially for one that was supposed to be this unique!

***

Now, I had a bit of trouble finding the actual text in which Cope made this analyais, but when I found it, it turned out that Cope came to his conclusion through the examination of eleven living specimens.  His analysis appears in The American Naturalist, Volume 15. Cope describes the unusual dentition of the final 8 specimens– one of which was half poodle!

This species of Canidae was characterized in the Proceedings of the Philadelphia Academy for 1879 (July), under the name of Dysodus pravus, and the diagnosis was based on four skulls and one skeleton. In the Naturalist, for 1879, p. 655, appeared notes on three living specimens examined by the writer in San Francisco, which confirmed the characters previously ascribed to the genus and species. Subsequently I had the opportunity of examining eight additional specimens in San Francisco, of which three were born there, and two certainly and others are probably, Japanese born. The characters of these are as follows:

No. 1. Premolars 2/2, molars 1/2; first premolar a minute cusp; two years old; Japanese.

No. 2. Premolars 3/3 ; first and second superior minute.

No. 3. Premolars 4/3; first and second superior minute cusps; first inferior do.; nine months old; American born.

Nos. 4 and 5. Exactly like number 3.

No. 6. Premolars 2/2; an old dog from Japan.

No. 7. Premolars 2/3; young; daughter of No. 6.

No. 8. One-half poodle; premolars 2/2; molars 1/2; four and a half years old.

From the above it can be seen that the absence of the first inferior premolar is constant, as is also, I may add, the absence of the last inferior true molar. In only three specimens was the first superior premolar present, and then as a cusp-like rudiment; and these are young dogs American born. The tooth is doubtless shed before maturity. Finally, even the poodle mixture did not restore the two lost inferior molars; and two superior molars are also missing, as in the typical Dysodus pravus. In all, the superior incisor teeth were present. Thus, though this species shows a remarkable tendency to shed the molar teeth with age, its normal dentition, when perfectly preserved, differs materially from that of the genus Canis.

This species has some marked peculiarities of habits. It does not appear to possess the senses of sight or smell in the same degree as the species of Canis. It cannot follow its master through a crowded street, and is readily lost, even on open ground where opportunities for sight are good. As house dogs they are cleanly, and intelligent in certain directions. They do not learn tricks easily, but seem to understand the disposition and wishes of their master very readily They are often very vivacious and energetic, and not at all indisposed to use their canine and flesh teeth on persons whom they do not especially regard (pg. 233-234).

Cope was trying to see if environmental factors had produced the unusual dention, which is why he examined the American-born dogs and the half-poodle.

He didn’t seem to understand the lack of these teeth were actually the result of extreme brachycephaly.

These dogs have these teeth, but they are not visible in the mouth.  They remain withdrawn into the gum, much like the wisdom teeth of humans.

So Hellwald’s view that the teeth were the result of evolving for a vegetarian diet isn’t even substantiated in Cope’s text.

Cope just thought that the teeth were gone, and because the teeth weren’t there, we had to be looking a different species– with its own genus.

Never mind that this “species” could have produced intergeneric hybrids with domestic dogs!