I think the other sheep is a Stone sheep.
Posts Tagged ‘Dall sheep’
Posted in domestic animals, evolution, Uncategorized, wildlife, tagged aoudad, argali, Barbary sheep, bighorn sheep, Dall sheep, domestic sheep, European mouflon, mouflon, sheep, snow sheep, urial on February 24, 2010 | 10 Comments »
I got interested in sheep because of a disagreement I had with a particular sermon that I heard as a young boy. The elderly Methodist minister said that the reason why sheep and lambs were so revered in the Bible was because they had no wild ancestors. The sheep exists solely as a domestic animal for man to use, just as man exists solely for God’s purposes.
Of course, I was skeptical. I had never heard of a domestic species that had no wild variant. Animals didn’t just appear.
So I began to research it. I didn’t have the internet, but I did have some old encyclopedias and some National Geographic magazines.
And I thought I had seen a show about wild sheep on PBS. It was Marty Stouffer’s Wild America series, which always popularized the combat of the bighorn rams in its opening sequence. I do remember watching this particular sequence from the series:
(When the Marty Stouffer scandal broke, I refused to believe it. I still have a bit of a soft spot for the show.)
However, no wild sheep could be found in my part of the country, so I really couldn’t point the bighorns as evidence for a wild form of sheep. I later learned that these wild sheep were a different species from domestic sheep, and that North America actually has two species of wild sheep. The bighorns ranged from the mountains of southern British Columbia through to the Mexican states of Chihuahua, Sonora, and Baja California.
Then there are the Dall or thinhorn sheep of northwestern Canada and Alaska. I was impressed with their white color. However, I found out that these white Dall sheep are found only in the northernmost part of their range. In the more southerly parts of their range, the animals are grayish brown. These are called Stone sheep. In between the white and grayish brown populations, there are gray and white ones called Fannin’s sheep. At one time, I remember reading about these sheep as separate species. However, they may not even be clear subspecies. They may be nothing more than color phases of the same animal.
This confusing taxonomy is not unique to this species of North America sheep, as I would later find out.
But I knew that none of these North American sheep could be the ancestors of domestic sheep.
It wasn’t until I saw a particular program on PBS series Nature that I realized what a wild sheep was.
This particular program was about the domestication of sheep and the development of various forms of sheep dog.
The opening sequence featured a wolf hunting a strange-looking animal, which the narrator (George Page) identified as a mouflon. It was a contrived sequence, and neither wolf nor mouflon were ever on screen together.
The sequence was meant to show the wolf in its wild form and the sheep in its wild form. The wolves hunted the mouflon for food, and the mouflon did everything possible to avoid the wolves.
The point of the sequence was to introduce how sheep dogs worked. In the case of the livestock guardian dogs, the sheep and dogs were nothing at all like the wolves and the mouflon. They were social partners.
In the case of the actual herding dogs, the dogs exhibited predatory behavior, but it was strictly controlled. The dogs, which were all black and white border collies, didn’t bite the sheep at all.
However, there was an exception that was shown. On the St. Kilda Archipelago, there existed a particularly wild sheep that had not been bred to flock. Because these sheep would just scatter, the shepherds had use their collies very differently. The collies were used to catch the sheep and hold them, which was not all that different from the way that the wolves were hunting the mouflon.
I now realized that the wild sheep was a mouflon.
But was it really the wild ancestor of the domestic sheep?
Well, it turns out that the European mouflon is actually the dingo among sheep. Just as dingoes descended from fully domesticated dogs, mouflon descend from some population of wild Asian sheep. These sheep went wild after been introduced to Europe. They first appeared in Corsica and Sardinia 7,000 years ago, and from there, they began to appear on the European mainland. For a long time, it was believed that the European mouflon was the ancestor of domestic sheep.
But it is actually the other way around. Domestic sheep are the ancestors of the European mouflon.
That is nice to know, but it still doesn’t tell us what the wild ancestor was.
There are some populations of mouflon in Iran. However, no one has found a genetic connection between these mouflon and the domestic sheep.
To make matters even less clear, it turns out that Asian domestic sheep and European domestic sheep have a considerable amount of genetic divergence. That means that domestic sheep could come from two unknown subspecies of wild sheep. It could also mean that domestic sheep are a hodgepodge of various mouflon subspecies, including some unknown or extinct forms. It could also mean that domestic sheep descend from at least one unknown species that is closely related to the wild mouflon of Iran.
The argali, the urial, and the snow sheep of Siberia are all relatives of the wild sheep. Although the urial is considered the same species as the various forms of mouflon, it has a different chromosome number. The argali and the snow sheep also have a different number of chromosomes from the mouflon and domestic sheep. In fact, it is sometimes suggested that the snow sheep are the same species as the Dall or thinhorn sheep. (In fact, it is sometimes suggested that bighorns and Dall sheep are the same species! I’m not going that far.)
My question isn’t really answered yet. All we know is that domestic sheep are closely related to some Iranian mouflon. However, these Iranian mouflon aren’t the ancestor. And domestic sheep are not derived from the European mouflon. The European mouflon is a feral sheep.
So maybe the old sermon was right.
But I doubt it.
My bet is that the European mouflon and the domestic sheep are derived from some unknown subspecies of Asian mouflon that has either gone extinct or has been totally absorbed into the domestic sheep. In fact, I wouldn’t be surprised if two of these unknown subspecies were totally absorbed into the domesticated form.
Whatever the wild species from which domestic sheep descend, the fact that the sheep is the second animal that man domesticated has always struck me as a little strange.
It seems to me that domesticating the sheep would be much harder than domesticating other animals. All subspecies of mouflon prefer alpine habitats, so if humans were going to domesticate them, our ancestors were going to have to do a lot of work. Wild sheep have an instinct to run for higher ground when frightened, and because none of these animals flocked, even hunting them for food sounds like a very difficult process. Hunting wild sheep with rifles today is not for the uninitiated. I can only imagine what people living 11,000 years ago would have had to do to catch these animals.
However, these assumptions might be false.
It is often suggested that dogs were necessary for the domestication of the sheep. I do see some merit in this theory. After all, dogs can run uphill faster than we can, and the dogs could be used to drive the sheep into traps or ambushes.
It is also possible that man was able to gain the trust of some bands of wild sheep that were attracted by the salts in our urine. These sheep grew to trust people, who then began to follow the sheep as they traveled up and down the mountains. In the spring, the sheep would go into the alpine meadows in search of the fresh green grass that grow there, but in the winter, the sheep would have to go back down into lower elevations, where the snow did not cover up so much of the forage. Some people would keep the wild predators off the sheep, and the sheep that learned to tolerate people were better able to survive.
This scenario makes some sense, simply because the original sheep cultures were nomadic pastoralists. Pastoralists live very much like hunter-gatherers. However, they have a constant food source in the form of the animals they are herding. Unlike people who are reliant upon grain agriculture, pastoralists are not bound to a single piece of land. They simply move their flocks to the better pastures, which means that these people developed a migratory lifestyle. Pastoralist cultures still exist today, but it is very likely that the first people to keep sheep were entirely caught up in this lifestyle.
There is a certain amount of freedom that goes with this life. After all, even we modern Americans still romanticize the freedom of that the cowboys of the Old West must have experienced. We even romanticize the various native peoples of the Great Plains who were in a sort of proto-pastoralist relationship with the plains bison. Their lives were without fences. Their lives were tied up in the need for fresh grass and water, for their lives were ultimately tied up in the animals.
This is the freedom that these first sheep-keeping pastoralists would have experienced. Unlike hunter-gatherers who had to be experts in bringing down prey or collecting berries, these people were much more secure. Their main food source was always grazing but a few yards from them. It was combination the security of agriculture and the freedom of the nomad.
Now, I should also note here than no wild sheep has wool like a domestic sheep, and none of these early domestic sheep had this type of wool either. The reason for this is pretty clear.
Have you ever seen a wild poodle?
Poodle hair and sheep wool are not shed. Both grow continuously. A wild animal that has hair that grows continuously is at a disadvantage. Unshorn wool sheep are very uncomfortable with such long wool, and they are also prone to infections and parasites. Just as poodle hair must be trimmed, wool sheep must be shorn.
Because none of the original sheep had wool to shear, the sheep were kept for their meat and hides. They were also kept for their milk. The first domestic animal milk that humans ever tasted was from a sheep.
Now we don’t often think of sheep as dairy animals, but there are still dairy sheep herds in the United States.
As the first hoof stock that people were keeping, sheep provided a constant source of meat, hides (which could be used to make leather), and milk. Although we could eat dogs and make something out of their pelts, dogs were far too useful for other purposes. Sheep really can’t guard settlements or assist in the hunt. They also produced more meat than dogs ever could.
Man, sheep, and dogs were now joined together, and soon other creatures were to join us. The goat was domesticated not long after the sheep. Then came the pig and then the cow.
Man was figuring out how to tame animals and selectively breed them for his own purposes. The first selective breeding was definitely haphazard. Indeed, the first modern selective breeding did not occur until the middle of the eighteenth century.
But we never would have gotten to that point if we had not started somewhere.
And we started with the wild ancestor the domestic sheep. Whatever that was.
I should finally point out that one animal called a wild sheep that could never be considered an ancestor of the domestic sheep is the aoudad or Barbary sheep. It looks superficially like a bighorn sheep with very strangely shaped horns. However, it is not a true sheep at all. It is in its own genus (Ammotragus), while all true sheep are in the genus Ovis.
See earlier post: