On science blogs this week: Dogs
On science blogs this week: Dogs
THE ORIGIN(S) OF DOGS. I'm not much of a dog person. Dogs are nevertheless of great interest to me, so dog people, please don't waste your time appending nasty comments to this post.
What I love about dogs is the Idea of the Dog.
Dogs exemplify a defining trait of our own species. That's the trait that got us where we are for good and ill: a passion for tinkering. Dogs are probably the earliest human invention. (If you don't count tools — and we won't count them because tools were invented by earlier hominid species, and even chimpanzees, to say nothing of birds and other non-primate creatures.)
Dogs don't exist in nature. We made them out of wolves. Exactly where this creative act took place is a matter of controversy. The current contenders are the Middle East and and Southeast Asia.
You can get a compact fill-in on this debate from a post at Dienekes' Anthropology Blog. It provides links to Dienekes Pontikos's previous dog origin discussions while also describing the latest broadside for the Asian case, just published. See also an EarthSky post by Deborah Byrd, who definitely is a dog person.
At Gene Expression, Razib Khan tackles the dog-origin question as a shirttail to his discussion of a new paper showing how the distribution of the black rat tracks patterns of human migrations (and trade). Khan speculates that a reason for the conflict over the dog center-of-origin could be this: the animal that would eventually be a dog may have been pre-adapted for domestication. So people could have turned wolves into dogs more than once and in more than one place, perhaps beginning much earlier than present archaeological evidence suggests — even as early as pre-Neolithic times. He says:
My position isn’t that modern dogs aren’t the descendants of a small ancient population which crystallized in the early Neolithic. Rather, it may be that they’re just the last in a long line of dog-human co-socialization experiments.
BAD TINKERING: THE SAD CASE OF THE BULLDOG. So, okay, there's this natural human inclination to, um, monkey around. Sometimes the consequences are good, but monkeying is is the first step toward another human tendency that is not so good, which is to tinker for the sake of tinkering and to Go Too Far. Khan has another doggy post on that topic. He considers the plight of bulldogs.
Bulldogs, like all pure breeds but more than most, have severe health problems and perpetual misery consequent on the extreme anatomical traits forced on them by standards required for the breed. Khan points out that, genetically speaking, these burdens are not the result of inbreeding per se. They come about because of pleiotropy, the fact that a particular gene often shapes more than one trait. When a breeder alters one characteristic in search of an anatomical goal, others are altered as a byproduct.
Which brings us to a different species.
THE DOMESTICATION OF SILVER FOXES. Khan doesn't mention it, but there's evidence for pre-adaptation and superb demonstrations of pleiotropy in an undeservedly obscure research project begun more than half a century ago in Russia. The project didn't involve wolves or dogs, but rather another canid, the silver fox. Back in the days, not so long ago, when we were permitted to wear fur, the silver fox was a mainstay of the Russian fur trade, and breeding them was an industry.
Dmitri K. Belyaev and colleagues were interested in the process of domestication and had access to a large number of the foxes. They began a long-term experiment in selective breeding, choosing and mating the foxes that were the most tame, the least aggressive and fearful of people. Here's a free paper describing the study from some of the Russian scientists involved recently. To date, more than 10,000 foxes have been mated, resulting in more than 50,000 pups.
After only 4 generations of selective breeding for tameness, some pups began to exhibit dog-like traits, for example tail-wagging. After 6 generations, some pups began to seek human company. After many generations of continued selective breeding of the tamest foxes, nearly all pups exhibited behavioral and physical doggy characteristics in addition to tameness. These included the ability to read human social cues and absence of seasonal breeding, along with floppy ears, curly tails, and other "juvenile" traits. The researchers were breeding for none of these characteristics; their only selection criterion was tameness. Pleiotropy.
This research also seems to me a demonstration of the sort of pre-adaptation that Khan is talking about. Some species, it appears, can be domesticated relatively quickly and easily. That's because of characteristics they already possess. Wolf social organization, for instance. Wolves live in packs with a pack leader, predisposing them to adapt to living in human social groups and attaching themselves to a human leader.
SILVER FOX THE BLOGGER. Mention of the silver fox research permits me a seamless transition from behavioral genetics to an entirely different field of science, geology. Meet another Silver Fox, this one human, a pseudonymous minerals exploration geologist who works mostly in the western US and is a long-time blogger. I assume she's a fine geologist, but her blog, called Looking for Detachment (very classy, with tag line from the French Christian mystic and philosopher Simone Weil), makes it quite clear that she's a fine photographer too.
Sand Mountain in a windstorm. Photo by Silver Fox
As you can see if you check out the other photos, Sand Mountain is a dune with many faces. But it also is a booming or singing dune. Silver Fox links to a post by Jennifer Ouellette defining same at Cocktail Party Physics and explaining how and why some dunes sing. What are singing sands? Ouellette says:
Marco Polo did claim to have journeyed across the Gobi Desert, and said the dunes filled the air “with the sounds of all kinds of musical instruments, and also of drums and the clash of arms.”
That makes Silver Fox's Sand Mountain quite special. Ouellette says there are only about 30 singing sand dunes on this world, although there are possibly many more on Mars.
As it happens, this is Sand Dune Week among blogging geologists, and Silver Fox provides a list of links to other dune posts. Unless you're a geologist, you wouldn't think there were so many kinds of dunes — and so many things to say about them,
One of the best things about blogs is that they urge you to pursue links aimlessly in hopes of discovering gems, which you often do. It's one of the more productive forms of Writing Avoidance.