In this month’s Science magazine, on page 1213, there is a short piece under the heading of In Other Journals.
I share it with you.
Canine Behavior Friends from the start
By Sacha Vignieri.
The closest relative to dogs, “man’s best friend,” is the wolf, a wily predator that generally avoids human interaction. For decades, researchers and dog owners have wondered how the leap to domestication occurred.
The main hypothesis invoked very early selection for wolves that “liked”—or least tolerated—humans, and the connection strengthened from there.
However, there is still some debate about whether the degree to which dogs interact and communicate with humans is a learned trait.
Two recent studies appear to close the book on this learning hypothesis. Bray et al. looked at about 400 puppies and found that at this young age and without much human interaction, they were adept at following human gestures and positively responded to high-pitched “puppy talk.” Further, there was variation in these responses with an association between relatedness and social communication skills, which supports a genetic driver.
Salomons et al. compared dog and wolf puppies and found no difference in general cognitive responses, but much greater responsiveness to human gestures and eye contact, in dog puppies. Importantly, this happened even though the dog pups had received less actual human interaction than did the wolf pups.
These studies confirm that dogs’ interest in communication with humans is an evolved trait unique to their lineage.
Curr. Biol.31, 3132, 3137 (2021).
That is fascinating. Dogs have evolved this trait on their own, so to speak. It further underlines the precious nature of the relationship between dogs and humans.
Dogs’ noses just got a bit more amazing. Not only are they up to 100 million times more sensitive than ours, they can sense weak thermal radiation—the body heat of mammalian prey, a new study reveals. The find helps explain how canines with impaired sight, hearing, or smell can still hunt successfully.
“It’s a fascinating discovery,” says Marc Bekoff, an ethologist, expert on canine sniffing, and professor emeritus at the University of Colorado, Boulder, who was not involved in the study. “[It] provides yet another window into the sensory worlds of dogs’ highly evolved cold noses.”
The ability to sense weak, radiating heat is known in only a handful of animals: black fire beetles, certain snakes, and one species of mammal, the common vampire bat, all of which use it to hunt prey.
Most mammals have naked, smooth skin on the tips of their noses around the nostrils, an area called the rhinarium. But dogs’ rhinaria are moist, colder than the ambient temperature, and richly endowed with nerves—all of which suggests an ability to detect not just smell, but heat.
To test the idea, researchers at Lund University and Eötvös Loránd University trained three pet dogs to choose between a warm (31°C) and an ambient-temperature object, each placed 1.6 meters away. The dogs weren’t able to see or smell the difference between these objects. (Scientists could only detect the difference by touching the surfaces.) After training, the dogs were tested on their skill in double-blind experiments; all three successfully detected the objects emitting weak thermal radiation, the scientists reveal today in Scientific Reports.
Next, the researchers scanned the brains of 13 pet dogs of various breeds in a functional magnetic resonance imaging scanner while presenting the pooches with objects emitting neutral or weak thermal radiation. The left somatosensory cortex in dogs’ brains, which delivers inputs from the nose, was more responsive to the warm thermal stimulus than to the neutral one. The scientists identified a cluster of 14 voxels (3D pixels) in this region of the dogs’ left hemispheres, but didn’t find any such clusters in the right, and none in any part of the dogs’ brains in response to the neutral stimulus.
Together, the two experiments show that dogs, like vampire bats, can sense weak hot spots and that a specific region of their brains is activated by this infrared radiation, the scientists say. They suspect dogs inherited the ability from their ancestor, the gray wolf, who may use it to sniff out warm bodies during a hunt.
“The study is consistent with other research that describes the combined dog nose and brain as a sophisticated platform for processing a broad range of signals,” says Gary Settles, an emeritus professor of mechanical engineering at Pennsylvania State University, University Park, who has studied dogs’ sniffing abilities. He doubts, however, “that the dog rhinarium can distinguish patterns of hot and cold objects at a distance,” suggesting dogs’ thermal detection skills may not be useful for long distance hunting. “[T]hat needs further study.”
If nothing else, the work suggests the extraordinary skills of the sled dog Buck, who tracked prey “not by sight or sound or smell, but by some other and subtler sense” in Jack London’s Call of the Wild, aren’t completely fictional after all.
Dogs are in the news again. For their incredible noses; this time we are learning how they track heat.
Few traces remain of the domesticated dogs that populated the Americas before the arrival of Europeans in the 15th century. On page 81 of this issue, Ní Leathlobhair et al. (1) shed light on the origins of the elusive precontact dog population through genetic analysis of ancient and modern dogs. Building on earlier work, they show that American dogs alive today have almost no ancestry from precontact dogs, a monophyletic lineage descended from Arctic dogs that accompanied human migrations from Asia. Instead, the authors found that their closest remaining relative is a global transmissible cancer carrying the DNA of a long-deceased dog. It remains unclear why precontact dogs survived and thrived for thousands of years in the Americas only to swiftly and almost completely disappear with the arrival of Europeans.
From the article I would add:
It is unclear why there is so little evidence today of this thriving precontact dog population. Early European colonists may have discouraged the sale and breeding of native dogs, or even actively persecuted them (10). Yet, cultural preferences alone seem insufficient to explain their rapid decline. Most dogs worldwide are free-breeding scavengers, with minimal human control and high reproductive rates (11); native American dogs were likely similar.
There is a chart in the same article that shows the first human sites in the Americas were about 15,000 years ago with the oldest dog remains, also in America, being about 10,000 years ago.
Returning to the fascinating topic of how dogs understand us humans.
At the beginning of the month I published a post called Be Careful What You Say. It featured an item on BBC Radio Four regarding the science report from a team in Hungary seeking better to understand how dogs process human vocal sounds, as in speech. (The science report was rapidly featured in many other media outlets.)
Anyway, I am delighted to say that the Rights & Permissions Department of the AAAS pointed out that:
Virginia’s article is freely available on our open news website (http://www.sciencemag.org/news) so rather than post, please link to it (http://www.sciencemag.org/news/2016/08/video-your-dog-understands-more-you-think). Your site visitors will encounter no barriers to viewing the article on our website. We welcome hyperlinks to Science articles provided a plain text link is used and providing our content is not framed. We also ask that the text surrounding the hyperlink not imply any endorsement of your website, products or services by AAAS/Science.
The article, written by Virginia Morell, primarily features a video (see below) but I will just republish Virginia’s opening paragraphs.
It’s the eternal question for pet owners: Does your dog understand what you’re saying? Even if Fido doesn’t “get” your words, surely he gets your tone when you let loose about another accident on the carpet. But a new imaging study shows that dogs’ brains respond to actual words, not just the tone in which they’re said. The study will likely shake up research into the origins of language, scientists say, as well as gratify dog lovers.
“It’s an important study that shows that basic aspects of speech perception can be shared with quite distant relatives,” says Tecumseh Fitch, a cognitive biologist at the University of Vienna, who was not involved in the work.
The finding “doesn’t mean that dogs understand everything we say,” says Julie Hecht, who studies canine behavior and cognition at City University of New York in New York City and who was not involved in the study. “But our words and intonations are not meaningless to dogs.” Fitch hopes that similar studies will be done on other domestic animals and on human-raised wolves to see how much of this ability is hardwired in dogs and how much is due to growing up among talking humans.
What a wonderful relationship dogs and humans have with each other!