Archive for the ‘Dogs’ Category

Dire wolves aren’t wolves at all—they form a distinct lineage with jackals

January 13th, 2021
Two canid skeletons facing each other.

Enlarge (credit: Wikimedia commons)

Dire wolves had a burst of newfound fame with their appearance in Game of Thrones, where they were portrayed as a far larger version of more mundane wolves. Here in the real world, only the largest populations of present-day wolves get as large as the dire wolf, which weighed nearly 70 kilograms. These animals once shared North America—and likely prey—with predators like the smilodon, a saber-toothed cat. Prior to the arrival of humans, dire wolves were far more common than regular wolves, as indicated by the remains found in the La Brea tar seeps, where they outnumber gray wolves by a factor of about 100.

Like the smilodon and many other large North American mammals, the dire wolf vanished during a period of climate change and the arrival of humans to the continent, even as gray wolves and coyotes survived. And with their departure, they left behind a bit of a mystery: what were they?

A new study uses ancient DNA from dire wolf skeletons to determine that they weren't actually wolves and had been genetically isolated from them for millions of years.

Read 10 remaining paragraphs | Comments

Posted in dire wolves, Dogs, evolution, Genetics, Genomics, paleontology, science, wolves | Comments (0)

Dogs were domesticated once from a lost population of wolves

October 29th, 2020
Close up of a dog's face.

Enlarge (credit: Elizabeth Tersigni)

Genomics researcher Anders Bergstrom and his colleagues recently sequenced the genomes of 27 dogs from archaeological sites scattered around Europe and Asia, ranging from 4,000 to 11,000 years old. Those genomes, along with those of modern dogs and wolves, show how dogs have moved around the world with people since their domestication.

All the dogs in the study descended from the same common ancestor, but that original dog population split into at least five branches as it expanded in different directions. As groups of people split apart, migrated, and met other groups, they brought their dogs along. Dog DNA suggests that their population history mirrors the story of human populations, for the most part.

“Understanding the history of dogs teaches us not just about their history, but also about our history,” said Bergstrom, of the Francis Crick Institute, in a statement.

Read 18 remaining paragraphs | Comments

Posted in ancient DNA, Archaeology, dog domestication, Dogs, domestication, mesolithic, neolithic, paleolithic, population genetics, science | Comments (0)

A common plant virus is an unlikely ally in the war on cancer

October 11th, 2020
A cowpea plant flower.

Enlarge / A cowpea plant flower. (credit: Maria Dattola Photography | Getty Images)

Jack Hoopes spends a lot of time with dying dogs. A veterinary radiation specialist at Dartmouth College, Hoopes has spent his decades-long career treating canine cancers with the latest experimental therapies as a pathway for developing human treatments. Recently, many of Hoopes’ furry patients have come to him with a relatively common oral cancer that will almost certainly kill them within a few months if left untreated. Even if the cancer goes into remission after radiation treatment, there’s a very high chance it will soon re-emerge.

For Hoopes, it’s a grim prognosis that’s all too familiar. But these pups are in luck. They’re patients in an experimental study exploring the efficacy of a new cancer treatment derived from a common plant virus. After receiving the viral therapy, several of the dogs had their tumors disappear entirely and lived into old age without recurring cancer. Given that around 85 percent of dogs with oral cancer will develop a new tumor within a year of radiation therapy, the results were striking. The treatment, Hoopes felt, had the potential to be a breakthrough that could save lives, both human and canine.

“If a treatment works in dog cancer, it has a very good chance of working, at some level, in human patients,” says Hoopes.

Read 34 remaining paragraphs | Comments

Posted in cancer, Dogs, plant viruses, science | Comments (0)

Infectious cancer hasn’t done much over the last 4,000 years

August 3rd, 2019
Image of a dog.

Enlarge / Does this dog look concerned because he realizes he can catch an infectious cancer? (credit: Martin Astley)

Cancer is a horrific disease, with its damage only limited by the fact that it only harms the individual in which it arises—except when it doesn't. In a few extremely rare cases, cancerous cells have evolved the ability to move from host to host, essentially becoming an immortalized parasite. The best known instance of this is in dogs, where a cancer has essentially become a sexually transmitted disease.

While the cancer's been known about for some time, there's been a bit of confusion about its origins. Now, a huge team of researchers has looked at parts of the genome gathered from hundreds of dogs from around the globe, and they've reconstructed the cancer's history and evolution. In the process, the team found that it's not actually doing much evolving anymore.

Dogs can catch cancer while having sex

It's hard to know what to call this thing. Cancer? Parasite? Disease? To an extent, its formal name covers things nicely: canine transmissible venereal tumor, or CTV. As the "venereal" implies, dogs transmit CTV during sex. It results in tumor growth, often on the external genitalia. But, unlike the cancer spreading among Tasmanian devils, the immune system quickly suppresses CTV, and the tumors quickly regress. But it does last long enough to spread throughout dog populations. With fewer working dogs and strays, CTV is rare in Europe and North America, but it remains prevalent elsewhere.

Read 14 remaining paragraphs | Comments

Posted in Biology, cancer, Dogs, evolution, Genetics, Genomics, science | Comments (0)

We may have inadvertently selected for muscles on dogs’ faces

June 18th, 2019
Two images of a dog showing different facial expressions.

Enlarge / A muscle flex raises the inner portions of the eyebrow at right. (credit: Waller et al.)

Humans domesticated dogs about 30,000 years ago. Since then, we've worked with them, hunted with them, played with them, and come to rely on them for companionship. And, in the process, we've bred them for everything from general cuteness to the ability to guard and fight for us. Figuring out who's manipulating whom and who's getting more out of the relationship is a hopeless task.

But that doesn't mean that some aspects of the changes dogs have undergone aren't amenable to study. After studying the facial muscles of dogs and wolves, a US-UK team of researchers has now found that dogs have two muscles that wolves mostly lack. These muscles control the movements of the face near the eyes, and the researchers suspect that the muscles' presence helps the dogs make a sad-eyed face that we find appealing.

A “take me home” look

The new work arose from an earlier paper done by several of the same researchers (Juliane Kaminski, Bridget Waller, and Anne Burrows). In it, they looked at what's technically called a "paedomorphic facial expression" in dogs. Paedomorphic means that adults retain features that are commonly associated with young animals—we tend to view these as cuter. In this case, the expression was raising the skin above the eyes, closer to the bridge of the nose. This expression, shown above, has been interpreted as "sad-eyed" and thought to tug on humans' heart strings.

Read 9 remaining paragraphs | Comments

Posted in artificial selection, Biology, Dogs, domestication, evolution, science | Comments (0)