Biologists reconstruct genome of 11,000-year-old “almost immortal” sexually-transmitted dog cancer

Canine transmissible venereal tumours (CTVT) is one of only two natural transmissible cancers, and could hold the key to better organ transplants in humans.

Veterinary biologists have discovered that a sexually-transmitted cancer found in dogs around the world first originated 11,000 years ago, making it potentially the oldest living mammalian creature.

The study from the Wellcome Trust’s Sanger Institute, published in Science, analysed the genome of canine transmissable venereal tumours (CTVT), a disease that is one of only two known cancers of its type to have been observed in the natural world (the other, transferred via bites, affecting Tasmanian devils). It’s not a cancer caused by the transfer of a virus, like with cervical cancer and the HPV virus in humans - it’s the transfer of actual cancerous dog cells from dog to dog.

“They are actually a parasite, they need to have their host in order to survive, but they’re actually derived from the same species as their host,” Dr Elizabeth Murchison, the study’s lead author, explained to me. “They’re quite a strange disease. They are an infectious disease, but they’re originally from the same species as their host, which makes them a kind of very tricky to combat.”

“It’s the oldest continually surviving mammalian lifeform that we know of,” she said. “It is almost immortal.”

Genome analysis of samples from a dog in Brazil and another Australia found that the cancer had undergone a huge number of mutations, in the order of two million, since it first began metastasising within the first dog to contract it.

Murchison said: “Between humans we each have about three million mutations, the natural variance that makes us different to other people. Similarly dogs have about three million natural variants that make one dog different to another dog. But cancers themselves, in humans, don’t tend to differ from their host very much. They usually have between 1,000 and 5,000 mutations in the genome that makes the cancer different to the host. Whereas this dog cancer has acquired about two million, which is almost making it like a different individual to the original host that gave rise to it.”

Relying on recent research which found that, within cancer patients, the number of mutations within a cancer correlates both to the type of cancer and the age of the patient, the study team were able to trace back in time to the point at which mutations must have started - giving the age of CTVT at 11,000 years.

Yet CTVT stayed within the small population where it first emerged for roughly 10,500 years, until suddenly spreading elsewhere around the globe - a time that coincides with the beginnings of the European age of exploration. While there’s no way to know where in the world the cancer first appear (yet), the earliest known historical mention of it is by a London doctor in 1810.

With the information from the origin dog’s genome, the team was able to create an image of what it probably looked like. Here's a video from the team further explaining their work:

What’s more, the cancer appears to have been caused by in-breeding.

“It was a relatively inbred individual,” explains Murchison. “Similarly, the Tasmanian devils are relatively inbred population - they live on an island, and they have a small population. The cancer might have originated in a dog that lived in an in-bred population, but from there it managed to adapt into all sorts of out-bred dogs. It can even survive in other species of canids, including jackals and coyotes and foxes. It’s pretty remarkable.”

Theoretically, this type of cancer could emerge at any time in any species, Murchison pointed out, but the experience of the dog and Tasmanian devil transmissible cancers - and from a third variant, which emerged briefly in a population of laboratory hamsters in the 1960s - seems to indicate that in-bred populations are more at risk. There are human populations which suffer from low genetic diversity around the world, and this research could be important in understanding transmissible cancers in the case of a variant appearing.

“These cancers have to overcome one of the most fundamental immunological barriers, and how they do it is still a mystery,” Murchison said. “It’s incredibly important to understand how they do it, as it has implications for how cancers evade the immune system, but also potentially how other infectious diseases might work, and have implications for how to design better methods for helping transplant recipient patients not to reject their graft transplant organs.”

Murchison is also keen to see if further research could help the endangered Tasmanian devil, whose variant is much more aggressive than CTVT and which can kill its host in a matter of months.

What the first dog to get CTVT may have looked like. (Image: Sanger Institute)

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

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The mother lode: how mums became the ultimate viral fodder

The internet’s favourite joke used to be "your mum". Now it's "my mum".

“I was like: oh my.”

Terri Squires is describing her reaction to the news that she had gone viral. Last month, more than 213,000 people shared a tweet about Terri – but it wasn’t sent from her account. The 50-year-old Ohioan was propelled to internet stardom by her son, Jeff, who had tweeted about his mother.

“I didn’t really realise what it meant at first until he was like: ‘Mum, you do realise that millions of people have looked at this?’ … When I started seeing those numbers I was like: ‘Oh boy’.”

It’s a funny story – and Terri laughs heartily all she tells it. After coming out of a meeting, she checked her phone and noticed a picture of a missing – white – dog on Facebook. She quickly texted 17-year-old Jeff to check that the family dog, Duey, was safe. “That’s not Duey… Duey’s face is brown,” replied her son. “OK – just checking,” replied Terri.

More than 600,000 people “liked” Terri’s mistake after Jeff shared screenshots of the text message exchange on Twitter. But Terri is just one of hundreds of mums who have gone viral via their sons and daughters. Texts mums send, mistakes they make, things they fail to notice – these have all become the ultimate viral fodder.

In the last three months alone, Gerald’s mum went viral for a microphone mishap, Adam’s mum shot to Twitter fame for failing to understand WhatsApp, Lois’ mum got tricked by her daughter, Harry’s mum was hit in the head with a football, Hanna’s mum misunderstood a hairstyle, and Jake’s mum failed to notice her son had swapped a photo in her home for a portrait of Kim Jong-un.

But how do the mothers behind these viral tweets feel?

“I'm pretty much a mum that everybody wants to talk to these days,” says Terri, with another warm laugh. The mum of three says going viral “is not that big of a deal” to her, but she is happy that her son can enjoy being a “local superstar”. But is she embarrassed at being the punchline of Jeff’s joke?

“Believe me, I have thick skin,” she says. “I kinda look at what it is, and it’s actually him and his fame. I’m just the mum behind it, the butt of the joke, but I don't mind.”

Not all mums feel the same. A handful of similar viral tweets have since been deleted, indicating the mothers featured in them weren’t best pleased. A few people I reach out to haven’t actually told their mums that they’re the subject of viral tweets, and other mums simply don’t want any more attention.

“I think I’ve put my mum through enough with that tweet already,” says Jacko, when I ask if his mum would be willing to be interviewed. In 2014, Jacko tweeted out a picture of his family writing the word “cock” in the air with sparklers. “This is still my favourite ever family photo,” he captioned the tweet, “My mum did the ‘O’. We told her we were going to write ‘Love’.”

“No one ever expects to call home and say ‘Mum, have you heard of something called LADbible? No, you shouldn’t have, it’s just that a quarter of a million of its fans have just liked a photo of you writing the word ‘cock’ with a sparkler’,” Jacko explains.

Although Jacko feels his mum’s been through enough with the tweet, he does say she was “ace” about her new found fame. “She’s probably cooler about it all than I am”. Apart from the odd deletion, then, it seems most mums are happy to become viral Twitter stars.

Yet why are mums so mocked and maligned in this way? Although dads are often the subject of viral tweets, this is usually because of jokes the dads themselves make (here’s the most notable example from this week). Mums, on the other hand, tend to be mocked for doing something “wrong” (though there are obviously a few examples of them going viral for their clever and cunning). On the whole: dads make jokes, mums are the butt of them.

“We all think our mums are so clueless, you know. They don’t know what’s going on. And the fun thing is, one day we come to realise that they knew way more of what was going on than we thought,” says Patricia Wood, a 56-year-old mum from Texas. “People always kind of make fun of their mums, but love them.”

Last year, Patricia went viral when her daughter Christina tweeted out screenshots of her mum’s Facebook posts. In them, Patricia had forgotten the names of Christina’s friends and had candidly written Facebook captions like: “My gorgeous daughter and her date for formal, sorry I forgot his name”. Christina captioned her tweet “I really can't with my mom” and went on to get more than 1,000 likes.

“I felt, like, wow, it was like we’re famous, you know. I thought it was really cool,” says Patricia, of going viral. Her experiences have been largely positive, and as a part-time Uber driver she enjoys telling her customers about the tweet. “But I did have one bad experience,” she explains. A drunken passenger in her car saw the tweet and called Patricia an “asshole”.

Another aspect of viral fame also worried Patricia. She and her daughter were invited on a reality show, TD Jakes, with the production company offering to pay for flights and hotels for the pair. “I have too many skeletons in my closet and I didn't want them to come dancing out,” says Patricia, of her decision not to go. “By the time I got off it, it would be the Jerry Springer show, you know. I’m kind of a strange bird.”

On the whole, then, mothers are often amused by going viral via their offspring – and perhaps this is the real beauty of tweeting about our mums. Since the moment they earn the title, mums can’t afford to be fragile. There is a joy and relatability in “my mum” tweets – because really, the mum in question could be anyone’s. Still, from now on, mums might be more careful about what they tell their sons and daughters.

“When I send Jeff a text now I make sure I’m like: ‘Is my spelling correct? Is what I’m saying grammatically correct?’,” says Terri, “Because who knows where the words are gonna end up?”

Amelia Tait is a technology and digital culture writer at the New Statesman.