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 Tinder dating app isn't just about sex – it's about friendship, too. And sex

The lines between sex, love and friendship are blurrier than ever, as I found out quickly while using the app.

The first time I met someone using Tinder, the free dating app that requires users to swipe left for “no” and right for “yes” before enabling new “matches” to chat, it was an unqualified success. I should probably qualify that. I was newly single after five years in a committed relationship and wasn’t looking for anything more than fun, friendship and, well, who knows. A few weeks earlier I had tried to give my number to a girl in a cinema café in Brixton. I wrote it on a postcard I’d been using as a bookmark. She said she had a boyfriend, but wanted to keep the postcard. I had no date and I lost my page.

My Tinder date was a master’s student from Valencia called Anna (her name wasn’t really Anna, of course, I’m not a sociopath). When I arrived at the appointed meeting place, she told me I was far more handsome IRL (“in real life”) than my pictures suggested. I was flattered and full of praise for the directness of continental Europeans but also thought sadly to myself: “If only the same could be said about you.”

Anna and I became friends, at least for a while. The date wasn’t a success in the traditional sense of leading us into a contract based on exclusivity, an accumulating cache of resentments and a mortgage, but it had put me back in the game (an appropriate metaphor – people speak regularly of “playing” with the app).

According to Sean Rad, the co-founder who launched Tinder in late 2012, the service was invented for people like me. “It was really a way to overcome my own problems,” he told the editor of Cosmopolitan at an event in London last month. “It was weird to me, to start a conversation [with a stranger]. Once I had an introduction I was fine, but it’s that first step. It’s difficult for a lot of people.” After just one outing, I’d learned two fundamental lessons about the world of online dating: pretty much everyone has at least one decent picture of themselves, and meeting women using a so-called hook-up app is seldom straightforwardly about sex.

Although sometimes it is. My second Tinder date took place in Vienna. I met Louisa (ditto, name) outside some notable church or other one evening while visiting on holiday (Tinder tourism being, in my view, a far more compelling way to get to know a place than a cumbersome Lonely Planet guide). We drank cocktails by the Danube and rambled across the city before making the romantic decision to stay awake all night, as she had to leave early the next day to go hiking with friends. It was just like the Richard Linklater movie Before Sunrise – something I said out loud more than a few times as the Aperol Spritzes took their toll.

When we met up in London a few months later, Louisa and I decided to skip the second part of Linklater’s beautiful triptych and fast-track our relationship straight to the third, Before Midnight, which takes place 18 years after the protagonists’ first meet in Vienna, and have begun to discover that they hate each others’ guts.

Which is one of the many hazards of the swiping life: unlike with older, web-based platforms such as Match.com or OkCupid, which require a substantial written profile, Tinder users know relatively little about their prospective mates. All that’s necessary is a Facebook account and a single photograph. University, occupation, a short bio and mutual Facebook “likes” are optional (my bio is made up entirely of emojis: the pizza slice, the dancing lady, the stack of books).

Worse still, you will see people you know on Tinder – that includes colleagues, neighbours and exes – and they will see you. Far more people swipe out of boredom or curiosity than are ever likely to want to meet up, in part because swiping is so brain-corrosively addictive.

While the company is cagey about its user data, we know that Tinder has been downloaded over 100 million times and has produced upwards of 11 billion matches – though the number of people who have made contact will be far lower. It may sound like a lot but the Tinder user-base remains stuck at around the 50 million mark: a self-selecting coterie of mainly urban, reasonably affluent, generally white men and women, mostly aged between 18 and 34.

A new generation of apps – such as Hey! Vina and Skout – is seeking to capitalise on Tinder’s reputation as a portal for sleaze, a charge Sean Rad was keen to deny at the London event. Tinder is working on a new iteration, Tinder Social, for groups of friends who want to hang out with other groups on a night out, rather than dating. This makes sense for a relatively fresh business determined to keep on growing: more people are in relationships than out of them, after all.

After two years of using Tinder, off and on, last weekend I deleted the app. I had been visiting a friend in Sweden, and took it pretty badly when a Tinder date invited me to a terrible nightclub, only to take a few looks at me and bolt without even bothering to fabricate an excuse. But on the plane back to London the next day, a strange thing happened. Before takeoff, the woman sitting beside me started crying. I assumed something bad had happened but she explained that she was terrified of flying. Almost as terrified, it turned out, as I am. We wound up holding hands through a horrific patch of mid-air turbulence, exchanged anecdotes to distract ourselves and even, when we were safely in sight of the ground, a kiss.

She’s in my phone, but as a contact on Facebook rather than an avatar on a dating app. I’ll probably never see her again but who knows. People connect in strange new ways all the time. The lines between sex, love and friendship are blurrier than ever, but you can be sure that if you look closely at the lines, you’ll almost certainly notice the pixels.

Philip Maughan is Assistant Editor at the New Statesman.

This article first appeared in the 26 May 2016 issue of the New Statesman, The Brexit odd squad