The reintroduction of the otter into British waterways is one of the conservation success stories of recent years. Indeed, the Otter Trust has now closed its Bungay captive breeding centre to the public, its once apparently impossible aim of repopulating the rivers with capering otters brilliantly realised. There is a slight blip in the story at the moment, in that an as yet unidentified new strain of chemical in our waters is currently giving male otters reproductive problems. But for men in our modern toxin-ridden world, loss of libido, pathological fear of physical contact, extreme genital shrinkage and unusual changes in the texture and colour and smell of their reproductive organs are tragically inevitable, as I have explained to my unsympathetic wife time and time again.

The British otter's cautious success story is an exception to the coming global lifeform mass death apocalypse. Polar bears, rhinoceroses and elephants are all on the immediate critical list. The rhino is doomed due to increasingly cash-rich Asia's belief that its horn has some kind of Harry Potter magical power, the beast's decline an object lesson in the dangers of giving idiots money. But it is not only our friends in the animal kingdom who are being destroyed by economic forces beyond their control. The world's thinkers are now also a gravely endangered species. And yet, unlike the conceited creatures who share their fate, there is not even the most perfunctory plan in place to protect them.

Once thinkers were everywhere, like butterflies, sparrows and bees, which have also virtually disappeared. As late as the early 1980s, you'd still come down in the morning and find some Marxist literary theorist had been on the doorstep and pecked off the top of the milk. But no one under 40 can be expected to remember the ubiquitous abundance of pure thought that once characterised our culture. It has disappeared incrementally, like roadside wildflowers and sticklebacks in streams, as if it never were.

In the early 50s, everyone was happy because there was only one TV channel and it was programmed by patronising and benign paternalistic liberals. Their crazy beliefs were encouraged by the hoary establishment buffers who held the purse strings and who saw arts, thought and culture as hallmarks of a civilised society, even as they retched in secret at the increase in downwardly angled thought ducts like cheap Penguin paperbacks, red brick universities and Play for Today.

In those halcyon days, the entire nation would sit down with bottles of stout and plates of dripping to watch a programme in which an enthusiastically cigarette-smoking Bertrand Russell, or someone of similar super-intelligence, sat motionless in a chair and discussed for hours the finer points of philosophy in incredible detail with an equally un-televisual man. Their noses and ears full of tufts of hair, their brains crackling with mental electricity, their flappy trousers hoiked biffin-tight, and their little odd socks showing, they reassured the hoi polloi that, although they were very clever, and we needed and valued them as a society, these people were loonies.

In the 1970s, even ITV, which is today a Galápagos of McGuinnesses, had some thinkers on its payroll, like the windmill-armed celebrity egghead Magnus Pyke. When I got a university place in 1986, Pyke was used by my anxious grandfather as an example of the dangers of education. "Be careful you don't learn so much that you send yourself mad like all these professors," he said, pointing at Pyke dancing about in a Thomas Dolby video.

Today the thinker is an endangered species. All our universities are turning into book-balancing business schools or results-driven scientific research centres, treating students as client-customers who deserve to see an investment return in the form of increased living standards and higher salaries in exchange for spending their student loans, and funded by patrons and public bodies wanting to see practical results. Once you joined a university to service the global advancement of ideas. Now you employ it to make you more employable. The notion that thinking about abstract ideas like art and life might be an end in itself is being priced out of existence and legislated into oblivion.

In popular culture thinkers are despised. A sick delight spread over the rapidly warming landscape when it was revealed that Sir David Attenborough had filmed some baby polar bear footage in a zoo to supplement the painstakingly gathered location shots, as if everything this wise old man had ever said ever could now to be gleefully erased from the record and replaced with recordings of Jeremy Clarkson snorting petrol fumes out of a slit in a life-sized inflatable model of David Cameron.

Cotswold kitchen-lingering Sunday Times columnists and violent internet sex-death fantasists unite, wolves and hyenas running against nature in a single bastard pack to hunt down the harmless Mary Beard. Her only crimes? Being clever, old and wearing a cardigan. Hilary Mantel is punished for daring to be a literary novelist in a world of celebrity autobiographies by having her words systematically decontextualised by the Daily Mail, and finding herself strapped into the stocks of public opinion and spattered by the overripe turnip of Twitter. And young critics, now educationally ill-equipped to process all but the most basic burlesques of human feeling, have been unable to give Stephen Poliakoff's new BBC4 drama, "A Dancer on the Edge of Time", the enthusiastic reviews it obviously deserves, preferring instead to spend their energies finding ways of tolerating Derek.

But we will miss the thinkers when they are gone. Our rulers' systematic extermination of thought may not be deliberate but one day, perhaps in 30 or 40 years' time, a momentarily bored David Cameron may turn to the bookshelf in an airport newsagents and wonder, for a second, why all the novels have embossed covers and don't seem to be about anything. We are unconvinced as to the actual practical value of rhinos, polar bears and elephants – though some hysterical agitators are making the case that we should save the bee to prevent the total collapse of the global food chain – but we have a sense that it reflects badly on us as a species if these things are allowed to disappear on our watch.

The same is true of thinkers. Now, from what I remember of the Otter Trust in Bungay, soon to be empty of its few remaining and ageing otters, there's a nice stretch of river, some cosy burrows, a toilet and a cafe serving tea and snacks. Perhaps we could put the thinkers there and allow them to swim, sleep, breed and, above all, think, just in case, one day, we find we miss them after all and have need of them again?

The Alternative Comedy Experience, curated by Stewart Lee, is showing on Tuesdays on Comedy Central at 11pm