Do you believe in monsters?

If news reports are to be believed, the Yeti is everywhere. That hairy hybrid of man and ape is either all-too-real or all-too-ridiculous, depending on your viewpoint.

In the last few months alone, sightings of the giant beast (a similar creature is known as Bigfoot or sasquatch in America) have been reported in India, Nepal, North America and, er, Redbridge in Essex. 

And last month a team of Japanese explorers returned from the Himalayas with photographs of what they say are bona fide footprints of a giant, un-catalogued ape-like creature.

The team, from Yeti Project Japan, say the large human-like imprints could not have come from any other animal known to inhabit the area.

Could they be right? Could a race of ape-like animals be living, undiscovered, on the isolated slopes of the Himalayas, or for that matter in the deep woods of darkest Kentucky, or even in the pub car parks of suburban Essex?

The odds on the last seem remote, but – despite scientific scepticism - a growing number of people think that Bigfoot, and a host of other un-catalogued monsters of land and sea – might actually be real.

Cryptozoology is the official name for unknown animals, though not every type of animal is included. All scientists agree that there are probably thousands of undiscovered insects out there. But cryptozoologists focus on the big stuff: yetis, sea serpents, big cats, giant lizards and the like.

Most cryptozoologists think that at least some of these creatures may be real. And even if others turn out to be fantasy, for humans to invent such enduring legends tells us something significant about ourselves.

"For those who consider that interest in animals is always high, that adventure can be fun, and mysteries are engaging, it's easy to understand the appeal of cryptozoology," says Loren Coleman, an American writer and one of the world’s leading crptozoologists.

Coleman dismisses the notion that the world is too small, and too well explored, to harbour populations of large unknown animals. Potential wildernesses in North America alone, he says, include the forests of the Pacific Northwest and the swamps of the South. "Most of Canada - except for a small strip along the US-Canadian border - is unexplored."

Globally, Cisco Serret, founder of the website www.cryptozoology.com, says much of the Earth could still harbour unknown animals. "There are still very big areas that have been barely investigated," he says. "The deep oceans are one. Other places include the huge forested areas in South America - so dense with vegetation that they are very difficult for humans to get into."

The latest Encyclopaedia of Cryptozoology lists around 1,600 unverified creatures that might – just might - be real. But is it really credible that viable breeding populations of yeti, or Nandi bear (a bear-like predator from Kenya), or chupacabra (a vicious giant carnivore of Central America) have evaded formal scientific discovery, when even illusive creatures like giant pandas and mountain gorillas have been scientifically verified?

Interestingly, cryptozoologists point to the giant panda as one reason bigfoot and others may actually be roaming the woods. It took 67 years from the time of the first sighting of a giant panda by westerners till the first live capture.

During that time, 12 professional expeditions failed to find a single animal. If the cumbersome panda can evade human discovery for so long, say cryptozoologists, why not the more nimble bigfoot?

Cryptozoologists are also encouraged by a handful of animals that were once cryptids (unverified animals) but have since been verified as real. The Komodo dragon, for instance – a giant monitor lizard – was once considered a cryptid. The pizzly – a polar bear/grizzly bear hybrid - is rare but real. 

Still, it’s fair to say that cryptozoology is a field open to abuse, error and hoax. The most famous piece of evidence pointing to the existence of bigfoot is a film taken in California in 1967 by Roger Patterson. Arguments about its veracity rage to this day. 

Sceptics think the hairy hominid in the shaky footage is a large man in a monkey suit. Supporters, including some scientists, say it’s too realistic for that, with the gait of a real, ape-like, animal. Sceptics counter that the costumes for The Planet of the Apes films were pretty realistic too. The debate goes on.

But what’s not in doubt is that the search for living, breathing monsters says a lot about the state of the human psyche. In 1976, at the height of the Patterson bigfoot film furore, sceptical scientist Dr William Montagna said a belief in unknown animals was just part of man’s ‘need’ to fantasise.

"(That need) created mythological characters, good and evil; visions of miraculous events, heaven, purgatory and hell," wrote Montagna. "And finally, it peopled man's world with monsters.”

A more modern theory is that our desire to see a living yeti is a symptom of our environmental shame. Having pushed so many species to extinction, we subconsciously yearn for new animal discoveries to assuage our guilt.

"This desire to seek out new animals… is part of a need to make a better connection to life all around us, which I think many of us feel a bit deficient in," says Cisco Serret.

Loren Coleman has another theory. We search for unknown animals because there are many still to be revealed. "Probably within 25 years a large new primate will be discovered," he says. "Modern human beings fool themselves into thinking all the world is known and all the animals have been discovered. It’s the biggest myth of all."