"Theories as to what Yetis are... range from surviving collateral hominid species, such as Homo neanderthalensis or Homo floresiensis, to large primates like Gigantopithecus, which were widely thought to be extinct,” says Sykes.
These theories were given a boost in 2004 when scientists published details of skeletal remains of a species of human (Homo floresiensis) from the Indonesian island of Flores. The adult species, previously unknown to science, was just 1m (3ft) tall and was likely a descendent of Homo Erectus, which arrived on the island 900,000 years ago. As far as scientists can tell, the “hobbit”, as it was nicknamed, survived for thousands of years unnoticed by modern humans and was still alive as recently as 12,000 years.
Finds like this make it more likely that accounts of mythical, human-like creatures could be founded on grains of truth, some say. For example, the Indonesian cryptid Orang Pendek (“short person”) is often described in Indonesian folklore as a small, hairy, manlike creature not dissimilar to Homo floresiensis.
As Henry Gee, an editor at the respected Nature Journal, wrote in 2004 following the discovery: “In the light of the Flores skeleton, a recent initiative to scour central Sumatra for 'Orang Pendek' can be viewed in a more serious light.
He also argued that new species of mammal – including oxen - are still occasionally discovered by scientists. “If animals as large as oxen can remain hidden into an era when we would expect that scientists had rustled every tree and bush in search of new forms of life, there is no reason why the same should not apply to new species of large primate, including members of the human family,” he wrote.
Gee has since stepped away from the debate, but it’s a theory that others buy into. “Given how people are encroaching on wilderness areas, it seems increasingly unlikely that large mammals, and especially human-like species, remain undocumented,” says Dr Murray Cox from the Institute of Molecular BioSciences, Massey University in New Zealand. “However, some parts of the world, including the Himalayas and the arctic forests of North America, still show very limited impact by humans. So perhaps the possibility of new mammal species there cannot be completely discounted.”
But, others are less forgiving. According to Prof. Darren Curnoe of the School of Biological, Earth and Environmental Sciences at the University of New South Wales in Australia, the chances of finding a completely new species of hominid are remote. He is also critical of the project efforts, especially linking it to the possibility of finding a Yeti.
“There are far better ways to spend scarce funding for science than chasing mythological creatures and more than enough real and mind-boggling mysteries in nature to keep many generations of scientists busy,” he says.
Sykes has heard that kind of criticism ever since the project started. Although he admits that the project is speculative and unlikely to find a new species of hominid, he argues the search is still valid.
“Science does not accept or reject hypotheses but evaluates them on the basis of evidence,” he says. “This is why I am confident that examining the evidence of alleged Yetis does not fall outside the realm of proper scientific enquiry.”
And, of course, the project has captured the public’s imagination in a way that much of science does not. Put simply, the idea of a Yeti – or some other undocumented mythical beast from folklore – remains a seductive idea for humans. It taps into our desire to explore and understand the world around us, and to believe there are still things left to be discovered. It is part of the reason there was recently a team of 38 people tramping into the remote mountains of the Shennongjia nature reserve in Hubei, China, in search of the yeren. And part of the reason that countless teams over the last 100 years have probed forests, mountains, jungles and islands from the Himalayas to Borneo in search of them.