The Tasmanian tiger

The Tasmanian tiger, or thylocine, was a carnivorous marsupial (a meat-eating mammal which carries its young in a pouch). It was given the name ‘tiger’ because it had striped fur, and because it was ferocious. Between 24 million and 15 million years ago, many types of thylocine roamed across Australia, their powerful jaws playing a role in maintaining a balance in the ecosystems of their day. Some species were fox-sized, while others were barely the size of kittens.

But when a period of climate change cooled Australia about 12 million years ago, the numbers of these ancient thylocines began to decline. By about 3 million years ago, only one species was left. About 4,000 years ago, these vanished completely from the Australian mainland, so that Tasmania, a large island to the south of Australia, was then the last remaining place where thylocines existed. They ruled the animal life of that island unchallenged until Europeans, with sheep, dogs and a great indifference to native flora and fauna, seem to have brought about their extinction. In 1936, the last captive Tasmanian tiger died in Hobart Zoo. Since then, many expeditions have searched for tigers in the Tasmanian bush, but no definitive evidence has been found. Despite this, there are many who keep searching.

In 1981, Dutch-born zoologist Hans Naarding was in Tasmania conducting a survey of Latham’s snipe, a species of endangered bird. One night he saw an animal in the light from the searchlight mounted on his vehicle. He described it as about the size of a large dog, but with slightly sloping hindquarters and a fairly thick tail continuing straight on from its backbone. He said that it had 12 distinct stripes on its back, running down to the point where the tail began. He reported the sighting to the Director of Tasmania’s National Parks. When the news broke, said Naarding, ‘I was besieged by television crews, including four or five from Japan, and others from the United Kingdom, Germany, New Zealand and South America.'

Government and private search parties combed the region, but no further sightings were made. The tiger, as always, had escaped to its lair -- a place that many insist exists only in the imagination. Others disagree: there have been more than 4,000 claimed sightings of the animal since it supposedly died out, and the average number of claims reported to the authorities each year is now 150. So is it out there? Even experts differ in opinion.

Randolph Rose, Associate Professor of Zoology at the University of Tasmania, says that he dreamed of seeing a thylocine, but is now convinced that his dream will go unfulfilled. The consensus among conservationists is that any animal with a population base of less than 1,000 is headed for extinction within 60 years. ‘Sixty years ago,’ he says, ‘there was only one thylocine that we know of, and that was in Hobart Zoo. Take it from me, the tiger is gone.'

But Dr David Pemberton, curator of zoology at the Tasmanian Museum, states that, despite scientific thinking that a relatively large number of animals is required to sustain a population, ‘the Florida panther is down to a dozen or so animals, and, while it does have some inbreeding problems, is still ticking along.’ After all, animals can be notoriously elusive. The strange fish known as the coelacanth, with its ‘proto legs’, was thought to have died out with the dinosaurs 70 million years ago until a specimen was dragged to the surface in a shark net off the coast of South Africa in 1938.

Wildlife biologist Nick Mooney has the unenviable task of investigating all so-called sightings of the tiger. It was Mooney who was first consulted in late February 2005 about the authenticity of new digital photographic images of a thylocine allegedly taken by a tourist. On face value, Mooney says, this particular account of a sighting and the photographs submitted as proof amount to one of the most convincing cases for the species’ survival that he has seen. Many other ‘sightings’ have been hoaxes, and many sincere seekers are victims of obsession. ‘It is a blind optimism that something is, rather than cynicism that something isn’t,’ Mooney says. ‘If something crosses the road, it’s not a case of "I wonder what that was?" Rather, it is a case of "That’s a thylocine!"‘

However, Mooney treats all sightings on face value. ‘I never try to embarrass people,’ he says, ‘… but the fact that I don’t pack the car immediately after they telephone can often be taken as ridicule. Obsessive characters get angry that someone in my position is not out there when they think the thylocine is there.'

Hans Naarding, whose sighting of a striped animal two decades ago was the highlight of a lifetime of animal spotting, remains puzzled by the time and money people waste on tiger searches. He says resources would be better applied to saving another endangered animal, the Tasmanian devil, and helping declining migratory bird populations. Could the thylocine still be out there? ‘Sure,’ Naarding says. ‘I know the vast south-west wilderness of Tasmania well. They could survive … [But] if this is the case, it will not be long before they do disappear completely.’ Naarding believes that any discovery of surviving thylocines would be ‘rather pointless’. ‘How do you bring a species back from extinction?’ he asks. ‘What could you do with it? If there are thylocines out there, they are better off right where they are.'

Thinking for themselves

Some insights into animal intelligence

In 1977 Irene Pepperberg brought Alex, a one-year-old African gray parrot, into her lab at Harvard University to teach him to reproduce the sounds of English. At that time most scientists considered animals mere machines, lacking the ability to think in a rational way or feel emotions as humans do. ‘I wasn’t trying to see if Alex could learn a human language,’ said Pepperberg. ‘My plan always was to use his imitative skills to get a better understanding of avian cognition.’ Given that Alex’s brain was the size of a walnut, most researchers thought Pepperberg’s study would be futile.

But by the time Alex died in 2007, he knew 150 words, could count, do simple arithmetic, and distinguish between objects according to shape, color, and material. Many of Alex’s skills, such as his ability to understand the concepts of ‘same’ and ‘different’, are generally ascribed only to higher mammals. But parrots, like higher apes (and humans), live in complex societies, and need to monitor changing relationships and environments.

’They need to distinguish colors to know when a fruit is ripe or unripe,’ Pepperberg noted. ‘They need to categorize things -- what’s edible, what isn’t -- and to know the shapes of predators. And it helps to have a concept of numbers if you need to keep track of your flock. For a long-lived bird, you can’t do all of this with instinct; cognition must be involved.'

Just how easily mental skills can be acquired is perhaps best illustrated by dogs. For abstract thinking, humans employ symbols, letting one thing stand for another. And Juliane Kaminski, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, believes that dogs can do this too. In 2008, Kaminski and her colleague Sebastian Tempelmann conducted an experiment with a border collie. The dog successfully selected and brought her owner toys which she had never seen before, prompted only by a picture of each toy.

Creativity is another skill which seems to have evolved in humans and animals alike. ‘People were initially surprised to discover that chimpanzees make tools,’ says behavioral ecologist Alex Kacelnik. ‘But then people thought, "Well, they share our ancestry -- of course they’re smart." Now we’re finding these kinds of exceptional behaviors in some species of birds.’ New Caledonian crows, for example, use their beaks and claws to fashion tools to poke out grubs from palm trees. ‘But the problem is we don’t have a recently shared ancestry with birds -- our last common ancestor was a reptile living over 300 million years ago.'

Kacelnik and his researchers at Oxford University were particularly impressed with the ingenuity of one of the crows -- Betty, a wild-caught female. In one experiment, Betty successfully selected a hook-shaped wire to get a piece of meat from a glass tube. Then, when another bird unexpectedly stole the hook, Betty took a straight piece of wire, shaped it into a hook, and retrieved the food. This was the first time Betty had seen a piece of wire like this. What she did, Kacelnik says, ‘is a major kind of cognitive sophistication.'

We are clearly not alone in our ability to invent or plan -- or even to plot and lie. Studies show that western scrub jays can guess another bird’s intentions and act on that knowledge. A jay knows that if another jay watches it hide a nut, there’s a chance it will be stolen. So the first jay will return to move the nut when the other jay is gone. ‘It’s some of the best evidence so far of experience projection in another species,’ says Nicky Clayton of Cambridge University. What’s more, the jays seem to know how long ago they hid a particular kind of food, and they manage to retrieve it before it spoils.

Human cognitive psychologists call this ability ‘episodic memory’ and argue that it only exists in species that can mentally travel back in time. They believe that animals cannot distinguish among past, present, and future the way humans do. Such skepticism is a challenge for Clayton. ‘We have good evidence that jays remember specific hiding events, which is the original definition of episodic memory. But now the goalposts have moved. Whenever we find a mental skill in a species that is reminiscent of human ability, the human cognition scientists change the definition.'

Cognitive psychologist Louis Herman has spent decades studying bottlenose dolphins. These intelligent mammals are highly interactive, social and cosmopolitan, living in subpolar to tropical environments worldwide. Among the many skills exhibited by Herman’s dolphins is the ability to imitate the motor behaviors of instructors. If a trainer bent backward and lifted a leg, the dolphin would turn on its back and lift its tail in the air. This requires the imitator to form a mental image of the other individual’s body, then adjust its own body accordingly -- actions that imply an awareness of one’s self, an ability once seen as the sole preserve of humans.

What Herman finds fascinating is that these aquatic creatures diverged from primates millions of years ago. That kind of cognitive convergence suggests there must be some similar pressures selecting for intellect. ‘We don’t share their biology or ecology, but do share the need to establish life-long bonds and alliances. This appears to be the likely common driving force.'