杏吧原创

THE world鈥檚 oldest known living animal is Harriet, a giant Galapagos tortoise living in the Australia Zoo in Beerwah, Queensland, who recently celebrated her 173rd birthday. But Harriet has a better claim to fame than that. She is widely thought to have been plucked from her island home by none other than Charles Darwin, who took her as a personal pet during the voyage of HMS Beagle in 1835, and studied her while formulating his theory of evolution.

I have been intrigued by this story for several years, and in 2001 I finally got to meet Harriet. Despite being in her 18th decade, she was a graceful and sprightly creature with a weather-beaten yet dignified face, who seemed entirely at ease living near the crocodiles and poisonous snakes that are the zoo鈥檚 main attractions.

Afterwards I became determined to find out a bit more about her link to one of the world鈥檚 most famous scientists. My quest has ranged from delving through Darwin鈥檚 personal papers, to unearthing some obscure genetic research on Harriet. While the tale of Darwin鈥檚 tortoise may not be quite as it appears, it is a fascinating one that is inextricably linked with the great man鈥檚 development of what is arguably the most important scientific breakthrough of all time.

Harriet鈥檚 famous provenance first came to the world鈥檚 attention after Ed Loveday, a retired historian living in Queensland, wrote a letter to his local paper in 1994. In it he reminisced about three giant tortoises he had encountered in the Brisbane Botanical Gardens in the 1920s. He revealed that the tortoises were said to have been donated in the mid-19th century by John Wickham, who was a shipmate of Darwin鈥檚.

Scott Thomson, a herpetologist working in Canberra, had been researching Harriet鈥檚 history for some time and knew that she had come to the Australia Zoo via the Brisbane Botanical Gardens. Together with Harriet鈥檚 owners, Thomson published a paper highlighting Harriet鈥檚 connection with Wickham (Intermontanus, vol 4, p 33). The authors also noted that Darwin and two of his shipmates were known to have taken live juvenile tortoises from the Galapagos Islands. Thomson and others drew the conclusion that Harriet was one of these very same creatures, given by Darwin to Wickham, who must have then taken her to Australia.

The story of Harriet having been Darwin鈥檚 tortoise has been reported as an established fact by the world鈥檚 media for nearly a decade. This is how her age of 173 was calculated, based on her being about four when Darwin collected her 鈥� a fact repeated in Guinness World Records. But this tale has always struck me as a little too good to be true.

My first step was to find out more about Harriet鈥檚 history. Between the Brisbane Botanical Gardens and her current residence in Queensland, Harriet had belonged to another zoo, owned by David Fleay (a celebrity naturalist, one of whose claims to fame was having been bitten on the buttocks by the last surviving Tasmanian tiger). Harriet had long gone by the name of Harry, but Fleay spotted that she was, in fact, female. Fleay had also investigated her history and heard a first-hand account of her being in the Gardens in around 1870.

Unfortunately it was not possible to push back Harriet鈥檚 story any further, as I found that the records relating to Brisbane Botanical Gardens鈥� early history had been destroyed by a flood in 1893. A search of Wickham鈥檚 papers in Sydney and some Brisbane city records held by the British Library was also unproductive.

My next step was to turn to events during Beagle鈥檚 voyage. During his time on the Galapagos, Darwin was fascinated by the giant tortoises and wrote about them in his science notebook and diary. He also ate quite a few, and even tasted the dilute urine from a tortoise鈥檚 bladder, following local custom. The liquid, he recorded, was 鈥渙nly very slightly bitter鈥�.

Darwin collected a juvenile from San Salvador Island as a pet, and his servant, Syms Covington, took another from Santa Maria Island (see Graphic). Robert FitzRoy, the Beagle鈥檚 fiery captain, collected two juveniles from Espa帽ola Island, and he seems to have been somewhat obsessed with them, plotting their growth in his diary. Harriet could theoretically have been any one of the four pets, so I tried to discover what happened to them after the Beagle docked in Plymouth, England, in October 1836.

In the immediate wake of the voyage, Darwin mentions his tortoises only once, in a manuscript now lodged in Cambridge University Library. Soon after his arrival home, Darwin recorded in an inventory of Beagle specimens that he had the following: 鈥淐ovington鈥檚 little tortoise (Charles Island) [also known as Santa Maria Island]. Mine from James [also known as San Salvador Island].鈥�

In the months after his return, Darwin travelled about England, visiting his relatives and some old scientific acquaintances. He is unlikely to have carried a small tortoise with him. His pets would probably have remained on board the Beagle, being looked after by Covington. The faithful servant stayed on the ship until just before Christmas 1836, while the enormous collection of wildlife was unloaded.

In early 1837 the tortoises were to become relevant to Darwin鈥檚 musings about the 鈥渢ransmutation of species鈥�. The governor of the Galapagos had boasted to Darwin that he could tell from which island a tortoise came merely by looking at the shape of its shell. Darwin began to speculate whether the geographical isolation of animals and plants on newly formed islands such as the Galapagos could lead to the development of new species. He knew the four juvenile tortoises had been collected from three different islands, and he wondered if they would bear out the governor鈥檚 claim.

Darwin gathered together the four young tortoises and presented them to John Gray, the British Museum鈥檚 reptile expert, in the hope that he might be able to find specific differences between the animals. Gray could not, for as Darwin later noted in The Voyage of the Beagle: 鈥淭he specimens which came home in the Beagle were too small to institute any certain comparison.鈥� Fortunately for science, Darwin was later able to support his geographical isolation theory by analysing the Galapagos finches collected on the voyage.

But what of the tortoises? Wherever they ended up, the colder British climate must have made their existence precarious. Zoo records suggest that no giant tortoises brought to Britain in the 19th century survived for more than a few years. Captain FitzRoy鈥檚 specimens had died by March 1837.

According to the legend surrounding Harriet, Darwin and Covington鈥檚 pair must have stayed with Darwin for several years before being taken to Australia by Wickham in about 1841.

But how likely is this? In March 1837, Darwin settled in London at his brother鈥檚 house, a tall building in Great Marlborough Street with only a small garden. It was hardly an ideal situation for a rapidly growing giant tortoise that would need to be kept inside in winter. Also, at no point in any of his journals, notebooks or letters does the revered naturalist mention owning any pet tortoises.

At this point the case in favour of Darwin having held onto his pets for any length of time after the Beagle voyage is at best thin. What could have happened to them? Darwin himself provided a clue. In 1874 he replied to a letter from Albert G眉nther, the keeper of the British Museum鈥檚 zoological section, who had become obsessed with giant tortoises (a feeling I鈥檓 not unfamiliar with). G眉nther was curious as to the whereabouts of the Beagle specimens. Darwin responded:

My Dear G眉nther,

I find that I did not bring home any tortoises from the Galapagos, as several were brought home by the surgeon and FitzRoy. I have vague remembrance that specimens were given to the Military Institution in Whitehall鈥�

Yours very sincerely,

Charles Darwin

Darwin鈥檚 denial of having brought back any tortoises is completely at odds with his own notes. But it does suggest that his involvement with them was brief. Could he have donated them to the Military Institution he cites? I managed to trace some of the archives from the now-closed institution, but sadly they don鈥檛 mention any tortoises.

My research into Wickham鈥檚 life has also cast doubt on his putative role in this saga. Wickham left the Navy after surveying the eastern coast of Australia in 1841. He is thought to have travelled to England one last time before returning to Sydney to marry a local girl. According to the story, that is when he brought back the then adult-sized Harriet. But Wickham鈥檚 letters and his presence on the 1841 Australian census strongly suggest that he did not return to England but instead remained living in Sydney. Indeed, Darwin records that the first time he and Wickham met after the two left the Beagle was at a reunion in London in 1862 organised by another shipmate.

While my literary research was leading to a dead end, Thomson informed me of a different kind of research that seemed to settle the matter. In 1998, Scott Davis, a researcher at Texas A&M University, carried out an analysis of Harriet鈥檚 mitochondrial DNA. The results have not been published, but I tracked down a summary in a PhD thesis by one of Davis鈥檚 students. They prove Harriet鈥檚 identification as Geochelone nigra porteri, the subspecies that comes exclusively from Santa Cruz Island in the Galapagos.

This is crucial because Darwin鈥檚 hunch about island speciation turned out to be right: most of the Galapagos Islands do have their own subspecies of giant tortoise. And sadly the four Beagle tortoises were collected from Espa帽ola, Santa Maria and San Salvador islands 鈥� not Santa Cruz. Ironically, then, the very facts that support Darwin鈥檚 own theory of speciation refute Harriet鈥檚 noble provenance.

Record breaker

This reasoning does not convince Thomson, however, who points out that the residents of Santa Maria, where Darwin collected his pet, were known to travel regularly to other islands to gather tortoises for food. Perhaps Darwin had picked up an imported Santa Cruz tortoise instead of the local subspecies?

But this is disputed by Frank Sulloway, a science historian at the University of California, Berkeley, and an expert on the Galapagos tortoise and the Beagle expedition. He told me most of the tortoises taken for food were from San Salvador, where there was a supply of natural salt that could be used to preserve the meat. In addition, it is unlikely that the inhabitants of Santa Maria would have visited Santa Cruz because of its impenetrable terrain and lack of fresh water.

The genetic analysis does have one silver lining, however. Harriet鈥檚 DNA shows significant differences to that of tortoises living today on Santa Cruz, suggesting that she was born before the great cull of this species that took place in the years after Darwin鈥檚 visit in 1835. That would make her at least 169 years old, so happily Harriet retains her place in Guinness World Records.

It is still possible that Harriet was once owned by Wickham. But she was probably taken from the Galapagos by a passing whaling ship: many other Galapagos tortoises found their way to Australia (and much farther afield) via this route.

It is highly unlikely that Darwin and Harriet ever had the pleasure of meeting, although it is conceivable that she was alive at the time of his visit to the Galapagos. Perhaps Harriet watched from Santa Cruz Island as the Beagle鈥檚 sails carried it away from the archipelago, carrying the biological revolutionary and his precious collection of specimens homeward and into the annals of history.