Of course these two questions could not at first be either asked or answered at the same time: biologists had forty-four years with only one site in front of them that they were able to study. In those early days there could thus be no kind of comparison. Ever since 1930 the three-island remnants of greater Krakatoa (if the scorched masses of Verlaten and Lang islands – Sertung and Panjang respectively – are to be counted, in ecological terms, as relics of the old volcano) and the brand-new single island of Anak Krakatoa have been standing there, beside one another, inviting inspection and comparison. Biologists from then onwards have been able to examine each, and try to work out if the mechanics of life-recovering-from-ruin (on the old islands) and life-starting-from-scratch (on their new neighbour) operated in the same way, in similar ways, or in altogether different fashions.
It is a study that continues today. More than a century after the creation in the Sunda Strait of what has turned out to be the extraordinarily useful biological laboratory of the new Krakatoa community, not all the answers are in, by a long chalk.
In considering the recovery of Krakatoa itself – which was all that could initially be considered – nineteenth-century scientists had one significant problem: because they could not be entirely certain what kinds of life had existed on the island before the eruption, they could not say – in what direction the island was likely to attempt to recover – what state it might be under pressure to return to.
Clearly it had once been richly endowed: John Webber's famous sketch, * drawn when Captain Cook's expedition made its melancholy † pause there in 1780, shows palms and ferns in gloriously feral abundance. Present-day botanists have pored over the picture to try to ascertain the various species Webber depicted: there is a type of grass that returned to the island in 1920, a palm-tree called Licuala spinosa that came back in 1982, and a fern that was first seen again in 1987.
Following the Resolution's sojourn, there had been some cultivation on the northern flank of the island, with a scattering of people (once even a small prison), and with goats, a vegetable garden and trees grown for firewood. The very few scientists who had landed on Krakatoa during the seventeenth, eighteenth and early nineteenth centuries had collected specimens of grasses, pepper plants, orchids and mahogany trees, as well as an unusual kind of parasitic mistletoe. One Dutch biologist went there looking for snails and found five types.
But no one had ever tried to produce a definitive systematic list of the entire populations that existed before the eruption: all that could be said with certainty was that Krakatoa had been covered with a snail-rich, orchid-rich, pepper-infested and grass-floored tropical rain forest, more or less similar to that found in today's Sumatra.
Despite this irksome lack of knowledge about what had gone before, the biologists from around the world who headed off in the direction of Sunda Strait knew that what awaited them in the aftermath of the eruption could well be fascinating. It would, one of those heading to the island wrote, ‘be very interesting to follow step-by-step the progress of the development of new life on this land now dead but which, in a few years, thanks to the intense heat of the sun and the abundance of equatorial rains, will surely have been recovered in its green mantle’.
The scientists fanned out with dispatch – and with care. Just like investigators who take elaborate precautions not to contaminate the scene of a disaster or a crime, so most of the biologists who came to Krakatoa did their best not to sully, with such usual contaminants as bacteria or seeds or rats or measles, the rare post-eruptive purity of the islands. It was a purity that remained untouched for some considerable while.
Rogier Verbeek was the first on to the island, in October, a scant six weeks after the eruption. And he was too early: when he first clambered on to the dusty shore, at a time when the islands' floors were still almost too hot to touch and mud flows were still pouring from the lava cliffs, he could see no living thing, nor any evidence that anything alive might be lurking near by. From a personal point of view it was a shame: given his heroic dedication to the story of the eruption, it might have seemed appropriate for him to be the first to find clear evidence of new life.
In fact it was a Belgian biologist named Edmond Cotteau who spotted the first stirrings, when he visited with a French government-sponsored expedition six months later, in May 1884. The leader of the expedition had reported finding much the same lifeless devastation as seen by Verbeek: ‘the magnificent vegetation which had been so often admired there remains nothing but a chaos of enormous trunks, whitened and desiccated, among the surrounding desolation’. It was dangerous too: Rakata's main cliff was eroding fast, and rocks were rolling down its sides in a ceaseless tumble, making an unending noise ‘like the rattling of distant musketry’.
It took the men a frustratingly long time to find a sheltered beach out of range of the fusillades of bouncing boulders. But then Cotteau, who had walked southward from the eventual first landing site on the north-west corner of Rakata, and who had managed to get all the way around the point to what is now called Handl's Bay, suddenly spotted something.
It was nestled between two rocks, on an otherwise arid and seemingly death-filled spit of grey and dusty land. This was the very first living thing that could with certainty be said to have appeared after the catastrophe: and it was, Cotteau wrote with measured excitement, a microscopic spider. He looked hard for
Nephila maculata, a ballooning spider.
another, but could find only this single specimen. Yet significantly, and with a nice symbolism, ‘This strange pioneer of the renovation was busy spinning its web!’ The lonely little spider was hoping, in other words, that it would eventually be lucky enough to catch a fly.
The arachnid's optimism was admirable, considering the trauma that must have otherwise unsettled him. Yet as it happened (though whether it happened for this one animal we cannot say), it was an optimism that was not at all misplaced. For within months an abundance of life – and that almost certainly included at least the modest sufficiency of flies required to satisfy a small army of spiders – began to return to the islands, in earnest.
This first spider's appearance on the island – and then the appearance of many of the life forms that subsequently resettled Rakata – in time triggered a question that has continued to vex the biological community for the many years since. Was there a chance that some of the animals and plants that first appeared did already in fact still exist on Krakatoa, as survivors? Or had life on what remained of Krakatoa been utterly extirpated – had it really been blasted and bombed and withered by the searing heat, and then buried under a hundred feet of ash?
Life returns to the Krakatoa beaches: a coconut husk, a morsel of random flotsam, sprouts a shoot, ready to become island vegetation.
If this last was the more likely explanation, then all of the new life that went into the repopulating of the islands must have arrived on their shores and crags from across the intervening stretches of sea. And if this was the case – if all the newly established forms of life were newcomers, in other words – how, exactly, had they come?
Had this one spider been lurking in a crevice and, though perhaps badly singed, been sufficiently compos mentis to spin his web for M. Cotteau? Or had a passing seabird, the spider lodged in one of his claws, landed on the otherwise uninhabited island, and left the insect behind when it flapped off into the air again? Had the spider floated in on a coconut husk, clinging grimly to the mesh of hairs until all the bobbing stopped? Or had it been borne in on the air, wafted on the breezes?
Today it seems most likely that wafting was the means by which this one baby spider reached the sea-red shoreline of Rakata. It is well known now that some spiders and other wingless creatures have a propensity for ‘ballooning’ – extending a strand of thread of silk from their bodies and allowing the wind currents to catch it and bear it and each of the creatures off to an unknown destination. Ballooning spiders can travel effortlessly for scores of miles: the sea crossing to Rakat
a from either Java or Sumatra would take no more than a trivial few hours. And in drifting and wafting on the breezes, this creature becomes a member of what has recently – and delightfully – been named the aeolian plankton, windborne kin to the microscopic drifters of the sea. *
Once properly under way the rush of life returning to the islands was impressive in both its speed and abundance. Crews of passing ships first thought they saw patches of green about a year after the eruption. In June 1886 an expedition spent four days on Rakata, and found they were right: they counted no fewer than fifteen flowering plants and shrubs – mostly beach plants, suggesting that these at least had arrived by sea – two mosses and eleven ferns. The visitors also found a gelatinous layer of blue-green algae in a moist film on top of the volcanic ash: this layer – wherever it might have come from – probably helped spores to germinate, it was later thought, and provided some kind of support for young and feeble rootlets.
Clearly something had helped – because by the time a new set of visitors arrived the following year there had been a positive orgy of rampant growth. There were now dense fields of grasses, so tall that a man could hide himself. The variety of grasses included Java's well-known alang-alang, which is always the first to grow (conveniently) after a forest fire and (rather less so) after a farmer has cleared a field for planting. There were tufts of wild sugar-cane poking out of the ash piles, many more ferns than the eleven that had been counted the previous year, scores of types of sand-binding creepers, hibiscus plants, self-fertilizing orchids, a very recognizable red-leaved coastal tree known as the Indian Almond, three varieties of fig trees and a pine-like tree that the Australians named (for its resemblance to the lush plumage of their native cassowary bird) the casuarina.
By 1906 the forests were thickening, the trees maturing, the climb to the 2,000-foot summit becoming ever more difficult as proper forests began to cloak the mountainside. Parties of visitors now had to hack their way in, getting attacked en route by red and black ants and carpenter bees, being surrounded by swarms of colourful butterflies, slipping on large earthworms, taking pleasure in seeing kingfishers, nightjars, green pigeons, wood swallows, bulbuls and orioles. Some visitors had reported seeing a large monitor lizard, and said that coconut palms had returned and were lining Rakata's southern shore.
Ever since then the island has become entirely overgrown. Casuarina trees on the coast stand well over a hundred feet tall. The mixed forests inland are alive with birds (among which are, prettily, the Zebra Dove, the Pied Imperial Pigeon, the Greater Coucal, the White-bellied Fish-eagle, the Brahminy Kite, the Orange-bellied Flower-pecker, the Pied Triller, the Mangrove Whistler and the Magpie Robin), together with beetles and centipedes, geckos, dragonflies, grasshoppers and tree-dwelling snails, a pompilid wasp that is designed solely to hunt and kill spiders (to the consternation of the descendants of M. Cotteau's first find) and a large snake that was initially identified as a boa-constrictor but that later turned out to be the species of the somewhat more congenial reticulated python. *
And civilian mankind's arrival, which was not always as carefully choreographed as the visits of those early biologists, resulted in the introduction of less comely animals. In 1917 a German named Johann Handl, to take one of the stranger examples, arrived on the southern end of Rakata with his family and servants, and announced that he was settling on the old volcano as a pumice collector. He built himself a small house on Rakata during (and presumably to get away from) the Great War; he planted a garden and lived comfortably in this somewhat unusual hideaway for the following four years. But it turned out that he had, presumably inadvertently, brought along with him in his boat a breeding pair of most unwelcome guests. A substantial population of Rattus rattus, the black rat, is now happily established on the island, and makes mayhem among the nests of most of Rakata's coastal birds.
And as the years wore on, so the numbers and types of plants and animals on the Krakatoan remnants waxed and waned, and in time created for themselves (by the way of what outsiders call the law of the jungle) some kind of biological equilibrium – a state that is never perfectly reached, a kind of biological nirvana, endlessly sought in every kind of complex community, yet rarely entirely attained.
Herr Handl's garden, once abandoned, filled quickly with ten kinds of weed. In the early 1920s a number of newly discovered large bees, velvet ants, * fungus gnats, scoliid wasps, mosquitoes, crane flies, swallowtail butterflies, fruit bats and woodpeckers were found. In fact Rakata was shown, forty years after the eruption, to be home to fully 621 species of animal. And by 1931 there were fully one hundred species of spider, according to a British spider expert called Mr Bristowe – the number and variety of everything having swelled almost exponentially.
Assuming for the moment that most of what exists today on the three islands of Rakata, Panjang and Sertung was brought in from across the sea (and was not born out of hidden survivors of the islands' original population) – how did it all arrive?
That first spider, as mentioned, very probably was of the ballooning variety. Other creatures and plants invaded by quite different means – all of them, when taken together, offering a powerful demonstration of the insistence of life to burst forth wherever it can, all showing the unquenchable nature of the fire in what the more romantic of today's biologists like to call ‘the crucible of life’.
The first samples of colonizing greenery, for instance, the creeping beach plants and shrubs and the small coastal forests, came by sea, rafted across on driftwood and pumice and other debris, * or hitch-hiking in with birds that feed on fruit and then excrete the seeds. The pioneering plants found in the inland areas were almost certainly created from wind-borne or bird-borne spores or seeds – and they had to be tough enough to survive with very little water and in the full glare of the sun. (Both they and their sea-borne coastal cousins would have an additional advantage if they were hermaphroditic, and could get along in an environment somewhat wanting for sexual partners.) The presence of the thin veneer of blue-green algae helped and it may well have been the key to getting the inland plant populations properly under way. The figs, especially, were typical of what could be brought in by this method – their presence in abundance being evidence of the way the fig tree, once settled, then manages to propagate itself.
As the spread of those first plants increased, and as new ones were introduced and started to compete and then struggle for existence and room – as the botanical ecology of the island began to change, in other words – so the zoological ecology changed too. As the coastal grassland began to give way to casuarina forests, as the woods on the mountain's upper slopes began to get darker and wetter and danker, so the populations of animals altered. The butterflies and beetles and open-country birds and reptiles that were the first to colonize the island, and that positively liked its dryness, started to be replaced by forest animals, geckos and skinks, bats and birds – the hobby, the barn owl and the hawk-eagle – that favour shade and like to live in a warm world dripping with moisture.
The overall result, a century and more after the eruption, is the existence today of a group of islands that have a markedly different biological and botanical make-up from the two great landmasses that lie fifteen miles to the north (Sumatra) and the east (Java).
One example will suffice: on the Javanese and Sumatran mainland there are twenty-four species of termite. Six of these live in hardwood trees, seven live in the dead trunks of living trees, six in wet softwood and five make their nests in the soil. On Rakata Island, though, there are a total of only eight types of termite. Not one of them lives in the soil; only one likes to inhabit the dead parts of living trees, just two like softwood and by far the greatest number – five species – prefer to live out their days in hardwood trees alone. Just why this marked difference might be is still a topic for much reflection. Perhaps Rakata's soil is still too newly volcanic, or the dead wood is perhaps just not dead enough. Perhaps the environment is fresher, more raw – there must
be some good reason why termites do not much care for the island that once blew itself to pieces, and why they like the islands that have gone untouched for thousands of years.
Because of unanswered questions just like these, Krakatoa has remained for many decades the focus of intense studies worldwide, a fascination for a score or more of the world's leading botanists, and the target of expeditions and field-trips by the dozen. And yet, though the mechanics of the repopulation of the islands are now reasonably well established, the principal question that we set aside earlier remains sturdily only half answered: was the first population entirely fresh and new? Did it arrive on the devastated islands by sea and by air, coming from the volcanically wounded but far from biologically sterile outside? Or was it not really new at all? Did it start off with seeds or with living animals that somehow managed to survive the original inferno?
The controversy became so established a part of botanical lore that it long had a name: the Krakatoa Problem. Its central question – survivors or outsiders? – dogged entire generations of scientists, and was the trigger over the years for some bitter, angry, recriminatory and downright invective. Most of the ugly words swirled around the person of a forthright and feisty Dutchman named Cornelis Andries Backer, who held the delightfully titled post of ‘Botanist with Special Responsibility for the Flora of Java’ at the Buitenzorg Botanical Gardens; he first visited the islands in 1906.