1996 - The Island of the Colorblind

by Oliver Sacks

  If the cycads conjured up for me the lush forests of the Jurassic, a very different, much older vision rose before me with the Psilotum: the bare rocks of the Silurian – a quarter of a billion years earlier, when the seas teemed with great cephalopods and armored fish and eurypterids and trilobites, but the land, apart from a few mosses and lichens, was still uninhabited and empty.87 Psilophytes, stiff stemmed as no alga had ever been, were among the first colonizers of the bare land. In the dioramas of ‘The First Life on Land’ I so loved as a child, one could see panting lungfish and amphibious tetrapods emerging from the primordial waters, climbing aboard the now-green margins of the land. Psilophytes, and other early land plants, provided the soil, the moisture, the cover, the pasture, without which no animal could have survived on land.

  A little farther on, I was startled to see a large accumulation of empty, broken coconut shells on the ground, but when I looked around, there were no coconut palms to be seen, only cycads and pandanus. Filthy tourists, I thought – must have come in and thrown these husks here; but there were few tourists on Rota. It seemed odd that the Chamorros, who are so respectful of the jungle, would leave a pile of refuse here. ‘What is this?’ I asked Tommy. ‘Who brought all these shells here?’

  ‘Crabs,’ he said. Seeing my confusion, he elaborated. ‘These large coconut crabs come in. The coconut trees are over there.’ He gestured toward the beach, a few hundred yards away, where we could just see a grove of palm trees. ‘The crabs know they will be disturbed if they eat them by the beach, so they bring them over here to eat.’88

  One shell had a huge hole, as if it had been bitten in half. ‘This must have been a real big crab to do this,’ Tommy observed, ‘a monster! The crab hunters know when they find coconut shells like this that there are coconut crabs all around, and then we search, and then we eat them – I would like to catch the crab that did this!

  ‘Coconut crabs love the cycads, too. So when I come out to gather the cycad fruit, I bring along a bag for crabs too.’ With his machete, Tommy cut through the undergrowth, making a path. ‘This is good for the cycads – it gives them room to grow.’

  ‘Feel this cone!’ Tommy said, as we came to a large male plant – I was surprised to find it warm to the touch. ‘It is like a furnace,’ said Tommy. ‘Making the pollen gives it heat – you can really feel it as the day cools, in the evening.’ Botanists have known for about a century (and cycad gatherers, of course, for much longer) that the cones may generate heat – sometimes twenty degrees or more above the ambient temperature – as they ready for pollination. The mature cones produce heat for several hours each day by breaking down lipids and starches within the cone scales; it is thought that the heat increases the release of insect-attracting odors, and thus helps in the distribution of pollen. Intrigued by the almost-animal warmth of the cone, I hugged it, impulsively, and almost vanished in a huge cloud of pollen.

  In his Useful Plants of the Island of Guam Safford has much to say about Cycas circinalis – its role in Chamorro culture, its use as food; but ‘its chief interest,’ he adds (one remembers that he is a botanist here), ‘lies in the structure of its inflorescence and the manner of its fructification.’ At this point he cannot suppress a special enthusiasm and excitement. He describes how the pollen settles on the naked ovules and sends a tube down into them, within which the male germ cells, the spermato-zooids, are produced. The mature spermatozooids are ‘the largest known to occur in any animal or plant. They are even visible to the naked eye.’ He goes on to describe how the spermatozooids, which are motile, powered by cilia, enter the egg cell and fuse with it totally, ‘cytoplasm with cytoplasm, nucleus with nucleus.’

  These observations were quite new at the time he was writing; for though cycads had been described by Europeans in the seventeenth century, there had been much confusion as to their origins and place in the vegetable kingdom. It was only the discovery of their motile spermatozooids, by Japanese botanists in 1896, that afforded the first absolutely clear evidence of their kinship (and thus of their whole group, the gymnosperms) with ferns and other ‘lower’ spore-bearing plants (which also have motile spermatozooids). The importance of these discoveries, made only a few years before he wrote, is strong and fresh for Safford, and enriches his account with a feeling of intellectual fervor. Longing to see this visible act of fecundation for myself, I pulled out my hand lens and peered into the male cone, then into the notched ovules, as if the whole drama might be enacted before my eyes.

  Tommy and Beata seemed amused by my barmy enthusiasm, and burst out laughing – for them, basically, cycads are food. Their interest is not in the male plant, its pollen, or the giant spermatozooids which are produced within the ovules – these, so far as they are concerned, are just instrumental in getting the female plants fertilized, so that they may bear their great, glossy, plum-sized seeds. These they will gather, and slice, and wash, and wash again, and finally dry and grind to form the finest fadang flour. Like connoisseurs, choosing only the best, Tommy and his mother went from tree to tree – this one was unfertilized, that one unripe, but there was a carpophyll of heavy ripe seeds, a cluster of a dozen or more. Tommy sliced the machete, and caught the cluster as it fell. He poked another cluster, too high to chop, with a stick he was carrying, and asked me to catch the seeds as they fell. I found my fingers covered with sticky white sap. ‘That’s really poisonous,’ said Tommy. ‘Don’t lick your fingers.’

  It was not just the reproductive structures of cycads which so fascinated me as a boy, or the sheer gigantism that seemed characteristic of the group (the biggest spermatozooids, the biggest egg cells, the biggest growing apices, the biggest cones, the biggest everything in the vegetable world) – though (I could not deny it) these had a certain appeal. It was rather the sense that cycads were brilliantly adaptable and resourceful life-forms, full of unusual capacities and developments which had enabled them to survive for a quarter of a billion years, when so many of their contemporaries had fallen by the way. (Maybe they had been so poisonous to fend off the dinosaurs which ate them, I used to speculate as a child – maybe they had been responsible for the dinosaurs’ extinction!)

  It was true that cycads had the largest growing apices of any vascular plant, but, equally to the point, these delicate apices were beautifully protected by persistent leaf bases, enabling the plants to be fire resistant, everything resistant, to an unusual degree, and to reshoot new fronds, after a catastrophe, sooner than anything else. And if something did nonetheless befall the growing apices, the plants had an alternative, bulbils, which they could fall back on. Cycads could be pollinated by wind – or insects, they were not choosy: they had avoided the path of overspecialization which had done in so many species over the last half-billion years.89 In the absence of fertilization, they could propagate asexually, by offsets and suckers (there was a suggestion too that some plants were able to spontaneously change sex). Many cycad species had developed unique ‘cor-raloid’ roots, where they symbiosed with blue-green algae, which could fix atmospheric nitrogen for them, rather than relying solely on organic nitrogen from the soil. This struck me as particularly brilliant – and highly adaptive should the seeds fall on impoverished soils; it had taken legumes, flowering plants, another hundred million years to achieve a similar trick.90

  Cycads had huge seeds, so strongly constructed and so packed with nourishment that they had a very good chance of surviving and germinating. And they could call on not just one but a variety of vectors for their dispersal. All sorts of smaller animals – from bats to birds to marsupials to rodents – attracted by the brightly colored, nutritious outer coat, would carry them off, nibble at them, and then discard the seed proper, the essential inner core, unharmed. Some rodents would squirrel them away, bury them – in effect, plant them – increasing their chances of successful germination. Large mammals might eat the entire seed – monkeys eating individual seeds, elephants entire cones – and void the endosperm, in its tough nut, unharmed in their du
ng, often in quite far-removed places.

  Beata was examining another cycad plant, speaking softly in Chamorro to her son. When the rains come, she was saying, the seeds can float. You can tell where they float to in the jungle, because new cycad plants sprout up all along the little rivers and streams. She thinks they float in the sea as well, and that this is how they get to other islands. As she spoke she split open a seed, and showed me the spongy flotation layer just beneath the seed coat – a feature peculiar to the Marianas cycad and the other littoral species of Cycas, which grow in coastal and near-coastal forests.

  Cycads have spread to many different ecoclimes, from the humid tropical zones they flourished in during the Jurassic, to near-deserts, savannahs, mountains, and seashores. It is the littoral species which have achieved the widest distribution, for their seeds can float and travel great distances on ocean currents. One of these species, Cycas thouarsii, has spread from the east coast of Africa to Madagascar, to the Comoros and the Seychelles. The other littoral species, C. circinalis and C. rumphii, seem to have originated in the coastal plains of India and Southeast Asia. From here their seeds, borne on ocean currents, have fanned out across the Pacific, colonizing New Guinea, the Moluccas, Fiji, the Solomon Islands, Palau, Yap, some of the Carolines and Marshalls – and, of course, Guam and Rota. And as the buoyant seeds of the ancestral species have settled on different islands, they have begotten striking variants, some of which have diverged now, in a manner which would have delighted Darwin, to half a dozen new species or more.91

  Although cycads vary greatly in size and character, from sixty-foot trees to delicate plants with underground rhizomes, many of the sixty-odd species of Cycas do not look that different (as opposed, say, to the species of Zamia, which vary so widely, and wildly, in appearance that one has difficulty believing they all belong to the same genus) – and that one of these species should be mistaken for another is very understandable. Indeed, I had been surprised, after my Guam visit, when I went into a nursery in San Francisco, thinking to buy a Cycas circinalis for a wedding present – and was shown a plant which was clearly different from the Guam one. When I queried the nursery owner, she indignantly insisted that it was a circinalis, and suggested that perhaps what I had seen in Guam was not. It seemed astonishing that there should be such confusion even among plant experts – but David Jones, in his Cycads of the World, speaks of the complexities of identifying the island cycads:

  The plants adapt over generations in various small ways to their own particular environmental circumstances and local climate.…The situation is further complicated by new arrivals being regularly carried on ocean currents. On reaching maturity these recent plants can hybridize with existing plants and the resulting complex range of variation may defy taxonomic separation. Thus C. circinalis must be regarded as an extremely variable species.

  And indeed, since I returned from Guam, I have learned that the cycad peculiar to Guam and Rota, regarded for centuries as a variety of C. circinalis, has recently been reclassified as a distinct species within the C. rumphii ‘complex,’ and renamed C. micronesica.92

  C. micronesica, it seems, is distinctive not only morphologically, but chemically and physiologically too – with a notably higher content of carcinogenic and toxic substances (in particular, of cycasin and BMAA) than any other cycad which has been analyzed. Thus cycad eating, relatively benign elsewhere, may be peculiarly dangerous on Guam and Rota – and the Darwinian process which has brought a new species into the world may also, conceivably, be contributing to a new human disease.

  I find myself walking softly on the rich undergrowth beneath the trees, not wanting to crack a twig, to crush or disturb anything in the least – for there is such a sense of stillness and peace that the wrong sort of movement, even one’s very presence, might be felt as an intrusion, and, so to speak, anger the woods. Tommy’s words, earlier, came back to me now. ‘All my life,’ he said, ‘I was taught to walk backwards in the jungle, and not to destroy anything…I have the attitude that these plants are alive. They have powers. They can invoke some kind of a disease to you if you do not respect them…’ The beauty of the forest is extraordinary – but ‘beauty’ is too simple a word, for being here is not just an esthetic experience, but one steeped with mystery, and awe.

  I would have similar feelings as a child, when I lay beneath the ferns, and later, when I entered through the massive iron gates at Kew – a place which was not just botanical for me, but had an element of the mystical, the religious too. My father once told me that the very word ‘paradise’ meant garden, spelling out for me the four letters (pe resh dalet samech ) of pardes, the Hebrew word for garden. But gardens, Eden or Kew, are not the right metaphors here, for the primeval has nothing to do with the human, but has to do with the ancient, the aboriginal, the beginning of all things. The primeval, the sublime, are much better words here – for they indicate realms remote from the moral or the human, realms which force us to gaze into immense vistas of space and time, where the beginnings and originations of all things lie hidden. Now, as I wandered in the cycad forest on Rota, it seemed as if my senses were actually enlarging, as if a new sense, a time sense, was opening within me, something which might allow me to appreciate millennia or eons as directly as I had experienced seconds or minutes.93

  I live on an island – City Island in New York – surrounded by the brilliant transient artifacts of man. And yet each June, without fail, horseshoe crabs come up from the sea, crawl on the beach, mate, deposit eggs, and then slowly swim away again. I love to swim in the bay alongside them; they permit this, indifferently. They have crawled up to the shores and mated every summer as their ancestors have done since the Silurian, 400 million years ago. Like the cycads, the horseshoe crabs are rugged models, great survivors which have endured. When he saw the giant tortoises of the Galapagos, Melville wrote (in The Encantadas ):

  These mystic creatures…affected me in a manner not easy to unfold. They seemed newly crawled forth from beneath the foundations of the world.…The great feeling inspired by these creatures was that of age – dateless, indefinite endurance.

  Such is the feeling inspired, for me, by the horseshoe crabs each June.

  The sense of deep time brings a deep peace with it, a detachment from the timescale, the urgencies, of daily life. Seeing these volcanic islands and coral atolls, and wandering, above all, through this cycad forest on Rota, has given me an intimate feeling of the antiquity of the earth, and the slow, continuous processes by which different forms of life evolve and come into being. Standing here in the jungle, I feel part of a larger, calmer identity; I feel a profound sense of being at home, a sort of companionship with the earth.94

  It is evening now, and as Tommy and Beata go off to gather some medicinal plants, I sit on the beach, looking out to sea. Cycads come down almost to the water’s edge, and the strand is littered with their gigantic seeds, along with the tough egg cases of sharks and rays, which are shaped like bizarre fortune cookies. A light wind has sprung up, rustling the leaves of the cycads, blowing up little ripples on the water. Ghost crabs and fiddler crabs, hidden in the heat of the day, have emerged and are darting to and fro. The chief sound is the lapping of waves on the shore, lapping as they have done for billions of years, ever since land rose out of the water – an ancient, soothing, hypnotic sound.

  I look at the cycad seeds curiously, thinking of Beata’s words, how they float and can perhaps survive long immersion in sea-water. Most, no doubt, have dropped from the trees above me, but some, perhaps, are nomads, brought here across the sea from Guam, or more distant islands – perhaps even Yap or Palau, or beyond.

  A large wave comes in, lifts a couple of the seeds, and they float, bobbing, by the shore. Five minutes later, one of the seeds has been cast up again on the shore, but the other is still bobbing atop the waves, a few feet from land. I wonder where it will go, whether it will survive, will be cast back here on Rota, or taken hundreds, perhaps thousands, of miles to another
island in the Pacific. Ten minutes more and I can no longer see it – it is launched, like a little ship, on its journey on the high seas.

  Notes

  1Most of the statues of Easter Island do not, in fact, face the sea; they face away from the sea, toward what used to be the exalted houses of the island. Nor are the statues eyeless – on the contrary, they originally had startling, brilliant eyes made of white coral, with irises of red volcanic tuff or obsidian; this was only discovered in 1978. But my children’s encyclopedia adhered to the myth of the blind, eyeless giants staring hopelessly out to sea – a myth which seems to have had its origin, through many tellings and retellings, in some of the early explorers’ accounts, and in the paintings of William Hodges, who travelled to Easter Island with Captain Cook in the 1770s.

  2Humboldt first described the enormous dragon tree, very briefly, in a postscript to a letter written in June 1799 from Teneriffe:

  In the district of Orotava there is a dragon-tree measuring forty-five feet in circumference…Four centuries ago the girth was as great as it is now.

  In his Personal Narrative, written some years later, he devoted three paragraphs to the tree, and speculated about its origin:

  It has never been found in a wild state on the continent of Africa. The East Indies is its real country. How has this tree been transplanted to Teneriffe, where it is by no means common?

  Later still, in his ‘Physiognomy of Plants’ (collected, with other essays, in Views of Nature ) he devoted nine entire pages to ‘The Colossal Dragon-Tree of Orotava,’ his original observations now expanded to a whole essay of rich and spreading associations and speculations: