The Island of the Colorblind

Stevenson and Norstog, along with other researchers (Karl Niklas, Priscilla Fawcett, and Andrew Vovides), have confirmed this hypothesis in great detail. They have observed that weevils feed and mate on the outside of the male cone and then enter it, continuing to feed not on the pollen, but on the bases of the microsporophylls. Their eggs are laid, and larvae hatched, inside the microsporophylls, and the adult weevils finally chew their way out through the tips of the sporophylls. Some of these weevils go to the female cones, which exude a special warmth and aroma when they are ready for pollination, but the weevils cannot feed here, since the female cones are toxic to the insects. Crawling into the female cone through narrow cracks, the weevils are divested of their pollen and, finding no reason to stay longer, they return to the male cones.

The cycad thus depends on the weevil for pollination, and the weevil on the cycad cones for warmth and shelter – neither can survive without the other. This intimate relationship of insects and cycads, this coevolution, is the most primitive pollination system known and probably goes right back to the Paleozoic, long before the evolution of flowering plants, with their insect-attracting scents and colors.

(A variety of insects can pollinate cycads, mostly beetles and weevils, though one species of Cycas is pollinated by a bee – giving the possibility, one likes to think, of a delicious cycad honey.)

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One cannot think of these beautiful adaptations without feeling how excellent cycads are, in their own way, and how meaningless it is to see them as ‘primitive’ or ‘lower’ plants, inferior in the scale of life to ‘higher’ flowering plants. We have this almost irresistible sense of a steady evolutionary advance or progress (culminating, of course, in nature’s ‘highest’ product – ourselves), but there is no evidence of any such tendency, any global progress or purpose, in nature itself. There is only, as Darwin himself insisted, adaptation to local conditions.

No one has written of our illusions about progress in nature with more wit and learning than Stephen Jay Gould, especially in his recent book, Full House: The Spread of Excellence from Plato to Darwin. They lead us, he writes, to a false iconography of the world, so that we see the Age of Ferns succeeded by the Age of Gymnosperms, succeeded by the present Age of Flowering Plants, as if the earlier forms of life had ceased to exist. But while many early species have been replaced, others continue to survive as highly successful, adaptable life forms, as with ferns and gymnosperms, which occupy every niche from rain forest to desert. If anything, we are really, Gould insists, in the Age of Bacteria – and have been for the last three billion years.

One cannot look at a single lineage, whether of horses or hominids, and come to any conclusions about evolution or progress, as Gould shows. We must look at the total picture of life on earth, of every species, and then we will see that it is not progress which characterizes nature but rather infinite novelty and diversity, an infinity of different adaptations and forms, none to be seen as ‘higher’ or ‘lower.’

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Darwin was the first to argue that dispersal of seeds by sea water might be an important means of their distribution, and made experiments to explore their ability to float and survive salt water. Many seeds, he found, had first to dry but then might float for remarkably long periods: dried hazelnuts, for example, floated for ninety days and afterwards germinated when planted. Comparing these time periods with the rates of ocean currents, Darwin thought that thousand-mile ocean journeys might be common for many seeds, even if they had no special flotation layer (like cycad seeds). ‘Plants with large seeds or fruit,’ he concluded, ‘generally have restricted ranges, fand] could hardly be transported by any other means.’

Driftwood, he noted, might sometimes serve as a transport across the seas, and perhaps icebergs too. He speculated that the Azores had been ‘partly stocked by ice-borne seeds’ during the glacial epoch. But there is one form of oceanic transport, Lynn Raulerson suggests, which Darwin did not consider (though he would have been fascinated had it come to his attention), and this is transport by rafts of pumice, blown into the ocean by volcanic eruptions. These may float for years, providing transport not only for large seeds but for plants and animals as well. A vast pumice raft, stretching across the horizon, with coconut palms and other vegetation, was reportedly seen off Kosrae three years after Krakatau blew.