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A very full discussion of the ecological disaster in Guam has recently been provided by David Quammen in his book The Song of the Dodo: Island Biogeography in an Age of Extinction. He describes how the native bird populations, which had been numerous and varied in 1960, were brought to the verge of extinction little more than twenty years later. No one at the time had any idea what was causing this:
Where had the birds gone? What was killing them? Had they been devastated by an exotic disease, as in Hawaii? Had they been poisoned by cumulative doses of DDT? Had they been eaten by feral cats and tree-climbing pigs and Japanese soldiers who refused to surrender?
It was only in 1986 that Guam’s ‘ecological murder mystery’ was solved and the bird-eating tree snake, Boiga irregularis, was proved to be the culprit. There had been a spreading explosion of these snakes, starting in the southern savannahs in the 1950s, reaching the northern forests by 1980, correlating precisely with the wave of bird extinctions. It was estimated in the mid-eighties that there were now thirteen thousand snakes to the square mile, three million on the whole island. Having consumed all the birds by this time, the snakes turned to other prey – skinks, geckos, other lizards, and even small mammals – and these too have shown catastrophic declines. Going with this there has been a vast increase in the numbers of orb-weaving spiders (I saw their intricate webs everywhere), probably due to the decline of the lizards. Thus the inauguration of what ecologists call a trophic cascade, the accelerating imbalance of a previously balanced ecosystem.
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Lynn Raulerson had told me of something even rarer, an immense tassel fern, Lycopodium phlegmaria, which used to be common in the forest, but had now almost vanished, because most specimens had been poached for cultivation as house plants. Both this and the great ribbon fern are also to be found in Australia, and Chamberlain, while cycad hunting there, was fascinated by these and wrote of them in his 1919 book The Living Cycads:
The immense Lycopodium phlegmaria, the ‘tassel fern,’ with tassel-like cluster of cones, and Ophioglossum pendulum, the ‘ribbon fern,’ were the most interesting features of the epiphytic vegetation of the treetops. If a tree with such specimens was a foot or less in diameter the bushmen were likely to cut it down; if larger they would climb; but when they found that fine, uninjured specimens were worth three pence or even six pence, a climb of eighty feet was not at all objectionable.
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It is sometimes said (the term goes back to Charcot) that patients with Parkinson’s disease have a ‘reptilian’ stare. This is not just a picturesque (or pejorative) metaphor; normal access to the motor functions, which gives mammals their delicate motor flexibility, is impaired in parkinsonism; this leads to alternations of extreme immobility with sudden, almost explosive motion, which are reminiscent of some reptiles.
Parkinson himself was a paleontologist, as well as a physician, and his 1804 book, Organic Remains of a Former World, is one of the great pioneer texts of paleontology. One wonders whether he may have partly regarded parkinsonism as an atavism, a reversion, the uncovering, through disease, of an ancestral, ‘antediluvian’ mode of function dating from the ancient past.
Whether or not this is so of parkinsonism is arguable, but one can certainly see reversion to, or disclosure of, a variety of primitive behaviors in post-encephalitic syndromes on occasion, and in a rare condition, branchial myoclonus, arising from lesions in the brain stem. Here there occur rhythmic movements of the palate, middle-ear muscles, and certain muscles in the neck – an odd and unintelligible pattern, until one realizes that these are the only vestiges of the gill arches, the branchial musculature, in man. Branchial myoclonus is, in effect, a gill movement in man, a revelation of the fact that we still carry our fishy ancestors, our evolutionary precursors, within us.
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About five years ago, John became intrigued by the number of lytico-bodig patients with gaze palsies. His colleague Terry Cox, a neuro-ophthalmologist, confirmed this with further eye examinations and found that half of these patients also showed strange tortuous tracks in the retina (these cannot easily be seen with an ordinary ophthalmoscope, but only with indirect ophthalmoscopy – and thus would escape notice on a routine eye exam). The tracks seem to affect just the upper layer of retinal pigment, and to cause no symptoms.
‘This retinal pigmentary epitheliopathy,’ John said, ‘is confined to the Chamorros – it has never been observed in a Caucasian immigrant, or in Filipinos, who have lived here since the 1940s. It’s rare in anyone under fifty – the youngest person we’ve seen with it was born in 1957. It’s present in twenty percent of Chamorros over the age of fifty; but in fifty percent of those with lytico-bodig. We have been following patients who showed RPE in the early 1980s, and more than two-thirds of them have gone on to develop lytico-bodig within ten years.
‘The condition doesn’t seem to be progressive; it’s more like the scar of some trauma to the eye many decades ago. We wonder if it could be a marker for the lytico-bodig, something which came on at the same time as the disease – even though we are only picking it up now. We are checking now to see if there are any similar findings in patients with PSP or post-encephalitic parkinsonism.
‘The tracks have some resemblance to those made by the larvae of a botfly, but we don’t have any botflies on Guam. Maybe the tracks are made by the larvae of some other fly – perhaps one which transmitted a virus that caused the lytico-bodig. Or maybe it’s an effect of a toxin. We don’t yet know if it is unique to the lytico-bodig or not, or whether it is significant at all. But all these coincidences are tantalizing, and this is another thing that makes me think that the lytico-bodig could be caused by an organism, a virus – perhaps one transmitted by an otherwise unobjectionable parasite.’
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The term ‘cynomolgus’ means, literally, ‘dog-milking.’ The Cy-nomolgi were an ancient human tribe in Libya. Why this name should be given to some macaques (which are also known as ‘crab-eating macaques’) is unclear, though John Clay suggests that a better translation might be ‘dog-suckling,’ as macaques may indeed suckle other animals.