The Best Australian Science Writing 2013 (25 page)

My father loved his orchids. He was very good at growing them too; he'd split them and feed them and get them to flower. Each new flower, a miracle. He tended them each morning before going to the hospital, shuffled them around in their places to rearrange the collection, fed them a special mixture with a
little watering can, snipped off dead roots. He'd exclaim when an orchid grew a bud, insist everybody have a look and admire, ooh and ah. In full flower they were allowed to come into the house, to perch in the middle of the dining table on a ceramic saucer. On full display. Sometimes, with some varieties, they'd stay there in full bloom for more than a lunar month.

Imagine my intrigue when I discovered that Darwin liked his orchids too – he described his plant experiments as ‘a grand amusement'. He tested his theories of cross-pollination on lady's slipper orchids,
Cypripedium reginae
, amongst others, and moths. ‘Wonderful creatures, these orchids,' he wrote, ‘beautifully adapted to leave pollen on the two lateral stigmatic surfaces. I never saw anything so beautiful'. Did my father read Darwin's considerations in his 1862 book,
On the Various Contrivances by Which British and Foreign Orchids are Fertilised by Insects, and On the Good Effects of Intercrossing
, at least out of mutual interest? Was he seduced by Darwin's methodical approach, his careful analysis?

My father doesn't read anymore; he can't make sense of the line of words. He doesn't know how to hold a newspaper or a book, doesn't know how to turn a page. What invariably happens is that he might read a word once, then twice, three times, four (and I know this because he sometimes rereads the same words out loud). Then he jumps forward and reads another single word from the bottom of the page, once then twice, three times, before doubling back to the beginning again. His brow knits together. His index finger tugs at the paper. Oh dash it, he says, looking at me with pleading, watery eyes. With each try it is as though he has never learned to read before, let alone written thousands upon thousands of words in published and unpublished volumes and for lectures and sermons. Occasionally he will remember to say, with unforced clarity: Did you know Father and I were in print for over a century? It's such a surprise when he speaks like
this: in a complete sentence, a whole thought. There is a trace of something
gone before
.

More often, though, he may as well be back in kindergarten, learning the basics about books, about writing and the sequence of letters, learning to point words out with his fingers, his body hunched over the page in concentration, learning to sound syllables in his mouth for the first time.

* * * * *

Dogs. Cats. Horses. Cattle. Goat. Asses. have all run wild & bred. no doubt with perfect success …There is no more wonder in extinction of species than of individual. –
The Red Notebook of Charles Darwin
(1831–1836)

Last Sunday, at the end of my visit, I went to church to say goodbye. The air was warm and a bit blowy as it shuffled in after me. It teased the top of my father's head, rustled his wispy hair so that small strands wafted like a flight of kites on the Mooloolaba sands. I thought of the warm salty water holding the bodies afloat out there, everyone swimming on this last day of school holidays, and how inevitably the road into Brisbane would be chockers with cars. That's why I ended up in his church.

If I was going to spend a morning with my father, then spending it in the church was my best option, the only option really. I wanted to beat the rush. I wanted to get ahead of the traffic jam. I couldn't wait until the service was over to see him, it would be too late. I had to swallow my pride and beliefs. What difference would it make, I reasoned? I could sit with him in his room in the nursing home listening to a videotape of
Hymns of Praise
, or sit with him here in church amidst the chorus of Presbyterian worshippers. The latter was more public, it's true, and slightly
more awkward at first, given I normally refused my father's offers ‘to worship God'. I comforted myself by watching the morning air push around the trees outside the vestry window and listening to the preacher stumble on the word ‘hedonist' when explaining why the ‘children of the sun' riding boogie boards and frolicking in togs in the Sunday surf would rot in hell, and take their families with them. Perhaps it didn't matter in this instance that the church didn't believe in women praying and thought homosexuality was an unforgivable abomination. I just wanted to be close to my father.

The hymns were quite nice too in the wafty warmth of a Sunshine Coast morning, especially the familiar doxology: ‘Praise God from whom all blessings flow'. This morning it was sung rather beautifully by all and sundry – maybe because they knew it so well with its theatrical chordal progression, because they sang it each week. Maybe it was just the way I heard it, my heart open to this particular carriage of love.

What I didn't take into account was my father's reaction to me being there. He kept saying over and over,
well done, well done
; he was beaming. He must have thought I was saved on the spot. He was BESIDE himself seeing me waltz into church. He had a direct line to God at that moment. Through the service he kept coming back to it as well, holding my hand, turning towards me, looking up at me, smiling, saying over and over and over,
well done, well done, well done
, with enough energy in his body to spin himself out of his chair, to circle above us exclaiming:
I'm off now I'm on my way!
Truly, I would not have been surprised if we'd grown wings together that day. My father certainly thought we had – he was in heaven. And if he took me there to keep him company on this Sunday morning, I didn't mind so much, I didn't mind at all.

[F]rom so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. – Charles Darwin,
On the Origin of Species
(1859)

Memory

Biblical battles

Rekindled

Sentinel chickens

Peter Doherty

The idea of ‘sentinel chickens' seemed pretty incongruous when I first heard the phrase as a young undergraduate. My reaction was no doubt conditioned by recollections of the scatty and fussy hens that scratched about in the dusty chicken run in my grandmother's backyard. The notion of the humble chicken waiting like a trained soldier, alert and focused, for some unseen and approaching enemy just didn't seem likely. Hens
en garde
!

Like most students in that distant era, I knew everything and knew nothing. Nowadays, any reasonably sophisticated young person would go immediately to the internet and find that, way back to mythological times, guard duty has been part of the avian job description. Gods with the body of a man and the head of a bird, like the ibis, falcon, hawk or heron, watched over the ancient Egyptians. In the Western tradition, the cockerel, or rooster, symbolises vigilance and has been widely used as a French heraldic device. Adopted as the national symbol at the time of the 1789 revolution, the proud, colourful rooster of France (
le Coq Gaulois
) went beak to beak with the black eagle of Germany during World War I.

When it comes to warning us of imminent danger, sentinel geese have long been associated with the human story. Geese go
on the attack and make an enormous noise if they perceive an incursion into what they regard as their patch. The trick is to provide feed and nurture so that they make our patch their patch. According to the Roman historian Titus Livius – better known as Livy – sacred geese in the temple of the Goddess Juno alerted the exhausted defenders of ancient Rome to a nocturnal attack by marauding Gauls. In modern times, Scottish whiskey distilleries are sometimes guarded by gaggles of geese that raise a loud hue and cry if a thief tries to make off with what many consider the most spiritual of all
aqua vitae
. Whiskey may be part of the local religion, but I doubt whether the pragmatic Scots would regard the birds as sacred.

Then there's the story of the ravens that somehow guarantee the integrity of the Tower of London and, beyond that, the continuity of the crown of England. Legend has it that the monarchy will fall when the ravens leave the tower. Following the spirit of a decree by Charles II, there are always at least ten ravens available, six on duty and four active reservists. The resident ravens are cared for by a raven master drawn from the ranks of the Beefeaters, the medievally attired tower guards. One wing is clipped to ensure they can't fly away.

* * * * *

I first heard the term
sentinel chicken
from an older cousin, Ralph Doherty, a medical scientist who was then building a substantial reputation in the study of the insect- or arthropod-transmitted viruses, known collectively as the arboviruses, also called togaviruses because they have an outer ‘envelope' or ‘coat'. Among the major achievements of his research group at Brisbane's Queensland Institute of Medical Research was the discovery that the mosquito-borne Ross River virus (RRV) is the cause of the human disease epidemic polyarthritis with rash, a painful and
debilitating condition that can persist for several months. With more than 4000 cases every year, this non-fatal disease is all too familiar to those who live in the northern parts of Australia and has been rapidly spreading away from the tropics.

Like all viruses, the arboviruses can only reproduce themselves within living cells. What makes the arboviruses special is that they replicate in the tissues of very different types of animals, though the individual viruses in this very large group do vary considerably in their overall host range. The ‘virus production factories' include biting arthropods, particularly mosquitoes and ticks, which, as they take their blood feed, either become infected or (if already carrying the virus) transmit the infection to warm-blooded species, including human beings and a whole spectrum of furry and feathered vertebrates.

And that's why we have sentinel chickens. The progressive spread of many arboviruses is monitored by placing caged chickens around the countryside at sites where they are likely to be bitten by mosquitoes. The widely distributed birds are sampled regularly, a comparatively non-intrusive process that involves taking a small amount of blood from the prominent wing vein. The blood is allowed to clot, and the yellowish serum supernatant is either frozen or taken on ice to a specialist laboratory, where the samples are analysed for seroconversion. That is, the technician uses a well-established assay to detect newly acquired (since the previous test) circulating antibodies specific for the virus in question. (That doesn't work for all mosquito-borne infections. Chickens aren't very susceptible to RRV, for example, which seems to prefer mammalian hosts, and they're of no value for tracking malaria, for which we humans are the most sensitive sentinels. Birds have their own distinct malaria parasites.)

If, for example, the birds were seronegative when taken to their guard station, then seropositive for some arbovirus six months later, it's obvious that they were exposed to an infected
mosquito at some time over that period. The relatively few virus particles injected by the feeding mosquito will have travelled via the circulation to invade susceptible cells in one or other organ of the new chicken host. Successive cycles of virus replication then lead to the presence of a great deal more virus in blood (viraemia), a process that terminates somewhere over the next 7–12 days or so, when the developing immune response will lead to the production of specific, neutralising antibodies. Those antibodies will continue to be made for the life of the bird. Once antibody-positive for the infection of interest, the chicken veteran is both permanently immune and eligible for honourable retirement and replacement with a new recruit.

* * * * *

Virologists further sub-classify the arboviruses into alphaviruses and flaviviruses. The alphaviruses include RRV and Barmah Forest virus (in Australia), eastern equine encephalitis virus (in the USA) and the Chikungunya virus that has lately been spreading from the Indian Ocean region to South-East Asia and the Mediterranean. Human infection with Chikungunya, RRV or Barmah Forest virus can lead to the development of persistent polyarthritis with rash, while chickens, at least, remain asymptomatic.

All the flaviviruses are broadly related to yellow fever virus, the terrible pathogen that kills humans by a combination of haemorrhagic disease and liver destruction. That's where the ‘flavi' (Latin for yellow) comes from, describing the severe jaundice that characterises the lethally compromised patient. The main vector is the mosquito
Aedes aegypti
, which is present in tropical North Queensland, though there have been no cases of yellow fever in Australia. A vaccine was developed in the 1930s by the South African medical scientist Max Theiler, an achievement recognised by
his 1951 Nobel Prize. There are, however, 70 known flaviviruses, with 30 of these being found in southern Asia and the Australasian region. Some are ‘orphan' viruses that are not associated with any known disease.