The Best Australian Science Writing 2015 (23 page)

‘The big goannas [monitor lizards] were slaughtered in droves, and quolls are hard to find. But both species are still hanging on,' Shine says. Some native species have even become more common. And the same seems to be true elsewhere, including in the ‘lost' Kakadu park. ‘So far as we know, the Kakadu story is very similar to Fogg Dam,' Shine says. The doomsayers – including himself from an earlier time – haven't been vindicated.

For example, one worry was that cane toads would outcompete native frogs, causing mass extinctions. In a review of the available evidence, Shine found toad invasions had almost no effect on native frog abundance.

What's more, many of the predators whose population had been destroyed by the toad arrival – like quolls and goannas – have learned surprisingly quickly not to eat them. ‘If you go to northern Queensland now, quolls and goannas are common. They kick toads out of the way, grab a frog and eat it,' Shine says.

One reason could be that once toad populations are established, there are a lot of baby toads hopping around. And for a young goanna or quoll, a baby toad is easier to catch than an adult. It will make the predator sick, says Shine, but is less likely to kill it, providing a life-saving lesson in bush tucker.

In the wild, for instance, adult freshwater crocodiles have died en masse after trying to eat adult toads. In the lab, Shine's team found that crocodile hatchlings would attack small toads. But although they showed no obvious signs of illness afterwards, half of them wouldn't touch a toad again.

Living with the enemy

Other animals are evolving to avoid toads. A decade ago, one of Shine's protégés, Ben Phillips at the University of Melbourne, showed that red-bellied black snakes and tree snakes living in toad-infested areas had evolved smaller heads over time, preventing them from eating large toads.

Now the head-size shift seems to have been overtaken by a more efficient adaptation: some snakes are no longer interested in toads. It couldn't be a learned behaviour, Phillips says, because programs teaching animals not to eat toads don't work with snakes.

So while the arrival of the toads is hardly good news, it hasn't been the disaster once feared. ‘Toads have changed everything,'
Phillips says. ‘Some of that change has been positive and some of it has been negative. The system is not the same as it was before.'

Shine is keen to make it clear that toads have not caused a single extinction. But Simon Clulow, a biologist at the University of Newcastle in New South Wales, thinks that could change. The reason is that the toads carry a lungworm parasite. Most Australian frogs aren't harmed by it, but it's deadly to the magnificent tree frog, a species found in the Kimberley. ‘It's a very social species and they huddle together,' Clulow says. ‘Once this worm gets into the magnificent tree frog population it will rip right through it.'

But even on this point, Shine is more positive. ‘I think the habitat differences are quite substantial and will reduce the risk of parasite transfer,' he says. ‘I don't think this is the death knell for the magnificent tree frog.'

Even though Shine doesn't think the toads will have as catastrophic an impact as some fear, he is in no doubt that it would be far better to keep the toads out. He, Clulow and others hope some key areas in the Kimberley can be kept toad-free by using pheromone traps, pheromone repellents and fences.

And while it might be too late for the Kimberley, many think the toads' advance could be stopped there. To spread into the Pilbara region 1000 kilometres to the south, the toads would have to cross a desert. Models suggest that they will have no problem passing through that desert, but only because of a network of water holes set up by farmers.

To stop this the water holes don't even have to go – they just need to have smooth walls about 50 centimetres high to stop adult toads entering and breeding in them. ‘It's a realistic place where they could be stopped. Almost everyone is in agreement,' Phillips says.

While north-western Australia fights for a toad-free life, the rest of the north has no choice but to live with the enemy. At
one point the government spent millions trying to develop a genetically engineered virus to kill the toads, but that plan has been abandoned. Many people around here despise the toads. Archer, for one, has never forgiven them for killing his quoll: ‘I haven't wavered a bit. I think they're a noxious horrible pest and they're going to cause a transformation.'

In fact, they are so hated it is common practice to hit them with golf clubs or drive over them with cars rather than killing them more humanely by placing them in a bag in a freezer for a few days. ‘You know it's not their fault that they're here,' says Shine, who has gone from hating toads to having a grudging respect for them. In fact, he seems to really love them. ‘We need to treat them with the same ethical care we would a koala.' He smiles and adds: ‘And if you pushed me I might say more than a koala.'

Holding a Queensland cane toad, I can even start to see what Shine and his students have come to like about them. For all the talk of their viciousness, they seem remarkably tame. Because their weapon is their toxicity, as soon as they feel threatened, they just sit still. And their eyes are magnificent: they look like an exploding star with black and gold speckles. It might just be the hallucinogenic toxins, but maybe I, too, could learn to love the toad.

Playing God

Lost in a floral desert

What shall we teach the children

George Clark

Of what is the world made, asked Thales,

it is the playground of the gods maybe,

but what shall we teach the children?

An ordinary man may capture fire, another will sing of its beauty

one will observe the earth shaking, another will sacrifice to his demons.

There are those who pray, those who fight and those who choose science,

While the emperor claims the credit for trigonometry of the temple.

The voyager consulting his barometer, chronometer and sextant

coordinating position from stars, declension tables the new liturgy.

Cataloguing plants, making maps, longitude, giving things names,

St Elmo's fire at the masthead, a reminder of god's presence.

Frogs legs and magnets, those bumping electrons,

Voltage differential, like man impatient and curious.

Lucky Faraday with his electric hum, felt the torque,

Found invisible magnetic field even affecting light rays.

Energy and the carbon factor, the heart of the diamond

the pale organic fire of methane, explosive at one in eight.

An element with beautiful bonding, electron spacing

revealing the clever poetic beauty of the periodic table.

Theoretical physicists playing god with infinitesimal particles

stripping atoms, behaviour and life in microseconds, but

not knowing the momentum and position of a particle.

Measuring disorder, increasing entropy, imagining absolute zero.

An experiment repeated is a conversation with nature,

knowledge owned by all, like the jugglers built in radar

his instinctive parabolic skill, anticipating gravity,

finding the trope for energy, work and equilibrium.

Let x be the unknown quantity until we run out of questions.

Facts are stubborn things, the age of wonder probably ended

with the silicon chip imagining all, matrix algebra

and differential calculus, mimicking evolution in tiny steps.

Light

The women who fell through the cracks of the Universe

The mind of Michio Kaku

Why aren't we dead yet?

Idan Ben-Barak

It was supposed to be simple.

Back in antiquity, disease came from the gods, or perhaps from God, or – if you were a rational, hard-headed, modern, clinically oriented, evidence-based sort of person and/or society – from an imbalance of the four humours of the body. The fourhumours explanation made sense. It was practical and workable. It led to treatment. It was wrong in every respect.

Some progress has been made since then, as I'm sure you've noticed. You'll find out a bit about that progress later on, but for the time being it's enough to say that humanity now has at least a partial understanding of the mechanisms and causes of disease – and it's turned out to be not very simple at all. If a scholar of yore had been able to read a modern medical textbook, what he would in all probability have been most struck by is how ridiculously, bewilderingly
complicated
health and disease are now understood to be. Demons, divine will, or an excess of bile have been replaced with the wonderful world of bacteria and viruses, toxins and free radicals, leukocytes and antigens and antibodies, cytokines and chemokines, MHC molecules and V(D)J recombination and hypervariable antigen binding and CD25+ regulatory T-cells and … It's enough to make anyone's head spin.

To make matters worse, diseases can be genetic, or infectious, or can be the result of the body's own workings breaking down in one way or another. Most diseases are caused by a combination of any of the above. For instance: you can't catch cancer from other people – except for the types that you can. Or: you get infected with malaria by mosquito bites – unless you're naturally immune to it by virtue of a certain allele of your DNA. And so on. The more we find out, the less well-defined it all seems to be.

And why, our hypothetical ancient scholar reading through the descriptions in a modern textbook would wonder, would Nature operate in so convoluted a way as to have a human disease, caused by an invisible organism, pass through yet another organism – in some cases,
two
other organisms – en route between one human and another? What sense does it all make?

‘Nothing in biology makes sense except in light of evolution', wrote Theodosius Dobzhansky in a famous essay. Charles Darwin provided us with the basis for the only satisfying answer we have for the overwhelming complexity of the natural world, and so immunologists have been applying the Darwinian perspective to their field in order to understand why the immune system looks and operates the way it does. Let's take that as read for now.

In the meantime, I have a problem. It's a problem I share with any writer who wishes to drive home the point that something is complicated. Simply saying ‘It's complicated' not only doesn't really convey any of the flavour, but it also sounds sort of lazy. On the other hand, this book is meant to be read by you – the interested layperson or student. It's not a textbook, and so while laying out the complications in agonising detail would indeed make the point, the reader would suffer for it, and readers don't tolerate this kind of behaviour anymore; I might find myself unceremoniously tossed back on the bookshelf, and it's cramped up there.

How, then, should I say how complicated the immune system is?

* * * * *

Let's do it the other way around: instead of telling you how complicated the immune system is, I'll tell you
how complicated it needs to be in order to keep us alive
, and let you have a go. Grab a pencil and a writing pad and try to think how you would design a system that would protect the body from harm.

Now, the operational parameters you need to take into account when drafting your proposal are these: an organism's immune system protects it from anything that would live inside or off of it. So, for instance, a raging bull chasing after you is the concern of your physiological fight-or-flight reaction, not a matter for the immune system. Unless the bull gets you, at which point the immune system is presented with any number of interesting challenges. Being eaten by a crocodile likewise does not fall under the jurisdiction of the immune system, because the crocodile starts off from the outside and works its way in. If there were a species of very small crocodile whose modus operandi was to infiltrate your body, auger into the bloodstream or inside one of your inner organs, and set up camp there, munching away and raising offspring – that would definitely be looked into by the immune system, and the parasitic microcodile would be added to the long and varied list of species the immune system has to handle.