Seven Worlds, One Planet

Professor Iain Stewart: Struggles of the Serengeti

The Serengeti plains of Tanzania, Eastern Africa, are home to the largest concentration of grazing animals to be found anywhere on Earth. But few of the safari tourists that crowd here in early summer realise that this mass gathering of herbivores owe its very existence to a geological struggle going on beneath their feet.

The annual migration of between one and two million wildebeest is one of the great animal movements on our planet. But look closely at the skittish throngs and something rather odd about these animals jumps out at you. All the calves are exactly the same size. That’s because February is when the wildebeest deliver their babies, all of them. Hundreds of thousands of calves born not only at the same time but also in exactly the same place. And the reason why they all descend on the same area to have the babies at the same time is the grass that grows on the ground.

At the start of every rainy season, one particular small patch of the Serengeti becomes covered with some of the most nutrient-rich grass on earth. The grass contains four times the calcium and nine times the amount of phosphorous in grasses just a few kilometres away. These are nutrients crucial to healthy calf development. It means this one comparatively tiny patch of fortified ground can support millions of nursing wildebeest.

The reason why this grass is so unusual can be found looming over the herds. Towering almost 3,000 metres above the Serengeti plains is one of Africa’s strangest, most explosive volcanoes - Ol Doinyo Lengai, or mountain of god. Back in 2007, an eruption lasting almost 12 months threw up a giant column of ash, destroying countless crops and forcing thousands of local Maasai to flee their homes.

But the ash that rained down was unlike most other volcanic ash on the planet. Its chemical make-up was so odd that the grass around the volcano effectively became super-charged in a weird cocktail of minerals.

The secret of Ol Doinyo Lengai’s weird chemistry can be uncovered by looking at lava flows that its past eruptions have left behind. Drop a spot of weak acid on a fresh lava surface and it froths away. The gas being released is carbon dioxide. 

That’s because, as well as these lavas being rich in sodium, calcium and phosphorous - all vital elements that make the Serengeti grasses so nutrient-rich - it’s also incredibly rich in carbon. 

Such ‘carbonatite’ lavas are incredibly rare, and only really form when rocks rich in carbon are melted at incredibly high pressure. 

And to find carbon-rich rock at high pressure you need to go to the same place that diamonds are formed - many tens of kilometres down at the base of the Tanzanian continent.

Deep below this part of Africa lurks a giant, rising mass of magma - a super-plume. And for the last 45 million years, this vast upwelling hot rock has been steadily forcing its way upwards. Africa’s super-plume may be hidden from sight, but its surface volcanoes have created the very DNA of this landscape. Virtually everything you see around along East Africa’s great Rift Valley comes, in one way or another, from them.

So, back in the Serengeti, the reason why Ol Doinyo Lengai is so unusual, why it’s so nutrient-rich, is because of a carbon-rich magma store that lies deep beneath Tanzania. And it’s this volcano, this lava, this ash, that enables the Serengeti wildebeest to breed in such huge numbers here. Quite simply, without Ol Doinyo Lengai this spectacular annual wildlife spectacle wouldn’t exist.

Dr Lucy Obolensky: Ahhhhhh Africa - Sunrises, sunsets, acacia trees, wildlife, people, beauty

I have worked and intermittently lived in Sub-Saharan Africa over the last 22 years. I have had the opportunity to set up health programmes, work with large scale NGOs, lead overland expeditions, trek desserts and summit mountains. One of the communities I’ve worked with has literally seen me grow up over this time: become a doctor; get married; have children and return with them. Yet with all this experience I was unable to protect my two-year-old daughter from contracting malaria.

Malaria is one of the most severe public health problems worldwide. It is a leading cause of death and disease in many low and middle-income countries (after trauma). Approximately 500,000 people die from Malaria each year in Sub-Saharan Africa, most of these are children. Whist this figure is massive, it is a 25% reduction from the figures seen prior to the introduction of the Millennium Development Goals and the funding and interventions that followed. Yet still, nearly half the world’s population lives in areas at risk of malaria. The most saddening message of these statistics is that fundamentally, malaria is a preventable disease.

Malaria is spread by the female Anopheles mosquito which transmits the Plasmodium parasite. Plasmodium falciparum is the most predominant species and the most fatal. Contradictory to popular belief this mosquito does not hum and does not leave a bite mark so you may not know you have been bitten.

Strategies to prevent malaria can be divided into:

• Bite prevention;
• Chemoprophylaxis
• Rapid diagnosis and treatment. 
  
  

Bite prevention involves covering between dusk and dawn when the mosquitoes bite, applying insect repellent and using insecticide impregnated bed nets.

Chemoprophylaxis comes in many forms. Chloroquine used to be the most abundant however many malaria parasite strains are now resistant to this. My choice of drug is Malarone (atovaquone and proguanil hydrochloride) as it is once daily and has minimal side effects, except in children where it can cause vomiting and diarrhoea (I’ll return to this with my two-year-old!). The downside of Malarone is that it is expensive until it comes off patent. Larium and doxycycline are also options. Although larium offers excellent prophylaxis, there have been many cases of this causing psychiatric side effects. Doxycycline causes severe photosensitivity and can cause oesophagitis so I don’t recommend this for long term use.

Rapid diagnostic tests (RDTs) are now available to give accurate parasitological tests and early treatment can, therefore, be started.

The symptoms of malaria are an acute febrile illness usually 10-15 days after exposure. This includes high fevers >38°C, feeling hot and shivery, vomiting, muscle aches, headaches and diarrhoea. 

These may be quite non-specific symptoms so a high index of suspicion should be had for all those returning from a malarial area. Due to the life cycle of the parasites in the bloodstream you will frequently see a 48-hour cyclical nature of the symptoms and fever.

Treatment is with an Artemisinin-based combination therapy (ACT) for three days with artemether plus lumefantrine being the most commonly-used drug. Treating as early as possible is life-saving and if P. Falciparum is suspected this should ideally be within 24 hours.

So we understand the malarial disease, the life cycle, the transmission. We have a prevention and a treatment. Then why do so many people die and how did I allow my daughter to contract malaria? I think what this demonstrated to me is that even if you are a well-educated individual with money to spend on bed nets and prophylaxis, in areas where the malarial load and you are not meticulous with preventative measures malaria is still high risk.

If we use the 'Swiss cheese’ model of risk to look at this my daughter was two years old which immediately makes her more high risk. She had diarrhoea and vomiting so was not absorbing her Malarone. Her pyjamas had short sleeves and the bed net did have a few holes in it. I had not seen any bites so I had assumed I had done well in preventing her from being bitten. You could say this was just unlucky.

If we then look at another example from the community I work with where another two-year-old girl is unwell with a high fever, abdominal pain and diarrhoea. Maria is a single mother of five children. She is illiterate which already puts her children at a 50% higher risk of dying by their fifth birthday than those born to a literate mother. She is from a population which sees a high malarial burden and lives in a manyatta (mud hut) with no access to nets. The nearest health clinic is a 10km walk which she would have to undertake with her other four children.

Maria is unlikely to afford either the test or the treatment for her two-year-old daughter even if she got there. This is one of the many reasons that the worldwide malarial burden is still so high. Until we invest in Universal Health Coverage (equitable access to health services without financial hardship) these figures are unlikely to change.

I would urge anyone with the opportunity to travel and explore the world to do so. I would equally urge you to look at the global challenges that face that country, consider which of the Sustainable Development Goals are a priority and what, if any part we can play to support these goals such that travel and exploration can be more about sustainability and partnerships.

Dr Lucy Obolensky: The Yukon - Baby, it's cold outside

The Canadian Yukon is remote and stunning yet in winter is fraught with the dangers of exposed water and freezing temperatures. We have a saying in medicine “you’re not dead until you’re warm and dead” and this would certainly apply in this setting. But how do you warm up your casualty when you are out in the field, potentially with a film crew?

The first step, predictably, is prevention. Ensure everyone is adequately clothed and prepared for the cold. Use a buddy system to look out for each other and spot the ‘UMBLES’ of early hypothermia:

• Grumbles – feeling of cold;
• Fumbles – loss of fine motor coordination. They may not be able to do up a jacket or open a food packet;
• Mumbles – slowness of thinking and speech;

As it gets colder you with then notice:

• Stumbles – gross motor incoordination and stumbling gait.

At this stage, you are able to prevent more severe hypothermia. Put up a tent, make a brew and add a layer or two. Those more at risk of hypothermia include: children (with a high surface area to volume ratio); lean males; dehydrated; malnourished; poor fitness; immobility; alcohol intake and inadequate clothing.

Hypothermia is classed into 4 categories 

• Stage 1 with a core temperature of 32-35°C. The patient will still be conscious and shivering;
• Stage 2 with a core temperature of 28-32°C. The patient will have stopped shivering and be confused or unable to speak;
• Stage 3 with a core temperature of 24-28°C. The patient will be unconscious but will have vital signs of a slow heart rate;
• Stage 4 with a core temperature of <24°C. The patient will look dead and have no vital signs present. 

In hypothermia, your brain oxygen requirements decrease by 5% per degree of cooling of blood. The body will cool at 3-9 degrees per hour. This is why we have the mantra ‘you’re not dead until you are warm and dead’ as if brain cooling was achieved before the heart stopped then brain recovery is likely as you are warmed up.

Anna Bågenholm is a Swedish radiology doctor who survived after a skiing accident where she was trapped in a lake under a layer of ice for 80 minutes. On arrival in hospital her body temperature was 13.7 degrees. Anna was rewarmed in the hospital and, using a treatment called ECMO (Extracorporeal membrane oxygenation), she not only survived but made an almost full recovery and returned to her career in radiology.

Following the number of deaths related to cold water in Canada, Dr Gordon Giesbrecht, a Canadian physiologist, set up a public health awareness campaign to help dispel myths around cold water immersion and to understand how to survive. Giesbrecht set up the Cold Water Boot Camp which outlined the 4 phases of cold water immersion:

• Cold shock response. This is where the immediate shock of cold water causes involuntary inhalation and hyperventilation. This lasts for approximately one minute;
• Cold Incapacitation. After approximately 10 minutes you lose the ability to make any meaningful movements with your arms or legs;
• Hypothermia. Hypothermia sets in only after approximately 1 hour of being in cold water;
• Circum-Rescue collapse - discussed below. 

Cold Water Bootcamp widely advertised the 1:10:1 rule:

• 1 - You have one minute to control your breathing. If you can keep your airway clear and above water for this one minute, that will prevent drowning;
• 10 - You then have 10 minutes to self-rescue where your limbs are working and you are able to swim to the water's edge;
• 1 - If unable to self extricate from the water you have 1 hour before you become hypothermic to call for help or get in a safe position to increase your chance of survival.

Circum-rescue collapse

This was first documented in World War II when it was noted that soldiers were alive in the water but dying shortly after being rescued. Further research on this phenomenon was called for after the Lyme Regis kayaking disaster when, again, the teenagers involved were noted to be alive in the water, but had died by the time they were winched into the helicopter.

This occurs as when in cold water, the cold causes a reduction in the body’s ability to auto-regulate heart rate and blood pressure. The water around the body also acts as a pressure squeezing blood back from the legs to the heart. When rescued vertically, you lose the squeeze pressure from the water yet the body is still unable to auto-regulate blood pressure. There is a massive pooling of blood to the legs and sudden lack of blood back to a cold, fragile heart and the heart goes into ventricular fibrillation.

Horizontal resus techniques have been widely practised since this disaster and this is something we regularly practise on the lifeboat at home. If you can extricate casualties gently and in a horizontal position you are likely to prevent cardiac arrest and maintain survival.

In summary, in cold conditions ensure you prevent hypothermia by minimising risk factors, spot the Umbles and rewarm early. Remember the 1:10:1 rule with cold water immersion and treat cold casualties gently and horizontally where possible.

Professor Iain Stewart: The Grand Canyon

Not just one of the planet’s great natural wonders, The Grand Canyon is a portal into the heart of the earliest life and times of North America.

It’s an amazing vista – perhaps one of the most breath-taking in the world – but for a geologist like me, looking out over the precipice, what you see really is time. A whole lot of time. Deep time, from Earth’s geological youth exposed in the sheer canyon walls. Down at the base, amongst the currents and cataracts of the Colorado river, the oldest rocks are 1.7 billion years old and the only life on the planet was single-celled algae. Slimeworld. Mid-way up, rock layers that are 500-550 million years old mark a time when great ice sheets covered much of the temperate globe and complex multi-cellular life was brewing in the oceans.

But it’s the highest levels of the Grand Canyon that tell perhaps the most remarkable tale of life on land because it directly related to you and me. First, near the top, layers of red-coloured silts and sands of the Supai Group are sediments washed off the land to pile up in coastal swamps and deltas. Fossils in those iron-stained layers reveal the kind of life that flourished in this waterworld. Amphibians.

These days amphibians like frogs and salamanders are relatively rare here, but 300 million years ago, when the Supai layers were deposited, amphibians were the dominant animals on the planet. Think of modern frogs and salamanders and you quickly appreciate just how important water is for them, particularly in that early spawning stage in the development of the young like tadpoles. That fundamental attachment to water for breeding meant that the coastal swamps and wetlands of proto- America were critical to the amphibians’ evolutionary success.

But take a short trek up the trail towards the top of the canyon rim and you discover just how that ancient world quickly changed. Immediately above is a layer of yellow rock, the Coconino - a thick sequence of fine sands identical to those you’d find on modern desert dunes. Huge dunes, maybe a 100 metres or so high, that coalesced to form a vast sand sea.

That vast ancient sand sea was truly colossal in scale, spreading across almost all of what is today the Americas, Africa and Europe. That’s because, 250 million years ago, the coastal waters of the Supai age had disappeared as the planet’s land masses came together, fused into a single super-continent called Pangea. And this part of North America was pretty much right at Pangea’s barren heart. With most of the land distant from the sea, rain-bearing winds struggled to water the centre. Bad news for the amphibians, which found the Pangean deserts an essentially impenetrable barrier.

And so in this arid world, a very different type of animal flourished. The clues are in the desert rock layers. Odd markings. Traces of footprints. A track way of an animal that was walking up the soft dune faces, pushing down and displacing the sand. A reptile. A reptile with a tail, because in places you can spot the sinuous track of this reptile that’s dragged its tail up.

To adapt to these hyper-arid environments required these creatures to evolve a biological innovation that would be inherited later by all the reptiles, by birds, by mammals, by you and I. 

The reptiles of Pangea are long extinct, but a creature that shares an anatomical connection with those ancient reptilian fossils is the alligator. One shared anatomical trait is the ankle joint - the cora-tarsal joint – which is a distinctive adaptation that allowed animals to push themselves more upright and move faster. But the biggest biological breakthrough was something that perfectly equipped them for Pangea’s desert world. It was the way they had sex.

Now, alligator sex is pretty much like human sex. Certainly in the style of copulation. The key is internal fertilisation, delivering the sperm inside the female and directly to the ova. And that process involved the invention of sex. Sex is the most efficient direct way of achieving fertilisation. It’s how modern reptiles, birds and mammals impregnate.

Up until this innovation, fertilisation could only occur externally in water. Amphibians were the first vertebrates to emerge onto land but because they fertilised externally they had to return to water to breed. The newly evolved reptiles did things differently. They fertilised and developed their eggs inside their females. So by the time the eggs were laid they had hard, impermeable shells. These eggs didn’t need water to survive. Instead, inside was the amniotic fluid – a transparent liquid that contains the energy and the life-sustaining waters that amphibians would have found in the rivers and seas.

So, the egg was the revolution. The development of internal fertilisation and the amniotic egg allowed reptiles to spread into, and thrive in, those arid environments. Mammals took those life-supporting fluids inside their selves, and supply nutrition through a placenta, but we’re still children of that first amniotic reptile. It’s a wonderful example of how environmental change can be a catalyst for evolutionary advances. And those advances would lead eventually to the evolution of us.

It’s interesting to think that the way that we have sex, and the way that we rear our young, has been shaped by these ancient North American deserts.

Professor Iain Stewart: Europe’s Mediterranean - A Ruined Landscape?

“Surely it is obvious enough if one looks at the whole world, that it is becoming daily better cultivated and more fully peopled; all places are now accessible, all are well known, most pleasant farms have obliterated all traces of what were once dreary and dangerous wastes; cultivated fields and subdued forests, flocks and herds have expelled wild beasts; sandy deserts are sown, rocks are planted, marshes are drained; and where once there were hardly solitary cottages, there are now large cities.

"No longer are islands dreaded, not their rocks shores feared; everywhere are houses and inhabitants. Our teeming population is the strongest evidence; our numbers are burdensome to the world that can hardly supply us from natural elements; our wants grow more and more keen, and our own complaints more bitter in all mouths, whilst Nature fails us in affording us her usual sustenance. In very deed, pestilence and famine and wars and earthquakes have been regarded as a remedy for nations, as a means of pruning the luxuriance of the human race."

These words, written by Tertulian, a third-century AD theologian, show that our concern that humanity is living beyond our planetary means is not new. Tertulian’s ancient blog on the environmental pressures starting to bite on the great Roman empire conveyed a dramatic sense of the ruination of the Mediterranean landscape. 

Centuries later, Victorian travellers and writers on the Grand Tour through the Classical world were equally disillusioned to find the ‘barren’ lands of ancient Rome and the ‘bare’ hills of Pericles’ Attica. Viewed against the lush backdrop of northern Europe, they assumed that the landscape of the Mediterranean must have ‘gone bad’.

No doubt it is a view that many visitors from northern Europe have today as they arrive in the dry heat of the summer to be confronted with the fawn hues of a rocky landscape of sparse trees and shrubs (often burnt trees and shrubs). Compared to the green rolling hills and woodlands many left behind, it must seem a fragile natural world clinging on to existence. But the reality is very different. Mediterranean countries have a richer diversity of plant life than the rest of Europe.

The diversity arises because plants have had to evolve to make the best of the environments into which the accidents of climate and geology have thrust them. Probably the most versatile plants are the thick-leafed evergreen shrubs and small trees called ‘maquis’: long-lived, deep-rooted, relatively palatable and combustible, but not killed by wood-cutting, burning or browsing, they are ideally adapted to the capricious Mediterranean environment.

Burning is particularly essential for success here. Some tree and plants insulate against natural fires with fire-proof barks, while others design themselves to sprout or germinate after the fire has swept through, producing flammable resins and oils to encourage the flames that will regenerate them and set back their less fire-adapted competitors. Over thousands of years, the Mediterranean environment had adapted itself to rely on natural conflagrations.

Fauna too have adapted to this changeable world. The most prevalent animal is the goat - much maligned for its efforts in laying bare the barren rocky skeleton. As they scour the craggy uplands for meagre sustenance, it seems that they strip away the soil and eat away at young plant growth. But the soils on the abundant limestone plateaux and hills are naturally thin and patchy, yet they still offer far more sustenance to animals than do the small, better vegetated pockets of sediment trapped in the upland valleys.

Soluble phosphate, the principal vegetational contribution to the calcium compounds from which growing animals make bones, is between two and four times higher on limestones than on most other rock types. And only the limestones offer adequate trace elements for animal growth, such as copper and cobalt. Goats, long seen by European incomers as inferior to the sheep and cattle of the lush northern pastures, are along with deer the perfect animals to root out the varied edible plants that prosper in this natural rockery. They nibble too at the woody shrubland, consuming much of the plant debris that would otherwise fuel fires.

The natural history of Europe’s southern margin is the story of life land adapting to a world that switches seasonally and annually and over centuries and millennia, between cold and hot, wet and dry. It is a story in which the ups and downs of climate and geology have acted together with the ebb and flow of civilisations and peoples to shape the present-day Mediterranean world. Today, on a planet where the robustness of the natural world is being tested as humanity becomes the main geological force on the planet, the Mediterranean offers hope. While it has the appearance of a land laid bare, the natural history of the Mediterranean is a story of the remarkable resilience of life against the odds.

Dr Lucy Obolensky: Staying close to home just to be safe … but are you?

We may all be guilty of thinking that by not venturing too far from our own little bubble we remain safer than setting off to unknown lands. To a certain extent this could be true, however this can lead to complacency and many places in Europe are far from benign. Reasonable precautions should always be taken when setting off on any adventure.

For example: Think of one of our European friends arriving on our lovely Devonian beaches in summer. Stepping on a weever fish can be one of the most excruciating pains ever experienced. Knowledge of hot water treatment or prevention through using booties would be useful.

There was an influx of false widow spiders in Cornwall last year. Although not deadly can produce nasty infections in the affected limb if not treated early. There were 41 deaths due to hypothermia in Scotland in 2018. Taking the UK hills seriously and having the right kit and adequate communications may have prevented some of these.

I take my husband and two small children for a week hut to hut hiking in the Alps every summer. Many may consider a jaunt through spectacular scenery in Alpine summer of limited threat. However, when the temperature changes from +25 to -8 in the space of 10 minutes, the mist and cloud descends so you can’t see your hand in front of your face and you still have 4km to go before reaching your hut, your perceptions change.

The first items to go in my pack are a GPS, a storm shelter and emergency food rations. The ability to use a map and compass and navigate off the mountain in the fog or dark is a useful skill to have even in European setting: the helicopter may not be able to fly or land in bad weather.

Some key aspects to consider when on micro-adventure in Europe are:

Where are you going and what are the likely risks? Road traffic accidents remain the highest cause of death and morbidity worldwide… and drivers may not uphold the same etiquette as we do in the UK!

What medical kits do you take with you? Even if travelling in Europe you should consider what medical kit you will need on your trip – being unwell in the middle of the night and trying to communicate with health professionals who don’t speak your language or have the same name of drugs is challenging.

Some other factors to consider are what medical services are available? Do you have an EHIC card? Do you know where your nearest hospital is, or what emergency services are available? How do you contact them?

If you’re going out into the wild, have you got means of communication? Can you survive a night with the equipment you’re carrying? Do you have a plan B if it all goes wrong?

Dr Lucy Obolensky - The Australian Outback (hot, vast and harsh):

In 1860 The Victorian Exploration Expedition to Australia, led by Robert O’Hara Burke (1820-1861) and William John Wills (1843-1861), aimed to make the first transcontinental crossing of Australia. Setting off with 19 men, 23 horses, 27 camels, 6 tonnes of wood, a cedar topped oak table with chairs, rockets and flags, a chines gong and 16 gallons of rum. 18 men died and only returned alive to Melbourne.

Do we still underestimate the challenges of this unforgiving environment? As an expedition medic, your main concern in this terrain is heat illness. Heat illness encompasses a spectrum of disorders from mild being heat cramps to severe heatstroke. It occurs mostly in unacclimatised individuals who are volume depleted and carrying out excessive work.

The severity of heat illness depends on three main factors:

• The environmental temperature and humidity;
• The activity undertaken and duration of exposure;
• The ability to thermoregulate.

Some are more at risk of heat illness and those risk factors include: extremes of age – young and old; concurrent illness; obesity; certain drugs such as diuretics, beta blockers or illicit drugs like ecstasy; lack of fitness; alcohol intake in the heat; previous heat illness.

Once the body starts to heat up your thermoregulatory mechanisms are lost. At temperatures greater than 41°C there is a disturbance of the cellular lipid membranes and alteration to chemical bonds within cells.

Dehydration increases sodium/potassium pump activity which increases metabolic rate and this leads to further failure of compensatory mechanisms for dissipating heat. Multi-organ failure ensues, affecting kidneys and brain initially.

Patients with heatstroke have up to 75% risk of mortality so recognition early is key. Initial signs may be heat cramps or heat rash followed by heat syncope. At this point, treatment is possible through cooling, rest and rehydration.

Of the four mechanisms of heat transfer (conduction, convection, radiation and evaporation) evaporation is the most effective. Spray your patient with water and fan them to cool them down. If available put wet, cold sponges in the groin, armpit and back of the neck. It should be noted that paracetamol does not work as an antipyretic in heat illness.

Signs of more severe heat illness, progressing to heat stroke include a drop in blood pressure, severe headache, dizziness, temperature >40.5°C, nausea and vomiting. The skin may also become dry as the body loses its ability to sweat. At this point urgent treatment is needed with intravenous fluids and rapid, active cooling.

As with all aspects of remote medicine, prevention is better than cure. Educating your team on heat illness: how to acclimatise; how to drink the right quantity without under or over hydrating and how long it is reasonable to stay in the heat before taking regular rest breaks is essential to the prevention of any heat illness particularly heatstroke which carries a high mortality.

On expedition as the medic, ask yourself:

• Are your team at risk of heat illness?
• Are you all prepared for hot climates?
• Have you educated your team?
• Do you need to adapt/change daily goals?

Professor Iain Stewart - Australia and the Koala:

200 million years ago, the supercontinent of Pangea began to fragment. One by one, great land masses began to peel away. By 90 million years ago, the last two conjoined twins, Australia and Antarctica, broke apart. As a new ocean crust ocean opened up between them, both embarked on very geological different journeys. Antarctica drifted south and turned to ice. Australia headed north and turned to dust.

Australia’s northward push into ever warmer latitudes would have significant consequences for this land and anything trying to live on it. During the time of Pangea, the vast southern lands had been covered in temperate Glossopteris fern forest, but as it ventured into drier climes the fern forest died away, save for a few tiny pockets. It was replaced with bare red land and the one tree that thrived in these new arid conditions. The eucalyptus. Its a tree that today accounts for almost 80 percent of the forest in Australia.

For Australia’s cargo of animals, it was a brutal case of adapt or die. Only a few were able to evolve quickly enough to survive. And the classic case of that rapid evolution is the iconic Aussie teddy bear, the koala.

Technically it’s not a bear at all, but a marsupial. Anatomically, though, it’s basically a chewing machine. Having evolved to munch pretty much only on the Eucalyptus tree - a very chewy tree at that – most of the Koala’s head is designed for smelling and eating, using all its teeth and facial muscles to drive its powerful jaws.

Go back 20 million years old and you find that fossil koala remains are about half the size of the modern animal. In just a snapshot of geological time the koala’s dependency on the flourishing Eucalyptus forest had allowed it to become huge, with a gradually bigger and bigger face.

The eucalyptus trees didn’t only change the koalas’ machinery for eating but also for communicating. A bubble of bone inside its head acts as an echo-locating chamber that’s very good at picking up low frequency vibrations. The weird sounds they make transmit long distances, crucial because where they live the trees are far apart.

So, the koala’s teddy bear face reflects the dramatic climate shift that Australia has undergone, turning from verdant forest to mostly red dry desert. With its northward drift, the progressive drying of the island continent, it’s unlikely alliance with the flourishing tree helped secure the koalas future. Normally, animals that confine themselves to a single source of food end up as evolutionary cul-de-sacs. But in the case of the koala, these furry parasites really lucked out.

And it’s an evolutionary journey that is still in motion. As the fastest moving continent on the planet, Australia has moved so far north that it’s now colliding with Asia. With one continent grinding directly against another, it has forced up many of the volcanoes of Indonesia, even whole islands, such as Timor. And on the Pacific side, in Papua New Guinea, it has thrust up entire new mountain ranges as high as Europe’s Alps. As it does so, fresh evolutionary alliances are being forged.

So, Australia’s natural history isn’t over, not by any means, because the island continent’s future is to effectively become the southern margin of Asia. A remarkable continental makeover for a piece of planetary real estate that started life in the depths of the southern hemisphere. It is all down to the slow and steady movement of the one continent that’s always been considered quiet and stable.

Professor Iain Stewart – from salt flats to savannah:

It’s one of the most truly extraordinary landscapes on Earth. The Salar De Uyni. The biggest salt flat on the planet, stretching out across the Bolivian altiplano plateau, 3700 metres up in the Andes mountains of South America.

In winter, especially during the snowmelt of late March, water ponds on the Salar’s flat surface, turning the land into a vast natural mirror. But at this altitude, any runoff from the mountain is subject to the cyclical and seasonal evaporation, laying down layer after layer of salt brine. 

A stunning white vista made all the more remarkable because this vast expanse of high plateau was originally part of a complex of great lakes at low altitudes, which gradually became uplifted over millions of years as the Andean mountains themselves began to rise.

The upheaval of the Andes has shaped South America’s natural history, not least by creating some of the world’s most rich, unique and biodiverse natural habitats. The continent is a true patchwork of ecological zones: from deserts, flooded plains and savannah, to lofty salt flats, cloud forest and mountain peaks. And at the continent’s heart, a vast rainforest that overflows with life: the Amazon.

That Amazon basin is itself a creation of the towering Andes. Before the Andes, the main rivers on the continent flowed in the opposite direction to today, westward into the Pacific ocean. When the mountain barrier started to rise it diverted rivers to the north, where they flowed out into the Caribbean, creating a huge expanse of wetlands close to the growing mountains.

Later, further uplift blocked the route north and forced the rivers to converge towards the Atlantic. From around 20 million years ago, the resulting wall of high mountains disrupted rain-bearing air masses. With the increased rainfall on its eastern flank, more and more sediment flowed off the Andes in new rivers that drained down into the Amazon basin. And with that flow came nutrients that enriched the Amazon forest and its flora.

With the growing Andes on one hand and the flourishing Amazon on the other, South America saw the development of an astonishing diversity of life. 

Many species are still only found on this continent. Species like the xenathrans – armadillos, anteaters, and sloths – found in diverse habitats across South America, not only in the rainforest but also in the savannah-like regions of southern Brazil and Argentina. Or the iconic llama, restricted to the steep Andean peaks and high salty plateau.

Few animals are better suited to the high-altitude mountainous terrain of the Andes than the llama. Unlike other hoofed animals, their feet have two toes. The bottom part of the foot is divided in two and is covered by a tough leathery sole. Because of these flexible pads, llamas have an amazing foothold on rocky and slippery ground. What’s more, they have unique blood that adapts well to the poor oxygen in the high elevations where they live. Llamas have more red blood cells (haemoglobin) per unit volume of blood than any other mammal. So their bodies are super-charged with oxygen.

These clever adaptations make llamas perfectly at home in the Andean high lands. But they didn’t originate in the mountains. In fact, they are not even from South America. Instead, they evolved in the low plains of North America. They are living proof of a dramatic tectonic union of the two continental Americas which fundamentally shaped the destiny of South America and its wildlife.

For it is the llama, perhaps more than any other animal, that highlights the remarkable biological transformation of the South American continent. When their ancestors first appeared in North America, about 40 million years ago, the northern and southern Americas existed as separate continents. Slowly, plate tectonic motions were edging them closer together and, by around 30 million years ago, an intervening archipelago of scattered volcanic islands linked up as stepping stones between the two approaching land masses.

And so it was that, 3 million years ago, that a narrow land bridge emerged and the llamas crossed into South America. Their arrival was part of an epic intermingling of species – the Great American Interchange. In reality, it wasn’t an especially even interchange; roughly half of today’s South American species are derived from North American forms, including cats, rabbits, bears, deer, and foxes. In contrast, only 10% of North American animals are descended from South American – armadillos and opossums being the most successful.

It seems that North American animals were more robust. Perhaps the relative isolation of the South American animals made them more vulnerable when new species encroached on their habitat. Whatever the reason, North American carnivores flooded south to find a wealth of large and lumbering herbivores.

In among the bloody northern invasion, the formation of the Central American isthmus dramatically increased animal and plants both north and south. But it was South America in particular that witnessed a true transformation in its biological wealth. And of course, among the most successful arrivals was that most quintessential of all South American mammals, the llama, now long extinct in the north, and gradually adjusting to the new heady heights of the Andean peaks.

Professor Iain Stewart – origins of a dramatic continent:

For fishermen in the backwaters of Kerala, southern India, the prize catch is a fish that is locally called carmin. For scientists, that fish is a distinctive type of cichlid – Latin name etroplus suratensis – whose peculiar anatomy reveals the evolution of an entire continent.

The peculiarity of the etroplus cichlids comes from a couple of anatomical quirks – multiple anal fins and a head that masks an enlarged swim bladder, the sac that controls its buoyancy. They are traits shared by only one other group of fish, the closely related paretroplus cichlids. But they live 4000km away, in Madagascar.

Now, etroplus cichlids can tolerate slightly salty conditions but they’re essentially a freshwater fish, so one thing’s for sure – they didn’t swim to India. Instead, it’s not the fish that moved – it was India.

120 million years ago, just before the emergence of the first cichlid fishes, India was located way beyond the equator in the southern hemisphere, tucked snugly in beside Madagascar. Then about 90 million years ago, as the southern fragments of the great supercontinent of Pangea began to break apart, India and Madagascar went their separate ways.

Over the next few tens of millions of years, the piece of continental flotsam destined to be the Indian subcontinent sped northwards, closing the stretch of ocean ahead of it. By 50 million years ago, its leading edge had reached the southern margin of the vast landmass of Asia.

As India slowly ploughed into the bulwark of Tibet, Nepal, and China, the immense power of the collision twisted and contorted solid rock as if it were plasticine. The result was the rise of the greatest mountain range on Earth – the Himalayas.

Hidden in amongst towering peaks up to 8000 metres high are tell-tale signs that the region’s crumpled rock strata began as muddy sediment on the deep ocean floor. Those clues can be found in hard, black nodules that fall from soft grey shale cliffs along Nepal’s spectacular river gorges. The nodules break open to reveal curious coiled stones which the locals call ‘saligrams’, traditionally worshipped as manifestations of the Hindu god Vishnu and sold at roadside stalls to passing tourists. Geologists know them better as ammonites, the fossilised remains of an extinct member of the squid family.

Their modern-day version would be the Nautilus. And just like the today’s Nautilus, these creatures didn’t live in the mountains.

150 million years ago, back in the Jurassic age when dinosaurs roamed the land and India was still conjoined with Madagascar, these ammonites were swimming around in the deep ocean. Similar marine fossils have been found right across the Himalaya, including at the top of Mount Everest, meaning that rocks that started out at the bottom of the ocean now form the roof of the world.

So, as India collided with Asia, the Jurassic floor of that ancient ocean which geologists call Tethys was gradually thrust up to form the planet’s most formidable mountain barrier. It is a barrier that has had a profound effect on the course of the natural history of the region. Because mountains this high can’t help but interfere with the climate.

Mountains create their own weather, and the bigger they are, the bigger the weather they create. So, as home to the biggest peaks on the planet, it’s no real surprise then that the Himalayas produce one of the most important weather systems on the planet – the Asian monsoon.

Every year, moisture-laden winds from the Indian Ocean feed intense monsoonal air masses that sweep across the flat lands of India and Bangladesh and slam into the ramparts of the Himalaya. As much rain falls in the Amazon basin in a year as empties on the slopes of northern India and Nepal during monsoon season, dumped by thunderhead rain clouds struggling vainly to climb over the Himalayan peaks.

The resulting torrential monsoonal deluges loosen snow and ice from mountain ice-fields and thundering avalanches deliver glacial debris directly into bloated milky-white headwaters, which twist and plunge through gorges that bite deeply into the mountains. These sediment-laden rivers flood out and spread their cargo of liberated ancient sea floor over the great plains of India, Pakistan and China on their way to the distant ocean.

Driven by the monsoon rains, the rivers and resulting nutrient-rich soils shed from the Himalayas have helped to create and maintain Asia’s astonishing richness of natural and cultural diversity. The margins of its mountain heartland set the fragmented geological template for an abundance of amazing species, whilst its extensive fertile plains support the livelihoods of three billion people.

Few living in their shadow, however, probably appreciate that this extraordinary legacy is 100 million years in the making – the epic consequence of an unstoppable landmass meeting an immovable object. And revealed in a story written into the bones of a rather remarkable fish.

Professor Iain Stewart – the geology of Antarctica:

March 1912. The Plymouth-born explorer and adventurer Robert Falcon Scott and his team are returning from their ill-fated attempt to be the first to the South Pole. Blighted by frostbite, snow blindness and malnutrition, and man-hauling 16 kg of rock samples, they still take time to ‘geologise’ the Transantarctic Mountains. Ultimately, it would cost them their lives. Almost eight months later, when their frozen bodies were found, Scott’s rock samples were carefully laid out. He had clearly considered them precious cargo.

Scott had been persuaded to collect the rocks by a young English palaeo-botanist, Marie Stopes. Later in life she would find fame as a pioneer of women’s rights and family planning, but in the early 1900s she was an expert on ferns and seed plants from Carboniferous times, 300 million years ago. Certain that such rocks would be found in Antarctica, she had pleaded with Scott to take her on his expedition. He refused, but promised to bring her back some samples.

When analysed back in England, Scott’s samples were found to be packed full of plant debris. Many of the leaves were from a fern-like tree called Glossopteris, indicating that in the Carbonifeorous age, this icy wasteland had been carpeted with fern forest. The spores of these trees couldn’t be transported great distances but Glossopteris had been found in Carboniferous strata right across the southern hemisphere, from India to South America. All those land masses must have been welded together, including, now, Antarctica.

And, 255 million years ago, much of what is today icy wasteland must have been covered in lush temperate forest.

Southern Right whales – the third largest whale species on the planet – spend most of the year in Antarctica feeding, but in August they journey over 2000 kilometres north to breed along the edge of Australia’s Southern Bight. The deep waters here mark where the once conjoined twin continents of Australia and Antarctica finally split apart.

90 million years ago, volcanic activity from deep within the earth’s mantle gradually created a new ocean seaway between Antarctica and Australia. As they spread apart across a mid-ocean ridge, Australia drifted northwards leaving Antarctica sitting all alone over the south pole, still temperate and forested.

But that isolation created an unusual effect in the waters around it. Without land in the way, ocean currents circulating that huge mass, got stronger and deeper, creating the circum-Antarctic current and cutting off the continent from warm waters to the north. In just 1 million years, Antarctica changed from a temperate forested land, to one entombed in ice.

Amazing to think that if I’d been walking along here, 90 million years ago, there would have been no cliff, there would have been no ocean. Instead, I would have been able to take a single step from here directly on to Antarctica.