2016-17 has been a great year for Australian farmers, with record production, exports and profits. These records have been driven largely by good weather, in particular a wet winter in 2016, which led to exceptional yields for major crops.
Unfortunately, these good conditions go very much against the long-term trend. Recent CSIRO modelling suggests that changes in climate have reduced potential Australian wheat yields by around 27% since 1990.
In general, the drier inland parts of the cropping zone have been more heavily affected, partly because these areas are more sensitive to rainfall decline. Smaller effects have occurred in the wetter zones closer to the coast. Here less rain can have little effect on – and can even improve – crop productivity.
Farmers are reacting
However, it’s not all bad news. The study finds that Australian farmers are making great strides in adapting to climate change.
Much has been written about the fact that farm productivity in Australia has essentially flatlined since the 1990s, after several decades of consistent growth. The ABARES research suggests that changes in climate go some way towards explaining this slowdown.
After controlling for climate, there has been relatively strong productivity growth on cropping farms over the past decade. However, while farms have been improving, these gains have been offset by deteriorating conditions. The net result has been stagnant productivity.
Furthermore, there is evidence that this resurgence in productivity growth is a direct result of adaptation to the changing climate. Our study found that over the past decade cropping farms have improved productivity under dry conditions and minimised their exposure to climate variability.
This contrasts with the 1990s, when farms focused more on maximising performance in good conditions at the expense of increasing their exposure to drought.
Anecdotal evidence suggests that winter cropping farms have made a range of changes over the last decade, to better exploit soil moisture left from the summer period. The most obvious is the shift toward conservation tillage during the 2000s, where some or all of a previous crop’s residue (such as wheat stubble) is left in a field when planting the new crop.
It seems that farmers are adapting to new seasonal trends of rainfall, which for most cropping farms means less rain in winter and more in summer.
Is the Australian cropping belt moving south?
Previous research has suggested that the zone of Australia suitable for growing broadacre crops, known as the cropping belt, appears to be shifting south.
Our study found evidence to support this, with ABARES and ABS data showing increased cropping activity in the wetter southern fringe of the cropping belt in Western Australia and Victoria. At the same time, there have been declines in some more inland areas, which have been heavily affected by the climate downturn.
These shifts may be partly due to other factors – such as commodity prices and technology – but it’s likely that climate is playing a role. Similar changes have already been observed in other agricultural sectors, including the shift of wine grapes into Tasmania in response to rising temperatures.
What does this mean for the future?
At present there remains much uncertainty over future rainfall patterns. While climate models and recent experience suggest a clear direction of change, there is little agreement over the magnitude.
On the positive side, we know that farmers are successfully adapting to the changes in climate and have been for some time. However, so far at least, farmers have only been able to tread water: improving productivity just fast enough to offset the decline in climate. To remain competitive, we need to find ways to improve productivity faster, especially if current climate trends continue or worsen.
While it may not lead directly to impassioned critiques of climate governance, nor immediately sort the sceptics from the believers, talk of brewing storms or dried-up reservoirs now carries with it a whiff of trepidation about our collective forecasts.
Bridging the divide
Despite the growing politicisation of weather talk, weather and climate are usually understood as empirically distinct bodies of knowledge. Climate is, to quote British comedy duo Armstrong and Miller, “a long-term trend averaged over many years”, as opposed to weather, “which is what’s going on outside the window right now”.
The problem with this distinction is that climate change’s global reach and extended time scale can make it seem like it is happening somewhere else and to someone else (or, indeed, not at all). So perhaps the distinction is not useful for the cultural processes of adaptation. What might happen if we were to breach official definitions and disciplinary lines and think of the two things together?
Closing the distance between weather as event and climate as pattern can accomplish several things. Most obviously, it reminds us that there is a relationship between the two. Without weather, there would be nothing to amalgamate as climate.
While one heatwave does not equate to “climate change”, many and increasing ones give us pause to wonder. Leslie Hughes and Will Steffen are doing the data-driven work in this regard.
In other words, bringing climate and weather together can remind us that climate change is not only about abstract calculations on scales too big for our small and ultimately short-lived human forms to fathom.
Thinking about weather as part of climate underscores that we experience climate change with and on our bodies; climate change is lived by us at a very human scale, too.
The daily experience of weathering
So, what would it mean to harness the daily, mundane intrusions of weather as political? In contrast to terms like resilience (complicit with neoliberal incitements of bootstrapping) or sustainability (which suggests we get to keep something intact), weathering invites us to consider what we will lose along the way.
Weathered bodies, weathered houses, weathered cars, weathered clothes, weathered relationships, weathered dreams – these all bear scars of what has worn them down, and of what they have been asked to carry, to survive, and to hack.
Bringing this sense of lived climate change to our everyday perception is neither an easy nor comfortable thing. For one, discomfort is not a place we generally like to dwell for long. In a more political sense, though, paying attention to the weather as something in which we are intimately implicated, not just a disconnected backdrop to our human dramas, reminds us we are weather-makers too.
On a stable planet, nature provided a background against which the human drama took place; on the unstable planet we’re creating, the background becomes the highest drama.
This could be the epigraph for the Anthropocene.
Even in wealthy, climate-controlled places, weather inserts a reminder of one’s privilege, or luck, or vulnerability, or hardship, into those once mundane spaces. We may bemoan the slipping away of vacuous weather chats — “does everything have to be political?” — but perhaps noticing the weather can become an opening for everyday engagement in the politics of climate change instead.
In gender and cultural studies and the environmental humanities, rather than trying to leave weather-talk pregnant with fear, anticipation or political outrage, we are explicitly thinking with and through the weather to develop strategies for a rigorous and political response to climate change.
One way we are doing this is through a tactic or practice we call “weathering” – that is, cultivating attunement to how our own bodies, and bodies of others, experience weather. This includes how we and they manage it architecturally, technologically, professionally and socially.
We don’t all weather equally
Through the concept of “weathering”, our work forces a confrontation between large-scale climate data and embodied sociopolitical experiences that are too often treated as separate. It also underscores the politics and activism we hope this tactic can engender.
Such attentive acclimatisation reveals that, even though we’re all in the same planetary boat when it comes to global warming, we’re not all in it in the same way. This is something ecofeminists and environmental justice scholars have long known. Our work helps articulate how difference also marks our apparently banal encounters with the weather.
At a “Hacking the Anthropocence” symposium in Sydney this month, scholars, artists and activists are responding to the idea of “weathering”. The variety of experience that such a provocation reveals is astounding.
For Anne Werner’s and Genevieve Derwent’s work growing chickens on Autumn Farm and Cameron Muir’s reflections on life jackets for refugees, the weather holds a very different significance and function. Climate change is undoubtedly political – but all the more so because of these uneven individual and collective experiences of the weather.
Other kinds of bodily, socioeconomic, historical and geopolitical differences further complicate how we weather the world. When it comes to rising sea levels, or dried-up water holes, for example, racism, colonialism and gendered labour are all significant. Weathering as a concept thus asks us to think about what else, besides meteorological phenomena, one might be asked to weather.
Note that a more common meaning of “weathering” is as synonym for withstanding or enduring. Not only will different regions weather differently in a changing climate (drier, hotter in central Australia; more flooding on the US Atlantic coast; disappearing land in Pacific Islands), but people within those regions weather differently too.
Our human experiences of weather are linked to how the non-human world is weathering what we have forced it to carry. Artist Victoria Hunt will ask us to imagine with her “The Cry of Water”, while archaeologist Denis Byrne will explore the significance of seawalls, which are weathered by erosion. Human and non-human worlds weather together in a fraught and desirous intimacy.
The animal world is also constantly weathering. We know about catastrophic events such as the endangered bats that cannot cope with heat above 42℃. We’ve learned that the Great Barrier Reef is bleaching as water temperatures rise.
But what about the less-well-known water-holding frog or, indeed, ants and brine shrimp? How do they weather? At our symposium, Rebecca Giggs, Kate Wright and Emily O’Gorman (respectively) will let us know how, and suggest what we humans might learn about weathering the world differently.
These contributions invite us to explore how our experiences of the weather are highly mediated by a range of social, political and cultural forces. Anthropologist of institutions Tess Lea will investigate how bureaucracy (materialised as mountains of paperwork) orients different populations’ capacity to weather. Cli-fi expert and petrocultures scholar Stephanie LeMenager invites us to speculate on what a new kind of civic engagement might look like in this context.
Weathering directly connects human social, cultural and economic structures such as racism, colonialism and gender oppression to climate change. It insists that we think about global warming on a massive scale as always textured by acute experiences of social phenomena.
We recognise that the weight of a changing climate will not be borne equally by bodies – across geographies, economic status, or species.
So next time you curse a forgotten umbrella as the skies open up, or welcome the sun shining on your kid’s birthday party in the park, remember that when it comes to the weather, the personal is getting more and more political.
Hacking the Anthropocene II: Weathering (May 25-31) is supported by the Sydney Social Sciences and Humanities Advanced Research Centre (SSSHARC); the Australian Research Council Centre of Excellence for the History of Emotions; the Sydney Environment Institute at the University of Sydney; the Planetary Health Initiative at the University of Sydney; and the Seed Box: a MISTRA-FORMAS Environmental Humanities Collaboratory (hosted at Linkoping University, Sweden).
If we are to slow these disturbing trends and stabilise the climate at a level with which we might be able to cope, only a relatively small amount of the world’s remaining coal, oil and gas reserves can actually be used.
The majority must be left unburned in the ground, without developing vast new coal deposits such as those in the Galilee Basin.
To give ourselves just a 50% chance of staying within the 2℃ Paris target, we can burn only 38% of the world’s existing fossil fuel reserves. When this budget is apportioned among the various types of fossil fuels, coal is the big loser, because it is more emissions-intensive than other fuels. Nearly 90% of the world’s existing coal reserves must be left in the ground to stay within the 2℃ budget.
When the carbon budget is apportioned by region to maximise the economic benefit of the remaining budget, Australian coal in particular is a big loser. More than 95% of Australia’s existing coal reserves cannot be burned, and the development of new deposits, such as the Galilee Basin, is ruled out.
The health case
Exploiting coal is very harmful to human health, with serious impacts all the way through the process from mining to combustion. Recently the life-threatening “black lung” (coal workers’ pneumoconiosis) has re-emerged in Queensland, with 21 reported cases. Across Australia, the estimated costs of health damages associated with the combustion of coal amount to A$2.6 billion per year.
In India, the country to which coal from the proposed Carmichael mine would likely be exported, coal combustion already takes a heavy toll. An estimated 80,000-115,000 deaths, as well as 20 million cases of asthma, were attributed to pollutants emitted from coal-fired power stations in 2010-11. Up to 10,000 children under the age of five died because of coal pollution in 2012 alone.
Compared with the domestic coal resources in India, Carmichael coal will not reduce these health risks much at all. Galilee Basin coal is of poorer quality than that from other regions of Australia. Its estimated ash content of about 26% is double the Australian benchmark.
This is bad news for children in India or in any other country that ends up burning it.
The economic case for the Carmichael mine doesn’t stack up either. Converging global trends all point to rapidly reducing demand for coal.
The cost of renewable energy is plummeting, and efficient and increasingly affordable storage technologies are emerging. Coal demand in China is dropping as it ramps up the rollout of renewables. India is moving towards energy independence, and is eyeing its northern neighbour’s push towards renewables.
All of these trends greatly increase the risk that any new coal developments will become stranded assets. It’s little wonder that the financial sector has turned a cold shoulder to the Carmichael mine, and Galilee Basin coal development in general. Some 17 banks worldwide, including the “big four” in Australia, have ruled out any investment in the Carmichael mine.
From any perspective – climate, health, economy – the proposed mine is hard to justify. And yet the project keeps on keeping on.
De-extinction – the science of reviving species that have been lost – has moved from the realm of science-fiction to something that is now nearly feasible. Some types of lost mammals, birds or frogs may soon be able to be revived through de-extinction technologies.
But just because we can, does it mean we should? And what might the environmental and conservation impacts be if we did?
Without an answer to “where do we put them?” — and to the further question, “what changed in their original habitat that may have contributed to their extinction in the first place?” — efforts to bring back species are a colossal waste.
These are valid concerns, and difficult to consider in light of the many competing factors involved.
We’ve recently outlined a deliberate way to tackle this problem. Our new paper shows that an approach known as “decision science” can help examine the feasibility of de-extinction and its likely impact on existing environmental and species management programs.
Applied to the question of possible de-extinction programs in New Zealand, this approach showed that it would take money away from managing extant (still alive) species, and may lead to other species going extinct.
Solving complex problems
The potential to reverse species extinction is exciting from both a science and a curiosity perspective. But there is also great concern that in the passionate rush to implement new technology, we don’t properly consider environmental, economic and social issues.
Decision science methods simplify complex problems into parts that describe the benefit, cost and feasibility of the different possible solutions. They allow for “apples to apples” comparisons to be made about different but essential aspects of the projects being considered.
Decision science in action
When applied to de-extinction projects, decision science lets researchers:
compare different possible outcomes of de-extinction approaches
better understand future expected costs and benefits, and
see impacts of using de-extinction technology on other species that we care about.
Over the past decade their management agencies have built on a decision science approach to prioritise their conservation efforts, and increase the number of species they are able to put on the road to recovery.
New Zealand in particular is a prime candidate for considering de-extinction because they have had many recent extinctions, such as the huia.
A recent study took the process that was developed to rank New Zealand species according to priority for action, and included 11 possible candidates for de-extinction in the ranking process. These were birds, frogs and plants, including the little bush moa, Waitomo frog and laughing owl.
By applying a decision science process, the authors found that adding these species to the management worklist would reduce their ability to adequately fund up to three times the number of currently managed species, and essentially could lead to additional species going extinct.
The study also showed that private agencies wishing to sponsor the return of resurrected extinct species into the wild, could instead use the money to fund conservation of over eight times as many species, potentially saving them from extinction.
Crucially, this study could not examine the initial costs of using genetic technology to resurrect extinct species, which is unknown but likely to be substantial. If it could have included such costs, de-extinction would have come out as an even less efficient option.
Could de-extinction ever be the right option?
The New Zealand example is not a particularly rosy picture, but it may not always be the case that de-extinction is a terrible idea for conservation.
Hypothetically, there are situations where the novelty and excitement of a de-extinct species could act as a “flagship species” and actually attract public interest or funding to a conservation project.
There also is an interesting phenomenon where even just the possibility of having a management action such as de-extinction may change how conservation problems are formulated.
Conservation management currently aims to do the best it can, while operating under the constraint that biodiversity is a non-renewable resource. With this constraint we can apply theory that is used for managing the extraction of non-renewable resources like oil or diamonds to determine the best strategy for management.
However, if extinction was no longer forever, the problem could be considered as one that would be managing a renewable resource, like trees or fish.
Of course, the ability to revive species is nowhere near as simple as regrowing trees, and a species being revived does not necessarily equate to conservation.
But changing the way that conservation managers think about the problem could present conservation gains in addition to losses.
Theoretically, different methods may be used for conservation benefit and there may be different strategies to produce the best outcomes. For example, species that could easily be de-extinct may get less funding attention that the ones for which the de-extinction technology isn’t available, or are too costly to produce.
This research does not advocate for or against de-extinction, rather, it provides strategies to deal with alternatives from the start with a clear representation of the trade-offs.
This work aims to step back and take a realistic look at the implications of new technology, including its costs and its risks, within the context of other conservation actions. Decision theory helps to do just that.
What can creative literature tell us about radical environmental change? Most people accept that literature can be closely connected to places. Whether it is Dickens’s London or Hardy’s Wessex, we also accept that imaginative works deliver something about the nature of place that does not necessarily come to us by any other means.
It is a regional literary history that nevertheless encompasses some of the nation’s finest writers — Albert Facey, Dorothy Hewett, Peter Cowan, Jack Davis, Randolph Stow, Elizabeth Jolley, Tom Flood, John Kinsella. Facey’s A Fortunate Life (1981) is a landmark in Australian autobiography; Hewett, Cowan and Stow helped define literary modernism in Australia; Jack Davis was a leading figure in the Aboriginal literary renaissance; and Jolley’s The Well (1986) and Flood’s Oceana Fine (1990) both won the Miles Franklin literary award.
What unites these works? Is it simply a quirk of fate that a sparsely populated hinterland in Australia’s most isolated state produces a body of literature that rivals in many ways the literary outputs of the great Australian metropolitan centres in Melbourne and Sydney?
For the answer to this question one has to understand the history of the WA wheatbelt. In two 30-year periods (1900-1930 and 1945-1975) an area of land roughly the size of Britain was stripped of its native vegetation for the production of grain and livestock. It is a crescent of land that begins just north of Geraldton on the west coast and sweeps south and east to Esperance on the south coast.
When the Swan River Colony was founded in 1829, six years before Melbourne, it was with the intention of forming an agricultural colony of closely settled yeoman farmers, who would own their own land and congregate in small, nicely spaced villages.
However, the antique soil of WA bore almost no resemblance to the fertile soils of recently glaciated northern Europe. Four to five more or less rainless months, where dry desert winds blow steadily across the vegetation was also an unprecedented challenge to farming methods learned in the British Isles. Lastly, there were almost no rivers to speak of, and permanent summer water was a rare commodity.
For all these reasons, the agricultural dream of WA remained largely unrealized. The game-changing event was the goldrush of the 1890s. The population of the colony trebled between 1889 and 1896, from 44,000 to 138,000.
Knowing that the gold would be dug out before too long but wanting to capture this new cache of colonists, the colonial government passed the Homesteads Act in 1893 to parcel out land, and established an Agricultural Bank in 1894 to finance farmer-settlers. An army of land surveyors fanned out through the southwest and provisions for water, fertilizer and rail transit were quickly put into motion. Towns were gazetted, one-teacher schools popped up and WA took the lead in distance learning.
Albert Facey’s uncle Archie McCall had come over from South Australia to work the goldfields and was one of those who leapt at the land offer. Dorothy Hewett’s grandparents had made their money selling goods to diggers heading out to the goldfields at Kalgoorlie and Coolgardie and with this they purchased an extensive parcel of prime land at Yealering not far from McCall’s farm at Wickepin.
The dream refracted
What we get in both of these very different writers is a distinct picture of the dream of the wheatbelt. It is this dream — a settler-colonial ideology of farming independence — that we see refracted through the wheatbelt writers all the way through the 20th century.
The animating vision of the wheatbelt was an amalgam of ideals. On the one hand, it appealed to the basic material prospect of upward mobility. In the late 19th and early 20th century, opportunities for advancement through education were not generally available.
But the wheatbelt vision seemed even more deeply situated than this, offering itself as an antidote to the ills of modern city life. As the various states all moved to convert low-yield pastoral production to high-yield cash-cropping, there emerged a veritable ideology of wheat in the post-Federation years, and right through to the Depression.
C.J. Dennis joined the chorus in his bouncy ballad simply called Wheat from 1918:
Tho’ it ain’t a life o’ pleasure,
An’ there’s little time for leisure,
It’s contentin’, in a measure, is the game of growin’
Dennis and others helped to drag crop-farming away from its associations with European peasant drudgery and into the noble task of nation-building and feeding the “bread-eating” (i.e. European or European-derived) countries of the world.
For Facey, even though his memoir was not published until 1981 (the year before he died), the dream of the wheatbelt and the ideology of wheat remain preserved as if in amber. The basic tasks of “clearing” the wheatbelt — particularly the regimes of annual burning and cutting — are remembered with particular pride by Facey.
Born a generation and a half later, Hewett grew up in a farm that was already in place. Although she left Lambton Downs (as it was dubbed) at the age of 11, Hewett’s writing returned again and again to the wheatbelt. Hewett’s wheatbelt had a mythic, gothic flavour in which the dream of it is present but often in inverted form. This wheatbelt is beset by a pernicious fatality and mired in the sexual miseries of her extended family.
Hewett deserves credit for being the first writer to take seriously the fact that the wheatbelt was built on land whose traditional owners had not disappeared but were still there, either impoverished in fringe-camps or incarcerated in government or church institutions.
The other side of the farming frontier
But it was the emergence of Aboriginal writing in the generation politicized by the citizenship referendum that brought a powerful voice from the other side of the wheatbelt frontier. Jack Davis had spent time in the notorious Moore River Native Settlement on the edge of the mid-northern wheatbelt, and then (after the untimely death of his father), with relatives of his mother’s sister at the Brookton reserve in the Avon valley. There he did the usual itinerant work that Aboriginal families did in the wheatbelt’s early years — clearing, fencing, shearing, rabbiting.
What Davis gives us in his poetry of the 1970s and the great plays of the 80s is a completely alternative vision of the wheatbelt. It doesn’t look like wheatbelt literature for the simple reason that it does not proceed either positively or negatively from the wheatbelt dream. Instead, it proceeds from Aboriginal presence in the land.
The tragedy of the Noongar is shown in all its woeful extremity, but tempered by Davis’s astringent sense of humour—his black humour if you like. But really Jack Davis is writing about survival. His example has provided a platform for a writer like Kim Scott to foster new forms of Noongar creative re-emergence, and also new forms of penetrating critique.
At the same time that a consciousness of Aboriginal dispossession began to force its way into the understanding of the wheatbelt, a much sharper sense of its ecological cost was also starting to emerge. Certainly, right through my literary history of the wheatbelt there was a realization that the waving fields of wheat were planted on lands stripped of their native ecosystems.
Everyone knew this because everyone spent a considerable part of each year toiling to clear the land. But the view tended to be that there was always more bush. Each bit of clearing was a merely local matter. Likewise, as rising salinity became directly associated with the clearing of native perennial vegetation, it was repeatedly explained away as a small, local, confined phenomenon.
But in the writing of Peter Cowan and that of the naturalist, Barbara York Main, the full picture of environmental destruction began to appear without the customary euphemism. It would be wrong to say that public opinion, particularly in the wheatbelt, changed decisively in the 1960s or even the 1970s. The cart-blanche denial, however, of environmental value — that the natural world of the wheatbelt had a value — became harder and harder to maintain.
By the 1980s, the wheatbelt had become uncanny. No longer the sign of the natural cycles of life replenishing the earth with seasonal regularity, but a vast and even repellent monocultural expanse. The wheatbelt was something profoundly unnatural in the eyes of writers like Elizabeth Jolley, Tom Flood and John Kinsella.
Of these, it has been Kinsella who has proved to be both durable and prolific. His poems, stories and other writings specify a wheatbelt that exists in strange cross-currents of science, tradition and avarice. The natural world is prised out of its familiar romantic categories and, in his remarkable work, exists in eerie counterpoise to the techno-scientific mania of modern agribusiness.
The central fact of the wheatbelt is radical disappearance. On one hand there was the destruction of the sovereign culture of the Noongar, custodians for millennia. Noongar people continue to practice and uphold their culture in spite of everything and the land continues to speak through them.
But on the other hand we must also contend with the fact that in the central wheatbelt shires, at least, only something like 7% of the natural vegetation (and the animal habitat it provides) remains. This, in a place that has a biodiversity as stunning as a rainforest canopy.
Literature cannot, in and of itself, make these losses good. A thousand novels cannot replace one extinct species. But in human terms there is hope. The Noongar language is being revitalized. And here literature certainly does have a role to play. Jack Davis used Noongar in his plays and provided his own glossaries. Kim Scott’s fiction, and occasional poetry, gives its readers Noongar — in fact teaches its readers Noongar and the deft sonics of a language adapted to country. And many of today’s farmers are now at the forefront of conservation initiative and Landcare groups.
The role, though, that I see for literature in coming to terms with the facts of the wheatbelt lies in its capacity to continuously disabuse us of the complacent certitudes by which we think we know the world. It need not require the experimental bravura of Kinsella’s postmodern verse to do this unsettling. Even the older writing does it in surprising ways.
What Dorothy Hewett and Jack Davis do within the broad parameters of theatrical realism nevertheless succeeds in unpicking the simple pouches we tend to pack our conceptions in. Barbara York Main’s natural histories throw open the dazzling singularity of wheatbelt life forms, and at the same time their intricate interconnections. Peter Cowan’s quietist studies of disillusioned loneliness, defamiliarises the wheatbelt just as certainly as Facey’s childhood glee at burning the bush to smouldering ashes.
It is not a particular kind of literature that gets to the “heart” of the wheatbelt. It is the fact that the wheatbelt falls into the prism of literature that allows us to see this place in terms other than the ones it gave itself via its animating dream of agricultural plenitude and generational continuity.
Creative writing is not blind to the natural or economic forces that determine the fate of the wheatbelt, but it will always approach the matter through the medium of human subjectivity. In this sense, it is only literature that allows us to see inside the wheatbelt that was created, geologically speaking, in the blink of an eye.
Orangutan populations in the wild are criticallyendangered, and one of the things that may hamper their survival is the time they take to rear new offspring.
An orangutan mother will not give birth again until she’s finished providing milk to her previous offspring. Nursing can take a long time and vary across seasons, as we found in research published today in Science Advances.
Primate mothers, including humans, raise only a few slow-growing offspring during their reproductive years.
Differences in infant development have a profound effect on how many children a female can have over the course of her life – the key marker of success from an evolutionary vantage point.
Great apes have a high-stakes strategy. Chimpanzee mothers nurse their offspring for five years on average, twice as long as humans in traditional small-scaled societies.
Orangutans have been suspected of having even longer periods of infant dependency, although determining just how long has been a particular challenge for field biologists.
Living high up in dwindling Southeast Asian forests, these apes are adept at evading observers. Their nursing behaviour is often concealed, particularly while juveniles cling to their mother or rest together in night nests.
Maintaining continuous field studies to track their development is expensive, and efforts are hindered by frequent forest fires and devastating deforestation for palm oil plantations.
Teeth tell the story
I have spent the past few decades studying how orangutans and other primates form their teeth. Amazingly, every day of childhood is captured during tooth formation, a record that begins before birth and lasts for millions of years.
I’ve also teamed up with researchers Manish Arora and Christine Austin, at Icahn School of Medicine at Mt Sinai in New York, who have pioneered methods to map the fine-scaled elemental composition of teeth, as well as primate lactation expert Katie Hinde at Arizona State University.
We have shown in a previous study that tiny amounts of the element barium are an accurate marker of mother’s milk consumption. Like calcium, barium is sourced from the mother’s skeleton, concentrated in milk, and ultimately written into the bones and teeth of her offspring.
Once animals start nursing after birth, their teeth show increases in barium values, which begin to decrease when solid food is added to the diet. These values drop further to pre-birth levels when primates stop nursing and are weaned.
We’ve recently used this approach to explore the nursing histories of wild orangutans in collaboration with orangutan expert Erin Vogel at Rutgers University. In order to do so, I borrowed teeth housed in natural history museums from individuals that had been shot many years ago during collection expeditions.
Orangutan teeth show a gradual increase in barium values from birth through their first year of life, a time of increasing consumption of their mother’s milk. After 12-18 months, values decrease as infants begin eating solid foods consistently.
But surprisingly, barium levels then begin to fluctuate on an approximately annual basis. We suspect that this is due to seasonal changes in food availability. When fruit is in short supply, infants appear to rely more on their mother’s milk to meet their nutritional needs.
Another surprising finding is that nursing may continue for more than eight years, longer than any other wild animal.
This information is the first of its kind for wild Sumatran orangutans, as they have been especially difficult to study in their native habitat. Previous estimates from two wild Bornean orangutans suggested that juveniles nurse until about six to eight years of age.
Rather than spending so much time and energy breastfeeding their children, human mothers in traditional societies transition their infants onto soft weaning foods around six months of age, tapering them off milk a few years later.
Humans also benefit from having help such as older siblings and grandparents who lend a hand with childcare and enable women to energetically prepare for having their next child.
Orangutan mothers have it hard by comparison. They live alone in unpredictable environments with limited nutritional resources. In order to survive they use less energy than other great apes, raising their young more slowly.
Female orangutans begin reproducing around age 15 and can live until 50 years old in the most favourable of circumstances. They bear new offspring every six to nine years, producing no more than six or seven descendents over their lifetime.
Having a long nursing period and slow maturation makes orangutan populations especially vulnerable to environmental perturbations.
Recent work has also implicated poor habitat quality and the pet trade as additional factors in their rapidly declining numbers, which is underscored by their critically endangered status.
Research on collections housed in natural history museums provides timely evidence of how remarkable orangutans are, how much information we can retrieve from their teeth, and why conservation efforts informed by evolutionary biology are critical.
A remote South Pacific island has the highest density of plastic debris reported anywhere on the planet, our new study has found.
Our study, published in the journal Proceedings of the National Academy of Sciences, estimated that more than 17 tonnes of plastic debris has washed up on Henderson Island, with more than 3,570 new pieces of litter arriving every day on one beach alone.