Bones and all: see how the diets of Tasmanian devils can wear down their sharp teeth to blunt nubbins


Zoos Victoria, Author provided

Tahlia Pollock, Monash University; Alistair Evans, Monash University; David Hocking, Monash University, and Marissa Parrott, The University of MelbourneTasmanian devils are expert scavengers, with strong jaws and robust teeth that give them the notorious ability to eat almost all of a carcass — bones and all.
Scientists have even found echidna spikes in their poo.

But regularly crunching through bone comes at a cost: extreme tooth wear. In our new study, we analysed the skulls of nearly 300 devils, and show how regularly crunching through bones wears a devil’s teeth down from sharp-edged weapons to blunt nubbins.

Tasmanian devils are endangered and their wild population is continuing to decline. A key part of conserving this marsupial is by maintaining healthy and happy devils in captivity.

Understanding how their food affects their teeth can help us see if captive devils have the same types of tooth wear as their wild counterparts, and look for signs of any unusual or harmful wear.

Is there anything a devil won’t eat?

Tasmanian devils are the largest marsupial carnivore alive today. As scavengers, they occupy a unique niche in the Australian ecosystem by disposing of dead animal carcasses.

Devil standing over a dead carcass
Captive Tasmanian devils are given a variety of foods to replicate what they’d find in the wild. This photo was taken during a carcass feed at Healesville Sanctuary.
Zoos Victoria, Author provided

Devils are highly opportunistic and can eat many different types of prey. While their favourites are the carcasses of native mammals such as wombats and wallabies, they’ll also eat reptiles, amphibians, birds, fish, and even insects.

We know this because we find hair, feathers, scales, small bones, claws and more in their poo.

Almost nothing is off limits to devils — they’ll even have a go at a stranded whale given the chance. Although devils prefer to scavenge, they’re also accomplished hunters.




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But due to a transmissible cancer, devil facial tumour disease, wild numbers of these remarkable marsupials have plummeted by around 80%.

Right now, 45 Australian zoos and wildlife sanctuaries, plus an island and a fenced peninsula, are collaborating to maintain a healthy population of disease-free devils. It’s important for these institutions to provide captive animals with the right kinds of food for their health and to help make their future release back to disease-free wild locations successful.

Devils naturally wear their teeth down from sharp points and edges to blunt, almost flat surfaces by regularly eating bones.
Tahlia Pollock, Author provided

This is especially crucial for carnivores, who rely on tough foods to help them develop strong jaws.

Like hyaenas, but stronger

The types of food an animal eats will wear their teeth down differently. For example, big cats such as lions prefer to eat the softer parts of a carcass, like flesh or organs, and leave the bones behind.

Spotted hyaenas, however, will happily eat the bones. As a result, hyaenas have incredibly high tooth wear compared with lions.

This might not hinder the hyaena or devil as much as you might think. Both have very strong jaws that can compensate for the loss of sharp teeth. In fact, devils have the strongest bite force per body weight of any living mammal.

In the interactive below, you can check out 3D models of devil skulls to get a better idea of how much their teeth wear down.

Comparing wild and captive diets

By comparing the tooth wear of wild and captive devils, we can see if captive animals are encountering enough hard foods in their diets.

In the Save the Tasmanian Devil Program — an initiative of the federal and Tasmanian governments — captive devils are given a variety of small and large foods at different times, replicating what they’d find in the wild.

We found no signs of different or harmful tooth wear in captive devils, and they showed much the same patterns and types of wear as wild devils.




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However, we noticed captive devils wore their teeth more slowly than those in the wild. This may be due to eating higher quality food, such as carcasses that were fresh, whole, and yet to be scavenged.

This means captive institutions are doing a good job of providing devils with the right types of food for their teeth and encouraging wild behaviours.

Part of the health check for wild devils involves looking at their teeth. This particular devil has nice sharp tips and edges on their canines and molars.
Marissa Parrott/Zoos Victoria, Author provided

Collecting data about Tassie devils after they’ve been released confirms this. In 2012 and 2013, devils were released onto Maria Island in Tasmania after being born and raised for around a year in captivity.

Encouragingly, these devils kept the behaviours required to scavenge and hunt prey, and had diets similar to wild devils.

How you can help save Tasmanian devils

Our research is one small, but promising, piece in the overall puzzle. While captive research and breeding programs help conserve the Tasmanian devil, there are ways you can help, too.

Because they like to scavenge the carcasses of dead animals, road kill is especially tempting for devils. But being so close to the road is dangerous and road mortality is the second-biggest killer of wild devils.

So take care on the roads to help wildlife, especially if driving at night. And if you’re in Tasmania and see a devil that’s been hit on the road, log it in the Roadkill TAS app.

This will help identify road kill hotspots and protect this impressive, but endangered, species.




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The Conversation


Tahlia Pollock, PhD candidate, Monash University; Alistair Evans, Associate Professor, Monash University; David Hocking, Curator of Vertebrate Zoology and Palaeontology at the Tasmanian Museum and Art Gallery (TMAG) | Adjunct Research Associate at Monash University, Monash University, and Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

It takes 21 litres of water to produce a small chocolate bar. How water-wise is your diet?



A small chocolate bar takes 21 litres of water to produce.
Byline: CAROLINE BLUMBERG/ EPA

Brad Ridoutt, CSIRO; Gilly Hendrie, CSIRO, and Kimberley Anastasiou, CSIRO

Our diets can have a big environmental impact. The greenhouse gas emissions involved in producing and transporting various foods has been well researched, but have you ever thought about the water-scarcity impacts of producing your favourite foods? The answers may surprise you.

In research recently published in the journal Nutrients, we looked at the water scarcity footprints of the diets of 9,341 adult Australians, involving more than 5,000 foods. We measured both the amount of water used to produce a food, and whether water was scarce or abundant at the location it was drawn from.

The food system accounts for around 70% of global freshwater use. This means a concerted effort to minimise the water used to produce our food – while ensuring our diets remained healthy – would have a big impact in Australia, the driest inhabited continent on Earth.

Biscuits, beer or beef: which takes the most water to produce?

We found the average Australian’s diet had a water-scarcity footprint of 362 litres per day. It was slightly lower for women and lower for adults over 71 years of age.

A water-scarcity footprint consists of two elements: the litres of water used, multiplied by a weighting depending on whether water scarcity at the source is higher or lower than the global average.

Foods with some of the highest water-scarcity footprints were almonds (3,448 litres/kg), dried apricots (3,363 litres/kg) and breakfast cereal made from puffed rice (1,464 litres/kg).

In contrast, foods with some of the smallest water-scarcity footprint included wholemeal bread (11.3 litres/kg), oats (23.4 litres/kg), and soaked chickpeas (5.9 litres/kg).




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It may surprise you that of the 9,000 diets studied, 25% of the water scarcity footprint came from discretionary foods and beverages such as cakes, biscuits, sugar-sweetened drinks and alcohol. They included a glass of wine (41 litres), a single serve of potato crisps (23 litres), and a small bar of milk chocolate (21 litres).

These foods don’t only add to our waistlines, but also our water-scarcity footprint. Previous studies have also shown these foods contribute around 30% of dietary greenhouse gas emissions in Australia.

Sheep drink from a dried-up water storage canal between Pooncarie and Menindee in western NSW. Water shortages along the Murray Darling Basin have devastated ecosystems and communities.
Dean Lewins/AAP

The second highest food group in terms of contributing to water-scarcity was fruit, at 19%. This includes whole fruit and fresh (not sugar-sweetened) juices. It should be remembered that fruit is an essential part of a healthy diet, and generally Australians need to consume more fruit to meet recommendations.

Dairy products and alternatives (including non-dairy beverages made from soy, rice and nuts) came in third and bread and cereals ranked fourth.

The consumption of red meat – beef and lamb – contributed only 3.7% of the total dietary water-scarcity footprint. These results suggest that eating fresh meat is less important to water scarcity than most other food
groups, even cereals.

How to reduce water use in your diet

Not surprisingly, cutting out discretionary foods would be number one priority if you wanted to lower the water footprint of the food you eat, as well as the greenhouse gas emissions of production.

Over-consumption of discretionary foods is also closely linked to weight gain and obesity. Eating a variety of healthy foods, according to energy needs, is a helpful motto.

Aside from this, it is difficult to give recommendations that are relevant to consumers. We found that the variation in water-scarcity footprint of different foods within a food group was very high compared to the variation between food groups.




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For example, a medium sized apple was found to contribute a water-scarcity footprint of three litres compared with more than 100 litres for a 250 ml glass of fresh orange juice. This reflects the relative use of irrigation water and the local water scarcity where these crops are grown. It also takes more fruit to produce juice than when fruit is consumed whole.

Two slices of wholegrain bread had a much lower water-scarcity footprint than a
cup of cooked rice (0.9 litres compared with 124 litres). Of the main protein sources, lamb had the lowest water-scarcity footprint per serve (5.5 litres). Lambs are rarely raised on irrigated pastures and when crops are used for feeding, these are similarly rarely irrigated.

Consumers generally lack the information they would need to choose core foods with a lower water-scarcity footprint. Added to this, diversity is an important principle of good nutrition and dissuading consumption of particular core foods could have adverse consequences for health.

Workers process punnets of strawberries at a Queensland strawberry farm.
Dan Peled/AAP

Perhaps the best opportunities to reduce water scarcity impacts in the Australian food system lie in food production. There is often very large variation between producers in water scarcity footprint of the same farm commodity.

For example, a study of the water scarcity footprint of tomatoes grown for the Sydney market reported results ranging from 5.0 to 52.8 litres per kg. Variation in the water-scarcity footprint of milk produced in Victoria was reported to range from 0.7 to 262 litres. This mainly reflects differences in farming methods, with variation in the use of irrigation and also the local water scarcity level.

Water-scarcity footprint reductions could best be achieved through technological change, product reformulation and procurement strategies in agriculture and food industries.

Not all water is equal

This is the first study of its kind to report the water-scarcity footprint for a large number of individual self-selected diets.

This was no small task, given that 5,645 individual foods were identified. Many were processed foods which needed to be separated into their component ingredients.




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It’s hard to say how these results compare to other countries as the same analysis has not been done elsewhere. The study did show a large variation in water-scarcity footprints within Australian diets, reflecting the diversity of our eating habits.

Water scarcity is just one important environmental aspects of food production and consumption. While we don’t suggest that dietary guidelines be amended based on water scarcity footprints, we hope this research will support more sustainable production and consumption of food.

The author originally disclosed that he undertakes research for Meat and Livestock Australia. His disclosure has been updated to specify that the above research is among the projects to which the MLA has contributed funding.The Conversation

Brad Ridoutt, Principal Research Scientist, CSIRO Agriculture, CSIRO; Gilly Hendrie, Research scientist, CSIRO, and Kimberley Anastasiou, Research Dietitian, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How to get people to eat bugs and drink sewage



Disgust may be an impediment to many of us adopting more sustainable lifestyles, from considering alternative foods to drinking recycled water
http://www.shutterstock.com

Nathan S Consedine, University of Auckland

In wealthy societies we’ve become increasingly picky about what we eat. The “wrong” fruits and vegetables, the “wrong” animal parts, and the “wrong” animals inspire varying degrees of “yuck”.

Our repugnance at fruit and vegetables that fail to meet unblemished ideals means up to half of all produce is thrown away. Our distaste at anything other than certain choice cuts from certain animals means the same thing with cows and other livestock slaughtered for food. As for eating things like insects – perfectly good in some cultures – forget about it.

Disgust has its advantages. Its origins likely lie in the basic survival benefit of avoiding anything that smells or tastes bad. But disgust may also be an impediment to many of us adopting more sustainable lifestyles – from eating alternative sources of protein to drinking recycled water.




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Can anything be done about this? The fact that disgust varies between cultures and across ages implies it can. But how?

We set out to answer this by getting a better grip on how disgust works, focusing on disgust in everyday food choices, rather than aversions to the unknown or unfamiliar.

Our research suggests some disgust responses, once set early in childhood, are hard to shift.
But responses involving culturally conditioned ideas of what is “natural” may be modified over time.

Don’t eat that!

Disgust likely began as a powerful “basic” emotional reaction that evolved to steer us away from (and literally eject) potential contaminants – food that smelled and tasted bad. You can think of it as originally being a “don’t eat that” emotion.

The disgust system tends to be “conservative” – rejecting valid sources of possible nutrition that have characteristics implying they might be risky, and guiding us towards food choices that are ostensibly safer. Research by University of British Columbia psychologist Mark Schaller and colleagues suggests people who live in areas with historically high rates of disease not only have stricter food preparation rules but more “conservative” cultural traditions generally.

Is is unclear exactly how or when individual templates for what is disgusting are set, but generally what is seen as “disgusting” is set relatively early in life. Culture, learning and development all help shape disgust.

It’s just not natural!

In our study, we showed 510 adults pairs of “normal” and “alternative” products via an online survey, and asked them how much they would be willing to pay for the alternatives. We also asked them to rate which product was tastier, healthier, more natural, visually appealing and nutritious. Product pairs included:

  • shiny and typically shaped fruits and vegetables vs knobbly, blotchy, gnarled and multi-limbed examples.
  • plant protein foods vs insect-based foods
  • standard drinks vs drinks with ingredients reclaimed from sewage
  • standard medicines vs medicines with ingredients extracted from sewage.
Out of shape: using common fruits and vegetables meant the study’s results were not muddied by responses affected by fear of the unknown.
http://www.shutterstock.com

Our results show that, even after statistically adjusting for obvious factors like pro-environmental attitudes, those with a greater “disgust propensity” are less willing to consume atypical (weird-looking) products.

This may seem rather obvious but most prior studies have muddled a food’s “novelty” with its possible disgusting properties (by asking people, for example, whether they’d eat bugs). By asking about really common fruits and vegetables, our study shows just how far disgust may reach in influencing what we consume.




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As importantly, our results suggest evaluations of a product’s perceived naturalness, taste, health risk, and visual appeal “explains” about half of the disgust effect.

In particular, lack of perceived “naturalness” was a frequently reason for unwillingness to pay for product alternatives. This result was in line with previous studies that have looked attitudes to eating insects or lab-grown meat. This is a promising area for social marketing.

Therapeutic responses

Given evidence about how much of what we consider disgusting is cultural and learned, marketing campaigns could help shift attitudes about what is “natural”. It has been done before. Consider this advertisement to naturalise sugar consumption.

Thinking differently about emotion-eliciting stimuli is termed “reappraisal”. Reappraisal has been shown to reduce disgust effects among those with obsessive compulsive disorder. Desensitisation (repeated exposures) seems less effective in reducing disgust (versus fear) among people with diagnosed phobias, but it may work better among the general population.




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Of course, such speculations remain untested and their ultimate success remains unclear.

But it wasn’t so long ago that Western consumers turned their noses up at fermented foods, and the notion of “friendly bacteria” made as much sense as “friendly fire”. More than a decade ago the residents of a drought-stricken Australian town voted against recycling sewage for drinking water. Now the residents of an Australian city accept recycled sewage being pumped back into the city’s groundwater.

Given time, circumstance and a little nudging, a future meal at your favourite Thai restaurant may well involve ordering a plate of insects.The Conversation

Nathan S Consedine, Professor of Health Psychology, University of Auckland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Sustainable shopping: want to eat healthy? Try an eco-friendly diet



File 20180118 122935 6pu4zh.jpg?ixlib=rb 1.1
Healthy eating should include thinking about the environmental cost of your food.
Al Case/Flickr, CC BY-NC-SA

Michalis Hadjikakou, Deakin University

Following our annual Christmas overindulgence, many of us have set ambitious goals for the year ahead. But eating healthy shouldn’t just mean cutting down on snacks; given the environmental impact of food production, a more sustainable diet should feature high on everyone’s list of New Year’s resolutions.

Australians have one of the largest per capita dietary environmental footprints in the world, so there’s definitely room for improvement. But, as with all diets, radical and sudden changes like going vegan or vegetarian are notoriously difficult.




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Smaller, more achievable behavioural shifts are more realistic. This also makes sense from an environmental perspective – large-scale drastic changes might end up shifting one type of environmental impact to another.

This guide is about making informed, feasible changes towards a more environmentally sustainable diet. It starts with the food items you put in your shopping basket.

Meat, junk and waste

Sustainability researchers, like myself, track the life cycle of food from farm to fork, measuring the energy used and emissions generated by the entire process.

Australia’s food consumption contributes significantly to greenhouse gas emissions, water scarcity, land clearing and biodiversity loss, and ocean pollution.




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There are many reasons our diets have such a large environmental impact, but one of the biggest is that we’re a nation of meat eaters. On average, an Aussie eats 95kg of meat a year, significantly more than the OECD average of 69kg.

Generally, animal-derived foods require more energy and resources and release significantly more emissions than most plant foods. This is particularly true for red meat: the current average consumption is 24% higher than the maximum recommended intake.

Another reason is our overconsumption of total calories, often driven by junk foods. Eating more food than we need means the environmental resources used in producing that extra food are wasted. It also leads to a range of health problems such as obesity.

Finally, the extraordinary amount of household food waste in Australia – around 3.1 million tonnes of edible food a year – also has a major impact.

What is realistic dietary change?

Sustainable dietary choices aren’t just about environmental impact – it also means being realistic and consistent. Only 11% of Australians are vegetarian, so expecting a majority to drastically reduce meat consumption is impractical, and probably alienating.

Alternatives like flexitarianism (eating meat more rarely) are more achievable for most.

An added complication is that most Australian cows are raised on pasture, which has a high carbon footprint but requires less water than growing many plant foods. So, the complete substitution of red meat or dairy with plant-based products could simply change one environmental impact for another.

Putting it all together – simple shopping advice

Moderation: Cutting out staples of the Australian diet, like meat, is not a realistic goal for many people. But try moderating your cmeat that has the highest environmental impact (beef and lamb) and instead go for chicken or pork.

Reducing junk food is good for your wallet, waist and the environment. Processed meats or dairy-based desserts have the highest footprints amongst junk foods, so when the urge to indulge hits, go for fruit-only desserts such as sorbets. Or just buy more fruit to freeze and turn into delicious and healthy smoothies that you can enjoy even more regularly. (Grapes are very high in sugar, and when frozen are great summer treats.)




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Meal planning can also help cut down food waste, so it might be worth trying a pantry planning app.

Substitution: Think about your favourite recipes, and how you can swap out the most resource-greedy ingredients. Some meats can be replaced with alternative sources of protein such as legumes and nuts.

Sustainably-farmed or sourced seafood is another protein alternative with a lower environmental footprint compared to meat, as long as you choose your seafood wisely – for canned tuna make sure to check the label! Seasonal produce usually requires fewer resources and needs to travel less to the store, so it’s worth checking a guide to what’s in season in your region.




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Complex packaging of many food products, which is often unnecessary, also contributes to their environmental impact. Opt for loose fruit and vegetables and take your own shopping bags.

Experimentation: When you do buy meat, opt for novel protein sources such as game meat – we are lucky to have an abundance of kangaroo as a more sustainable protein alternative in Australia. If you’re feeling even more adventurous, you could also try some insects.

This guide is a starting point for thinking about a more sustainable diet, but food systems are incredibly complex. Animal welfare and the viability of farming communities are just part of the social and economic issues we much deal with.

The ConversationUltimately, while consumers can drive change, this will be incremental: transformative change can only be achieved by food producers and retailers also coming on board to drive a more sustainable food system.

Michalis Hadjikakou, Research fellow, School of Life and Environmental Sciences, Faculty of Science, Engineering & Built Environment, Deakin University

This article was originally published on The Conversation. Read the original article.