Why scientific monitoring of the effects of industry on our priceless WA rock art is inadequate



File 20171120 18578 1y881mz.jpg?ixlib=rb 1.1
The Burrup Peninsula, or Murujuga, contains over a million individual works of rock art by the Yaburara people.
Shutterstock.com

John Black, University of Western Australia

Scientific studies used to monitor the impact of industry on Aboriginal rock art in north west Western Australia are inadequate, potentially exposing more than a million individual artworks to damage, according to a recent paper published by myself and co-authors in the journal Rock Art Research.

The rock art is located near the towns of Dampier and Karratha and is known as the Burrup Peninsula, or Murujuga. It is a priceless, irreplaceable, cultural and archaeological treasure. The peninsula is also home to industry including an iron ore export port, natural gas processing, liquefying and export facilities, an ammonia-urea fertiliser plant and most recently, an ammonium nitrate production facility for explosives.

The industry and port produce thousands of tonnes of acid-forming emissions each year, permitted under environmental regulations. The impact of these emissions has been monitored through several scientific studies, which claimed there was no consistent impact on the rock art.

However our paper shows that the four main studies cannot be used to monitor the impact of industry on the art due to methodological errors. For example, one study subjected rocks to acid-forming emissions and concluded that there was no consistent change in colour. But there were just not enough repeat measurements to gain any sensible conclusion about the effect of emissions on rock colour.

Another experiment examining the effects of varying acid and other chemical concentrations was conducted using iron ore, which has no relevance to the rocks on which the art is situated. Measurements of colour change between 2004 and 2014 were also made on the rock art and background rock at seven different sites. But the instruments used for measuring change in rock surface colour were designed for indoor use and were inappropriate for the highly variable, hot rock surfaces of Murujuga. Typically, instruments were located at only one place on the rock surface during a measurement each year and this was insufficient to represent the highly variable rock surface.

These studies form the basis for government regulation, which permits industry to release acid-forming emissions. While there is no conclusive evidence that industry emissions have damaged the rock art, recent measurements of the surface of rocks near industry by Dr Ian MacLeod, former Director of the Western Australian Maritime Museum, found acidity to have increased 1,000 times above pre-industrial levels.

We showed in another scientific paper published earlier this year that acid dissolves the outer surface layer of the rocks causing them to become thinner, lighter in colour and to flake away. Once the outer surface layer is removed, the rock art is lost.

The federal government is conducting a senate inquiry into the health of the Murujuga rock art, with a delayed final report due in late November. I argue that, at the very least, industry must install technology to reduce acid emissions and ammonium nitrate dust particles to virtually zero. Other rock art experts have called for a cessation of all industry on the peninsula in a recent editorial in Rock Art Research.

Priceless history

The Murujuga rock art captures over 45,000 years of human culture, activity and spiritual beliefs through ever changing environments from when the sea was more than 100 km from its current position and through the last ice age, 20,000 years ago.

The petroglyphs include some of the oldest known representations of the human face in the world. There are images of extinct mammals including megafauna, the fat-tailed kangaroo and thylacine. There are elaborate geometric designs that could have been used for navigation or an early form of mathematics. There are many depictions of hunting and cultural ceremonies as well as existing animals, birds and sea creatures.

Artwork depicting a thylacine, a species which has been extinct in the Pilbarra for 3,000 years.
Friends of Australian Rock Art

The Murujuga inhabitants created this rock art until February 1868, when virtually the entire Yaburara indigenous population was exterminated in a massacre.

Massacre of the Yaburara, only three years after European settlement in 1865, has deprived us from knowing the storylines and cultural meaning of the petroglyphs. Equally significantly, the massacre broke continuous inhabitation of the area, which has allowed successive Western Australian governments to develop in the midst of the rock art one of the largest industrial complexes in the Southern Hemisphere.

Industry and art

Construction of the industries is estimated by archaeologists working on Murujuga to have resulted in the destruction of over 30,000 petroglyphs through removal and physical damage. Atmospheric emissions from the industries are immense.

Dampier port, which is adjacent to the petroglyphs, is one of the busiest bulk-ports in the world with over 19,000 ship movements each year. These ships burn high sulphur bunker fuel, with one ship emitting as much as 5,000 tonnes of sulphur dioxide per year.

The gas and fertiliser plants emit around 34,000 tonnes of acid forming compounds into the air each year. The recent starting up of the ammonium nitrate plant revealed a huge yellow-orange cloud of nitrogen dioxide with concentrations of over 1,000 parts per million. The emission of nitrogen dioxide from the plant will occur around six times each year, whenever certain industrial chemicals needed for ammonium nitrate production require replacing.

These emissions are permitted under state and federal environmental regulation. Both nitrogen and sulphur dioxide react with water to form acids which are deposited on the rock surfaces.

The construction of the LNG facility in 2008.
Friends of Australian Rock Art

Extraordinary origins

The rock art at Murujuga is threatened by acid because of its unique geological properties. The natural blue-grey rock, formed from cooling magma, weathers very slowly to form a yellow coloured weathering rind, which may grow by 5 mm in 30,000 years.

The yellow coloured rind is covered with a dark brown-black coating called a patina or rock varnish. The petroglyphs were formed by using hard pieces of rock to break through the patina and expose the rind.

This patina is an extraordinary substance. It is formed by specialised bacteria and fungi on the rock surface, where there is seldom moisture and rock temperatures can exceed 70℃. To survive the harsh conditions, the organisms build a mineral sheath. When they die, their body and sheath combine with clay from the dust to form the hard, dark-coloured patina.

Destruction of the outer patina results in disappearance of the rock art. There is evidence that the patina is flaking on some rocks with petroglyphs. The patina becomes thin and flakes away under acidic conditions.

Protecting the art

Elsewhere in the world countries have been vigilant in protecting natural and cultural heritage from acid emissions. In the US cars are banned or severely limited in many national parks because the acid formed from nitrogen dioxide, produced from vehicle exhaust, will damage the forests.

In France, the 1.4 million annual visitors to the 17,000-year-old Lascaux cave paintings do not see the actual paintings, but a replica in an adjoining cave because of the damage caused by emissions from human breath.

Similarly, the UK government announced in January this year they are building a £1.4 billion tunnel to remove cars form the vicinity of their 4,500-year-old heritage in Stonehenge.

The ConversationWhile removing industry may be the best solution to ensure the rock art’s safety, it may not be practical. Governments and industry must recognise their social responsibilities and ensure sufficient technology is in place to reduce acid forming emissions to near zero.

John Black, Honorary Research Fellow, University of Western Australia

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

Which square is bigger? Honeybees see visual illusions like humans do


File 20171120 18525 1l2j7n8.jpg?ixlib=rb 1.1
Flowers may take advantage of visual illusions to attract bees.
from www.shutterstock.com

Scarlett Howard, RMIT University and Adrian Dyer, RMIT University

When a human looks at a distant skyscraper, it appears small to the eye. It’s a visual illusion, and we use other contextual information to know the building is actually tall.

Our new study shows, for the first time, that honeybees see size-based visual illusions too. Whether a size illusion is seen, or not, depends on how a target object is viewed.

These new results help us understand how visual illusions evolved in different species over time.


Read more: Three visual illusions that reveal the hidden workings of the brain


How humans experience illusions

Humans see lots of different illusions such as mirages, illusions of shape, length, size, and even colour (remember that dress?).

The lines or shapes around an object can change the way your brain sees it.
Provided by Scarlett Howard

Visual illusions are errors in your own perception which can allow you to process the very complex visual information you see more easily.

One of the strongest geometric illusions we humans see is an illusion of size, called the Ebbinghaus Illusion.

Ebbinghaus Illusion: The central circles are of identical size, but are perceived as very different by humans because we use context to inform our vision.
Provided by Scarlett Howard

Interestingly, species such as bottlenose dolphins, bower birds, domestic chicks, and redtail splitfins see this illusion in the same way as humans. However, animals such pigeons, domestic dogs, and bantams see the opposite illusion to what we see, and baboons do not see an illusion at all.

To understand why different species see size illusions in such different ways, and how an insect with a miniature brain might view a size illusion, we developed an experimental design using honeybees.


Read more: Want a better camera? Copy bees and their extra light-sensing eyes


Bees can help us design better camera technology.

Why do animals perceive illusions differently?

It’s intriguing that some species view size illusions the same way as us, and some animals do not. Why is it that a baboon does not see any illusion when looking at the Ebbinghaus Illusion? Why do pigeons and dogs see the opposite illusion to us? Our team decided to look into the methodology of the past studies that had shown these differences.

When baboons, pigeons, dogs, and bantams were tested, they were looking at the illusion from either a set distance or from a forced close-range distance. For example, dogs had to touch the correct option with their noses, and birds had to peck the correct option meaning these species were viewing the illusion at a very close distance. Baboons, on the other hand, were viewing the illusion at a set distance, unable to move closer than a certain distance from a screen that presented the illusionary pictures.

With this knowledge, we decided to test honeybees using two study conditions:

  1. a free-flying set-up where bees could fly at any distance from the size illusion before making decisions, and
  2. a constrained viewing set-up where bees could only view and make decisions about the illusion from one set distance.

How does a bee view size illusions?

To determine if bees could perceive size illusions, we first had to find a way to ask them.

We trained one group of bees to always choose the larger black square on a square white background and another group of bees to always choose the smaller black square on a square white background.

When bees had learnt to either choose larger or smaller sized black square targets, we manipulated the size of the background, thus trying to induce the perception of a visual illusion (similar to the Delboeuf Illusion).

Stimuli used in experiments.
Provided by Scarlett Howard

We ran this experiment using our free-flying, unrestricted viewing condition and also using a restricted viewing condition where independent bees were unable to choose their own distance to make decisions.

Eureka! Training conditions explain why different animals see illusions differently. Bees in the unrestricted viewing condition perceived illusions, while bees in the restricted viewing condition did not see size illusions.

Now, we are interested in whether some past study results were due to experimental set-up: maybe more or even all animals could perceive illusions like humans, depending on the context in which they are viewing these illusions.

What does this mean for the evolution of vision?

Visual illusions are useful because they allow us to process complex scenes, with multiple pieces of information, as a whole by using context as a cue. Since different animals see size illusions, understanding how this works could help us learn more about how vision itself evolved.

One explanation of why such different animal species, from humans to bees, see size illusions is because an ancient ancestor had this ability, and it has been conserved throughout evolution. However, a more likely scenario is that the evolution of visual illusion perception is due to convergent evolution. This occurs when different species evolved the ability to perceive illusions separately.

The ability of bees to perceive a size illusion in a free-flying environment also has implications for flower evolution. Flowers could have evolved to exploit the ability of bees seeing illusions to make nectar areas look more appealing. One genus of flower, Wurmbea, appears to have illusionary properties such as differently sized flowers with patterns reminiscent of size illusions such as the Ebbinghaus and Delboeuf Illusions.

Wurmbea flower as seen through a special camera simulating bee vision.
http://ro.uow.edu.au/asj/vol5/iss1/7

The ConversationA very important lesson from this study is that viewing context can make scenes appear very different to reality. This is very important to remember when working on vision in humans or any other animal.

Scarlett Howard, PhD candidate, RMIT University and Adrian Dyer, Associate Professor , RMIT University

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