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When Plastics Saved Turtles

Mark VKearney25 May 2019

As you may now know, UCL Culture has decided to defund our program next month and so this will be my final post. I thought I would take this opportunity to give a little back story to my PhD project and tell you all about how once upon a time plastic saved the fate of turtles!

Throughout history, natural materials such as tortoise shell and ivory have been coveted by the rich and famous. This led to two things happening – the price of these materials became very high (meaning it really was the rich and famous who could afford them) and the stock levels declined. By stock levels I mean the killing of thousands of animals such as the Hawksbill turtle to feed the needs of the bourgeoisie.

The Grant Museum has three fantastic examples of Hawksbill turtles on its back wall. I normally stand beside them so that I can kidnap engage with people about my work.

Figure 1 – Eretmochelys imbricata or known by its common name Hawksbill Turtle that is on display at the Grant Museum. (Object Number X1226)

By the mid-18th century, the farming of turtles for their shells had gotten to the point where we almost caused their extinction. A similar point had been reached with ivory where demand far outweighed supply. To give you an idea of the scale of what can only be described a mass slaughter, have a look at this doll’s house currently on display at the Rijksmuseum in Amsterdam – the outside is totally covered in tortoise shell!

Figure 2 – Dolls’ house of Petronella Oortman. Part of the collection at the Rijksmuseum. The object is totally covered with tortoise shell. It measures h 255.0cm × w 190cm × d 78cm which is a huge surface area to cover in shell!

These natural materials were being used for everything: shirt collars, corset boning, piano keys, knife handles, spectacle frames, combs and brush handles, to name the most common ones. The rising cost and demand for these materials lead to a prize of $10,000 being offered to anyone who could develop a material to replace one particular use of ivory: billiard balls. $10k in 1860 s was a huge sum of money — about $300k today!

Around this time, a material called cellulose nitrate had been discovered and was being used in England by Alexander Parkes. John Wesley Hyatt, an American scientist, added heat, pressure and camphor to this material and created what we consider the first successful plastic. This material was hugely popular and allowed the democratisation of many goods which up to that point had been exclusively in the literal hands of the 1%ers.

However, the only issue with cellulose nitrate was that it was HIGHLY flammable. Even today, it’s considered highly dangerous. Even in UCL’s chemistry department, where we have all the safety precautions, you could expect, when we asked to make some for our research we were turned down as the method carries so much risk. Storing this historic plastic is also a major issue. In 1929 a major fire at a hospital in Cleveland, where 123 people were killed, was caused by x-ray negatives made from cellulose nitrate igniting. Because of this danger, the material was changed and cellulose acetate was developed instead. Cellulose acetate is most noted for its ability to mimic tortoise shell and is highly prized in glasses frame manufacture.

While the development of plastic didn’t totally stop the culling, it did slow it enough so that these fantastic animals are still around today.

These two materials are known as semi-synthetic plastics because they are based on cellulose rather than petroleum. It’s not till the development of Bakelite in at the turn of the 20th century that we get fully synthetic plastics. But even at this point plastics held a privileged place within the hierarchy of materials. This changed after the second world war, where mass industrialisation and production of plastic altered its role from being a highly prized replacement for natural materials to what we unfortunately now know it to be – a mass-produced, often poorly made, single-use throwaway object.

Clearly this move away from small scale production of plastic has produced horrific results for the natural environment. But history is starting to repeat itself again and many of the new plastics being developed are based on cellulose, which naturally decays and can be composted.  So, in a way, cellulose acetate is again saving turtles!

The case of the yellow T-Rex

Mark VKearney24 January 2019

When I joined the engager team, we were given a great tour of all three UCL museums so as to help us relate our own research to their respective collections. In a simplified nutshell, my work focuses on trying to monitor plastic artworks as they fall apart, by smelling them (more on that in a future blog post). Natural History and Egyptology collections aren’t known for their large plastic collections, so I was naturally a little nervous about how I might relate my work – or at least I was until I spotted the amazing dinosaur collection the Grant Museum has!

Figure 1 – A selection of dinosaurs at the Grant Museum (Author’s own photo)

My earliest memory of a museum was when I was about 10 and I visited the Natural History Museum in London, for an exhibition which had animated robot dinosaurs. One clear memory I have of that trip was how they looked – the colours and patterns. They all looked like my own toy models, which to a kid is amazing but now as a scientist I find it all little sketchy.

Figure 2 – The museum label for the dino collection — notice the lovely yellow T-Rex in the background! (Author’s own photo)

The models in the Grant are accessioned objects, meaning they are formal museum objects with the same status as some of the most important objects in the collection. They were used to teach students about the form of the animals they were studying. It’s not clear from the label if the colour of the models was also used in their studies. But judging by the bright yellow T-Rex, one would hope not!

But if a T-Rex wasn’t yellow, is there any way that we could know what colour it — or any of the other dinosaurs — might have been? Unfortunately, 65 million years ago they didn’t have quite as active an Instagram as the quokka does.

Amazingly, scientists have found a way to view the colour patterns from fossilized feathers that adorned some dinosaurs. In fact, feathered dinosaurs were more common than initially thought. In a paper published in Science, in 2010, scientists based in China looked at the morphologies (aka the shapes) of melanosomes. These are a small subunit , around 500nm,  of a cell which are used for ‘synthesis, storage and transport of melanin’. Using a clever bit of statistics, they learnt that depending on density and length, they could figure out the creature’s colours. Basically, if these melanosomes are long and narrow or short and wide then you ended up with either black and grey colours or with reds and browns respectively.

The team in China looked at one dinosaur in particular, Anchiornis huxleyi, which had enough preserved feathers to recreate a full profile of what it would have looked like. What is most striking about their reconstruction is how closely it matches one of the models at the Grant. So while not as totally outrageous as the yellow T-Rex, basing patterns on animals alive now gets you pretty close to what their ancestors may have been like.

Figure 3 – Image of Anchiornis huxleyi showing the resulting colour pattern from the scientific analysis. Photo taken from Quanguo et al (2010)

 


Figure 4 – A model featured at the Grant, notice its tail whose pattern is similar to that found in the research by Quanguo et al. (2010 )(Author’s own photo)

However, there’s one clear area where the research falls down, and where it’s unlikely that we’ll ever know. Many animals have the ability to camouflage themselves, but given the uncertainty about their habitats millions of years ago (combined with a low number of preserved samples and the fact the only certain types of cells can be preserved), it is very unlikely that we will ever know if dinosaurs were able to blend into their environment.

Let’s end on this thought – through looking at the shape and size of certain parts of cells, and through some fairly understandable stats, scientists are basically able to do some paint-by-numbers on animals that lived over 65 million years ago. Sometimes I am left in utter awe of what science can tell us!

P.S – Plastic Dino figures are not only used in science but also in art – check these out at the new exhibition at the UCL Art Museum.

Figure 5 – A piece by Edward Allington which is currently on display at UCL Art Museum (Author’s own photo)