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Chapter 3 - The allograft theory

3.8 Conclusion

The research into the different strains of cancer may be important but it has not provided proof that the cancer is contagious; in fact if anything, it has weakened the evidence. Instability is the hallmark of cancer.132

regulates the dog’s immune system, with the dog eventually developing resistance and the cancer going into remission, on rare occasions it becoming malignant. This does not occur in the devils. A lack of diversity in the devil MHC was proposed as the reason DFTD could establish in a new host, but this has now been revealed to be incorrect.

There are however studies undertaken by the DFTD researchers that were not undertaken by CTVT researchers. For example, studies to understand the apparent instability in the devil tumour cells were done. DFTD researchers also undertook studies into the spread of the devil cancer as shown in Table 3:3 below, which reveal nothing consistent or conclusive.

Table 3:3 Studies into spread of DFTD

Year Authors Findings

2006 Hawkins et al134 No evidence for density dependence as prevalence high, even with 80% decline in population

2006 McCallum & Jones135 Mating key to transmission

2007 McCallum et al136 Transmission during sexual encounters – frequency dependent

2009 Hamede, et al137 Transmission – frequency dependent

2009 Hamede, et al138 Devils highly connected spread likely results from single infected devil

2012 Hamede, et al139 No ‘super spreader’ but a ‘super receiver’ due to aggressive behaviour

134 Hawkins CE, Baars C, Hesterman H, Hocking GJ, Jones ME, Lazenby B, Mann D, Mooney N, Pemberton D, Pyecroft S, Restani M & Wiersma J, 2006, Emerging disease and population decline of an island endemic, Biological Conservation, Vol 131, pp 307-324, p 319

135 McCallum H & Jones ME, 2006, To lose both would look like carelessness: Tasmanian Devil Facial Tumour Disease, PLoS Biology, Vol 4(10), 1671-1674, p 1674

136 McCallum, H, Tompkins, DM, Jones, ME, Lachish,S, Marvanek, S, Lazenby, B, Hocking, G, Wiersma, J & Hawkins CE, 2007, EcoHealth, Vol 4(3), pp 318-325, p 318

137 Hamede RK, McCallum H & Jones M, 2008, Seasonal, demographic and density-related patterns of contact between Tasmanian devils (Sarcophilus harrissi): Implications for transmission of devil facial tumour disease, Austral Ecology, Vol 33, pp 614-622

138 Hamede RK, Bashford J, McCallum H & Jones M, 2009, Contact networks in a wild Tasmanian devil (Sarcophilus harrisii) population: using social network analysis to reveal seasonal variability in social behavior and its implications for transmission of devil facial tumour disease, Ecology Letters, Vol 12, pp 1147-1157

139 Hamede RK, McCallum H, & Jones M, 2013, Biting injuries and transmission of Tasmanian facial tumour disease, Journal of Animal Ecology, Vol 82(1), pp 182-190

Some of the studies undertaken in CTVT, such as the transmission studies by Novinski in 1876, were abandoned in DFTD after variable results. The identification of a set of genes that occur in all dog tumours across a number of countries has not been identified in the devil tumours. There has been a lot of expensive and highly technical research into DFTD genetics but the basic studies, to prove the cancer is transmissible, still remain undone.

Further, it would appear that some articles published in support of the allograft theory of DFTD, rather than being a genuine representation of the scientific experiments undertaken to confirm that the devil cancer is indeed transmissible, falsely assume or imply the theory has already been proved. This is particularly evident in the issue of EcoHealth containing several articles relating to DFTD. Whilst there is nothing unusual in focusing on a particular topic for an issue, all articles reference the Pearse and Swift Nature article as confirmation of the allograft theory of DFTD, which is clearly not the case. There are also other assumptions made confirming the transmission of the devil cancer that are premature and claims not supported by evidence as will be shown in the following chapters.

In both research programs today’s sophisticated knowledge creation relies on methods and the latest, often prohibitively expensive technology, resulting in those with the most funds having the most access; the study of genetics is one such area. In the case of CTVT these studies have been independently explored and supported. In contrast the Tasmanian Government through the DPIPWE, which operates the Mt Pleasant laboratory in Launceston, has controlled the DFTD studies. At the laboratory devil

samples are prepared and experiments are undertaken with access to expensive genetic testing equipment. The Tasmanian devil, listed as ‘endangered’ under the EPBC Act 1999, is a protected species making it illegal to ‘take’ without specific authority. This arrangement, whereby one government department has control over the research, the funding and the endangered species specimens, constitutes a capture of the scientific research. The outcome has been the effective silencing of any competing alternative hypotheses. Consequently, the impression is given that the dominant research community, with access to sophisticated equipment, is pursuing the only genuine science.140

The CTVT research program has a long history of independent studies directed to solving and understanding the dog transmissible tumour. By using this research program as the benchmark for the DFTD research program it is evident that not all the relevant and important studies have been undertaken. The transmission studies undertaken as early as 1876 to confirm that the dog cancer was transmissible have still not been completed for the devil cancer. Genetic studies identifying the mutated genes in CTVT also remain undone in the devil research. These are not the only studies to have been left undone, research into an alternative hypothesis that chemicals used in plantation forests may have played a role in the devil cancer, was abandoned following a pilot study. Before analyzing this aspect of the research the next chapter explores the DFTD research selected for study that has steered the research priorities in particular directions. These include a search for why, when the devil immune system is claimed to be functionally competent, the cancer can establish in a new host.

140 Hess, DJ, 2007, Alternative Pathways in Science and Industry, Activism, Innovation, and the Environment in an Era of Globalization, The MIT Press, Cambridge, Massachusetts, p 24