Creationism in Crisis - Evolving Cancers - Another Devilish Problem for Creationists

Creationism in Crisis

Evolving Cancers
Another devilish Problem for Creationists

Tasmanian devil, Sarcophilus harrisii

Photo: Max Stammnitz

Tasmanian devil, Sarcophilus harrisii

Evolution of two contagious cancers affecting Tasmanian devils underlines unpredictability of disease threat | University of Cambridge

Scientists have unwittingly thrown creationists another curve-ball, in the form of a genetic analysis of the transmissible facial cancers that are devastating the population of the Tasmanian devil, Sarcophilus harrisii. Some estimates put the decline in population at 80% in some areas.

Tasmanian devils are one of the few mammals known to be affected by transmissible cancers, specifically devil Facial Tumor Disease (DFTD). DFTD is an aggressive and usually fatal cancer that is spread from animal to animal through biting and other forms of physical contact.

The cancer is believed to have originated in a single Tasmanian devil over 20 years ago and has since spread rapidly throughout the Tasmanian devil population. DFTD is a clonal cancer, meaning that it is composed of cells that are genetically identical to each other and to the original cancer cell.

The spread of DFTD has had a devastating effect on the Tasmanian devil population, with some estimates suggesting that the population has declined by up to 80% in some areas. The disease is considered a significant threat to the survival of the species.

Researchers have been studying DFTD since its discovery in 1996, and there have been many advances in our understanding of the disease. One of the key discoveries has been that the cancer cells evade the immune system of the host animal by downregulating MHC molecules. This allows the cancer cells to avoid detection by the host's immune system, allowing the cancer to spread unchecked.

There have also been efforts to develop treatments and vaccines for DFTD. Some promising results have been obtained in laboratory studies, but there is still much work to be done before these treatments can be applied in the field.

References:

1. Pye RJ, Pemberton D, Tovar C, et al. A second transmissible cancer in Tasmanian devils. Proceedings of the National Academy of Sciences. 2016;113(2):374-379. doi:10.1073/pnas.1519691113.
2. Stammnitz MR, Coorens THH, Gori KC, et al. The origins and vulnerabilities of two transmissible cancers in Tasmanian devils. Cancer Cell. 2018;33(4):607-619.e15. doi:10.1016/j.ccell.2018.03.013.
3. Tovar C, Pye RJ, Kreiss A, et al. Regression of devil facial tumour disease following immunotherapy in immunised Tasmanian devils. Scientific Reports. 2017;7(1):43827. doi:10.1038/srep43827.

Tell me about the transmissible cancers in Tasmanian devils, please, with references

The study, by an international team from the UK, Australia and USA, led by scientists from Cambridge University, UK, has analyzed the DNA of the devils and their two cancers (DFT1 & 2) and worked out how the cancers evolved by the classic evolutionary process of mutation and selection. They have identified that DFT1 arose in a single individual in the 1980 and this individual infected six other adult devils in Northeast Tasmania, which resulted in six different strains and an explosive spread of the disease across the island. The second, DFT2, arose spontaneously shortly before it was first observed in 2014, since when it has spread slowly but is mutating about three times faster than DFT1, probably because it has a faster growth rate.

So, the problem for creationists is that they either accept that evolution works, or, if they insist there was an intelligent agent causing the observed changes, that that agent, who is invariably the same as the Christian and Moslem god, malevolently designed these cancers and is ensuring their perpetuation in the face of any resistance the devils might evolve. And, not content with creating it once about 40 years ago, it repeated the exercise about 30 years later, presumably because killing 80% of the population was not enough.

Quite why it would have chosen such a nasty way to devastate the Tasmanian devil population rather than simply casting a magic spell to wipe out 80%+ of the population, is a matter for creationists to explain.

As the Cambridge University News release explains:

Transmissible cancers, which occur only rarely in the animal kingdom, are spread by the transfer of living cancer cells. In the case of Tasmanian devils, the cells are transferred through biting – a behaviour that is common in devils especially in fights over mates and food.

Tasmanian devils are susceptible to two fatal transmissible cancers called devil facial tumour 1 (DFT1) and devil facial tumour 2 (DFT2) that have caused rapid population decline in recent decades. The two cancers both manifest with disfiguring facial tumours.

In a new study, University of Cambridge researchers, together with a global team of scientists from Europe, Australia and the United States, mapped the emergence and mutations of DFT1 and DFT2 and characterised these cancers’ ongoing evolution. The findings underline the continued threat that transmissible cancers pose to Tasmanian devils.

The results are published today in the journal Science.

The incredible fact that Tasmanian devils have not one, but two, transmissible cancers, makes it possible to compare their evolution, and this gives us new insights into the key mechanisms involved

By looking at the mutations that have accumulated in these cancers’ DNA, we can trace the origins and evolution of these diseases. Our results show that the two cancers arose through similar processes and that both have striking signals of ongoing evolution. It is difficult to predict how this continued cancer evolution will impact devils.

I come from Tasmania and love Tasmanian devils – they have a special place in my heart. Transmissible cancers pose an unprecedented and unpredictable threat to Tasmanian devils. This research highlights the continuing importance of monitoring and conservation programmes. It also gives us new insights into the evolutionary mechanisms operating in cancer more broadly, including in human cancers.

Professor Elizabeth Murchison, lead author
Professor of Comparative Oncology and Genetics
Department of Veterinary Medicine
University of Cambridge, Cambridge, UK.

The researchers created an improved ‘reference genome’ – essentially a map of the entire DNA sequence – of the Tasmanian devil and compared this to DNA taken from 119 DFT1 and DFT2 tumours. DFT1 was first observed in 1996 in Tasmania’s northeast and is now widespread throughout Tasmania. DFT2, on the other hand, was first observed in 2014 and remains confined to a small area in Tasmania’s southeast. The scientists identified mutations in the tumours and used these to build ‘family trees’ of how the two cancers had each independently arisen and evolved over time.

By tracking mutations the researchers discovered that DFT2 acquired mutations about three times faster than DFT1. As mutations usually occur during cell division, the most likely explanation is that DFT2 is a faster growing cancer than DFT1, say the researchers, underlining the importance of DFT2 as a threat.

DFT2 is still not widespread in the devil population, and very little is known about it. We were really startled to see just how quickly it was mutating, alerting us to what could be a very unpredictable threat to the devils in the long term.

Maximilian Stammnitz, first author
Transmissible Cancer Group
Department of Veterinary Medicine
University of Cambridge, Cambridge, UK.

The team found that DFT1 arose in the 1980s, up to 14 years before it was first observed, whereas DFT2 emerged between 2009 and 2012, only shortly before it was detected.

Mapping the mutations revealed that DFT1 underwent an explosive transmission event shortly after it emerged. This involved a single infected devil transmitting its tumour to at least six recipient devils.

DFT1 has now spread throughout almost the entire devil population and has recently been reported in the far northwest of Tasmania, one of the few remaining disease-free regions of the state.

Researchers also identified for the first time an instance of DFT1 transmission between a mother and the young in her pouch. Additionally, they found that the incubation period – the time between infection and the emergence of symptoms – can in some cases be a year or more. These findings have important implications for conservation scientists working to protect the species.

More detail is given in the team's paper on Science which sadly is behind a paywall. However, the abstract is freely available:

Abstract

Tasmanian devils have spawned two transmissible cancer lineages, named devil facial tumor 1 (DFT1) and devil facial tumor 2 (DFT2). We investigated the genetic diversity and evolution of these clones by analyzing 78 DFT1 and 41 DFT2 genomes relative to a newly assembled, chromosome-level reference. Time-resolved phylogenetic trees reveal that DFT1 first emerged in 1986 (1982 to 1989) and DFT2 in 2011 (2009 to 2012). Subclone analysis documents transmission of heterogeneous cell populations. DFT2 has faster mutation rates than DFT1 across all variant classes, including substitutions, indels, rearrangements, transposable element insertions, and copy number alterations, and we identify a hypermutated DFT1 lineage with defective DNA mismatch repair. Several loci show plausible evidence of positive selection in DFT1 or DFT2, including loss of chromosome Y and inactivation of MGA, but none are common to both cancers. This study reveals the parallel long-term evolution of two transmissible cancers inhabiting a common niche in Tasmanian devils.

Maximilian R. Stammnitz et al.
The evolution of two transmissible cancers in Tasmanian devils.
Science380, 283-293(2023).DOI:10.1126/science.abq6453

© 2023 The authors. Published by American Association for the Advancement of Science.
Reprinted with kind permission under license #5534200658047

Clearly, creationist cult leaders prefer people to see their putative god as the malevolent designer behind cancers as well as so many other causes of suffering in the world, rather than have them accept that evolution is a far simpler explanation for which there is masses of evidence, in contrast to creationism which has none.

To understand why, one needs to read the Discovery Institute's "Wedge Strategy". The Wedge Strategy is a plan to undermine public confidence in science as a way to describe and explore the world, in the belief that they will then turn to religion and superstition and vote a theocratic Taliban-style evangelical Protestant government into office which will then govern according to Old Testament laws and morality, much like the Islamic fundamentalist states.

In other words, it is a plan to overthrow democracies and impose self-appointing theocratic autocracies, in the belief that White evangelical Christian male privilege is God's preferred form of government.

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