Understanding adaptations and evolution while evaluating Shin Godzilla

Shin Godzilla sticks out to me as the Godzilla series’ most explicit probing of molecular biology at this point in the franchise. Specifically, its depiction of mutations and evolution. Today’s discussion will go over the actual history and concepts behind DNA, genetics, and evolution and how they are represented through this incarnation of Godzilla.

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I believe it serves best to provide a summary for how the theory of evolution as we know it began. For a very long time in human history, up into the 1700’s, it was believed that the species that existed on Earth were static and did not change in their traits. However, as maturing geological studies and the growing fossil record had shown, this was not the case. In 1809, Jean Baptiste de Lamarck proposed the first formal theory of evolution. His model suggested that inherited phenotypes (physical traits) were acquired through life and altered how a creature’s offspring looked ( i.e. modern giraffes had long necks because their ancestors kept stretching them out to reach the top of trees). This theory was eventually abandoned, and was replaced by a more well-known explanation that’s still widely supported today, natural selection.

Prior to developing his theory of evolution by natural selection, Charles Darwin was influenced by others in the fields of economics and geology. Thomas Malthus was an 18th century philosopher and economist well known for his views on human overpopulation putting a strain on finite resources. Reading Malthus’ works made Darwin notice that a similar ”struggle for existence” exists for plants and animals: many more individuals are born compared to those who survive. Darwin was also influenced by the geologist, Charles Lyell, who introduced him to the concepts of uniformitarianism, that geological processes occurring now also occurred in the past, and gradualism, weak forces over a long period of time can eventually lead to great change. Gradualism was particularly important as it was recently recognized that the Earth was much older than initially thought.

While looking within the fossil record, extinct species were discovered, and many resembled extant species. Some even displayed transitional features, traits that were intermediate of younger and older species. Darwin noticed that some animals possessed vestigial traits, incompletely developed structures that either removed or decreased function compared to ancestral species or currently-living relatives. And while observing extant creatures across South America, he noticed how related species, such as finches, varied in traits which aid their survival. After taking all of this data, Darwin proposed that evolution was influenced by ‘natural selection’. Natural selection had several major components.

  • Within a population, there is variation in traits.
  • Among these traits are those that are heritable.
  • There is unequal chance for survival between individuals of a population.
  • Survival is not random: individuals that inherited more favorable traits are more likely to survive and reproduce than others. These very traits will become more common in future populations as they are passed down.

One of the key difference between Darwinian and Lamarckian evolution is that Darwinian evolution describes adaptations as pre-existing traits that became more common, rather than being acquired through an organism’s lifetime. In double-checking his theory, Darwin corresponded with a colleague, Alfred Russell Wallace, who astonishingly came to very similar conclusions as Darwin while doing observations in Indonesia and Malaysia. Despite openly contributing a lot to Darwin’s work, Wallace was not nearly as credited. In fact, Wallace consistently refused most of the scholarly recognition that Darwin offered, and only attributed the theory of natural selection to Darwin, despite Darwin himself practically viewing Wallace as a co-author. In 1859, Darwin published his theory in his book, On the Origin of Species, where he describes natural selection as the mechanism that allowed for the speciation of life on Earth, which all descended from a common ancestor. 

Now note that in Darwin’s theory of natural selection, there is no explicit mention of genes or mutations, only ”heritable traits”. That is because a precise understanding of heredity and genetics had yet to be formed. The science behind heredity came with the Austrian monk and scientist, Gregor Mendel. Through his work with pea plants, he observed the ratio of traits exhibited by the offspring that were both self-fertilized and cross-fertilized. Mendel found that the ”heritable determinants” for certain traits were discrete units (that later authors dubbed ”genes”)  and there existed variants of genes ( later dubbed ”alleles”). For example, Mendel identified that there was a gene that determined seed texture that had two alleles, one that made the seed wrinkled (r) and another that made the seed smooth (R) . Mendel’s patterns applied to many other traits of the pea plants he studied. After meticulous research, he was able to accurately predict the ratio of traits among future generations of offspring using Punnett squares.  By 1865, he provided a basic model for genetics that observed the rules he noted. However, his work went unnoticed until after his death. The reason Mendel’s work went unnoticed was because he failed to replicate his findings using hawkweed, leading him to believe his rules for heredity weren’t universal. Unbeknownst to Mendel, hawkweed are primarily asexual reproducers that yield mostly clone offspring, which rendered it a bad model organism for testing his own heredity patterns that were based on the pollination between an egg and sperm. In 1900, three different botanists independently rediscovered Mendel’s research. Mendel’s observations with the peas were consistent with how the recently discovered structures known as chromosomes arranged themselves in the division of sex cells. Experiments with fruit flies confirmed that cells stored their genetic information in chromosomes.

While it was known at the time that chromosomes were complexes of both DNA and protein, biologists were unsure which macromolecule composed the genes within the chromosomes. An experiment by Alfred Hershey and Martha Chase in 1952 revealed that the genes themselves were made out of DNA. This was accomplished by growing viruses in a culture with DNA and proteins that were tagged with their own respective radioactive isotopes. By tracking these isotopes separately, Hershey and Chase observed that the genetic material viruses were known to inject into bacteria was DNA and not proteins. In 1953, James Watson and Francis Crick proposed a model for the secondary structure of DNA using the data collected from other researchers such as Erwin Chargaff, Maurice Wilkins, and the under-credited Rosalind Franklin. Crick went on to describe the ”Central Dogma” of molecular biology. DNA is transcribed or copied into RNA, a molecule that’s a nucleic acid like DNA but less stable, which is then translated into a sequence of proteins responsible for a phenotype. There are some exceptions to this where RNA itself is the functional product for a gene, but the basic framework holds true as the fundamental pattern to gene expression. 

As cells divide, their DNA is replicated and mistakes are made by the enzymes responsible for copying their sequence. These mistakes are how mutations accumulate. Mutations can lead to the expression of different phenotypes. This is also expanded further with non-genetic heritable factors that are studied in the field of epigenetics. These are the sources of the variation that Darwin describes in natural selection. Now here are some clarifications I want to make clear about natural selection:

  • Natural selection and evolution are not synonymous terms, as everyday language would suggest. Evolution is the broad term that refers to the change in the genetics of a population over time. Natural selection is only one of the means for how evolution occurs. Other evolutionary forces exist outside of natural selection such as genetic drift, gene flow, and simply the continuous accumulation of mutations in a population.
  • Natural selection itself doesn’t direct new adaptations. It simply changes the frequency of pre-existing mutations within a population. Environmental pressure can influence the rate of mutation, but not the directionality toward beneficial ones. For example, poaching has led to an increase in tusk-less elephants, which are less likely to be hunted due to the lack of ivory. However this trait was pre-existing in these populations and it simply became more common because of the selective pressure of poaching. 
  • Natural selection is not goal-oriented. Pakicetids didn’t evolve aquatic adaptations to eventually become a dolphin, it did so because an amphibious lifestyle in of itself was beneficial. Cetaceans only became fully aquatic because each transitional step towards their current state was evolutionarily favorable.
  • Fitness, the driving component of natural selection, is not just a measure of an organism’s ability to survive but an organism’s ability to survive and reproduce. A mutant trait that increases an individual’s lifespan by 30%, but causes a 90% loss in the total number of viable offspring is very likely to be maladaptive.
  • Which traits are ‘more fit’ can be very conditional. A trait that improves an organism’s fitness in one setting can be detrimental in another and vice-versa. So even though we may perceive one organism as being more complex and ‘superior’ to another. Neither is truly better than the other because they have adapted to their own niches.

Now that I’ve provided that basic summary, we can transition to Shin Godzilla. Now it’s quite obvious, being a sci-fi creature that Godzilla breaks some rules: this evolution is occurring within an individual and not a population, its mutations are apparently deliberate, and novel adaptations arise as direct responses to the environmental pressures. Now scrutinizing this would be boring, especially when the characters’ themselves clarify that Godzilla’s evolution is very inconsistent with how every other organism evolves. On the other hand, I would like to acknowledge some of the more interesting aspects that are pertinent to the real-life evolution.

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One interesting detail of note is that Shin Godzilla’s genome is stated to be about eight times the size of that of  human’s. In reality, there are a fair number of organism in real life with larger genomes than ours, including corn. However, it should be noted that genome size alone is not a precise indicator of an organism’s complexity . Part of the reason is that only a small portion of the genome actually codes for genes in the way the Central Dogma states. For humans, less than 1% of our genomes are protein coding-regions of DNA. The majority of it is non-coding, and was at one point considered ”junk DNA”. However we now know that’s not true, and that non-coding regions actually play a crucial role in regulating the way genes are expressed. Many adaptations are the result of mutations in the non-coding regions rather than the synthesis of new protein sequences. So the way gene-expression factors into the complexity of an organism makes it harder to assess an organism’s complexity based on genome-size or the number of protein-coding genes alone. In the case of Shin Godzilla, however, it’s probably full many genes and non-coding regions that regulate gene-expression.

A misconception that many people have is the idea that evolutionary adaptations are progressive improvements over previous traits. The reality is that adaptations are often changes to an organism’s constrained physiology: an improvement in one trait often results in the impairment or loss of another function. So very often an adaptation imposes trade-offs for the net benefits that they grant. For example, I was recently taught in my microbiology course about a treatment to combat antibiotic resistance in bacteria. It exploits how in the early stages of resistance evolution, mutations that provide resistance against one antibiotic often confer increased sensitivity to another. So with proper timing, frequent switching of different antibiotic treatments can greatly eradicate resistant bacterial strains. An analogous situation exists for Godzilla in this movie. While this incarnation is perceive by many fans to be essentially unstoppable, with nearly every successive mutation, a new weakness is uncovered. As this Godzilla grows larger and continues to develop means to defend itself, it places further strain on its thermoregulation, and requires a dormancy state to compensate. This downtime is what eventually allows the Japanese’s defenses to counter the monster and at the very least ”defeat” it, even if the cliffhanger suggests it’s still not dead. Nonetheless it is clear that even this creature has its own limitations within its physiology, as all life does.

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Honestly, I believe the comparison to antibiotic resistance is quite apt, as Godzilla’s means of rapid mutation and impact on society is more directly comparable to what’s observed of microbial evolution rather than that of complex multicellular life like plants and animals. Microbial evolution is an interesting field of study as some microorganisms superficially appear to evolve in ways that seemingly violate how we understand natural selection, but soon become more consistent with better scrutiny. One process is hyper-mutation, where environment pressures cause the rapid mutation in microorganisms, which increases the likelihood of a beneficial mutation to arise within a population. Being able to draw these parallels is what makes this movie relatively more interesting for me compared to most other Godzilla films. It’s a wonderful feeling for me that within the fantastical elements, I can still see how legitimate concepts of the natural world can be conveyed and gives me something for me to mentally chew on.

Sources

Darwin and Lyell:

https://www.nature.com/articles/ngeo436#:~:text=As%20the%20journey%20continued%2C%20Darwin’s,later%20became%20known%20as%20uniformitarianism.

Darwin and Malthus:

https://ucmp.berkeley.edu/history/malthus.html

Darwin and Wallace:

https://www.sciencedirect.com/science/article/pii/S0960982213013201#:~:text=The%20scientific%20friendship%20between%20Alfred,in%20the%20history%20of%20science.&text=Wallace%20greatly%20admired%20On%20the,of%20evolution%20by%20natural%20selection.

Mendel and his rediscovery:

https://www.nature.com/scitable/topicpage/gregor-mendel-and-the-principles-of-inheritance-593/

https://www.genome.gov/25520238/online-education-kit-1900-rediscovery-of-mendels-work#:~:text=Three%20botanists%20%2D%20Hugo%20DeVries%2C%20Carl,inheritance%20in%20the%20scientific%20world.

Hershey-Chase:

https://embryo.asu.edu/pages/hershey-chase-experiments-1952-alfred-hershey-and-martha-chase

DNA structure and the Central Dogma:

http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/dna.html

Tuskless elephants:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4972762/

 

Author: CallmeJoe

A 23-year-old College Graduate in Biology who's primarily a fan of Godzilla and other properties.

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