Fiction – Joe's Thoughts/ Cetology Hub

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/

Insights from the close examination of Godzilla Junior (Godzillasaurus gojira adonoa)

Greetings folks,

Today we are going to cover my single favorite Kaiju of all time, not the Heisei Godzilla, but rather his adopted-offspring, Junior! I briefly covered some stuff on him in my previous two articles, but now I am going to treat all of you to a more in-depth look at him across the three movies he appeared. Usual stuff applies, if I get anything incorrect about either the movie or scientific details I mention here, feel free to critique me so I will know. Also shout-outs to the @biorante_blog for the subtitles he provides on his site. This was crucial for the Godzilla vs Mechagodzilla II portion of this analysis as the Sony Blu-ray is plagued with dubtitles. Let us begin!

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Now to provide context for Junior’s significance in the Heisei series to me, we should go back to a line from the original film. In, Gojira, Dr.Yamane laments the pursuit of killing Godzilla. Rather, he hopes to study Godzilla since he is a paleontologist, and Godzilla is apparently a one-of-a-kind specimen that resembles prehistoric animals. One would normally rationalize that with Godzilla being the last of its species, killing him would mean losing the chance to learn everything about its kind. However, I would point out that with Godzilla being the last specimen, Yamane already lost the opportunity to learn everything about Godzilla’s species. The individual from the 1954 film would only have been able to provide direct observations of the anatomy and physiology of a single adult of one sex. Especially with the techniques available during the 1950s, you would not be able to learn everything about an animal using just one specimen. You need multiple specimens to be able to get a full grasp of the information regarding mating behaviors, prenatal development, previous life stages, social structure, etc. Deep examinations of genetic material and anatomical structures may provide some indirect evidence for inferences, but they by no means compare to simply having more animals of various ages, sexes, and lineages to observe. So what Yamane really wants is to preserve what little he can still learn from a single specimen of a lost species.

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The Heisei Godzilla faces similar limitations during his first 4 films. Now given how he is a straggler of his species, one of the major topics that prove difficult to discern is social structure. Because there are no other known members of his kind, we cannot quite discern whether Godzillasaurs were naturally social creatures that formed in groups or if they were naturally solitary like tigers, most bears, or great white sharks. The Godzillasaurus in Godzilla vs King Ghidorah was seemingly solitary, but that could have easily been circumstantial as we only see him fight off the American soldiers for a few minutes, and afterward, he was left mortally wounded and immobile. He would have been in no position to return to any group if he had one. Interestingly enough though, Godzilla’s ability to remember Mr.Shindo after about almost fifty years hints that Godzillasaurs were likely social animals. Such a trait is mainly known to evolve in animals that rely on some form of reciprocity or cooperation. This adaptation allows them to recognize which individuals can be counted on for help. Junior, as a separate specimen whose incubation, maturation, and social interactions are observable, becomes the most important piece in fleshing out the Heisei Godzilla as an animal. And that is why Junior is my favorite Kaiju of all time. In fact, he is presented in an even more animalistic light than even Godzilla himself. Atleast, in two out of his three incarnations.

Godzilla vs Mechagodzilla II is an interesting film. The best way I choose to describe it is that it serves as a litmus test to see which viewers are familiar with ethology and which ones are not. Ethology parallels both explicit and implicit are entwined in the plot, and I have not seen any reviewers bring particular mention to it. I have always held the position that the Heisei Godzilla’s character ought to be treated like an animal as that is the most prevalent angle these films invite the viewer to interpret him. This movie, I believe, serves as the strongest example of that.

When Junior’s egg is discovered on Adonoa island, it is near the egg that the Heisei Rodan had hatched from. I wish to point out that Rodan looking over his ”younger sibling’s” egg can be compared to cooperative breeding. Cooperative breeding is a behavior in birds where the older siblings would take part in raising their younger siblings rather than dispersing from the nest once they reach sexual maturity. This delaying of their own dispersal has been theorized to have evolved for multiple reasons. A leading hypothesis being that delayed dispersal evolves in habitats where vacancies to build a nest and reproduce independently are scarce, so behavior encouraging birds to stick close to natal groups is adaptive. Another hypothesis is that leaving the nest to reproduce too soon after achieving sexual maturity would leave the young adult at a high risk of mortality. Staying at the nest to gain experience as a caregiver would allow for better lifetime reproductive success, which is the main force driving natural selection. This interpretation of Adonoan pteranodons would help explain how they likely became the ideal host species for parasite eggs. Though we will get to that a bit later.

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At the Kyoto research center, we learn that Junior’s egg starts glowing whenever Azusa Gojo is too far away from it. Dr. Omae suggests that this phenomenon is due to Junior having imprinted on Azusa Gojo. Imprinting can generally be used to describe any sensitive learning period that is specific to a certain life stage. In this case, Junior is engaging in filial imprinting. Now this storyline where Junior imprints on a human is where the ethology parallels are at its strongest and most explicit. One of the founding fathers of modern ethology, Konrad Lorenz, was particularly well-known for his research on imprinting that he conducted using geese and ducks. In these experiments, Lorenz would try to mimic the hatchlings’ species and cause them to imprint on him as their parent. And if we want to get really technical here, birds are both taxonomically and phylogenetically classified within the clade of theropods. One can somewhat get away with saying he was also imprinted on by dinosaurs (wink!). Similar to what made Lorenz’s work famous, this movie presents the consequences of imprinting, as it seems to have affected Junior’s species-recognition. His social recognition of Godzilla during the end of the film was impaired because he was fostered to socially engage with humans. This consequence is observed in real life imprinting studies with cross-fostered offspring in labs. This movie even gets some of the idiosyncrasies of imprinting correct, as Dr. Omae describes that Junior was ”searching” for his mother even while still incubated in the egg. This is consistent with what we knew of the imprinting mechanisms at the time, as birds would rely on the in ovo input of external stimuli during the early stages of filial imprinting. Examples include olfactory input in zebra finches that allows them to recognize their mother’s odor and acoustic/vocalization input in domestic chicks for vocal recognition. The latter example is what the English dub for this movie specifies. And to the dub’s credit, I also believe Junior’s in ovo imprinting is regulated by acoustic input. And that leads us to a topic that I do not believe many of you would expect me to connect to real-life, the ”plant music”.

Now, I am just gonna give it straight, plant bioacoustics are a real area of research. I know, I did not initially expect to find a real-life parallel either. Now I have no clue if that was exactly what the writers were going for, but by the time this movie was being made, it was established that plants were capable of emitting sound. What researchers have traditionally attributed to this occurrence was the release of tension from a plant’s xylem, the vascular tissue involved in the water-transport system. However, more recent studies are now arguing there are many other sound emissions that cannot be sufficiently explained by the cavitation of xylem alone. The mechanisms for these other sounds continue to remain unknown as plant bioacoustics is very understudied and not well understood. Now while the plant sounds may seem goofy, I actually think it serves in filling out Junior’s imprinting mechanism. It seems that Junior imprinted on Azusa Gojo back when Dr.Omae’s research team was at Adonoa. During that time, the prehistoric plant is attached to Junior’s egg. Once the egg is in the incubator in the Kyoto lab, the plant appears to have been removed. Junior’s imprinting mechanism seems to have made him respond to the vocalizations that are paired with the plant music. This seems consistent with how the movie ends, where Azusa tells Miki to play the plant music for Junior, which causes him to join Godzilla. This would mean that the plant serves as some acoustic cue that triggers Junior’s imprinting mechanism whenever he is currently without an identifiable parent. The English dub/dubtitles fudge this up, where it suggests Miki sent orders to either Godzilla or Junior to leave by using her telepathy. The plant also seems to have some stimulating effect on Junior when emitted at a volume audible to humans, such as during his hatching and when the psychic children are singing the song in person. But why has Junior’s mechanism adapted to activate from the plant’s music? What adaptive purpose does it serve? Our next topic may be the key to this.

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The next explicit use of ethology in this movie also comes from Dr.Omae, who chalks up the presence of a Godzillasaurus egg in Pteranadon nesting grounds to brood parasitism. Brood parasitism is a parental care strategy where egg-laying animals, mainly birds, would lay their eggs in the nests of non-genetic parents. Under the right conditions, such as finding a suitable host, this strategy is quite adaptive as leaving a host to tend to the eggs and hatchlings would allow the parent to maximize their mating opportunities and lifetime reproductive success. Both the Japanese and the English dub describe brood parasitism in its interspecific form, where the parasite eggs are laid in host nests belonging to a different species than the parent. Now some observable evidence supports this theory, as Junior’s egg was very similar in both size and pigmentation to Rodan’s. Egg mimicry is analogous to camouflage, which increases the success of interspecific brood parasites as it would be harder for the host to kick out the parasite egg. In real life, host species have only evolved means to distinguish parasite eggs from their own, so once the parasite offspring has hatched, the host parent will not be able to distinguish it from their own offspring. Furthermore, from observing Rodan, Adonoan pteranodons’ apparent cooperative breeding behavior and vigilance over the nest would suggest that they were optimal caregivers, which would be an ideal quality for host species of brood parasites.

Now where the English dub deviates is by making the explicit comparison to the European cuckoo, which is an obligate brood parasite. Obligate brood parasites are species that only lay parasite eggs and do not build nests for any of their offspring. Their host nests are always heterospecific, meaning from a different species. This contrasts with facultative brood parasites, which raise some of their offspring. These parasites typically choose conspecific hosts, meaning within their own species. Now to the dub’s credit, the European cuckoo is the most popular example of brood parasites, and nearly all interspecific brood parasites are of the obligate type. However, the European cuckoo does not act as the best model of brood parasitism to model Junior’s species after. Junior appears to be a precocial hatchling, like the ducklings and goslings Lorenz had studied. Precocial offspring are very developed upon hatching and can walk around and forage on their own, not requiring their mothers to feed them directly. The European cuckoo’s offspring, like most obligate brood parasites, are altricial. Altricial offspring, by contrast, a very dependent upon their parents for feeding them and cannot properly move on their own. Altricial species includes most songbirds, raptor birds, and humans. Minilla would count as an altricial offspring prior to his rapid growth spurt. Altricial offspring are more costly to raise, which drives obligate brood parasitism to evolve almost exclusively in altricial species. Facultative brood parasitism usually evolves in precocial species, as precocial hatchlings are less costly to raise for both conspecific hosts and parents.

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Rather than an altricial cuckoo, a better species to model Junior after would need to be a precocial interspecific brood parasite of some sort. This is important because precocial species are more likely to share imprinting mechanisms that resemble Junior’s. Also, precocial parasite birds generally do not rely on heterospecific hosts for raising their offspring, only for defending the eggs. For my article on the Heisei Godzilla, I used the black-headed duck, which is a precocial obligate brood parasite, the only known one of its kind. I initially had trouble finding a facultative brood parasite that predominantly used heterospecific hosts. Now while I feel the black-headed duck theory is consistent enough with what is observable and suggested in this movie, I am going to present you all with an alternative hypothesis for this article! Since my Heisei Godzilla article, I have actually found a new duck to use as a model for Junior, the redhead. Like the black-headed duck, the redhead is the only known brood parasite of its kind, a predominantly interspecific facultative brood parasite! These ducks’ parasite eggs account for up to fifty percent of their total offspring. The existence of this species leaves room to interpret that Junior’s species did have the capacity to build their own nests, but simultaneously would parasitize another species. This hypothesis I feel improves upon my black-headed duck model as the redhead model alleviates some of the limitations my black-headed model required in order to work. I will go over those limitations in a future topic, but for now, let us briefly discuss something interesting about imprinting and interspecific brood parasitism.

What is fascinating about the inclusion of both imprinting and brood parasitism in this movie is that research suggests that imprinting may have had an important role as both a barrier and facilitator in the evolution of interspecific brood parasitism. Now some of you who have been paying attention may have started to ask ”Wouldn’t the imprinting mechanisms of parasite hatchlings cause them to imprint on their host species rather than their own, like seen in Junior or Lorenz’s ducks?”. Well, the answer to that would be ”yes” and ”no”. Ethologists pondered this question themselves and assumed parasite offspring had some modifications in their imprinting that allowed them to maintain their conspecific recognition. However, experimentally controlled cross-fostering studies have shown that parasite offspring imprint on their heterospecific foster parents just as easily as non-parasitic birds. Despite this discovery, there is little evidence of this occurrence among parasite offspring raised in the wild. This may suggest that in their natural environment, there are factors or stimuli that prevent their imprinting mechanisms from causing them to fraternize with their host species. And this is where the plant music becomes interesting. Not only is Junior removed from his natural environment, but the plant attached to his egg gets cleaned off as well. This may have disturbed some regulatory pathways in his imprinting mechanism, which led to him imprinting on Azusa, like the cross-fostered hatchlings. Now others may also ask ”If the imprinting mechanisms are so maladaptive for parasite birds’ species-recognition, why have the mechanisms not been weakened or strongly modified through evolution?”. Even though imprinting may seem to be a barrier, scientists believe that it remains intact in parasite birds because it serves an adaptive role in nest recognition. In order for interspecific brood parasitism to be evolutionarily stable, the parasite bird must be able to recognize both its own species and the host nest that it had hatched from. So instead of going away, the parasite bird’s imprinting mechanism is retained to rely on cues or stimuli that aid in recognizing the host nest. However, like many behavioral products of evolution, imprinting mechanisms are not always very precise and can be easily manipulated. So ultimately, the pathways the parasite birds utilize to spot their nest are likely not too different from what non-parasites use to recognize their own species. So the balancing act of the imprinting mechanisms for parasite birds is very reliant on environmental variables. And for Junior, I believe the plant music may have been a variable that contributed to his species’ ability to recall host nests. Junior’s imprinting mechanism probably did not necessarily evolve for the need of a mother. A plot detail from a future movie supports that interpretation.

Let us briefly go over Junior’s diet. In this movie’s English dub, Dr.Omae claims that Junior is a ”plant-eating Godzillasaur”, right before we see him eat the flower. Now, this screams malarky, and this line is not present in the subtitles that more closely translates the Japanese dialogue. This is important because people tend to cite how Junior is seen eating a burger later in the movie. Now without that ill-placed line, we can reasonably interpret that Junior’s species were omnivorous.

When Godzilla reaches the Kyoto lab, Junior’s eyes begin to glow and Godzilla is repelled back into the sea. A similar event occurs when Junior becomes distressed as he is almost forced to be separated from Azusa. Junior’s second reaction attracts Rodan and is likely what causes Godzilla to show up later. It seems to me that Junior is emitting some sort of alarm call, which is characteristic of young offspring that belong to social species. However, Junior’s signal is different in each scenario. When Junior forces Godzilla away, he is frightened by Godzilla’s presence and is most likely sending a ”go away” signal that could be an ultrasonic wave, as observed in rat pups. For the second alarm call, Dr. Omae speculates that it could be an ”S.O.S.”. This would be adaptive for attracting help, just as we see in rat pups and other social animals. However, the S.O.S was likely not ultrasound, but infrasound as this signal attracted both Godzilla and Rodan from far-away distances. Infrasound is known to be capable of traveling over long distances like observed in elephants. These creatures produce low rumbles that can be carried and heard by other elephants across distances of 10 km or further. I will also like to mention that the ”half-brother” line is not exactly reflected in the dialog discussing Rodan’s attraction to Junior. They rather simply suggest that their shared natal ground made Rodan and Junior ”related in a way”. This is technically consistent with the idea of fraternal imprinting.

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Now, let us discuss how Junior is utilized as a model organism. Research on Junior has shown that Godzillasaurs possess a secondary brain. This anatomical feature is based on an old misconception from Stegosaurus fossils that revealed enlarged portions of the spinal cavity. We currently understand that these areas housed expansions of the spinal cord rather than true brains. Now some people tend to use this scene to cite two potential plot holes, ”Why do they need Miki if they know where the secondary brain is from Junior?” and ”Shouldn’t have Miki noticed this before?”. Well, the first one to me is obvious if you are mindful of the limitations of model organisms. All the scientists know about Junior was that he is a related species to Godzilla, it is uncertain if they are the exact same (we are gonna get to that a bit later). Furthermore, Junior is a hatchling while Godzilla is an adult, we have very little insight on how proportionally developed the secondary brain is in an Adult Godzillasaur. Not to mention Junior is likely not as mutated to the same degree Godzilla is, as they have been exposed to separate sources of nuclear radiation. There are too many variables distinguishing Godzilla from Junior to ensure a precise shot for the G-crusher from the information of this diagram alone. The consequence of missing the brain with the G-crusher would have been too high given what happened during the first fight with Mechagodzilla. Now as for Miki’s inability to notice the secondary brain before? Well, there is a bit more of an argument here, but given how the secondary brain is connected to the same central nervous system as Godzilla’s primary brain, it likely acts as a less-developed extension of Godzilla’s psyche rather than an independent one. I can personally accept that it would have been hard to notice without knowledge of its existence. I have seen similar instances of this in chemical spectroscopy readings from my chemistry labs, where similar structures or chemical groups were harder to distinguish from each other. In the past, her powers seem to have been more proficient at identifying separate psyches. Even when she attacked Godzilla directly in Godzilla vs Biollante, she was most likely targeting the decision-making neural pathways of his brain. The secondary brain’s position on the spine would suggest that it is most likely an integration center for motor signals, likely a separate pathway. A form of ”tunnel vision” would have likely prevented her from noticing the secondary brain then.

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Now for our penultimate topic before leaving this movie, let us discuss adoption. Adoption of alien young is a real occurrence in animal behavior. Scientists normally attribute this to kin selection. By adopting the orphaned young of their siblings, the foster parents are improving their indirect fitness, because their relatives are genetically similar to themselves. However, this explanation is insufficient in the case of Godzilla and Junior because the geographical distance between Adonoa Island in the Bering Sea and Lagos in the Central Pacific suggests that Godzilla and Junior are not immediate relatives and are rather from separate populations altogether if not distinct species. Alternatively, the brood-dominance hypothesis may explain this, as Godzilla is likely part of a precocial species like Junior. Since precocial offspring are more independent than altricial offspring, there is less of a fitness cost when adopting them. In fact, there can be benefits, as shown in observations of social birds like pied avocets. These birds often engage in the adoption of non-genetic offspring because they can build their broods to help lower mortality against predators or gain access to better resources. Basically, brood dominance through adoption is analogous to armies getting stronger by recruiting more soldiers. Godzilla most likely inherited this behavioral trait because adoption was advantageous for his species. This provides some evidence that Godzilla’s species were likely social animals, rather than solitary animals.

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Now Godzilla’s adoption of Junior is mainly why I proposed my alternative hypothesis, where Junior’s species were interspecific facultative brood parasites like a redhead rather than obligate brood parasites, like the black-headed duck. The latter theory would require that Godzilla and Junior were definitely distinct species. If Godzilla was an obligate brood parasite as well, he likely would not have adopted Junior. The facultative theory allows for both of them to be of the same species. Now even if they were distinct species, the new theory would still allow for better parsimony within Godzilla and Junior’s clade. Parsimony is basically like the Occam’s razor for the evolution of new traits in across lineages. It is simpler to interpret that facultative brood parasitism evolved in the lineage predating the divergence of both species rather than that obligate brood parasitism suddenly evolved only within the lineage of Junior’s species. Now on that note, what exactly is Junior’s phylogenetic relationship to Godzilla?

Now in the Japanese dub, Dr. Omae suggests that Junior is a ”similar species” to Godzilla, and his English dub counterpart somehow manages to position them within the same genus! Though I guess I should expect nothing less from the guy who can spot a plant-eater before it even takes its first bite! In Godzilla vs Destoroyah, Kenichi Yamane claims that Godzilla and Junior are of the same species. Well, which is it? This may seem like a bit of an inconsistency, but I will actually defend this as fairly portraying how old terms like ”species” aged poorly upon the advent of modern biology and the debates that this generates. You remember learning basic taxonomy in science classes: Domain, Kingdom, phylum, class, order, family, genus, and species? The thing is that evolution and speciation do not occur in adherence to taxonomy. Taxonomy is an old, artificial construct made to better understand relatedness between organisms. The list I just presented is not even the current one, new taxa have been added to keep up with current biology! There are subphylums, subclasses, superorders, infraorders (which is different from a suborder, mind you!), subspecies, etc. Do not misunderstand me, taxonomy is a useful construct, but as we move down towards more precise classifications such as species, the criteria become more nebulous. I was directly taught by my evolution professor that there is no widely-accepted strict set of criteria for defining ”species” across all cases. Speciation can occur very differently across various organisms depending on the environments they live in, mode of reproduction, social interaction, etc. So this can create a lot of debate on whether closely-related organisms are distinct species, subspecies, sub-populations, or ecotypes. I became familiar with this discourse through my studying of whales. For example, some sources will identify orcas as being one species, others will argue there are almost a dozen different species and/or ecotypes to account for.

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Making such a distinction between Godzilla and Junior would prove difficult because even a DNA analysis between the two will be limited by the fact that they are both stragglers. Without consistent trends or patterns from reference populations or related species to work off of, the genetic variation between Godzilla and Junior could be challenging to interpret with certainty. So what is my opinion? I choose to treat them as members within a polytypic species, comprising of two distinct subspecies. I classified Junior after his natal ground, Godzillasaurus gojira adonoa. I provided a trinomial nomenclature that denotes genus, species, and subspecies. And in this fashion, I decided to name the Heisei Godzilla Godzillasaurus gojira ragosu, as he was discovered on Lagos island. I actually changed the title of my Heisei Godzilla article to reflect that.

Now, let us move on to Godzilla vs Spacegodzilla. Now the starkest change here is that Junior grew up into a more ”Chibi” version of Godzilla, rather than the more dinosaur-derived design from the previous film. The most distracting detail being his eyes. Now his previous design had somewhat large eyes as well. Though in that context, it was atleast comparable to the proportionally enlarged eyes of various bird hatchlings. Furthermore, they were smaller than either Godzilla’s or the Lagos Godzillsaurus’. In this film, Junior’s eyes are larger than Godzilla’s own. Now we all know this gets course-corrected in the next film, so I am not going to continue pining over it. Now as for his behavior, his curiosity and playfulness are not too far removed from what is observable of juveniles of many animals, especially social animals.

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We also get a return of the alarm call from the previous film, which attracts Godzilla to Junior’s location as the latter is under attack by Spacegodzilla. An interesting thing is that after being voluntarily separated from Junior, his behavior becomes more consistent with how he acted in the pre-Junior films. Social animals are known to experience adverse behavioral changes after being involuntarily separated from their brood. This allows the interpretation that the Heisei Godzilla’s aggressive behavior in the pre-Junior films could be due to his social frustration. His mental faculties are that of a social creature but Godzilla has been left to lead a solitary life as a straggler. This pattern is consistent with what we see in the next film.

In Godzilla vs Destoroyah, Birth Island explodes due to a reaction between the natural uranium within the island and an eruption of hot water. This ends up disturbing Godzilla’s thermoregulation of his nuclear fission and leaves him in his ”Burning” state. Junior is suspected to be dead until his sudden appearance halfway through the movie. He is now matured into a physical stage approaching adulthood. It seems the radiation from the explosion may have triggered some extreme form of induced maturation in Junior, possibly regulated by some hormonal pathway. Miki reveals that he is heading North to Adonoa, an example of natal homing or philopatry. Now, wait! Some of you may remember that he hatched in the Kyoto lab, what is up with this? Remember back when I talked about how imprinting mechanisms are active prior to hatching and are also theorized to aid in brood parasites’ nest recognition? Well, this is where the plant music becomes important. The sound-emitting plant attached to Junior’s egg from Godzilla vs Mechagodzilla II can be interpreted as being a sensory cue that triggers Junior’s imprinting mechanism. It is likely that Junior is heading back to Adonoa because it senses the plant sound, or possibly even some other unknown cue that allows it to navigate back to the island from long distances. No such cue would have likely remained in Kyoto. This is consistent with the behavior of say, salmon. These fish can travel thousands of kilometers from their natal stream into the ocean and manage to find their way back for the breeding season. They navigate back home using a combination of magnetoreception and olfactory cues, the latter allows them to track their natal stream through their imprinted scent. Magnetoreception is interesting as the Heisei Godzilla is also noted to have this navigational trait in The Return of Godzilla. Furthermore, it is part of a homing instinct that shares a pathway with auditory input as well. With this in mind, it is very possible that Junior has a similar mechanism facilitating his navigating towards Adonoa.

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After defeating the Destoroyah aggregate, Junior and Godzilla reunite in Tokyo. And this is where Godzilla’s behavioral shift becomes more obvious. Repeating the pattern set by Godzilla vs Spacegodzilla, Godzilla seems to interrupt his normal rampaging and feeding off of nuclear reactors to reunite with Junior. It seems that Godzilla’s social needs supersede even the feedback from his body that is pushing him to feed. And once we see the two interact, they are just talking to each other. Godzilla is very uncharacteristically calm while in the middle of the city. It serves to directly contrast with what the original Godzilla did in the same area forty years earlier. When Destoroyah develops into its complete form and attacks Junior, Godzilla mourns and inspects Junior’s body after fighting two rounds with Destoroyah. Now I have already elaborated on how animal grief rituals in response to death are significant to our understanding of animal behavior in my other two articles. In the article for the Heisei Godzilla, I emphasize how this scene is strong evidence that Godzilla is a social animal by comparing it to the displays exclusively seen from real social animals. In Destoroyah’s, I point out how this display of complex emotion contrasts with the very simplistic and reactionary behavior observed by Destoroyah throughout the film. So for the sake of keeping things fresh while revisiting old topics, let us contrast Godzilla’s grieving scene in Godzilla vs Destoroyah with the scene from Tristar’s 1998 Godzilla movie from an ethological point of view. What makes these two scenes different when trying to interpret a valid display of grief?

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One major difference between these scenes is the relationship between the mourner and the dead and/or dying individual. Godzilla and Junior, while possibly the same species, are not immediate relatives by any identifiable means. Kenichi describes Junior as Godzilla’s companion (or whatever term in Japanese that can be translated to that). They are simply members of a straggler brood. By contrast, the Tristar Godzilla is tending to its actual genetic offspring that had recently hatched. Interactions between genetic relatives, especially parents and offspring, have a more direct impact on fitness. This facilitates forming simpler explanations for what is driving their behavior. The other difference is the reactions from the respective caregivers. When Junior is harmed, Godzilla makes his way to his companion once Destoroyah is no longer in the way. As Godzilla reaches Junior, he immediately attempts resuscitation, mimicking the gathering of resources seen in social animals. Most importantly, Godzilla remains very fixated on Junior throughout the entire process. Godzilla only withdraws his attention when his nuclear fission causes him to have some sort of seizure. It is then followed by an ambush from Destoroyah. Had Destoroyah not return, Godzilla would have likely spent his last moments tending to Junior. The Tristar Godzilla inspects its offspring very briefly and immediately shifts its attention towards the humans that were merely standing nearby, not doing anything to even agitate it. The fixation on the corpse is very crucial when trying to interpret grief from animals, and the Tristar Godzilla seems to exhibit less of that compared to the Heisei Godzilla. The genetic relationship coupled with the more brief and reactionary actions from the Tristar Godzilla leaves more room for an ethologist to interpret its apparent grief as a simple inspection of non-responsive offspring followed by basic aggression. This kind of behavior holds a more obvious fitness benefit. The more social context surrounding the Heisei Godzilla and Junior’s relationship and explicit fixation from Godzilla can more easily qualify the 1995 scene as a bona fide grief display.

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After Destoroyah explodes and Godzilla dies from his meltdown, Junior absorbs the radioactivity contaminating Tokyo. Resusicated and matured further, Junior is revived in the spitting image of his former brood member. While Junior lives, he is unfortunately left in the same position as the Godzilla before him. A social animal left to lead a solitary life. Will he too embark on similar rampages that the previous Godzilla did or does he still retain his more docile temperament? If the latter, how long will that last until solitary life gets the better of him? That remains a mystery…

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Fun facts: Godzilla vs Mechagodzilla II‘s third act was my introduction into Godzilla. It recently was only my 13th favorite, but after giving a rewatch with some improved subtitles, it is now somewhere in my top 10 or even top 5. This movie was also where I first learned about brood parasitism, like how The Return of Godzilla was where I first learned about magnetoreception in animals. When I first saw Godzilla vs Destoroyah, I did not know that the silhouette at the end was a revived Junior, I thought it was only a ghost of Godzilla. It was not until I came upon a movie summary on the internet did I understand the full ending. My original interpretation of the ending made my first time seeing Godzilla vs Destoroyah all the sadder since Junior is my favorite character. I do not change Junior’s name to ”Babygodzilla” or ”Littlegodzilla” in accordance with his first two movies for two reasons. First, because ”Junior” is simpler and more consistent for addressing him. Second, I have been a Latin student for eight years, and ”Junior” is a Latin comparative adjective that translates to ”younger”. It is a name that I feel represents my appreciation for Junior as the younger specimen to observe and analyze so that I gain a better understanding of Godzilla.

Sources:

Cooperative breeding:

https://royalsocietypublishing.org/doi/10.1098/rsbl.2016.0316

https://www.cell.com/current-biology/fulltext/S0960-9822(07)01207-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982207012079%3Fshowall%3Dtrue

Konrad Lorenz and in ovo imprinting

Click to access lorenz.pdf

https://www.nature.com/articles/s41598-017-13110-y

https://pubmed.ncbi.nlm.nih.gov/15521556/

Plant Bioacoustics

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3677178/

Click to access 1-s2.0-s1360138512000544-main1.pdf

Redhead ducks, Cross-fostering, and the evolution of interspecific brood parasitism