Tuesday, January 31, 2017

Consciousness, Sentience, And Self-Awareness: An Overview

Consciousness, sentience, and self-awareness are among the most contentious topics in biology, as well as in popular culture. In the past, it was commonly assumed by eminent philosophers that only humans were conscious and sentient, and no other animals, let alone non-animalian organisms, were. Additionally, even now, it is commonly believed that even some humans younger than a certain age, such as in the prenatal stages of life, are not capable of being in possession of these qualities. But a mass of scientific research, welling up to a profound crescendo which cannot be ignored, has been accumulating over the years that contradicts these assertions. No longer can we claim, while still remaining on solidly grounded scientific footing, that only postnatal Homo sapiens are conscious, sentient biological entities. In fact, one of the core assumptions accepted even by many in the scientific community now, that a brain, or, at the very least, a nervous system composed of neuronal cells, is necessary for consciousness, sentience, and self-awareness has now started to be persuasively challenged by the evidence. This is what is the primary focus of this present article.

Firstly, we need to define these terms. Consciousness can be defined as an awareness of one's surroundings, sentience can be defined as an ability to perceive subjective states (i.e., "This situation is good for me", "This situation is bad for me", etc.), and self-awareness can be defined as awareness that one exists, and recognition of oneself, as an individual, distinct from others. Based on these very simple criteria, it shall be shown that the widely-accepted assertion that only humans, and only humans at a certain ontogenetic stage, at that, possess these qualities is simply not concordant with the evidence at hand presently.

Let us start with the evidence from those creatures closest to home, so to speak, with members of the same species in which these qualities are accepted as existing, Homo sapiens, but at an ontogenetic stage where it is assumed not to possess them: neonatal and prenatal humans.

It is very common to encounter statements that a fetus is not conscious, sentient, or self-aware. Some even go as far as saying that a newborn baby, after birth, does not yet have those qualities. Yet a cursory overview of the scientific literature on this subject reveals these assertions to be grounded more in preconceived notions than on fact. A study has shown that newborn babies can recognize the sound of their own cry when heard among the sounds of other babies' cries and the sounds of other animals, revealing a type of self-awareness at the neonatal stage of life. And this is purely anecdotal, and thus cannot count as empirical scientific data, but one of my own cousins once removed, at six months after her birth, has, according to her parents, already developed a preoccupation with her own reflection in mirrors, a preoccupation which she does not display when observing the reflections of other objects in mirrors, an indication of an awareness of a sense of self.

A study by Umberto Castiello et al. has revealed that, at least as early as fourteen weeks in utero, twins have been observed touching each other. The first inclination of the reader would be to dismiss these motions as mere reflexes, but the authors point out that they seem purposeful and directed. This study examined five pairs of twins in utero, and all displayed this same behavior, with the authors therefore arriving at the conclusion that "These findings force us to predate the emergence of social behaviour".

Let us now move on to the likely even more controversial portion of this article, that concerned with the research indicating the existence of these qualities, as well as numerous other cognitive capabilities, such as problem-solving and communication, in creatures completely lacking brains or nervous systems as we know them, such as plants, protozoa, and bacteria.

Any mention of plant sentience, consciousness, or self-awareness is immediately marred by association with the pseudoscience that, sadly, cast a dark shadow over investigations into this subject decades ago, beginning with the publication of The Secret Life of Plants, a book which claimed that doing things to plants such as playing certain varieties of music to them would allow one to communicate telepathically with them and convey emotions, among other such mystical claims. This has led to the investigation of plant cognition being seen as taboo by serious botanists nowadays, a rather unfortunate reality, now that renewed research is beginning to show that this avenue of investigation is, indeed, worth pursuing.

The work of scientists such as Stefano Mancuso, Richard Karban, and Monica Gagliano on plant communication and learning has spread shockwaves throughout the botanical community, bringing up memories of the not-too-pleasant specter of the pseudoscientific claims engendered by The Secret Life of Plants and its ilk. Yet this research cannot be ignored. It has been shown by the work of Karban and Mancuso that plants are capable of communicating to each other through chemical signaling, with some even likening the chemicals released after grass is cut that give it such a characteristic smell as "screaming" intended to warn surrounding plants of the impending danger. Additionally, experimental research carried out by Gagliano has shown that some plants are capable of learning that a given stimulus is harmless after being exposed to it repeatedly, while giving a defensive reaction, showing that they still suspect it might be harmful, once subjected to a different stimulus.

This has led to the development of a nascent branch of botany known as plant neurobiology, which is a misnomer, as even the botanists who study it are aware that plants do not possess neurons, in the same way that animals do. While still an emerging field, it already has made promising progress, and many more insights into plant social behavior and cognition certainly await in the future.

Let us now move on to the organisms that are commonly thought to lie at the very bottom of the Scala Naturae of old, the microbes and protozoa. Even these seemingly most unlikely of candidates for the presence of consciousness, sentience, and self-awareness have no shortage of studies expounding the evidence for the presence of these qualities in them.

Some of the most persuasive evidence in this area has come from research on a certain species of Slime Mold, Physarum polycephalum. This slime mold has been shown to be capable of memorizing its history of spatial location, and of navigating a maze with such precision and ease that it would fill the most clever of human engineers with envy, as it would be comparable to their most carefully calculated efforts.

In addition, bacteria offer an impressive reportoire of cognitive and social behaviors. Bacteria are capable of processing input from their environments and producing outputs in return based upon their computation of said information. They also possess an ability known as quorum sensing. That is the ability to detect when a group of their own species has reached a sufficient number to be able to carry out a certain operation, implying some degree of social awareness. According to a study by the late Eshel Ben Jacob et al., bacteria display some cognizance of the distinction between themselves and others, i.e., self-awareness. Indeed, the actions of bacteria within the bodies of host organisms, and their ongoing battle waged with said host organisms' immune systems, has been compared in its complexity to human guerilla warfare. Bacteria are also capable of genetic engineering, incorporating foreign DNA into their own genomes. In other words, bacteria have had the ability to genetically engineer for billions of years, while humans have now had it for less than a century. This evidence is too impelling to be ignored. Renowned bacterial geneticist James A. Shapiro states that "This remarkable series of observations requires us to revise basic ideas about biological information processing and recognize that even the smallest cells are sentient beings."

I will be posting much more on this topic in the near future, but it shall suffice to say that we must be more open-minded about consciousness, sentience, and self-awareness in numerous varieties of creatures, from microbes to slime molds to plants, and, therefore, by extension, to zygotes, embryos, and fetuses of all animals.

Sunday, January 15, 2017

Sasquatches And Yetis: An Overview

Some of the most well-known alleged creatures investigated by cryptozoology are, undoubtedly, the supposed undiscovered bipedal primates reportedly seen around the world, including such fabled beasts as the Sasquatch, or Bigfoot, of North America, and the Yeti, or Abominable Snowman, of Asia. These alleged creatures are highly controversial, with their existence being widely regarded as unlikely by much of the scientific community, albeit with some notable exceptions, such as Grover Krantz and Jeffrey Meldrum. The proponents of their existence are quite zealous, passionately defending their supposed evidence against the arguments of the skeptics. In this article, I will examine this situation from a neutral perspective, arriving at a conclusion on this topic at the end, starting with an exercise in vicariously seeing what goes on in the minds of witnesses, from a first-person perspective:

I am walking through the dense, temperate rainforests of the Pacific Northwest, heading back to camp after collecting and purifying drinking water from a creek. All of a sudden, behind a bush, I see something I cannot quite identify; coming closer, I see that it is a hair-covered mass, which proceeds to leap out from the underbrush and stare at me. I am stunned; it is quite tall, appearing to ambulate in the manner of a human. It stares me in the face for what seems like an eternity, before finally strolling off into the dense green cacophony of thickets, never to be seen again. After it leaves, I look down at the ground, seeing footprints. Spilling plaster into them, I take the casts home to show everyone. It has been a frightening, yet massively rewarding, day for me; I got the fright of my life upon seeing this creature, but now I have the privilege of being able to say that I have set my eyes on the notorious Bigfoot.

This scenario is by no means singular or unique. Since at least about sixty years ago, if not earlier, witnesses have reported coming face-to-face with creatures resembling upright-walking, bipedal hairy primates in various locales, ranging from the snow-covered peaks and valleys of the Himalayas, that mountain range formed by the collision of the former continent of India with Asia earlier in the Cenozoic Era, to all parts of North and South America, to even places such as Australia, where a similar creature known as the Yowie has been reported to roam the Outback.

Besides sightings and videos, including some famous examples, such as the Patterson-Gimlin Film, the evidence most often marshaled by supporters of these creatures' supposed existence consists mainly of footprints, excrement, and hairs. Recently, numerous hairs alleged to belong to anomalous primates from around the world were tested by hominid geneticist Bryan Sykes and colleagues. They arrived at the conclusion that the hairs came from a wide variety of known animals, ranging from ungulates to bears, with some hairs from the Himalayas, reportedly from a Yeti, being found by said study to belong to an as-of-yet unknown variety of Polar Bear. A subsequent study by Eliecer E. Gutierrez and Ronald H. Pine arrived at the conclusion that the hairs likely came from the known Himalayan Brown Bear, with there being no reason to suppose that they came from anything else.

Another study found that the reported range of Sasquatch encounters in North America where sightings were most frequently reported matched up nearly perfectly with the known range of the American Black Bear, Ursus americanus. The authors, reflecting on their findings, noted that the idea that two sympatric species of large mammals with reportedly similar superficial appearances and habits would inhabit the exact same region left them incredulous.

Reality television programs such as Finding Bigfoot on Animal Planet have now added fuel to the fire with their claims of investigating these reported creatures scientifically, while, with all due respect to the people involved in the series, their investigations are a prime example of what I consider to be the pseudoscience which mars cryptozoology and gives it a bad reputation among the scientific community. The investigators on that program repeatedly perform strategically-placed calls to attempt to attract Sasquatches with them, subsequently interpreting any response they get, however vague, as said Sasquatches responding to their communication. First of all, they need to provide evidence that these calls they are using are really Sasquatch calls, and how we can know they are such, if Sasquatch has not even been confirmed to exist, let alone discovered or studied in any intensive detail. Second, it seems to me like they too readily employ confirmation bias when it comes to interpreting their findings. Since they have the mindset that they are communicating with Bigfoot, they interpret any calls they hear as coming from Bigfoot, automatically, despite the lack of any solid evidence, whatsoever, that this is, in fact, the case.

Another recent event in the community of Bigfoot advocates was the claims by Melba Ketchum and colleagues that they had found Bigfoot DNA. However, Ketchum et al.'s study was published in their own scientific journal that had been purchased by Ketchum herself months earlier, without passing through the rigorous process of peer review necessary to cement its findings as scientifically sound. The process of publication of the article was also marred by scandalous events, including one researcher's insistent claims that he had photographed the face of a Sasquatch, really nothing more than a Chewbacca mask. Ketchum concluded that Sasquatches resulted from a hybridization event between humans and another unknown hominid species in the Pleistocene, about fifteen thousand years ago.

After all of these different avenues of investigation and recent events that have occurred surrounding Yeti and Sasquatch research, I must say that, as someone who once passionately thought that the evidence supported the existence of a species, or several species, of closely-related unknown bipedal primates inhabiting the Palaearctic and Nearctic ecozones, and possibly the Australasian one, as well, I have now drifted to a more skeptical point-of-view on these cryptids, given that the evidence that seemed most compelling to me in the past has now been tested, and, with the exception of Ketchum et al.'s controversially-derived results, genetic evidence of unknown primate presence was not detected.

What really caused me to reexamine my views and take on a more skeptical position, though, were two main reasons. One reason was the study comparing the distribution of Sasquatch sightings to the distribution of American Black Bears, which really impressed on me what a coincidence this would be if a Sasquatch was a real unknown primate species, as well as the study of alleged Yeti hairs carried out by Bryan Sykes et al., and the subsequent follow-up study conducted by Eliecer Gutierrez and Ronald Pine. As much as I wanted it not to be true, because of how much it dampened my hopes of discovering a real new species of bipedal, hairy hominid roaming the forests of North America and Asia someday, I had to admit that Occam's Razor supported misidentifications of ursids as being one of the most common reasons for reported Sasquatch and Yeti sightings. I myself have seen videos of bears walking bipedally, and it is striking how similar their method of ambulation can appear to that utilized by hominids. A witness could very easily be forgiven for mistaking a bear walking upright on its hind legs for a Bigfoot or a Yeti, especially if they were walking through an area of wilderness where Bigfoot or Yeti sightings have been reported in the past, and they were expecting to see one, creating a psychological condition in which they were more likely to interpret any large bipedal furry creature glimpsed by them as said cryptid.

The other reason was the fact that, as pointed out previously by American physical anthropologist and Sasquatch proponent Grover Krantz, since people have reported sightings of similar creatures to the Yeti and the Sasquatch all over the world, with sighting reports implying that they have nearly a cosmopolitan distribution, this undermines the credibility of the case that they furnish evidence of an actual species of undiscovered primate. The more widespread the sightings are around the world, and the more random their distribution appears to be, the less likely the putative existence of the creatures seems. Indeed, such worldwide distribution would seem to hint at common universal factors in the human psyche perhaps playing a role in the phenomenon of reported sightings of these creatures.

Overall, I am still open-minded, and I think it is still possible that Sasquatch, Yeti, and their ilk might, indeed, exist and are roaming the wilderness at this very moment. I just do not see enough evidence to cause me to commit to such a hypothesis at the moment. Meanwhile, there are still some other mystery primates whose potential existence is, I think, grounded in plausibility, such as the Orang-Pendek of Sumatra, which has the advantage of having reports of it be confined to a specific geographical locale, being described as sounding like a real, ordinary animal, rather than a mythologized beast, as the others sometimes sound like, the presence of fossil evidence at said locale which might be of pertinence (the "Hobbit", or Homo floresiensis), and the fact that it seems to inhabit a feasible-sounding habitat for a creature of its description.

The topic of mysterious primates in cryptozoology has attracted much controversy and consternation over the years, and I doubt this trend is going anywhere anytime soon. I remain open-minded about the whole situation, and trust me, I would be ecstatic with joy if I turned on my television set or looked in my newspaper tomorrow morning and saw that a Yeti or a Sasquatch had been captured, proving the existence of a new hominid species roaming the temperate ecozones of the Earth's Biosphere. Secretly, I hope my newfound skepticism is totally wrong, and, indeed, I would love nothing more than for it to be proven wrong. After all, at heart, I am a romantic in all things, not least the zoological, and few things, if anything, can captivate me more than the thought of new species of exotic animals, hidden for ages, being discovered in our own backyards.

Saturday, January 14, 2017

Epigenetics: An Overview

In my articles on zygotes and embryos, I mentioned non-genetic factors that play crucial and significant roles in the development of individual organisms; one of those processes I mentioned was epigenetics, which I alluded to in one sentence. In reality, such a brisk glossing over does this very important and complex subject no justice, so I have decided to pen this present article to cover this topic, in particular.

What is epigenetics? To understand, we need first to cover what genes and genomes are. Genes are portions of DNA (Deoxyribonucleic Acid), the nucleic acid macromolecule inherited from an organism's ancestors. Each individual gene is like an instruction to produce a particular characteristic, and the entire set of genes in the DNA, all taken together, is known as a genome. The process of how these instructions actually create the structures that they code for is known as gene expression. This is where epigenetics comes in. Epigenetics is the process of controlling and modfying how genes are expressed during the process of gene expression.

This seemingly innocuous fact has wider implications, for it shows that, thanks to epigenetics, it is truly inaccurate to say that we, as individual organisms, are the products of our genes alone, and that our genes represent our destinies. In reality, we are the products of genes, as well as processes such as epigenetics, which result in non-genetic factors, including other components of the cell, such as cytoplasm, and external factors in the environments inhabited by us, playing a critical role in shaping who we are as individuals.

Another important aspect of epigenetics to note is that it is, to some extent, heritable. At the time of fusion of the gametes, ovum and sperm, the resulting offspring inherits an epigenome (a set of epigenetic factors somewhat analagous to the genome, which is composed of genes, hence the name) from both of its parents.
Yet another important aspect of epigenetics is that, in addition to being heritable, unlike genes (which generally remain fixed throughout an individual organism's life cycle), epigenetics can be altered by an individual's experiences in their life, and this altered epigenome can then subsequently be passed down to offspring at the time of reproduction. In other words, changes to the epigenome incurred during an organism's life are heritable, allowing them to be existent in the offspring of said organism from the time of said offspring's conception.

An organism's epigenome is modified by its environment and experiences throughout its life, from the time it is conceived by the fusion of each of its parents' gametes to the time of its death.

This process of changes to an individual's phenotype brought on by an individual's life experiences that are subsequently inherited by its offspring is quite reminiscent of Lamarckism, a hypothesis regarding how evolution worked proposed by Jean-Baptiste Lamarck, positing that, for example, a giraffe stretching its neck, lengthening it slightly, to reach the tallest leaves on a tree would bear children with slightly longer necks than it, and so on, until, over time, the giraffe population, as a whole, became long-necked. This hypothesis was adopted by many early proponents of evolutionary theory, including noted American paleontologist Edward Drinker Cope, but was generally discredited once Charles Darwin's theory of evolution by natural selection arrived on the scene.

However, epigenetics has, in a sense, resurrected Neo-Lamarckism. In addition to noting this, it should also be noted that, according to recent discoveries, even phenomena normally thought to be entirely the providence of the nervous system, such as memories, might fall under the purview of epigenetics. I am planning to devote another full article to this later, but I think it shall suffice to say here that the existence of a phenomenon known as cellular memory, the ability of cells, including some besides those of the nervous system, to record information incurred during an organism's lifetime in the form of memories, has begun to be supported by studies. This means that experiences that were endured by an individual's ancestors and which left their imprints in said ancestor's cells were passed on to their descendants in the form of their gametes, meaning that even things such as memories could be, to some extent, heritable, in a sense, due to epigenetics.

Overall, epigenetics is among the most fascinating frontiers in the field of developmental biology and genetics, and research on it is still in its early stages. In the future, more research could shed light on this wonderfully intriguing, and strikingly imperative, area of biology.

Monday, January 9, 2017

Responses To More Claims About Zygotes And Embryos

Here are some additional arguments I have encountered, in various sources, against zygotes and embryos being living individual organisms, which I will review and judge on their own merits here, as well.

One of the most popular arguments, widely believed by many, including some in the scientific community, is that, prior to fourteen days after fertilization of the oocyte by the spermatozoon, the embryo is not yet an individual because there is the potential for monozygotic twinning to occur, causing there to be two individuals instead of one. This argument assumes that this split into two individuals erases the existence of the original embryo, leaving two progeny in its wake. However, in reality, it is thought that monozygotic twinning occurs at the blastocyst stage of embryonic development, in which the cells of the inner cell mass have separated from the cells on the outside of the embryo, which form a structure called the trophoblast. When monozygotic twinning occurs, part of the blastocyst separates from the rest of the embryo, splitting off and giving rise to a genetically identical clone, or twin. It is very important to note here that this process does not erase the existence of the original embryo, and, in fact, due to the embryo's amazing ability to heal its wounds and regenerate missing cells, it actually makes a pretty decent recovery afterwards. Neurobiologist Maureen L. Condic compared this process to the analogy of an adult human's arm being cut off and used to create a clone of itself, while the original is able to regenerate its missing arm afterwards.

Indeed, the very mention of cloning allows me to segue into the mention of the fact that, as human cloning, by the merging of any reprogrammed somatic cell with an oocyte, is at least hypothethetically possible, the truth is that you or I have the potential to be cloned, which is basically the same process as monozygotic twinning, at any moment. Therefore, if we utilize the argument against individuality from twinning/cloning, then, no adult animals, including humans, are ever individuals, as they could, potentially, be cloned at any time. This is obviously an absurdity, which means the above argument must be, as well.

Another argument, this one based more on lack of information than anything else, really, is that, as embryos are capable of being frozen and thawed back out many years later, emerging alive, while this has not been done to adult animals yet, this proves that embryos are less alive than adult animals. Yet a simple exploration of what actually happens during the embryo freezing process dispels this one entirely. During this process, water is expelled from the cells, as, since water forms sharp crystals that penetrate and kill cells when it freezes, it is dangerous and deadly to allow an organism to freeze without first doing so. Then, antifreeze is put into the cells in place of the expelled water. The only reason why this has, to date, been done successfully only on embryos, and not on adults, is simply because it is far less practically feasible to carry out this process on an adult organism, simply because the latter is so much larger than an embryo. It is only a matter of practicality based around physical size. There is nothing inherently different between an embryo and an adult that causes this difference. Who knows? Perhaps, in the future, preserved, frozen adult humans will be a reality, just like preserved, frozen embryonic humans are now.

Lastly, there is the argument that, since the trophoblast forms what are commonly referred to as extraembryonic tissues, including the placenta and yolk sac, while the inner cell mass forms what is thought of as the embryo proper, before the separation of the trophoblast from the inner cell mass at the blastocyst stage, the embryo cannot yet be an individual. However, a closer examination of this argument reveals critical faults. The fact that the structures formed by the trophoblast are referred to as extraembryonic structures is rather misleading; in reality, they are, indeed, part of the embryo's body, just like what is thought of as the embryo proper. The fact that they are utilized only during the antenatal stage of life, and subsequently shed upon parturition, does not make them any less part of the embryo's body than the fact that milk teeth are utilized only during childhood, and are subsequently shed, makes them any less part of postnatal children's bodies.

Overall, these three additional arguments against zygotes and early embryos being individual organisms can all be soundly rejected. The argument from twinning can be rejected due to the fact that twinning only produces a new embryo, while the original remains, and that any adult organism could potentially be cloned at any time, the argument from freezing and preservation can be rejected due to the fact that the difference between adults and embryos in this respect is only a matter of size, and nothing more fundamental than that, and the argument from extraembryonic structures can be rejected due to the fact that these are, indeed, parts of the embryo's body, which are subsequently shed after birth.

References:

Condic, Maureen L. (2014). Totipotency: What It Is And What It Is Not. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991987/)

Sunday, January 8, 2017

Yes, Zygotes And Embryos Are Individual Organisms: A Rebuttal To Common Claims

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  • In this article, I will go over several arguments I have found on the Internet arguing that zygotes and embryos are not individual organisms in their own right, but, rather, merely cells. In other words, they argue that a human zygote or embryo is not an individual human, or that a whale zygote or embryo is not an individual whale, but merely a cell or clump of cells of human/whale origin, no different from shed human/whale skin cells, for example.
  • I will examine these arguments to try to see if they hold any veracity. Overall, I am satisfied with the conclusions I reach, as I feel that they are the result of my application of logic and critical thinking to these arguments.
  • Alright, without further ado, let us delve right on in.

  • One of the most basic arguments I could find was that a human (to utilize the example of the species for which this issue is the most controversial) zygote or embryo does not resemble a mature human, and lacks none of the physical characteristics, or autapomorphies, necessary for classification as a member of the species Homo sapiens. As a human zygote is a unicellular organism, indeed, it resembles a protozoan, such as an amoeba, far more than an adult human. However, I find this argument incredibly myopic and spurious, due to the fact that a simple glance at the rest of the animal kingdom shows much diversity in physical forms at various stages of ontogeny. Most kindergartners are probably aware (I know I was) of the metamorphosis by which a caterpillar transmogrifies into a butterfly, and possibly also that by which a tadpole transmogrifies into a frog. Indeed, it shall be observed that, in many ways, a caterpillar bears far more resemblance, physically, to an annelid worm than it does to its older self, just as how a human zygote bears far more resemblance to an amoeba than to its older self. Yet it is uncontroversially accepted that a caterpillar and the butterfly it becomes are the same individual, and members of the same species, who only look that much different due to being at different ontogenetic stages in their life cycle. A human, at the earliest stage of life, is a unicellular organism, but it is still entirely a Homo sapiens, just as a Monarch butterfly, when it was a caterpillar, and lacked wings, was still entirely a Danaus plexippus.

  • Additionally, it shall be noted that many organisms are classified as members of various clades, be they species, genera, families, orders, classes, phyla, kingdoms, domains, or any kind of clade, while lacking key autapomorphies defining membership in said clade. For example, humans, due to their mammalian provenance, are classified in the clade Synapsida, membership in which is defined by the presence of one fenestra (literally translated as window, meaning an orifice, or a hole, in the skull) in the skull, as compared with anapsids, which have no fenestrae in their skulls, and diapsids, which have two. Humans lack this single fenestra -- they are secondarily fenestra-less -- yet they are still classified as synapsids because they are descended from ancestors that possessed it. To use yet another example, snakes and caecilians are classified in the clade Tetrapoda, defined as encompassing verebrate animals with four limbs, despite the fact that they lack limbs entirely in the adult ontogenetic stage of their life cycles.

  • Another argument I could find was that, as it is not genes alone, but genes in addition to environmental influences, that make an individual who they are, a zygote cannot be an individual of the species it belongs to. This argument asserts that saying that a zygote, immediately after a spermatozo√∂n fertilizes an oocyte, is an individual of the species it belongs to is a form of genetic reductionism that discounts the role of the environment in shaping the individual, and compares the assertion that a zygote is a member of the same species as the adult organism it will later become to a form of preformationism, the erroneous belief that the physical features the zygote will later have are already present within it. 
  • First, I need to make it clear that I am no preformationist; I acknowledge that the phenotype of the zygote is drastically different from the phenotype of the adult creature that it will eventually become. Second, I am no genetic reductionist, either; I acknowledge the key role that environmental influences, in addition to genetics, play in molding an individual.

  • The difference is that I am aware that the environmental influence on an individual's phenotype is a process that continues throughout life, until the individual's death. The phenotype of an individual organism, and humans are no exception, changes drastically as they age, up to the time of their death, and environmental influences continue to play a significant role in these changes up until death. One notable example is height, or body size. This is undoubtedly one of the most noticeable and characteristic physical features of any organism. And it is well-known that it is affected by environmental factors, such as nutrition, throughout childhood and adolescence. Let's say a human child, seven years after their birth, is now four feet tall. They could have a range of possible tallest adult heights in their future, depending upon environmental influences in the intervening years. They might have the genetic potential to grow to be six feet tall, but if they spend the next years of their life in a war zone, deprived of nutrition, they might end up reaching an adult height of only five feet, eight inches, while, if they live a healthy lifestyle, they could end up reaching the height of six feet. Since the child's final height seven years after birth is still indeterminate, and is, at least partially, contingent upon environmental influences, does this mean that the child, at seven years after birth, is not yet an individual person, as their environmental influences have not yet fully molded them into their adult form alongside their genes?

  • To furnish more examples, I can easily think of cases in which the environment continues to modify an individual's phenotype well into adulthood. For example, let's say a forty-year-old runner with unnaturally flat feet due to a lifetime of wearing unhealthy shoes decides to take up barefoot running, and subsequently experiences elevation of the arches in their feet. It is also well-known that the aging process comes with numerous physical changes, many of which seem to be due to the environment interacting with genetics. A thirty-year-old adult human whose height is 5'6'', with black hair, a mouth full of teeth, and high bone mineral density looks significantly different from an eighty-year-old adult adult human whose height is 5'2'', with white hair devoid of pigmentation, no teeth in an edentulous mouth, and low bone mineral density, yet, it is entirely possible, and, in fact, is true in a lot of cases, that these two disparate descriptions are of the same individual at different ontogenetic stages in their life history.

  • As it is established that the environment acting in concert with genes to shape an individual is a lifelong process that does not truly cease until death, it is totally arbitrary to draw a line at any age and say that "this is when enough of these environmental influences have accumulated to say that you are now you." To take this argument the only logical way, one would have to say that we are never truly ourselves, and, therefore, never truly alive as individuals, until the very end of our lives, when the environmental forces finally cease exerting their influence upon our genomes, which is, of course, absurd.

  • Since it is acknowledged that environmental influences upon genomes are an important aspect of shaping an individual, it also must be pointed out, at this juncture, that it has been shown that this process actually starts at conception. Recent embryological research has demonstrated that environmental influences are thought to be an important part of causing the zygote to undergo its first mitotic cleavage, through which it reaches its two-cell stage. So the assertion that the life of an individual organism has to begin later than at the time of its conception because only genes are present at this time is rendered moot, as environmental influences, as well as genes -- the whole package -- are actually present from conception onwards.

  • Finally, another argument is that, although a human zygote, for example, is human biological material in the same sense that a human somatic cell is, it is not an individual human in the same sense that a human adult is. This argument fails to comprehend and take into account fully the distinction between living matter and living organisms. The truth is that, subtle though it may seem, there is, indeed, a distinctive difference that separates cells that are organisms in their own right from cells that constitute parts of organisms. That is the ability to behave in an organized manner, with the different parts of the cell functioning together as a unified whole. A somatic cell, if removed from its owner and taken to a locality with conditions conducive for growth, will grow in a random, chaotic manner, unlike the organized, coordinated manner of a zygote as it undergoes repeated mitotic cleavages to become a morula, a blastula, a blastocyst, a gastrula, and so on and so forth. It is often asserted that, as some cells that sometimes form in a mature organism's body, like cancer cells, have genomes that are different from the other cells in the body, but do not constitute organisms in their own right, that it cannot be said that the zygote constitutes an organism in its own right due to having its own unique genome. However, this argument overlooks the crucial fact that a zygote displays behavior characteristic of an organism from the moment that the sperm penetrates the zona pellucida of the ovum, unlike somatic cells of any type, including cancer cells. It is not merely the fact that the zygote possesses its own unique genome that makes it an organism, but the way it displays a self-organizing, coordinated pattern of behavior, with the parts of the cell working together to allow the entity to function as a whole, to facilitate the transition to the following multicellular stages. For example, different regions of cytoplasm within the zygote coordinate their varying activities to allow the organism, as a whole, to function.

  • So the zygote not only has a unique genome of its own from the time of its conception, but environmental forces are already affecting it and exerting their influence on its genes from the time of its conception, and it displays a pattern of behavior characteristic of living organisms, as opposed to mere living biological material, from the time of its conception.

  • And, yes, it is true that the sperm cell and the egg cell that formed the zygote were just as alive as it was. However, it needs to be clarified that, unlike the zygote they gave rise to, they were not individual organisms in their own right, but, rather, parts of organisms -- the ovum to the adult female animal which produced it, and the sperm to the adult male animal which produced it. This is not entirely because they lacked a distinct set of genes, but mainly because, unlike a zygote, they do not exhibit organismal patterns of behavior.

  • Another argument, which that, as human cloning is now possible, and as any somatic cell from an individual's body could be used to produce a clone of them, this renders these somatic cells the equivalent of zygotes, can also be summarily rejected due to one critical flaw. This argument makes the mistake of overlooking the fact that, before said somatic cells can produce a clone, genetic information from them first needs to be transplanted into an egg cell, rendering the new combination equivalent to a zygote in terms of its molecular composition and its properties.

  • Overall, the argument from physical appearance can be refuted by a simple cursory glance at the various ontogenetic stages numerous species pass through during their life cycles, the argument from environmental influences can be refuted by the fact that environmental influences that shape individuals, such as epigenetic processes, start acting on an individual's genome at conception and do not cease doing so until death, the argument from false equivocation of zygotes and embryos with somatic cells and tissues can be refuted by the fact that the former display clearly organismal behavioral patterns, whilst the latter do not, and the argument from cloning, closely connected to the last argument, can be refuted by the crucial fact that, in order for cloning to occur, an ovum must be involved, as in the formation of a zygote.

  • I must arrive at the conclusion that the embryological evidence seems to point firmly to the conclusion that, from the moment that the sperm and the ovum form a zygote, it is a living individual member of the species to which it belongs. Indeed, this seems to me to be the predominant view in most of the field of embryology. I penned this article because I felt the need to clear up the numerous misconceptions surrounding this subject that I kept repeatedly encountering on the Internet. I felt a duty to set the record straight, and allow the world to know the truth.

  • References:
  • Condic, Maureen L. (2014). Confusions About Totipotency: Stem Cells Are Not Embryos. (http://www.thepublicdiscourse.com/2014/03/12361/)