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| Quote from X-Men: First Class. Picture from www.welovefine.com. |
Believe it or not, but growing up, I was a comic book
geek. I was a huge Spiderman fan and my
sister was an X-men enthusiast. This
does not mean that I was not an X-men fan.
I just could not admit that because of the competitive nature that existed
between my sister and I. To summarize
the series and its plot for those unfamiliar them, the X-men was a team of “mutants”
who had special abilities and powers and were locked in a war amongst
themselves and with nonmutant human beings who did not understand them (a
comprehensive review can be found here). In the recent reboot of the franchise, in the
movie X-men: First Class Charles
Xavier (Professor X) says, “Mutation is evolution and a part of human nature.” He goes on to talk about how mutation(s) are
what separated our Australopithecine and Homo ancestors from anatomically
modern Homo sapiens, but the scene trails off somewhere in there, leaving the
audience with a basic and incomplete understanding of what exactly he is
talking about. Today’s blog post is dedicated
to explaining mutations and how they are in their own way a driving force in
evolution, as pointed out in Professor X’s quote.
Before we begin, one
must first have a basic understanding of genetics. Genetics is the study of the mechanism of
inheritance, and it is from studies of genetics that we have a basic
understanding how individuals become biologically what they are. We know that individuals are biologically
diverse both within and among species due to their genetic makeup/the genes
that they have, which are portions of the DNA molecule that codes for a
specific protein that makes up part of the body that they inherit from their
parents. The DNA molecules in the body carry
the genetic code of an individual, which defines whether, in humans at least, if
you have two eyes versus three, two legs versus eight, and skin versus scales. It is what defines one biologically.
Mutations are
changes in an organism’s genetic material and are responsible for the creation
of new alleles in a population. Alleles
are variants of genes that define if
you have blonde or brown hair, brown or blue eyes, a “widow’s peak” versus a
straight hair line, etc. Each gene has
two alleles, and these alleles can be dominant, meaning it is always expressed,
or recessive, meaning it may not be expressed.
For example, if we are speaking about the genes that code for eye color
and you carry an allele for brown eyes (a dominant allele) and one for blue
eyes (a recessive allele), you will have brown eyes, but if you carry two blue
eye alleles, the absence of a more dominant allele means that the recessive
will be expressed and you will have blue eyes.
Dominance or recessiveness is not a matter of good or bad. It is simply a matter of which allele is
stronger and more apt to be expressed.
Alleles present in
any population (be it human, animal, or plant) are often times created through
mutation because, as the above definition already descries, mutations are
simply changes in an organism’s genetic material. The term mutation is associated with negative
connotations, but not all mutations are bad!
Scholars believe that the different alleles for eye (brown, green,
hazel, grey, and blue) and hair color (black, brown, red, blonde) are due to
mutations. None of these alleles are correlated
with serious negative biological consequences, and some are dominant (e.g.
brown hair and eyes) while others are recessive (e.g. blonde hair and blue
eyes). Mutations are caused from
a variety of means, including mistakes in DNA replication (the process of DNA
copying itself), exposure to naturally occurring chemicals and temperature
fluctuations, or by various chemicals and exposure to radiation.
Mutations are considered to be a driving force in evolution
because of the genetic diversity it creates. This drive is marked by genetic
change over time and evidenced by changes in phenotypes (the physical appearance
of an individual based on their genetic makeup). Researchers note evolutionary change by
examining a population, or a reproductive unit that can successfully breed, and
certain alleles will be selected for that will either enable the species to
continue and prosper or die and become extinct.
In this way, mutations drive but to not dictate evolutionary pathways
because mutations produce random and new alleles in a population and other
forces select the specific alleles that will help or hinder the
population. So while Professor X’s quote
is not entirely correct, it does demonstrate how mutations, for better or
worse, are related to evolution.
References
Feder, Kenneth and Park M. Human Antiquity: An Introduction to Physical Anthropology and Archeology, McGraw-Hill.
Philip L. Stein & Bruce M. Rowe (2014). Physical Anthropology 11th Ed: Early Species of the Genus Homo. McGraw-Hill.
51 comments:
Is it a genetic mutation then, that is why people from Ireland or at least of Irish decent tend to have red hair more often than other peoples? If it is, how widespread of a mutation would it have to be to have such a wide effect on a whole nation of people?
Great questions, Brittnee. Yes, hair color, as well as eye color, alleles are believed to be mutations according to several scholars. Based on the prevalence of the red hair allele on the British Isle, which includes the modern day countries of Britain, Scotland, Northern Ireland, Wales, and Ireland, the red hair allele may very well have developed there, hence why we see it in such high prevalence. The genetic isolation of this trait for this population is most likely due to two factors: genetic drift & sexual selection.
Genetic drift is defined as "change in allele frequency by random fluctuations" (Feder and Park) and can be caused by two primary mechanisms, fission or gamete sampling. Because the British Isle is an island, some human populations could not go to the island and either pass on or collect genes from the red-haired populations present on the island. This caused the red hair allele to become more prevalent in the population because fewer non-red haired alleles were being introduced.
Furthermore, sexual selection, the active selection of mating partners with specific desirable characteristics, may have been at play. Individuals who were breeding probably chose other individuals with red hair over individuals with nonred hair, which would have increased the incidence of the allele in the population. Over many generations, specific nonred hair alleles would have either been systematically removed from populations or occurred at such a low incidence that it would be difficult to see them expressed phenotypically.
We actually see sexual selection occurring today with as red haired individuals are being negatively selected for in our populations. Several years ago, an article ran about how sperm banks were refusing sperm from red haired men because they had enough and there was not a high demand for it. We all hear all sorts of negative things said about red haired individuals, such as "gingers have no souls" or "It's hit a ginger day!", which produces a negative attitude against red haired individuals that may impede us from sexually selecting them as a breeding partner. There is already some historical precedence for this as in Europe and North America there is a history of the Irish being depicted as lazy and drunkards, furthering attitudes of them not being good breeding partners.
Wow ok so what started out as an anomaly then between nature and man became the norm and over time then became less desirable. I've always been curious about red hair, I knew it was a recessive gene, but when my son was small he had a very reddish tint to his blonde hair. His father and I both have Irish heritage even if it is rather distant now and I wondered if that's where my sons red came from.
Your son's red hair may have come from that "Irish heritage". We do find red hair more prevalent among the Irish and Scottish populations, but it does not necessarily mean it's a trait that is solely associated with that population. That would be similar to saying that everyone with blonde hair and blue eyes is of Nordic descent, which is not completely correct as blonde hair and blue eye alleles are found in all sorts of populations, not just Caucasoid populations. We will discuss human variation and the biological aspects of it more in the Race and Ethnicity chapter, which is after the midterm.
Ok. I will keep my questions in mind then for that chapter :)
If you are very interested in the topic, I recommend taking the Anth 102 Physical Anthropology course as we delve more deeply into this topic there.
I was actually planning on taking it. The subject in general has always caught my attention but I'm not very fond of traveling so I never really gave it much thought for something to study or try and turn into a career.
Hurray to joining anthropology. It is a great discipline with a lot of utility. As we will discuss in the last chapter (on applied anthropology) anthropologists are employed in a variety of areas, including business, education, and medicine, but even friends and colleagues who have left anthropology behind for other career pursuits comment on how invaluable their anthropological training has been, particularly in law as several are now lawyers.
Also, anthropologists do not necessarily need to travel in order to complete their work. All sorts of anthropologists study people in their own community-be it in the past or present. E.g. Pam Yuen studied gays in Toronto, Canada, which is where she grew up, and she used many of her friends as her key consultants for that study.
I have to agree that not all mutations are bad. It's weird when we hear the word mutation we automatically think of a negative outcome. Great blog!
-Cajen
I am a big fan of genetic mutations! I think that due to lack of education and a lack of individuals with basic knowledge of mutation, genetic mutations are misunderstood and get a bad reputation. X-Men mutations are clearly cool, although they do make such distinct differences between the mutated and the not that social issues arise. However, practically every function we have is the result of a mutation. Differences in eye structure and function between organisms is one of my favorite examples. Our human eyes are greatly different from those of chameleons or even giraffes because of how our ancestors' genetic mutations changed and worked for greater evolutionary fitness. We would not be the amazing naked apes that we are today without mutations! We actually may be strange, single-celled organisms had we never mutated.
Dr. Boston, thank you for shedding light on the subject and helping to educate us all in the area of genetic mutations.
-Teisha
My pleasure and thank you for the compliment.Now this is a cursory view of the topic and I am sure individuals, such as your father, could point out the flaws, but it is high praise from someone such as yourself to hear that I am doing well.
Okay, I understand that mutations occur at the genetic level. I believe our species mutates every day. Every day our body fights to survive in the world, against elements of nature and human nature. People in Atlanta Georgia are typically black in color. That would make that an adjustment to ones environment correct? What about the people immune to Malaria? since it is on the genetic level would that be a mutation?
- Tabatha Pringle
Tabatha,
The fact that there are black individuals in Atlanta is not environmentally determined. There are cultural preferences today that make Atlanta very desirable to the black community, just as moving to LA and Hollywood is desirable to anyone who wants to be an actress or moving to NYC anyone who wants to be involved in the fashion industry.
As discussed in class and in this blog entry, mutations are just changes in alleles (traits) that allow individuals to have more genetic variation and diversity in a population. We're not completely sure if there is a purpose to why mutations occur. I'm sure that many are purely accidental and the environmental conditions of the individual who possesses them are deemed beneficial or detrimental. E.g. In our culture, we view red heads as "soul-less beings", but in other places around the world, red heads are typical and have no biases against them. As one of my friends keeps saying, "My son will never date in high school because everyone thinks he's a soul-less ginger. He'll have to move overseas to find a wife." In this way, his red hair is being culturally (which is a type of environment) selected for in one culture but not the other. The natural selection processes that select for specific mutations are random and unpredictable.
But to answer your last question, an argument can be made that every allele in our gene pool was at one point a mutation. Heck, even we as human beings are mutants if you look at the course of our hominid evolution. :)
A mutation can be good or bad. But I would not see any bad in a mutation, it happens. People should see any mutation as bad, different maybe, but not bad. A mutation happens to someone or something, it is not chosen to happen. Red hair is red hair, blue eyes are blue eyes. Why do we see these things as bad mutations sometimes? People who do not like different, do things like Hitler did when he tried to commit genocide. The people he was killing were not mutants. They were human beings. And he looked the same as them if I am not mistaken. Mutation is a way of life, it happens and it can not be controlled. How do people think that we humans got here? We are mutations as well.
Are there any explanations to why these genes would mutate, lets say in regards to color change due to environmental issues, as with the red haired people of Irish decent. Using the bible as an example of history here, in the story about Esau and Jacob it states that Esau came out red and hairy all over like a garment. Would you consider this a genetic mutation considering that people of middle eastern decent generally have a bronze complexion though varying in a wide variety of shades? Here have attention brought to the forefront that he came out ruddy.
I find here that I would be known to some as a soul-less ginger, that is interesting. It is amazing how one chooses to look at others for their genetic attributes. I am glad that I live in a more excepting society with this Irish blood cursing through my veins. And on this note would we be able to possibly trace the red haired people back to Esau as he seems to be mentioned as the first red haired person in much historical literature?
Genes mutate for a variety of reasons, but they are usually not due to the body recognizing a biological need to change. Mutations can result from environmental factors (such as exposure to nuclear radiation, certain drugs, etc.), but as far as I know there is no evidence that suggests that genes go, "Crap, the environment is changing, and so must we" so to speak. As for Esau, it is difficult to say what may have caused his appearance. It is most likely genetic in nature, but is it necessarily a mutation, I cannot say. Since we carry two sets of alleles (genes) for each trait (e.g. eye color, hair color, etc.) and most often one shows itself (as it is the stronger allele) we can carry and pass off alleles/genes that are not as strong but will show up in our offspring but not us. So we can act as carries but not demonstrate it, whereas our offspring, who receive half of their genetic make up from each parent, could get a combination of alleles/genes that make they look similar but completely different from us. This is why my lil brother has blue eyes when neither of his parents have blue eyes. My dad and stepmom are both carries for the weaker blue eyed allele, but they both passed that allele on to him, hence why he demonstrates it.
This information on alleles is coming up in a future blog post, so if you stick around you'll see it as it will be be published sometime in August 2014.
Cultures put values on specific biological traits. For example, we, Americans, prefer blonde hair and blue eyes as the ideal beauty characteristic, whereas other cultures do not feel the same way. This is why we have such damaging ideas about certain traits (e.g. red hair, overweight/obese individuals, freckles, etc.)
As for Esau being the first individual in historical literature with red hair, I cannot say for sure, but I'm pretty sure that there were other incidences of red hair being recorded in the historical literature, and I'm pretty sure in the prehistoric literature/prehistoric contexts, which is irrelevant in regards to historic period subject matter. I'm not a historian, so I cannot speak to when such information was published.
When would a mutagen have to be introduced for an offspring to be different then the parents? Is it just when the gametes are formed? Or can the mutagen effect the developing zygote?
Good question. It ultimately depends on the type of mutagen that causes the mutation. Both situations you just described (during meiosis/gamete formation and in utero) can occur. An error can occur when the gametes form with the DNA itself, and there are a bunch of errors that can happen at this time. Fetuses can also be affected in utero by a variety of environmental and man made contaminants. Most environmental and man made contaminants are known as teratogens, and these include arsenic, nitrogen, radiation, and more.
Also, for you to gain extra credit I need to know specifically who you are. I'm not finding any clues of your identity in my grade books, so please either reply here or email me. :)
I've never really thought of mutations as evolution, but I've also never thought of them as being something negative. How could something like dimples be a bad thing? I understand that there are mutations that are not desirable, but I think that for the most part most are just slight differences from what is considered the norm.
It's a cultural misnomer to think of mutations as negative things. For example, Huntington's Disease, Down's Syndrome, and other negative health outcomes are associated with specific genetic mutations that have occurred and been successfully passed on through the generations. When medical practitioners and others explain these syndromes, they often refer to them as mutations, hence popularizing the notion of mutations as negative. But a variety of mutations, such as blue eyes, dimples, attached vs unattached earlobs, exist and have no negative outcomes to overall health (or at least at this time). Negative outcomes could take the form of diseases that attack individuals with unattached earlobes or cultural preferences where blue eyes is considered ugly and no one wants to mate with individuals with blue eyes. There really is an underlying level of cultural attitudes that exist when it comes to views of mutations and specific cultural traits, which is something I mentioned in the notes for Chapter 2. :)
after reading this blog I'm curious to know if people who were born with blonde hair and then grew up while their hair color changed is part of genetic mutation?
Good question, Mandy. It may be due to a mutation, although this is probably not common, but it could be due to a number of factors, including genetic and environmental factors. Myself and my brother both had red hair when we were young, and mine went more auburn/brown and his blonde, which suggests that there is a genetic predisposition to our hair changing colors. Environmental factors can also be at play, such as the sun that used to bleach out my hair, making it very blonde.
Its interesting when you think about how the mutations effect how we look. I bet when the first person showed up with blue eyes they were ridiculed for being different and now everyone wants blue eyes. So when you see people with blue/green eyes is that a new mutation? Also what about people that are half black/ half white. If the genes don't blend how does this work?
Hazel (blue green, blue brown, etc.) is based on a specific allele that codes for that eye color, and it may very well have been the result of a mutation. It can also be a result of environmental factors, such as early onset of blindness, exposure to chemicals, etc. As for skin color, as noted in the Chapter 2 lecture notes, skin color is a polygenic trait, meaning multiple genes code for what our skin color will be. This is why we can and do change colors throughout the year and our life times (which is why people burn and/or tan). So black/white skin tones are not genetic mutations, but the result of the genes that one receives from both parents. We will be learning more about this phenomenon in the last chapters of the class and you will be exploring it further in your Race Assignment. But if you want to get a jump start on the topic think about what is considered white vs black skin and who identifies as Caucasian and who identifies as African American. Are they all the same/does their skin color all look the same? Also, when you're in a supermarket or drug store. peruse the make up aisle and look at women's foundation, and take a moment to note all the colors of foundation that exist for "white" skin tones. You should see several (all dependent on make up brand). The purpose of this exercise is to realize that what we think is "white" skin tones is actually a multiple of colors, and the same goes for all other "races". Race is simply a cultural concept: http://humerusrevelations.blogspot.com/2013/07/coloring-outside-of-lines-rethinking.html
I really like the X-Men allusion you used in this blog post; it's definitely something that comes to mind quickly at the mention of mutation! While I believe it would be very interesting for mutations to happen as quickly and magnificently as they do in the Marvel Universe, that definitely could be more harmful than helpful in regards to science and society.
As far as mutations in OUR universe, this blog post was very helpful and informative in regards to how mutation factors into evolution. It's also interesting to think about how traits considered to be commonplace today may have found their way into the gene pool through mutation.
(A little off topic, but could you imagine being a mutant in the Marvel Universe and your mutation was something as simple or boring as having fingernails that grew 20% faster? Tough genetic luck, kid!)
I love the Family Guy reference in your comment, Jessica, and yes, I have actually thought about what it would be like to have an X-men like mutation but not that one. It goes with the territory of being a geek and the random questions we ask each other in regards to the geek things we experience. :)
I find it strange that mutations are generally viewed in a negative light, even though they are a natural and essential part of our progress as a species. without mutations we wouldn't have nearly as much variety in life. Due to mutations we have several variations of things such as Red Delicious apples!
-Hayden Lloyd
i wish we could control the mutations to cure diseases. how far into the future do you think that is for humanity?
I cannot say with any great certainty if and when that will occur. Several factors, from science to social perspectives, would have to line up for that to occur.
Mutation occurs in humans and we even tend to make a movie about it. Like from the talk we had, it was about X Men and that is all the movie is about is mutations and being different from everyone else. this creates new alleles in humans and can change the way we look.
briana banuelos
anthro 102 1001
I see mutation as the main component of evolution. Without genetic mutations over long periods of time, changes to human genetic makeup would never have occurred. As new genetic variations take place in populations, new traits are introduced. These new traits, most likely, aid in the continuation of the species. As these traits become dominant, the species evolves to become stronger and this may influence the process of natural selection, also.
Courteney Hedicke, Anth 101
wow! I can not believe how incredible all those questions are. I am just trying to get through this class and all these questions are way above me. Poor me! I enjoy the subject matter in this class, although it was a little difficult to wrap my brain around a lot of it. I still watch videos on the subject matter tho
interesting article! a little off topic but are allergies and other bodily rashes or skins defects mutations or passed on through genetics? Are warts and moles and freckles genetic or does this happen over time as a mutation in the DNA?
Zachary Forrester
anthro 101 3001 summer
Allergies at one point were mutations but are now part of the genetic material that is passed on through our DNA. Skin rashes are dependent on type. For example, rosacea is genetic but poison ivy reactions are just that-temporary reactions to environmental stimuli. And warts are the same. Freckles can be either as we can and do develop freckles from too much sun exposure but are also born with them )in some cases).
I call this basic animal husbandry. It is ok to tinker with this to produce a better beef cow but most of the world considers it taboo to tinker with humans.
Here is a question for you. Will genetic mutations, as a whole, in the end harm or benefit mankind? I would think initially it would harm the population as it tries to cope with this new onslaught. With continued appearances of the mutation it becomes the norm. Bipedalism in humans, a very important mutation if ever there was one, is considered what sets us apart from other primates. But the question remains, how painful was it for the very first person with this trait to walk?
This makes me wonder when we, as a country, first discovered the first genetic mutation as far as a negative connotation such as mental retardation or sickle cell anemia. For so long, even in today's vocabulary, mutations is a very negative word. But after reading this blog, it is just another synonym for different. We are all very much different in terms of body size, color of skin, foot size... and these are all considered genetic mutations. I think the population as a whole needs to realize this, before making more drastic measures and unfair judging on those who are different.
Well, Robert, based on what you learned in Anth 102 & 110L about mutations and their roles in evolution, what do you think?
I like Xmen, too. Back on topic, as too much exposure could kill someone, I'm guessing the majority of mutations are a result of problems with replicating DNA. That makes me wonder, as I know not every mutation is beneficial, if still births are at all caused by a mutation (caused by bad replicating) that causes the infants body to shut down.
I have to agree that not all mutations are bad!
Jovie Black
I always thought that Mutation was the process, like if you tear your whole finger nail off and it grown back. That was mutation, But i think I confused that with Mitosis?
My gene pool is a very interesting one. My family thinks I am a mutant myself, being the only one in my family with blue eyes, being a southpaw, and even not having olive skin like the others. Unfortunately I don't seem to be a cool one like Nightcrawler.
You're not a mutant. You're the product of the unlikely probability of a certain suite of genes, known as recessive traits, all coming together and producing you. You're like the one person who won the raffle. That does not mean you won something good or bad. It just means that statistically speaking you were less likely to occur. Not impossible but less likely. You should take a physical anthropology or biology class to understand genetics better. :)
This article was very interesting. Even knowing the concept and the importance of mutations, if they did occur then the genetic makeup in humans wouldn't change or occur.
While I do not believe it is possible for humans to become mutants like the X-men, I do believe that mutations can appear in anyone. For example, my mother's colon is twice the normal length. The purpose of this is unclear, however it might be linked to evolution by possibly being a health benefit.
I have always thought mutations were related to something sinister, so it was enlightening learning mutations are not always bad! Since mutations are simply changes in the genetic material, there are mutations happening all the time. I am definitely going to have to watch the X-Men movies now.
Makayla Peterman
It's refreshing to learn that all mutations are not bad. I always thought mutations just happens in a lab, but they happen every day. - Lavonza Marshall
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