Home » Posts tagged 'evolution'
Tag Archives: evolution
With all that has been going on in the world and all the important societal problems, I have been despairing that my desire to push for a natural history museum and more evolution education seemed not as important. But it struck me today that it is perhaps one of the most important things we need to do. There are a lot of misunderstandings about evolution, even among people who accept it, that hinder our ability to get along in the world. Understanding two important truths of evolution will go a long way towards healing our societal divides. What are those truths? 1. We are all the same, and that is a good thing. 2. We are all different, and that is also a good thing. These may seem contradictory, but if you understand how they are meant, they make perfect sense.
- We are all the same, and that is a good thing.
When you start really studying life on this planet, it quickly becomes inescapable that we are all connected. We are all part of the same family. Strip off the skin from humans and we see essentially the same underneath. We all share the same skeletons, our muscles and organs are the same, there are no important differences in our brains. Sure, there are differences, but no matter what way we try to divide humans, especially by skin color or nationality, we find that the differences within the groups are greater than the differences between groups. What this means is that the dividing lines are arbitrary and have no biological basis.
When we go beyond humans and look at all vertebrates, we see the same thing. If we compare skeletons, we see the same bones over and over again. Every animal that has four limbs shares the same bone structure. They may look different, but the bones are all the same. All of our front limbs have a humerus, an ulna, and a radius. We all have the same number of fingers and toes. They may look different, they may lose some as they grow from fetus to adult, but they are all there. As we get farther and farther away from direct ancestry and relationships, the superficial differences start piling up, but the core is always the same.
Going even farther, we all share the same base code. We all use essentially the same DNA and RNA. The sequences may be different, but just as all computer programs are different, they all share the same underlying coding language. We all share metabolic pathways, from bacteria to humans.
Why do we see all these similarities? Because we all share an ancestor. Somewhere down the line, we are all related. We are one family. It may be a very extended family, but we are all together. All life on Earth is connected. Through that life, we are all connected to the very rock upon which we stand. Life has shaped the surface of the Earth. It has shaped the air we breath. We all sprang from the same roots. When you look at someone from a different culture, someone with a different skin color, you are not seeing an other, you are seeing a long separated family member. Embrace that connectedness. Now, I know that no one can get more under your skin and angry than a close family member, but at the end of the day, we don’t generally let that tear us apart. No matter how much we may disagree with our family, we still recognize they are family. Just take that feeling and extend it to recognize that every living thing on Earth is also part of your family.
2. We are all different, and that is a good thing.
So if we are all essentially the same, how can we all be different? No matter how closely we are related to someone, there are always differences. Even identical twins are not completely identical. Our DNA and life experiences mean that each and every one of us is different in some way from everyone else. While we all share the same basic body plan and organization, there are always some differences.
Those differences are important. Ask any agricultural scientist and they will tell you that one of, if not the biggest danger in our food supply is the monoculture crops we grow. When everything is the same, that means they also share all the same limitations and vulnerabilities. Monocultures only work when there is no change. But they do not handle change well. And if there is one thing we know about life, it is that change is inevitable. These days, we are pushing change faster than ever before, so this vulnerability to change is deadly.
Purity is the death of a species. We need diversity to weather changes. As new diseases crop up, as weather becomes more unpredictable and changeable, we will need the diversity to be able to handle whatever is thrown at us. The more diverse the population, the more changes we can tolerate. In a diverse population, there will always be some fraction of the population that is prepared for anything that happens. Those people will make sure that we continue. Moreover, they will help those of us unprepared for the changes make it through. When a new disease appears, those that are naturally immune will be key to developing medicines that will allow the rest of us to survive. Those that can handle climatic changes will be the ones to build the structures and infrastructure that will allow the rest of us to weather the storms. We need diversity. If we try to homogenize our culture and our people, we will die.
We need evolution education and a natural history museum.
So how do we get people to understand this? First of all, on a broad scale, we need to teach people a proper understanding of evolution and evolutionary theory. But we have to do it in a way that exemplifies its importance in our everyday lives. We need to get people to understand why they need to understand it. Evolutionary theory affects us every day. People need to understand how.
We need natural history museums for a multitude of reasons, but two very important ones apply here. First, they will stand as storage houses of information. They are a public recording of the changes that have taken place and are taking place. Secondly, they are a way to teach people who are not in school. Even if they don’t pay that much attention to the details in the museum, they will see a record of the changes. Museums can be designed to showcase the importance of evolution, the advantages of diversity, and the dangers of reducing that diversity. Museums are one of the most trusted sources of information. We need to leverage that to showcase both the interconnectedness of life on Earth and its diversity and why that has allowed its continued existence. It also can showcase what happens when that diversity is not there.
One may argue that history museums would be better at this. The advantage of history museums is that it makes it personal and easy to make it easy for people to relate to it. The disadvantage is that it makes it personal and easy for people to get defensive about it. Natural history museums can teach these lessons on a canvas that people can view and learn from more dispassionately, without it feeling like a personal assault upon their culture that can often happen in history museums.
To be sure, many people will feel that any mention of evolution is an assault upon their worldview, so I am not advocating the idea the natural history museums are inherently better. Instead, I am advocating the view that all types of museums work better when there is a diversity of museums that can tell the stories from different angles. Without a natural history museum, we lack an important viewpoint in the public arena. By building a museum network, we can spread the ideas much more effectively. A natural history museum will not hurt other local museums. It will help all of them. We don’t need just a natural history museum. We need a natural history museum, a local history museum, an international history and cultural museum, an art museum, and other museums. In Arkansas, we have some of the history, art, and culture, but we do not have a natural history museum. As such, we lack that long and broad view that can only come from an understanding of natural history.
On November 4th, I presented a workshop on evolution at the Arkansas Curriculum Conference. The workshop was sponsored by TIES, the Teacher Institute for Evolutionary Science, an organization dedicated to helping teachers teach evolution, itself sponsored by the Richard Dawkins Foundation for Reason and Science.
Unfortunately, the wifi died right at the beginning of my talk, so the videos embedded in the talk were not able to be played. So for those of you who attended, and for those of you who would like to see the talk, I am posting the powerpoint file here. I know, it is incredibly overdue, but in my defense, the world took a sharp turn into weirdness right afterwards and then we had Thanksgiving. Any of you who are teaches or students also know what a crazy time of year this is. At any rate, here is the powerpoint. I will see about trying to record some audio for it at some point, along with the other talks I have meant to put up. We will see how that goes over the holidays.
If you go to the TIES website, you will see a version of this talk. I have modified it to include more information on fossil formation, which I skimmed over, for the most part, in the workshop itself. I focused more on the slides discussing why learning evolution is important in the first place. It has far more everyday impacts than most people imagine and is well worth understanding even if one believes in creationism or doesn’t care about esoteric biological concepts at all (for instance, if you are a cutting edge software or robotics designer).
In addition, there are a couple of other things I wanted to post. First is an icebreaker activity that TIES provided. In this activity, participants determine whether or not a series of statements about evolution are true or false. In a twist that catches most people off guard, they are ALL false. They are all commonly held beliefs about evolution, but they are all wrong, which makes a good way to start a conversation about the topic.
Here are the statements and a very brief explanation of why they are wrong, as supplied in the document. Further clarifications and discussions are happily supplied upon request.
1. Charles Darwin developed the theory of evolution.
The theory of evolution existed before Darwin; it was Darwin’s Theory of Evolution by Natural Selection that became widely accepted.
2. Living things adapt to their environment.
As a whole, living things are adapted to their environment. Individuals are unchanging, they either live or die based on the traits they are born with.
3. Biologists “believe” in evolution.
Science is not based on belief. The theory of evolution provides a model for scientists to understand the relationships between organisms on the planet.
4. Monkeys will eventually become human.
There are many species of primates and all are adapted to their environment. A chimpanzee would not turn into a human over time anymore than a cheetah would turn into a lion (or vice versa).
5. Evolution is JUST a theory.
Saying that it is “just” a theory implies that it is a guess, or that its not well supported. There is much evidence to support the theory of evolution, as well as direct observation of species change.
6. Only atheists accept the Theory of Evolution.
Scientists of many religions across the world accept evolution, and do not find it incompatible with their faith.
7. If evolution is disproven, creationism must be true.
A problem with logic (disconfirming evidence). Even if you disproved evolution, you would have to develop and support another model of organism diversity. Disproving one, doesn’t
prove the other.
8. No one has ever seen evolution happen.
In organisms that reproduce quickly (like bacteria) changes in species can be directly observed, such as resistances to antibiotics.
9. Order cannot come from disorder, so evolution is false.
Many instances in nature show molecules and substance organizing, such requires energy. The sun provides the energy that ultimately fuels all of life’s processes.
10. There is evidence that dinosaurs lived with humans.
There is no evidence that suggests humans and dinosaurs lived at the same time.
11. Scientists regularly debate that evolution occurs.
Scientists debate elements of evolution, relationships between organisms, and fossils. The only place the evolution debate really happens is in the social settings.
12. Creationism is a valid scientific theory and should be presented with evolution. Creationism violates the scientific principle of natural causality.
13. There are no transition fossils. Museums are filled with fossils that show intermediate species.
14. Carbon dating is not accurate, therefore the age of the earth cannot be determined.
Carbon dating is one of many methods used to date the earth. Taken as a whole, the evidence is overwhelming that the earth is very old.
There is also a dice game that I want to share with you demonstrating how natural selection works, but that will have to wait until next post.
The natural world can be a very strange place. WTF evolution?! is a great site that takes a humorous look at some of nature’s weird turns. Today I am going to celebrate some of nature’s curiosities by playing a game. Some animals are so weird they look like combinations of other animals. For instance, the platypus is often said to look like a cross between a duck and a beaver. I will provide a fictional cross between a set of animals. See if you can guess what real animal it might be. Then come back later to see what animal it is and description of what makes it such a curious animal.
For today’s cross, what might you get if you cross a kiwi (the bird, not the fruit) with an anteater and a hedgehog? I will give you a hint. It is an extant animal, so you can rule out any fossil animals.
Yesterday was Darwin’s birthday. So instead of trying to shoehorn some sort of Valentine’s Day themed post for the week or an article about Darwin and his life and the importance of evolutionary theory, I thought I would briefly discuss a few of the most common Darwinian myths I have heard. For most people, it seems, it is accurate to say You Don’t Know Darwin, or Evolution, or Darwinian Evolution.
1. I don’t believe in evolution.
Yes, you do. You just don’t know it because you’ve been lied to by people who don’t understand evolution either and are threatened by it. But before we get into that, let’s please dispense with the term “belief”. Belief requires faith with no evidence. Since there are mountain-loads of evidence for evolution, don’t believe in it. Accept the evidence all around you. Once you understand what evolution is, you will agree that you have to be brain damaged not to accept it is true. Here is the big secret. Here is the definition of evolution.
Change over time.
Let me hear you say it!
Change over time.
I can’t hear you!
Change Over Time!
That’s it. See? Not so painful. You’d have to be an idiot not to understand that things change. If nothing ever changed, we would have no history books and people could never complain about the “good old days” when students were better (yes, people have complained that today’s students are worse than the previous generation for literally over 3000 years, one can only assume that either the ancient Greeks were God-like brilliant or people are biased).
What’s that, you say? That’s not what evolution means? Well, yes, it really is. But you want to talk about biological evolution. Some people think that simply saying change over time is overly simplistic and doesn’t really describe biological evolution. Ok, then. Here is a better definition of biological evolution. Ready?
Descent with Modification
Seriously, that’s it. Children are different from their parents. Now, unless you are going to argue that you are exactly the same as your parents, that everyone is in fact a clone, you are an evolutionist. Congratulations.
Oh alright. You may have heard that individuals don’t evolve, only populations, or even species. What that means is that one does not evolve over the course of one’s own lifetime. For most organisms, that is true. Of course, if you are a plant, which has what is termed modular growth, that is not strictly true. Plants can reproduce through one of two methods. They can reproduce through seeds, or they can reproduce through vegetative growth. In vegetative growth, the plants can send out tendrils (many people might call such tendrils “roots”). Those tendrils can grow horizontally through the soil and then spring up to grow what appears to be a new plant. The new plant is often called a clone, thus some people refer to this as clonal growth. Cottonwoods and sumac are great examples of this, most of them you see are actually clones grown this way. I say clones, but that does not necessarily mean they are genetically identical. If a mutation occurs at some point in one of the cells in that root tip, it can get passed along through the continued growth of that root so that the clone is indeed slightly genetically different. Considering that some of these plants can grow vegetatively for thousands of years through thousands of “clones”, a fair bit of genetic diversity can occur from one end to the other. I mentioned earlier that this is called modular growth. It gets that name because mutations that occur at the root tips affect all growth after that point, but do not affect the part of the plant before that point. Different parts of the plant are effectively separated from each other genetically and, to a point, physiologically. This is why you can grow new plants from cuttings. If the plant didn’t have modular growth, you couldn’t do this. Just imagine cutting an arm off of a person and trying to grow a new body from the arm. Animals, like us, do not generally have modular growth (unless you are a starfish, or planaria, or…).
Many people prefer a definition of biological evolution that takes populations into account. Thus, you will find this definition in many places.
A change in gene frequency in a population over time.
In this definition, evolution is restricted to changes that affect the DNA throughout a population. Ok, fine. But what does that really mean to a nongeneticist? It means that populations change over time in a way that those changes can be passed on to offspring. This is different than, say, changes in height and weight through strictly dietary changes. Just because Americans eat more and are thus typically taller and fatter than people in most other countries does not mean we have evolved to be taller and fatter, it just means we eat too much. It shouldn’t take a genius to realize this is true. A great example of evolutionary change in humans is our wisdom teeth, otherwise known as our third molars. Does it make any sense to anyone that we were created with jaws too small to fit all of our teeth so that we wind up having to pull some out? No, that’s ridiculous. The reason that our jaws are shrinking is that we have switched from eating tough, raw foods to softer, cooked, and processed foods that are easier to digest and we no longer have to chew as much. Some people are now being born who never have wisdom teeth. Eventually no one will have wisdom teeth and orthodontists will be very sad as a good chunk of their income will be lost to evolution.
But what really defines a population? It should be clear by now that biology does not lend itself to neat little boxes. Biology is messy (if it stinks, it is probably chemistry, but that’s another discussion). Typically, a population is defined as a set of individuals capable of interbreeding. This is very much like the biological species concept (BSC). The difference is that a species can be divided into multiple populations because not every member of a species has access to every other member. If something gets in the way, you get separate populations of the same species. And here we have a problem. What is a species? Most people have heard about the BSC. Unfortunately, it doesn’t work for a lot of organisms. It doesn’t work for plants, who hybridize at the drop of a hat and can grow vegetatively anyway. It doesn’t work for bacteria, or parthenogenic species who only need females to reproduce, or animals that can be cut up like sponges and starfish and planaria, etc. The last time I counted, there were 26 different definitions of a species. The idea that a species is the only “natural” unit in taxonomy is a myth. Even species are not natural. Researchers use the definition that is most applicable to their research. For instance, paleontologists can’t possibly use the BSC. It is really hard to get fossils to breed. Some might even say impossible. As a result, paleontologists are stuck with what is called the morphospeces concept. If it looks sufficiently different, it’s a new species. This means of course that you can’t realistically compare modern and fossil species because they don’t mean the same thing.
This is a really long-winded way of saying that it is much better to talk about evolutionarily discrete lineages, rather than populations or species and why I prefer sticking with the “descent with modification” definition of biological evolution. If that seems harder to deal with, biology is messy. Get used to it. But just because it is messy doesn’t mean it’s wrong. Life is usually messy. Just ask any parent. If you want absolutes and certainty, go talk to a physicist. Biologists have to deal with the real world in all its chaotic mess. I envy physicists, I really do. They have it easy. Yes, physics is easy. Biology is hard.
Ok, that was a lot. But if you still say you don’t believe in evolution, you are deluding yourself. The other myths can be dealt with much more succinctly.
2. You have to be atheist to believe in evolution. Darwin was an atheist until he converted on his deathbed.
I hear that a lot, but seriously? Are you seriously going to sit there and tell me these guys are atheists? Ok, maybe the last one, but this is an issue of pitting one faith against another, so please pardon the joke.
If you can’t trust that the Popes are devoutly religious, you have serious issues. But say you are one of those people that say the Popes may be religious, but they are going to Hell because they aren’t your sect of religion. Ok. Dr. Francis Collins is the head of the National Institute of Health. He led the Human Genome Project. He also happens to be an outspoken Evangelical Christian and has written extensively on why evolution does not conflict with Christianity. But Dr. Collins is a scientist, what does he know? What about Pat Robertson, leader of the 700 Club? Surely we can all agree that if Pat Robertson, of all people, does not think that evolution conflicts with Christianity, we can agree that you do not need to be an atheist to accept evolution.
Ok, you say that Pat Robertson is crazy. I won’t argue with you. But what about Billy Graham? If there is anyone more respected in the Evangelical Christian community, I don’t know them. Billy Graham has no problem with evolution. He is clearly not an atheist.
What about Darwin being an atheist? No, he wasn’t. He actually thought about going into the seminary to become a minister, but decided against it to pursue his academic interests. He didn’t seriously begin questioning his faith until his ten-year-old daughter died. After that, he lost faith in any sort of benevolent deity and he never recanted. The story that he converted to Christianity and denounced his views on evolution on his death bed is complete fiction. It was made up by someone who wasn’t even there. Why Lady Hope made up this story, I can’t say, but it is definitely a fraud. The important point here is that at no time did Darwin ever think that evolution conflicted with the Bible.
3. Evolution says that we evolved from monkeys, which can’t be true because A) I’m not a monkey, eww; and B) monkeys still exist.
Tell me, do most mothers die in childbirth? Then why would anyone think that a species has to go extinct when a new species arises? The reason that people think this is because they still have this view of the Great Chain of Being,” which was an old Christian view that everything had its place in the universal order. Rocks were at the bottom, then plants, then lowly animals, on up to humans being the most important mortal thing in all of Creation, topped only by the Heavenly Hosts, Jesus, and God Himself (that bit always confused me, if God is male, then there should be a female God, so where is She? Nevermind, I digress, that’s a whole other discussion.) Anyway, with this view in their head, people naturally assume that evolution works the same way. One species should naturally transform somehow into a new species.
Except it doesn’t work that way. Not all individuals of a species have to evolve together. If that species is divided into separate populations, or evolutionary discrete lineages, each population could evolve into a separate species. The original, or parent species, never has to change at all. Take the peripheral isolates concept. In this case, there is a species that has a broad range. At the edges of the range, members of the species find themselves in a different environment from the members of the species in the center of the range. The population exposed to the new environment will evolve in response to that environment, but the population in the center of the population never has to change. Thus, you have two or more species evolving from an original species that is still present.
But what about humans evolving from monkeys? No, that isn’t technically true either. Again, using the family analogy, let’s say your parents had siblings. Your aunts and uncles had kids of their own. You are related to your cousins through your parents. Pretty straightforward, right? Now replace everyone with species. You and all your cousins would be individual evolutionarily discrete lineages, you all have your own evolutionary path. Now, say that you represent all humans and your cousins represent all the species of monkeys. You aren’t a monkey, neither are your parents. your cousins, on the other hand, are (sorry, cuz). You (meaning all humans) share a common ancestor (your parents, or the ancestral species of humans) with your cousins (all the monkeys).
4. Evolution says that the earth is really, really old.
No, evolution has nothing to do with how old the earth is. The geologic time scale was actually put together by people correlating different rock units based on their relative position. Using the Law of Superposition, the oldest rocks were at the bottom, with the youngest rocks on top. Examining the rocks from place to place, they were able to line up different rock units into a long column. But it was all relative. They had no idea how old the rocks were. Finding the age of the earth didn’t happen until physicists discovered radioactivity. Some very smart physicists figured out that they could use the rate of radioactive decay to date rocks. All paleontologists and evolutionists did was say Thank You! So if you don’t like the age of the earth being over 4.5 billion years old, go talk to the physicists, it has nothing to do with evolution. Of course, when you do talk to them, you will have to deal with the fact that they have tested the theories quite well. We know they work because if they didn’t, we would not have nuclear bombs, nuclear power plants, x-ray machines, and a whole host of other things that work because of our understanding of radioactivity.
5. How does evolution explain the origin of life?
Easy, it doesn’t. Evolution only works on life that already exists. If you want to complain about the origins of life, go talk to a chemist. The origins of life is a chemical and physics problem, it has nothing to do with evolution.
5.Darwin invented evolution.
The last one for today might surprise people the most. Darwin did not invent, discover, or in any way introduce evolution. People knew that organisms change long before that. Joseph Buffon discussed the mutability (change) of species and that they had common ancestors in the 1700s. What Darwin did was provide a plausible mechanism for how evolution worked. Darwin provided evidence for natural selection. Of course, Darwinian evolution via natural selection is not the only mechanism. There is gene flow, which involves new material being introduced by immigrants into a population, and genetic drift, which is simple, boring, old random chance. But that is a topic for another day.
“I have a dream…”
Almost everyone will have heard this most famous line by Martin Luther King, Jr. in the past few days. In honor of the holiday, rather than introduce another fossil, review a book, or some such thing, I thought I would do something a little different. I have a dream too, one in which teachers are not afraid to talk about evolution within the classroom, one in which people don’t recoil from the word because they think it goes against their religion, a dream in which everyone embraces the concepts, not because some scientist or teacher tells them they have to, not because they think it is part of a body of education they need to sound smart, but because they see the logic of evolutionary theory and the application of it in their everyday lives, because they understand how it affects them every day in ways they normally never even think about. In this essay, I am going to discuss a few of the many ways evolutionary theory helps us in practical applications. Next post I will discuss why I think most people deny evolution (it’s not what most people say, what people say and really think are often entirely different things), and why that denial is something we need to get past.
Cancer is an inescapable fact of life. All of us with either die from it or know someone who will. Cancer is so prevalent because it isn’t a disease in the way a flu or a cold is. No outside force or germ is needed to cause cancer (although it can). It arises from the very way we are put together. Most of the genes that are needed for multicellular life have been found to be associated with cancer. Cancer is a result of our natural genetic machinery that has been built up over billions of years breaking down over time.
Cancer is not only a result of evolutionary processes, cancer itself follows evolutionary theory as it grows. The immune system places a selective pressure on cancer cells, keeping it in check until the cancer evolves a way to avoid it and surpass it in a process known as immunoediting. Cancers face selective pressures in the microenvironments in which they grow. Due to the fast growth of cancer cells, they suck up oxygen in the tissues, causing wildly fluctuating oxygen levels as the body tries to get oxygen to the tissues. This sort of situation is bad for normal tissues and so it is for cancer, at least until they evolve and adapt. At some point, some cancer cells will develop the ability to use what is called aerobic glycolysis to make the ATP we use for energy. Ordinarily, our cells only use glycolysis when they run out of oxygen because aerobic respiration (aka oxidative phosphorylation) is far more efficient. Cancer cells, on the other hand, learn to use glycolysis all the time, even in the presence of abundant oxygen. They may not grow as quickly when there is plenty of oxygen, but they are far better than normal cells at hypoxic, or low oxygen, conditions, which they create by virtue of their metabolism. Moreover, they are better at taking up nutrients because many of the metabolic pathways for aerobic respiration also influence nutrient uptake, so shifting those pathways to nutrient uptake rather than metabolism ensures cancer cells get first pick of any nutrients in the area. The Warburg Effect, as this is called, works by selective pressures hindering those cells that can’t do so and favoring those that can. Because cancer cells have loose genetic controls and they are constantly dividing, the cancer population can evolve, whereas the normal cells cannot.
Evolutionary theory can also be used to track cancer as it metastasizes. If a person has several tumors, it is possible to take biopsies of each one and use standard cladistic programs that are normally used to determine evolutionary relationships between organisms to find which tumor is the original tumor. If the original tumor is not one of those biopsied, it will tell you where the cancer originated within the body. You can thus track the progression of cancer throughout a person’s body. Expanding on this, one can even track the effect of cancer through its effects on how organisms interact within ecosystems, creating its own evolutionary stamp on the environment as its effects radiate throughout the ecosystem.
I’ve talked about cancer at decent length (although I could easily go one for many more pages) because it is less well publicly known than some of the other ways that evolutionary theory helps us out in medicine. The increasing resistance of bacteria and viruses to antibiotics is well known. Antibiotic resistance follows standard evolutionary processes, with the result that antibiotic resistant bacteria are expected to kill 10 million people a year by 2050. People have to get a new flu shot every year because the flu viruses are legion and they evolve rapidly to bypass old vaccinations. If we are to accurately predict how the viruses may adapt and properly prepare vaccines for the coming year, evolutionary theory must be taken into account. Without it, the vaccines are much less likely to be effective. Evolutionary studies have pointed out important changes in the Ebola virus and how those changes are affecting its lethality, which will need to be taken into account for effective treatments. Tracking the origins of viruses, like the avian flu or swine flu, gives us information that will be useful in combating them or even stopping them at their source before they become a problem.
Another place that evolutionary theory comes into play is genetically modified organisms. I won’t get into the arguments about whether or not they are safe to eat, other than to say that there is very little evidence to indicate GMO food is any more dangerous than normal food (i.e., yes, there are certain dangers, but nothing that you won’t find in regular, non-GMO food). There are two things about GMOs that I do want to discuss here. First is the belief that GMOs are somehow altogether different from natural organisms. In truth, DNA is swapped between unrelated organisms all the time. Horizontal gene transfer, such as this DNA swapping is known, has been well known in bacteria for over a hundred years. In the past few decades, it has also been found throughout the plant kingdom and even (what people like to call) higher order animals. It has been estimated that as much as 8% of human DNA comes originally from viruses that made their way into our cells, some of which allowed the evolution of the placenta. We even have bacterial DNA in us.
GMOs also may have an effect on natural ecosystems. They can and do occasionally escape into the wild. Genes from the GMO oilseed rape plant that provide herbicide resistance has spread into wild mustard plants. These plants have spread quite far. Herbicide resistant weeds are springing up all over the world, to the detriment of our farmers and food supply. What was once only a concern for agriculturists is now a concern for anyone concerned about conservation of natural ecosystems. How much of an effect? Unless you understand how evolutionary changes can spread through an ecosystem and what ramifications that may have, you are simply guessing, which is of no use to anyone. People often think of this as a genetics problem or an ecology problem, but this is the effects of evolution at the ecosystem level.
The problems we see in GMOs are not really related to the fact that they are GMO, as evidenced by the natural horizontal gene transfer we see. We see similar problems with no GMOs involved. Pests becoming resistant to pesticides after generations (of the pest) of exposure is a common issue farmers need to address. Weeds will become resistant to herbicides on their own, with no help from GMOs needed. Evolutionary theory will help deal with this problem, guiding us to solutions we may never have reached otherwise.
Another highly controversial topic these days is climate change. Whether we caused it or not is really beside the point and is not a topic we will discuss here. It is undeniable by a quick glance at the evidence that the earth is getting warmer. We will have to deal with it, and so will every other living thing on the planet. Organisms respond to climate change in one of three ways: adapt, move, or die. There are numerous accounts of animals and plants shifting ranges in response to climate change. This is most easily seen in highly mobile organisms. Plants are not generally considered mobile, but pollen and many seeds have huge dispersal potential, so some plants can spread surprisingly quickly. The difference in dispersal ability is a big factor in how the plant communities adapt to climate change. This is not biological evolution in the strict sense of the word. However, over time, these shifts will cause evolutionary change as the population spatial patterns are disrupted.
Unfortunately for many animals and plants, humans have so sliced up the land that mobility is limited (for others, it is greatly expanded, but that is chiefly for things we don’t want to expand, like fire ants or zebra mussels and numerous other invasive species). For these organisms, they have the options of adapt or die. Obviously, this isn’t a conscious choice they make, but conscious or not, these are the options available to them. For these, if we want to know how they will respond to climate change, we need to know their evolutionary potential, what is their ability to adapt and how fast can they adapt. This will depend (assuming similar selective pressures based on climate change) in large part on the genetic variation within the species, their generation rate (the shorter the time between birth and reproduction, the faster evolution can function), and population size. As a result, their conservation depends on our understanding of their evolutionary potential.
A critical component here is time. It can be hard to tell whether or not evolution is occurring or more simple phenotypic plasticity (the ability of an organism to respond to changes via changes in gene expression rather than actual genetic change) without substantial genetic study. If an organism has a high phenotypic plasticity, they will be able to adapt quickly. However, if it requires real evolution in the strict sense, that takes time, meaning they will be less likely to adapt in time to prevent extinction. Again, this is a question that can only be answered by proper application of evolutionary principles.
These are just a few examples of how scientists are using evolutionary theory to save lives by improving medical treatments and protect our food supply and environment. I did not provide much in the way of specific examples of these processes, as that would expand this essay far beyond comfortable reading times. However, the links throughout the essay will lead to you several specific examples. Some people may argue that these examples are all microevolution and adaptation, not true macroevolution. In truth, there is no significant difference between the two. Microevolution and adaptation are simply subsets of a larger concept, processes that cause macroevolution over longer time frames.
More importantly, the argument doesn’t matter anyway. It is not important that doctors and farmers know the evolutionary history of earth. The application of evolutionary theory is the same whether one is looking at the present or eons in the past. One can incorporate evolutionary thinking and utilize the theory without ever having to deal with things that are millions of years old, but only if one understands the theory in the first place. Evolutionary theory touches on so many aspects of our lives that if we want to be able to make good decisions on many of the most pressing issues of our time, we need to have some basic understanding of how evolution works. If we do not teach evolutionary theory to our kids, we are crippling our future doctors, farmers, conservationists, fish and game managers, coastal development planners, lawmakers,…
I was talking with someone at an educator’s conference of all places that asked me how, if evolution was true, could monkeys still exist. Surely evolution meant that if we evolved from monkeys, that monkeys should no longer be around, right? This is a common misconception. I might even say it is the most common misconception I run across. It is so common, in fact, that paleontologists really get tired of hearing it because it means the person does not understand how evolution works at all. Matt Bonnan, a well respected paleontologist that mostly works on the giant, long-necked dinosaurs called sauropods, in a period of frustration, penned this cartoon. In it, he explains the first thing I ask people: Did your parents die when you were born? Did your parents become you? No, of course not, that’s silly. So why would you think that an entire species has to go extinct when a new one evolves?
Evolution generally works the same way. Just as your parents and their siblings continued to exist after you were born (barring tragic occurrences of course), species seldom evolve all at the same time in the same way. There are almost always some populations of a species that do not noticeably evolve, at least, not in the same way. As a result, one can usually find populations of the parent species long after new species evolve. We see the same thing in TV shows. Just because CSI spun off CSI:New York and CSI: Miami, that did not mean the original show was cancelled. All three happily continued to air alongside each other.
This is pretty obvious when you think about it in other contexts. So why do people think evolution works differently? It all has to do with an old belief called the Great Chain of Being. While it had its origins as early as Aristotle’s Scala Naturae, it reached its heyday in the medieval Catholic Church. This chain organized all of existence into a hierarchical system with rocks and minerals at the bottom and God at the top. Some of them got very detailed, even putting different minerals in order. Of course, all of them had humans as the pinnacle of earthly creation, with the nobility and kings above all as the highest order of Man. This type of classification still holds sway to this very day for many people for a very powerful reason.
For people with a hierarchical worldview, this is very appealing. Everything has its place and the Great Chain of Being strictly lays out who has authority over who. It is neat, tidy, and ordered. It also feeds into normal human desire to feel special. It enshrines human exceptionalism into the very soul of the worldview.
And this is where people run into a brick wall with evolution. Evolution tears apart this neat, ordered hierarchy. Life becomes messy, without clear boundaries and order. Most importantly, evolution, as they see it, makes no distinction between humans and the rest of the system of life. It puts humans as just another branch on the great family tree, with nothing inherently special putting humans on top and that simply will not do. I do not mean for this to be taken as derogatory of any particular religious belief or religion in general. The need for order and security and to feel important and with a purpose are understandable human desires with a rational basis at their core that we all feel to some extent. Unfortunately, when applied to natural history, all available evidence indicates it is wrong.
So if evolution does not work this way, how then does it work? How should evolutionary lineages be considered and how do species evolve? Let’s tackle the latter question first and then see how it looks on a grander scale.
There are many ways organisms can create new species, or speciate. But there are two main patterns. One is similar to the incorrect view of evolution shown above, in which a species gradually evolves into another species as a unit due to changing environmental conditions, such that the original species and the new species are only in existence together for a brief transitional period. This is called “anagenesis”. This sort of speciation has been proposed most commonly in groups like ammonoids (Mesozoic shelled squid-like creatures) and foraminifera (a large part of plankton in the oceans). On a side note, this sort of speciation plays havoc with interpreting the fossil record because it creates what is known as “pseudoextinctions”, in which the original species appears to have gone extinct when in reality it just changed.
The other pattern, and the one that is considered far more common, is called “cladogenesis.” In this case, different populations of the same species evolve into two or more species. Much of the time, populations of the original species stick around and can do so indefinitely, so long as the environment allows.
There are several ways cladogenesis can happen. Most commonly, populations get separated by some sort of barrier, like a river or mountain, possibly a volcano. It can be anything, so long as it prevents breeding and thus gene flow between the populations. This can even happen if populations diverge from each other by specializing in different parts of the same area. Probably the most famous examples of this are the cichlid fish in Africa. They have formed numerous species by specializing in different microhabitats within the same geographic area.
Another way cladogenesis can occur is by what is known as “peripheral isolates”. In this situation, you have a generalist species that has a wide range due to its ability to fit into multiple niches. However, subpopulations can evolve to specialize into the different niches to the point they no longer breed with the main ancestral species. This form of cladogenesis is very similar to the ones listed above. In a way, it can be considered a combination of them, with subpopulations adapting in different geographic areas.
The important point in all this cladogenesis talk is that at no time is it ever required that the original species go extinct. They can and often do at some point, but cladogenesis does not involve a species changing into another, it involves a species splitting up into multiple species. Much like parents are free to live their own lives once the children leave the nest (and even while the kids are still at home), once a species splits, each new species follows its own evolutionary path that is separate from the original species. In short, there is no linear chain of species going from one to the next.
So what does this look like over geologic time? It looks something like a branching tree (or, if it happens over a short time, like a bush). The ancestral species forms the trunk at the bottom and each branch represents another split, until finally, you reach modern day, represented by the leaves.
It is often argued that this does not get rid of the line of species from distant ancestor to descendant. If you look at the family tree of horses, for example, you can still draw a line straight from Hyracotherium all the way to the modern Equus. It is true, you can. However, it is not a straight line. It proceeds in fits and starts, with many branches, most of which die off. It follows environmental changes and interactions with other organisms. Here is the big kicker though. All the species sharing a common ancestor that survive at any given point of time have all evolved equally. It may not be apparent, some species may show far more changes than others, but all of them have experienced the same evolutionary time. There is no hierarchy of dominance in evolutionary terms. Every bacteria has experienced the same amount of evolutionary time as the lineage that led to humans. One can draw a straight line from a root of a tree to any leaf, but one would be hard-pressed to claim that single leaf is more important than any other leaf. So if you are looking for a reason to support human superiority, evolution will not help you. As a result, evolution can be a serious blow to the human id.
To those people who have problems with evolution on this basis, I ask you to consider that simply because bacteria have experienced the same time for evolution, that does not diminish human accomplishments. We have built communities that span the globe, we have explored the edges of the solar system and beyond. We have accumulated vast stores of knowledge that we have preserved for our descendants. We have glimpsed the inner workings of life itself. We have witnessed the awe-inspiring glories of the universe. If you need something to take pride in humanity, do not look to our evolutionary heritage, look to what we have achieved that is unmatched (as far as we know) by any other organism. As we so often tell our children, it is not where we came from that determines our worth, it is who we make ourselves to be.
The Tangled Bank: An Introduction to Evolution
Publication date (2nd ed.): 2013 according to publisher (my copy says 2014), 452 pg.
Roberts and Company Publishers. ISBN: 978-1-936221-44-8.
Author: Carl Zimmer is one of the best science writers in the business. You can keep up with him on his blog, which is part of the National Geographic “science salon” called Phenomena, a collection blogs by Carl Zimmer, Brian Switek, Ed Yong, Virginia Hughes, and Nadia Drake, all of whom are experienced science writers with a talent for accuracy and clarity. They cover everything from dinosaurs to DNA to dark matter and are the first place I go to in the morning for interesting science news. If it sounds like I am selling them, I am in order to convince you that a book by Carl Zimmer is both more accurate than the current textbook you are using and better written. Zimmer and the others are not just authorial guns for hire, they care about science communication and they do it well. My first introduction to Carl Zimmer was a book called “Parasite Rex“. You probably are thinking that a book about parasites would not be the most interesting of books, but you would be wrong. Read it and it will open up a whole new (albiet disturbing) world for you.
The name of the book is derived from the opening line of the last paragraph in The Origin of Species, by Charles Darwin, a fitting name for a book introducing evolutionary topics. While I have a few complaints, none are major and I highly recommend the book. My chief complaints are that I always want more, but there is only so much one can put into a book, especially an introductory text.
The book is filled with high quality pictures and graphs that break up the text, but whereas many books have flashy graphics that serve little purpose other than to distract from the text, all the figures in the book clearly relate to the topic at hand without excessively cluttering up the book. They also provide data that get the reader to go beyond the “because I told you” format so many books use and actually look at some of the data supporting the scientific concepts (and serve as a great way to integrate math, geography, and art standards into the science). Each chapter also have a list of resources for further reading and an extensive bibliography, so anyone can check the data presented in the primary and peer-reviewed literature for themselves.
One thing that might make some teachers and students a little annoyed is that important terms are not in bold font, nor does it have problem sets. However, it explains all the terms as they come up, it does not require flipping to the end of the book for every new term, although there is also a glossary for those that need it. The book is designed to be read, not just skimmed through while one picks out the bold words, like so often happens. However, there is also a study guide for the book written by Dr. Alison Perkins, which includes all the learning objectives, questions, activities, and pedagogical suggestions that teachers are looking for.
The book begins with a detailed discussion of whale evolution as an example to introduce several general concepts of evolution and various ways in which evolution may be studied. It covers fossils, placing them into phylogenetic and geologic context, DNA studies, embryology, and ecology from their earliest beginnings to today. Zimmer doesn’t go into the disputes that arose about whale origins, instead just focusing on what has become the consensual understanding, which I find a bit disappointing, but perfectly understandable for the context of this book and especially this introductory chapter. Nevertheless, I like presenting disputes because it shows the dynamic nature of science as an exploration, not just a book of facts. He presents the exploration through a discussion of the fossils being discovered and how they were interpreted, he just cleans up the historical path and makes it neater than it really was.
Chapter 2 brings a history of evolutionary thought, starting in the 1600s and the development of evolutionary concepts before Darwin. Zimmer correctly explains that Darwin was not the first to conclude that organisms evolved, but he did provide a plausible mechanism for how it happened. He then continues with a discussion of the changes and additions to evolutionary theory in the decades since Darwin. He tackles the important misconceptions of evolution, including the common misunderstanding of what a scientific theory really means, which form the basis of most people’s arguments against evolution.
Chapter 3 presents geological data, including how radioactive decay is used to date rocks and biomarkers to detect traces of life within rocks. He tells us how fossils tell us about the past, followed by a brief overview of the major transitions in life from the dawn of life to today.
Chapter 4 is probably one of the most important chapters that is left out of many introductory biology texts. Zimmer tells us what phylogeny is and how to read a phylogenetic tree to understand evolutionary relationships. It is particularly disturbing so many books skip this step because it is vital to understanding much of what comes after. Misunderstandings here reverberate throughout one’s ability to understand evolutionary theory, yet reading phylogenetic trees is not as intuitive as most teachers think. He talks about homology and how that affects our understanding of evolution. After he introduces the concepts, he demonstrates the concepts through a series of phylogenetic trees, such as early mammals, dinosaurs, and hominids.
Chapter 5 talks about DNA and how variation is introduced. Zimmer does a great job of discussing the various types of mutations and showing the typical view of point mutations is but the smallest way of introducing variation. His discussion of the role of sexual selection in creating diversity is short, although his description of Mendel’s experiment with peas helps somewhat. He also gives short shrift to lateral (aka horizontal) gene transfer, in which genes are transferred not through descendants but sometimes through completely unrelated organisms by, for instance, viruses. Zimmer also completely ignores endosymbiosis, which helped create mitochondria and chloroplasts, and hybridization, which makes this chapter not as satisfying for me.
Chapter 6 covers the role of genetic drift and selection well, although he leaves out a discussion of gene flow from one population to another. I like that he talks about fitness in terms of more than one gene, showing that what may be good for one gene is not necessarily good for another in terms of fitness, so that evolution is limited by the interplay between genes that each have their own optimal conditions. This would have been a good place to address the misunderstanding of “survival of the fittest,” which is commonly viewed as a tautology (the fittest survive, but how do you determine who is fittest? The ones that survive) but he does not mention it. This is a very common misconception. First, the phrase was never used by Darwin and is incorrectly and second, it is being incorrectly interpreted. It is not the overall fitness of a particular organism that matters, but a measure of how many offspring successfully survive and reproduce. It doesn’t matter evolutionarily if you are the toughest guy on the block if you don’t breed and produce successful offspring.
Chapter 7 discusses molecular phylogenies, figuring out evolutionary relationships from their DNA or protein sequences. One complaint I have here is that he talks about how successful the molecular clock is, how you can tell time using the amount of mutations separating species. In all actuality, the molecular clock has some serious issues, as in, it doesn’t work very well. Fortunately, he does discuss some of the challenges of the molecular clock (genes don’t mutate at the same rate either between each other or within different parts of the same gene, or through time, it requires fossils to calibrate and then tries to claim better results than the fossil data, etc.). The problems with the molecular clock mean that its usefulness and accuracy are limited and requires statistical manipulation of the data to try to take into account the known issues. Unfortunately, the figures lead one to believe the molecular clock actually acts clock-like, reducing the impact of the text describing its problems and the examples in the text downplay the problems. A bonus to this chapter is that he brings back the topic of horizontal gene transfer and shows its importance in a box at the end of the chapter. I might have put this in the last chapter and discussed it more, but it could be that Zimmer thought it might confuse people by introducing too much complexity at once and wanted the readers to develop a bit more understanding before throwing another wrench in the works.
Chapter 8 gives a great discussion of adaptation, taking it from the gene to species evolution. I particularly like his discussions showing how gene duplications and rewiring without the need for further point mutations can make huge differences. This is a really important concept to understand, that variation is more than just the single point mutations most people think about. He ends the chapter with a discussion of the limits of evolution based on physical limits and baggage from previous evolutionary steps, although I would have liked to see a brief mention at least of the constraints imposed by having genes with different optimal conditions that all have to be balanced.
Remember when I said chapter 5 gave short shrift to variation through sexual reproduction? That is because chapter 9 is completely devoted to the topic. Here he goes into several aspects of sexual selection, including trade-offs that may limit evolution in any one particular direction. Trade-offs in this case refer to the fact that improving one thing takes away from another. The genes with different optimal conditions are an example of this. Improve and you hurt another until a balance is achieved.
Chapter 10 defines what a species is (which is nowhere near as easy as it sounds) and how species evolve into other species. Chapter 11 extends that to evolution on a grand scale, showing the development of global biodiversity through time. I would have preferred to see a discussion of the difficulties in determining fossil biodiversity, such as the relationship between the amount of outcrops of a particular time and the number of species known, but there is only so much one can put into a textbook. Inevitably, the chapter discusses the major extinctions of the world, although he only talks about two of them, the Permo-Triassic and the Cretaceous-Paleocene extinctions, probably because they are better known by far than the others. His discussion of the Permian extinction doesn’t mention that the reason the volcanoes at the time put out so much carbon dioxide was that they apparently burned through huge coal deposits, which pumped up the carbon dioxide way beyond what the volcanoes would have done alone, but he gets the gist of the cause of the extinction. He also discusses briefly the debate in why the extinction occurred at the end of the Cretaceous, which is good. The chapter ends with a discussion of the current mass extinction taking place and the causes for it.
Chapter 12 discusses coevolution, both mutualistic and antagonistic. Here Zimmer finally discusses endosymbiosis and the important role it played in evolutionary history. Chapter 13 is an interesting discussion about the evolution of behavior in both plants and animals.
Chapter 14 will of course be the most controversial chapter because it deals with human evolution. Zimmer does a good job with this chapter, although I would have preferred a clearer statement that hominids and apes both evolved from a common ancestor, but where our ancestors became adapted for savanna life, the apes evolved more towards forest life. He talks about the interbreeding that happened between neanderthals and Homo sapiens, as well as with the Denivans, according to the genetic research published recently, which will make a few people uncomfortable, but is the truth nevertheless. The chapter wraps up with a discussion of some evolutionary psychology, which is highly controversial, but the parts he discusses are well supported by experimental evidence.
The last chapter is arguably the most important one in the book. Here Zimmer discusses the role of evolution in medicine, with examples of disease progression, vaccines, antibiotics, and cancer. If, by the time people have worked their way through the book and are still asking themselves why it is important they understand evolution, this chapter is a sledgehammer wake-up call. One cannot finish the book without having a strong understanding of the importance of this concept of evolution and why biologists consider it the central tenet of all biology. As Dobzhansky said, “Nothing in biology makes sense except in the light of evolution.”
I have been working on lectures on early amniote evolution, along with the following reptilomorph and synapsid lectures for my vertebrate paleontology course. We will be getting into dinosaurs and the other Mesozoic animals very soon, hooray! However, in preparing these talks, it has brought to my attention just how prevalent two sites in particular are: Reptileevolution.com and Pteresaurheresies.wordpress.com.
When I did a search for “pterosaur”, Google actually responded by saying “Did you mean pterosaur heresies” and provided images that all but one are either from the site or sites complaining about the site.
This is quite unfortunate. Both sites present an abundance of beautiful artwork done by a stellar paleoartist. There is an abundance of information on the animals and their relationships. All in all, the websites look fantastic and are quite the draw for paleo-enthusiasts.
But it is all wrong.
None of the hypotheses presented on these pages is accepted by virtually any other paleontologist. The techniques used to gather the information is not considered valid and no one who has tried to reproduce the data using the methods have had any success.
I won’t get into details about why the websites are wrong. I am frankly not qualified enough to provide a step-by-step breakdown of the problems (not being an expert in either pterosaurs or basal tetrapods), nor do I really have the time. I will say that many years ago, I heard the author of these websites give a talk about his evidence for a vampiric pterosaur and even as a young undergraduate, it was clear to me that neither the technique nor the conclusions were valid. I found it very unfortunate because the idea of a vampiric pterosaur was incredibly cool and the technique, which involves detailed image study, is useful in many contexts. However, it is very easy to let personal biases enter into conclusion based on these methods, to allow oneself to extrapolate well beyond anything the data can actually support. Oftentimes, those biases are completely unknown to the observer simply due to the way our brains interpret sensory input and modifies them based on past experience. We really do not see everything we think we see, which is why the scientific method requires other scientists examining your conclusions and your methods and trying to poke holes in your ideas. So it is vital to recheck one’s conclusions with many detailed images from various angles and lighting methods and, most importantly, detailed examination of the fossil itself.
So instead, I will point you to articles written by people who are experts in the very animals that are discussed on those pages and what they have to say about them. The first is an article by Dr. Christopher Bennett, who is an expert on pterosaurs. In this article, he discusses the validity of the techniques and discusses specific claims of two pterosaurs in particular, Anurognathus and Pterodactylus. Anurognathus is a very odd-looking pterosaur and is quite aptly named “frog mouth.” Pterodactylus is probably the most famous pterosaur next to Pteranodon and is why so many people mistakenly refer to all pterosaurs as pterodactyls. Dr. Bennett does an excellent job critiquing the science in a professional and readable way.
The second article is a blog post by Darren Naish, a noted researcher and science author that has researched pterosaurs and many other animals who has a deep understanding of both the accepted science and the author of these websites and the work presented therein. Here is what he says: “ReptileEvolution.com does not represent a trustworthy source that people should consult or rely on.Students, amateur researchers and the lay public should be strongly advised to avoid or ignore it.” The emphasis is completely his. The post is quite long and discusses several aspects of the work, discussing the accepted science and the material on the websites that is not accurate, including the techniques used to arrive at the conclusions, both accepted techniques and those by the website author that are not.
The next site is an article by Pterosaur.net, a website devoted to research on pterosaurs by pterosaur researchers. It is a brief article that uses Naish’s article as a starting point and continues on with a discussion of why they think it important for people to know why these sites should be avoided. To quote: “The issue taken with ReptileEvolution.com is not that it exists, but that it’s internet presence has grown to the point that it is now a top-listed site for many palaeo-based searches. Tap virtually any Mesozoic reptile species into Google and either ReptileEvolution.com or the Pterosaur Heresies is likely to be in the first few hits. The situation is even worse for image searches, which are increasingly dominated by the many graphics that Peters’ uses on his sites.” This would not be a problem that the sites are so well known if they were correct, but their prevalence presents a highly flawed version of what scientists really think. People are taking these sites as truth, when in fact they are regarded by professionals as seriously wrong.
Finally, Brian Switek, a science writer who authors the blog Laelaps, which moved from Wired Science Blogs to National Geographic and the now-defunct blog Dinosaur Tracking for the Smithsonian, wrote a piece on the site, in which he urged more paleontologists and paleontology blogs to call out misleading websites like these. In that spirit, I hope I can help some avoid getting a mistaken impression of dinosaur science and help steer them to better, more reliable sources.
* If you are wondering why I say “the author” or “the artist” rather than using the person’s name, it is because I don’t want this to be about the person, but the information. I don’t personally know the author, nor have I ever had direct contact, so I have nothing to say about the person. The work, however, can be and should be open for criticism, just like any other researcher, including my own.
I’m sorry, but I forgot to post the Mystery Monday fossil on the blog. I posted the fossil on the Facebook page, but somehow failed to get it posted here, for which I apologize. Here is the fossil I posted, including the identifying portion cropped from the original picture. This image was taken from trilobites.info, a great website for all things trilobite.
It was correctly identified as a trilobite, although this one is the species Irvingella, not Bristolia as was guessed. Irvingella is very similar, but lacks the tail spine and the second set of spines is a little farther down the body. They are both listed as “fast-moving low-level epifaunal” feeders by the Paleobiology Database, which means they scurried quickly about over the ocean floor. But whereas Bristolia is thought to have been a deposit feeder, much like a crawfish, Irvingella was a carnivore, preying on worms, bugs, and such. They both lived in offshore marine environments, but whereas Bristolia has been found mostly in shallower waters, Irvingella has been found widespread from offshore throughout the continental shelf and even deeper water. This may have more to do with Bristolia having only been found in a few places in the southwestern United States while Irvingella has a much broader range throughout much of North America and Asia. They both lived in the Cambrian Period, although Bristolia seems to have lived a little earlier than Irvingella (there are some discrepancies in the published records making it difficult to compare exactly, this is partly due to revisions of the time scale and refinements in age estimates over the decades making detailed comparisons problematic).
Since our last Forum Friday recap, we have started a new year. We have reviewed the Walking with Dinosaurs movie. We identified an Exogyra ponderosa oyster, Archimedes bryozoan, Aetobatus eagle ray, and this Irvingella trilobite.
Over on the Facebook page so far this year, we have seen some amazing animals, including sharks that glow in the dark, a fish that walks on land, and a caterpillar who’s tobacco breath repulses spiders. We even learned why sharks don’t make bone, but polygamous mice have big penis bones and an organism that changes its genetic structure seasonally.
We saw two articles on fighting dinosaurs. We learned how they took over the planet and discussed scaly dinosaurs for a change. We found out some ancient marine reptiles were black and Tiktaalik had legs.
A lot of articles hit the press on human evolution in 2013. We also found out (some) humans developed the ability to tolerate lactose to not starve and how we smell sickness in others. We also found a great book on Evolution & Medicine. We also saw evidence of how our actions affect the evolution of other animals and someone who thinks they can understand dog language.
We read that plants may have caused the Devonian extinction event, a genetic study saying placental mammals originated before the end-Cretaceous extinction event despite no fossils ever having been found, and that small mammals with flexible schedules handle climate change better than big mammals that keep a stricter schedule.
We found a great , concise explanation of evolution and three different short videos on the history of life on earth, two of them animated and set to music. We also heard Neal DeGrasse Tyson urge more scientists to do more science outreach (and how to cook a pizza in 3 seconds). Unfortunately, we also heard about the deplorable conditions during filming on Animal Planet and creationism in Texas public schools, as well as how the failure to take evolution into account can screw up conservation efforts.
So what did you like? Did you guess the fossil? Is there anything you want to see? Let us know.
It’s the beginning of December and more than a month since we’ve had a Forum Friday, but since most people were either still enjoying their Thanksgiving dinners or fighting through crowds of shoppers, I opted for a Monday meeting. October was a busy month and November followed suit. Most of what we posted on Paleoaerie since the last Forum was a rundown of the Society of Vertebrate Paleontology annual meeting in Los Angeles. A huge amount of material was presented at the meeting, of which we barely scratched the surface. We also reviewed The Big Golden Book of Dinosaurs, a great book for elementary kids.
We covered a lot on the Facebook page. Evolution in medicine got a lot of attention, including a whole online, open-access journal about it. We learned about evolutionary theory being used in the fight against the flu, malaria, HIV, and cancer, twice, no three times! We even learned why we have allergies, and if that isn’t enough for you, we found a whole series of papers on evolutionary theory in medicine for you.
Studies of human evolution had a good showing this month, starting with a new skull of Homo erectus changing our views of our ancestors and a book called “Shaping Humanity: how science, art, and imagination help us understand our origins.” We learned how women compete with other women and how natural selection can be tracked through human populations.
Modern experimentation has demonstrated how life may have gotten started chemically and how clay hydrogels may have helped. We watched the evolution of bacteria in a lab over 25 years. We also learned how evolution can evolve evolvability.
Evolution outdid itself with deep sea animals eating land plants and an amazing mimicry display. We learned why bigger isn’t necessarily better, why monkeys have colorful faces, and that large canines can be sexy.
In addition to all the news from SVP, we learned about two new giant theropods, the tyrannosaur Lythronax and the allosauroid Siats. We also learned about the toothed bird, Pelagornis and pachycephalosaurs. We also learned about research on what modern animals tell us about dinosaur brains. We also saw evidence that the Mesozoic may not have had as much oxygen as we thought.
Dinosaurs weren’t the only fossils of interest to be announced. A new unicellular organism is providing insights into the evolution of multicellularity. The oldest fossil of a big cat and a suction-feeding turtle were found, as well as the oldest known fossil ever, providing evidence of life almost 3.5 billion years ago. We read the beginning of a series on the evolution of whales and how the first tetrapods crawled onto the land. We learned about fossil giant mushrooms and watched the Red Queen drive mammals to extinction.
Putting 3D images of fossils on paleoaerie has always been one of the goals of the site and the potential for this to revolutionize geology has not gone unnoticed. The Smithsonian has taken up the challenge. If you want to learn how to do it, here is the paper for you.
We celebrated Alfred Russell Wallace and American Education Week. Along the way, we listened to the great David Attenborough describe the history of life and Zach Kopplin tell us about his efforts to keep creationism out of public schools in Louisiana.
For educational techniques and resources, we looked at BrainU and a website by the ADE and AETN. We examined the usefulness and pitfalls of gamification. We saw how to build your own sensors and use them in class. We discussed how to change people’s idea of change through business concepts the truth about climate change. We even saw doctoral dissertations via interpretive dance.
Do you have any gift ideas to share? Any of the stories particularly pique your interest? Let us know. Don’t just talk amongst yourselves, talk to us.