Archaeology – An Overview

For my final four-field overview post, I want to talk a little bit about archaeology.  You can find some more specific information about bioarchaeology in my previous posts, but there’s far more to archaeology than just the bones!

First and foremost, let’s clarify, archaeology is not the study of dinosaur fossils.  That would be paleontology, which is a subfield of geology.  Archaeology is, broadly speaking, the study of ancient communities through what they left behind–i.e. their artifacts, architecture, their bones etc. It may seem like an obvious distinction, but it’s a mistake made hilariously often.  My supervisor at the American Museum of Natural History volunteered to talk to a kid on a radio show, and this boy was only interested in dinosaur bones. So please learn the difference and save the soul of an archaeologist today.

Much like biological anthropology, archaeology has some pretty iffy roots in colonialism and eurocentricity.  The first ‘archaeologists’ emerged from something called Antiquarianism.  Interest in artifacts, or even bodies, was superficial in the sense that antiquarians were only concerned with aesthetic.  Provenience (the artifact’s location of origin) and context (what the artifact was associated with in situ, including geological features) were incidental to these early ‘archaeologists,’ and whatever deductions were made about these ancient cultures were correspondingly superficial. A PRIME example of the antiquarian archaeologist is Indiana Jones.  Another good way to break an archaeologist’s heart is to compare them to this particular character.  From an archaeological perspective, the boobytraps that Indy nonchalantly destroys are far more informative in regard to the community that created them than the shiny statue!  These early attitudes lead to the pillaging of colonized countries for their national treasures under the guise of ‘rescuing history.’  The Ishtar Gate, which now resides in Berlin, was originally ‘saved’ from Iraq, and the museum even uses this kind of language to justify their continued possession of this beautiful Babylonian treasure.  Even here in merrie olde England, the debate rages on about many of the collections in British museums across the United Kingdom.  The most famous, or infamous really, is the case of the Elgin Marbles. The British Museum came by these sculptures while Greece was under the control of the Ottoman Empire, bought from a man who literally lassoed them down from the Parthenon and sold them for pennies.  Most of the damage done to these statues is not because of age, rather their acquirement by the British.

This is a cringeworthy history, on a social level by stealing the ancient heritage of disenfranchised peoples, and on an academic level because we could no longer examine these artifacts and monuments in context. Thankfully archaeology has come a long way, producing truckloads of theory. With some stops in between, Antiquarianism morphed into Processual Archaeology, meaning that archaeologists began to look at artifacts in order to learn about the culture they came from.  To the Processualists, artifacts were culture manifested outside of the body and could be used to objectively examine the ‘evolution of culture’ through the scientific method. I put the phrase ‘evolution of culture’ in quotation marks as this concept is based upon the erroneous notion that evolution is a strict line of progression, with civilization (i.e. European civilization) as the pinnacle of progress to which every other culture naturally aspires.  Processualism then became Post-Processualism, which emphasizes the subjectivity of the archaeologist when analyzing archaeological remains. To the Post-Processualists, archaeological finds could only be interpreted in relationship to material that exists in the archaeologist’s experience, and in order to gain the most insight, archaeologists must remain as reflexive as possible.  And when archaeology became a subjective practice, it opened up the discipline to all types of different paradigms of analysis. With this mindset, archaeologists could look at artifacts through a Marxist, structuralist, or feminist lens to name a few. And these conversations are still happening today. Some of my thesis is based upon something called Sensorial Archaeology, which deals with the preeminence of the visual in the practice of archaeology, and how problems with the western hierarchy of the senses manifest in excavations.

Hopefully that didn’t put you straight to sleep, although I wouldn’t blame you. The methods used in archaeological excavations and analysis are a bit more interesting, but probably not nearly as exciting as the movies make them out to be. There is a lot of tedious digging in spots where you’ll inevitably find nothing. My first proper fieldwork was the test pitting stage of an excavation run through Cambridge University. It involved wading through endless fields of rapeseed in the rain, with a grim sandwich for lunch, and looking for lithics (manipulated stone) in a field brimming with flint deposits. It was an exercise in character development.

Working on the more advanced stages of an excavation was far more satisfying.  Barring the 5am wake up call, the excavation of a Roman Necropolis in Spain was incredibly enjoyable. Each dig produced finds, as we were trained how to identify the graves before we began troweling. You can see the edges of the tomb beginning to emerge here after 4 days with a literal broom and dust pan.

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From my personal experience, putting eager young undergrads into the field is an entertaining yet probably foolhardy decision.  I was so keen to get to the bottom of the grave that it took every fiber of my being to excavate slowly.  I could see from the grave I had taken over from the previous field school group, that they had suffered from the same problem. There were two individuals in this grave, with one full individual laying supine (on his back), which was a rare find, but in their excitement they had removed the femurs before the skeleton had been fully excavated.

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Look at all the loose femurs!

In these scenarios we need to be careful. A fundamental paradox in archaeology is that we excavate to reveal the context, but in so doing we destroy the context. So each step needs to be documented through field notes and sketches at the very least.  This can be a glacial process that the untrained archaeological student can mess up in a matter of minutes. Nothing is more tempting than to pull out a pesky root as you would when gardening, but roots are sneaky and you cannot risk damaging any artifacts they may have grown through by pulling them willy nilly. And as a novice I was so excited to do things like cranial reconstructions, but the taphonomy that lead to the breakage of the skull in the first place is just as much part of the context as anything else in the grave, and so it’s actually frowned upon now to glue pieces of the skeleton back together.  Undergrad Sarah didn’t understand that the reconstructed skull on the left was actually inferior to the one on the right held together by soil.

Forensic anthropology is, of course, a bit different because if we reconstruct a cranium we can then attempt a facial reconstruction or to match dental records. And in the instances when we do find relatives to return the skeleton to, a full skull helps to humanize the skeleton–which is incidentally another aspect of my doctoral thesis!

Have any questions about archaeological theory or methods?

As always, ask away!

 

 

Who were the Neanderthals?

After several weeks of eager anticipation, yesterday was finally the day.

Yesterday I received my results for 23andMe, the DNA analysis programme that gives you the lowdown on your ancestry and any genetic health risk factors you may carry.
And while my results were pretty much as I suspected, I found out something pretty cool. According to 23andMe, 2.6% of my genes come from Neanderthals!
Now that’s actually slightly lower than average for someone with who is predominantly European. But what exactly are Neanderthals and why are they so cool?

If you managed to take a look at my post about evolution from last week, you’ll remember that anthropologists have actually found a number of our evolutionary ancestors. Most of these ancestors died out before anatomically modern humans were on the scene — but not so with the Neanderthal! We had a pretty significant overlap, which we clearly made the most of in a reproductive sense. As we (humans) could successfully mate with Neanderthals, this makes us fellow subspecies of human. Modern humans are known as Homo sapiens sapiens, and Neanderthals are known as Homo sapiens neanderthalensis. There has been a lot of back and forth between their species classification, but the DNA evidence proves we could and did mate with them, so they are absolutely positively a subspecies.  So if anyone, including an anthropologist, gives you flack for this subspecies attribution–send them to me.
Neanderthals are called this because the first fossil associated with the subspecies, or holotype, was found in the Neander Valley in Germany. Although other Neanderthal remains had been found before this, they were only later categorised as such.  Here is the geographical area that Neanderthals were thought to inhabit courtesy of Wikipedia:

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So what makes a Neanderthal different from a modern human? There are a few notable differences.
Neanderthals had prominent supraorbital tori and occipital buns, meaning that their foreheads and the base of their skulls were quite large. And because their skulls were shaped differently, their brain architecture was also different. In fact, their cranial capacity was higher than ours, but because the parts of the brain responsible for speech, like Broca’s and Wernicke’s areas, were smaller in Neanderthals they would not have had the same capabilities for language.
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Image source 

In this sense, the stereotypical grunting caveman is correct. BUT there are several studies that indicate their hyoid bone, the bone in our throat, was situated higher than ours. This would make their voices correspondingly higher! So imagine a caveman with a high pitched grunt instead.
Neanderthals also had larger nasal apertures (where your nose goes). This is an adaptation to cold weather, as the air they breathed through their noses was warmed more effectively before entering their lungs. And we can still see a similar adaptation in populations from colder climates, although not as big as the Neanderthals.

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Image source Fun fact: this is Gibraltar I, and my absolute favourite. I grew up with a cast of it in my house.

Neanderthals were barrel chested and their arms burly. This has been attributed to spear thrusting but also to the scraping of animal skins. Click here for some interesting reading on the subject.

As part of the genus Homo, Neanderthals were tool makers and are also thought to have made clothing, the only other animal to have made clothing besides us.

This brings us to the question of cultural diffusion.  We know that humans and Neanderthals were living near each other and having sex, what we don’t quite know is how much influence there really was between the two groups in terms of material culture. We can identify tool making techniques that are associated with one subspecies or the other, what is slightly strange is that there seems to be little or no crossover–even when we know they were interacting with each other.  Some anthropologists argue that this makes us different species, but that is a remnant of archaic palaeoanthropological theory (more on that later).

Some anthropologists posit that the reason why humans eventually outlived Neanderthals is that we are better at learning new techniques and thinking outside the box, and Neanderthals just couldn’t keep up. But it’s still unclear. We may have just killed them all off. What we know is that they went extinct about 40,000 years ago.

Have any Neanderthal related questions? Let me know!

Question re: Sticks and Stones

A good friend of mine, Nicole, has asked a great question about the post Sticks and Stones: Basics of Skeletal Trauma.

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She says: “Love this! Also if this is the superior view would you say that the trauma occurred along any suture lines? Also out of curiosity, which bone of the skull is pictured?”

Thanks for the question, Nicole! This gives me a great opportunity to talk a little bit about the anatomy of the skull.

As the original picture only shows a bit of the skull, I’ll bring in my lovely assistant!

Here is Stan the Standard Scientific Skeleton. And here is the top of Stan’s head.

You can see that this image of Stan’s head corresponds to the left side of the image above Nicole’s question.  I’ll just take the top of Stan’s head off to make it easier to handle.

Cool. If you look carefully, you’ll see something on Stan’s skull that you can’t see on original skull. Those squiggly lines are called sutures. These sutures connect the different bones of the skull. Yes, the skull contains multiple bones! When we’re born, in order to fit through the birth canal and then give our brains enough room to grow, our skulls are divided into many different pieces. As we get older, these bones grow and then fuse at these suture lines. This is why babies have soft spots, or what anthropologists call fontanelles. Their skulls aren’t fused yet.

Nicole wants to know if the trauma on the first skull involved these sutures, and which bones of the skull are pictured.

The bones of the superior aspect of the skull are as follows:

One frontal bone (pictured pointing downwards here), two parietal bones, and the top bit of the occipital bone.

The angle of the trauma to the first skull looks approximately this. The frontal bone is now facing upwards.

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As you can see, there are two sutures involved. The vertical suture, called the saggital suture, is cut transversely.  The horizontal suture, called the coronal suture, is impacted on the right.

But why are the sutures visible on Stan and not the first skull?  Well there are two options.

As we get older the sutures fuse, but it doesn’t just end there! Often the sutures will begin to fade and become obliterated. Sometimes anthropologists will use the level of fading to establish age at death. Buuuuut they shouldn’t. Sometimes the sutures don’t fade at all, and they certainly never fade on a predictable timeline.

The second option might be that the surface of the bone is poorly preserved.

As I don’t currently have access to the bone in question, I can’t confirm, but looking at the picture I suspect it’s a mix of both.

Thanks Nicole!

Sticks and Stones: Basics of Skeletal Trauma

What you’re looking at above is the superior aspect of a human cranium, i.e. the top of someone’s head.

If your first thought was ‘holy hell, what happened to that poor guy?’ well done. You have the makings of a human osteologist.  The answer is what forensic anthropologists and bioarchaeologists call sharp force trauma, or when a sharp object injures tissue.  This unfortunate fellow was most likely the victim of a broadsword attack.

There are several types of trauma that we can see in human bone. When the injury is caused by a blunt object we call it blunt force trauma.  When the injury is caused by a projectile, like a bullet, we call it projectile trauma.  Pretty self explanatory.

Trauma is classified as antemortem (before death), perimortem (at the time of death), or postmortem (after death).  We can tell when an injury occurred by looking for remodeling, by looking at the manner in which the bone was broken, and by the colouration of the trauma itself.

Remodeling, which is the term for bone healing, will only be present in antemortem injuries.  If we can see remodeling, the injury must have happened before death.  This is the reason why doctors must set bones.  Bones are smart and will try to heal themselves, even if they are no longer aligned. So we find individuals with bones like this:

 

We can also look at how the bone actually broke. The bones in living bodies, which are considered wet bone, react to force differently than long dead bone, or dry bone.  When we see fractures that could have only happened to wet bone, we know that the trauma was antemortem or perimortem.  Greenstick fractures are an excellent example of this.  Much in the same way that a stick is easier to break in half if it’s dead, so is bone.  The wet, fragmented bone will stick together like a twig from a living tree.

(Access the original image and some complicated reading on trees here)

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Here you can see a greenstick fracture of the fibula (original image)

Comminuted fractures are another good example. This is when a fracture contains multiple fragmented pieces of bone. Below is an example of a comminuted fracture created by blunt force trauma.

This would never happen to dry bone, as it would simply shatter the skull.

In less clear cases, we can look for differences in the colouration of the fracture and the surrounding bone.  If the fractured area is lighter, it usually means that it has not been exposed to the elements as long and has therefore occurred after death in the grave or after excavation.  When damage happens after a person has been buried it’s called the taphonomic process, when it happens after excavation we call it students.

 

For more information about skeletal trauma, as always, feel free to comment or follow up in a message!

A Bone to Pick: Basics of Palaeopathology

Palaeopathology is the study of ancient diseases, trauma, disability etc. by examining human remains. Like forensic anthropologists, palaeopathologists also work with a degree of uncertainty. When most of our data comes from the examination of human bones, there are specific limitations we must contend with.

Bone can only react in one of two ways when something is wrong; the bone tissue can either grow or it can resorb. Both bone growth and resorption are normal and happen throughout your life–this process is caused by cells called osteoblasts and osteoclasts–but disease, trauma, and malnutrition can create abnormal formations of bone called lesions. The lesions formed by excess bone growth are called proliferative, and lesions formed from resorption are called lytic.

Each disease will affect bone in slightly different ways, that is if they affect the bone at all. But because of these limited types of bone reaction, certain diseases can look very similar. For example, scurvy and cribra orbitalia are both characterised by lesions in the orbitals (eye sockets) which can be hard to distinguish without training and practice.

Scurvy is a metabolic disease caused by a lack of vitamin C. As our bodies need vitamin C to form collagen, and our blood vessels require collagen for structural stability, the capillaries in the eye sockets of those with scurvy begin to bleed. The presence of blood in the orbit stimulates new bone growth and creates proliferative lesions.

Cribra orbitalia, which is often attributed to iron difficiency anaemia (rightly or wrongly is still up for debate), is charaterised by lytic lesions in the same area.

Below are pictures of both conditions, can you tell which one is which?

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These are excellent examples of each type of lesion, so this is pretty much as easy as it gets. Most presentations of these lesions will be less pronounced, more fragmented, or both. Which makes our job a bit harder.

You can check your answers and access the original images here and here.

Too easy? Let’s try this one:

Do these skulls all feature the same pathology? Or are there two pathologies? Or even three?

What differences in these lesions, if any, can you observe?

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Hint: there are two diseases and one trauma featured above. Can you tell which ones are which?

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The first skull is an example of caries sicca, a major sign of venereal syphilis.

The second skull has a penetrating gunshot wound to the forehead.

And the third skull is an example of lesions associated with calvarial tuberculosis.

We can differentiate all of these conditions by looking at the remodeling (healing) process, or the origin of the lesion–for example, did it start inside the skull and move outwards or start on the surface and move inwards?

Another practical issue palaeopathologists face is something called the osteological paradox.  And while this term seems big and scary it’s actually pretty simple.  In order for a disease to show up in the bone, it has to be around long enough in a living body. We call this kind of disease chronic.  If a disease is too deadly and kills a person quickly, it won’t have time to affect the bone.  We call this kind of disease acute.  Therefore, when we see an individual from an archaeological site with a pathology, we know that actually this individual was probably one of the healthier ones. So ironically, when palaeopathologists study pathology, we’re usually studying the healthier individuals of a community.  This can be problematic when trying to ascertain general health trends and quality of life.

 

If you’re interested in the diagnostic criteria for any specific diseases or want more info about bone biology, keep your eye out for upcoming posts or comment below!

Biological Anthropology – An Overview

Biological anthropology is one of the four major subfields of anthropology. Very generally, biological anthropology examines the biological development of human beings–meaning that we study everything from human evolution, our evolutionary cousins (other primates), comparative anatomy, osteology (the study of bones), and ecology.

Here are just some of the many subfields of biological anthropology:

Palaeoanthropology – the study of human evolution and diversity
Primatology – the study of nonhuman primates
Forensic Anthropology – the use of human osteology in a legal context
Bioarchaeology – the study of human remains from archaeological sites
Human Ecology – the study of human interaction with the environment

All of these subjects seek to shed light on our history as organisms, but they also have direct and practical relevance to our world today. A major aspect of primatology, for example, is primate conservation. And forensic anthropology is used all over the world by police departments, major investigative parties after war, and in the wake of mass casualty events such as terrorism or natural disaster.
Very often, the practical subfields of biological anthropology are considered ‘anthropology’s jock-y younger brothers’ because we lack the theoretical framework that social anthropology and archaeology have in spades. But more on that later.

For everybody in New York City (my hometown), there’s a fantastic permanent exhibit at the American Museum of Natural History called the Hall of Human Origins. It gives the lowdown on all of the major themes of biological anthropology and its many subfields. Also worth looking at is the Hall of Primates for just a small taste of the enormous diversity found in our taxonomical order.

It also provides an opportunity to compare your body to those of other apes!amnh

Notice the similar brachial morphology between the human and the orangutan!

 

On a solemn note:

Anthropology as a whole had a considerable role in proliferation of racist tropes in the late 19th century and well into the 20th. But biological anthropology’s involvement in the proliferation of these tropes is arguably the most sordid. Because we were able to mask our racial bias in the cloak of science, our research into the different ‘races’ of humans could be used as ‘proof’ of white and male supremacy. I put the word race in quotations because in the world of biology race literally means species! Anthropologists had a hand in creating this narrative. One particularly infamous study measured the cranial capacity of different races with the intention of proving that white people had bigger brains and were therefore smarter. This is, of course, bad science and there remains no relationship between brain size and intelligence anyway. When anthropologists began examining human evolution, their research was used to ‘prove’ that people of colour were less evolved and therefore more closely related to other primates than white people were. And these stereotypes have managed to stick around until today! There is also evidence that members of the Nazi Party utilised the same osteological collections that anthropologists rely on today to search for observable differences in the skeleton based on race. So it is critical that biological anthropologists acknowledge their discipline’s history and stand in staunch academic opposition to its lingering effects.

Have any questions about biological anthropology? As always, feel free to leave a comment or message me on the contact page.

The Evolution Debate

Another subfield of biological anthropology that I’ve worked in is palaeoanthropology. Which, very simply, is the study of human evolution.

And one of the most frustrating things I’ve experienced as an anthropologist is not evolution denial, but the very clear inability of people who do believe in evolution to give good answers to the questions put to them by those evolution deniers. I’ve seen Bill Maher laugh off a question posed by Michelle Bachmann about evolution, not because it was too ridiculous to acknowledge but because he didn’t know the answer.  Even people like Bill Nye have trouble articulating answers in an accessible way.  

Evolution has become a dirty word.  Most people who aren’t convinced by evolution have no problem believing in other things that are dependent on evolution. 

If you believe in the flu vaccine, you believe in evolution.

If you believe in DNA, you believe in evolution.

And if you believe that the rhinoceros is almost extinct, then you also believe in evolution. 

I’ll explain.

We know that animals don’t just go extinct for no reason, something always happens to drive that animal to extinction — like drought or overhunting. Another term for that something is pressure. So the pressure for the rhino in this hypothetical scenario could be poachers who take their horns.

We also know that while some animals are on the verge of extinction, other animals are not. This means some animals aren’t affected by this particular pressure like the rhinos. If poachers don’t bother with hippos because they don’t have horns, hippos will last longer than rhinos. 

Recap: some animals can survive more easily in an environment than others.

Most people can accept this, so let’s continue.  

If a rhino was born without a horn, poachers would have no interest in it and leave it alone. Then that rhino could go off and have hornless babies which the poachers would have no interest in either.  Now suddenly, you have a bunch of hornless rhinos happily hanging around while the rhinos with horns dwindle.  

There you go. That’s it. This is all that Darwin was describing (except with birds) and it’s called selection. 

An animal is born with a mutation, like a bird with a strange beak or a rhino without a horn. When this mutation is useful, like it makes it easier to find food or it makes you unattractive to poachers, then that animal can live longer and have more babies who then might also have this mutation.  These useful mutations are called adaptations. 

And there are different types of selection. When the pressure is environmental, we call it natural selection. When humans breed plants or animals for certain traits, it’s called artificial selection. 

Darwin had no sense of how these mutations happened or were passed on, but we do!  When we discovered DNA, everything really fell into place.  We could see that all of our traits were written in our genetics and could be passed down to our children.

The most stunning example of this selection process can be seen (yes actually seen!) when tracking antibiotic resistant bacteria. Please go watch this clip.  

The antibiotic is the pressure, like the poacher to the rhino, and we can see where and when the bacteria mutate, like the hornless rhino.  Flu vaccines get updated every year because the virus adapts very quickly, much in the same way the E. coli adapts in this video.  

Now how does all of this translate to the bigger picture? 

The more rhino babies born without horns, and the more poachers kill rhinos with horns, the more likely it becomes for hornless rhinos to end up mating with other hornless rhinos, as they survive better. If we were to fast forward a million years, the hornless gene could become so separated from the horn gene that if a hornless rhino were to come across a horned rhino and mate, they either would have a sterile baby or no baby at all.  This is called speciation.

These new species will face other pressures, adapt, and maybe speciate again! And this goes on and on and on until the world ends. Which is why we have such a wonderfully diverse world.  All it would take to create the world we see today is one microbe in the right conditions and time. Reproduction, mutation, and adaptation have been happening every single second of every single day for millions and millions of years.

Some common questions/statements I’ve encountered:

Michelle Bachman’s question mentioned above was ‘why are there still monkeys if humans evolved from them?’ 

Good question, Michelle! The monkeys we evolved from existed millions and millions of years ago. We did not evolve from current species of monkey.  We are evolutionary cousins, if you will, with current monkeys because we share what’s called a common ancestor. Say there was another rhino who was born with a mutation that gave it camouflage to hide from poachers. Then it went through the same selection process as the hornless rhino to become its own species.  The hornless rhino and this camouflage rhino would share a common ancestor.   

Another common question is ‘where is the missing link?’ 

Well get ready to have your mind blown.  There is no missing link and there has never been.  We have found numerous remains of our evolutionary ancestors! Each species we’ve identified has multiple samples associated with it.  Before Darwin was even on the scene, neanderthal remains had been discovered!  So never from the inception of evolution as a concept has there been a missing link.

A common misconception is that ‘Lucy,’ the Australopithecus afarensis skeleton from Ethiopia, is the only sample we have. This could not be less true. Lucy is just one great example of many from that particular species.

‘Link’ is also an inappropriate word.  As you can see from the antibiotic resistant bacteria, evolution happens in many places at once. Instead of thinking about evolution as a line, we like to use the phrase rivers and tributaries.  And you can quite literally see what we mean by that as you watch the video.

‘Evolution is just a theory!’  

The word theory has a different definition in the scientific community. A theory is a scientific explanation that is supported by all existing evidence and continues to be supported by new research.  Decrying evolution as ‘just a theory’ is equivalent to saying you don’t believe in gravity because general relativity is ‘just a theory.’

‘I believe in adaptation but not evolution.’

They are literally the same thing.

 

Do you have any questions about evolution? Have you ever had to explain evolution to someone before?  Tell me about your experiences in the comments or on the contact page!