#Takemeback: How faunal material can recreate the paleolandscape

Remember that vacation you took when you were with your squad? They looked good, you looked good, the weather was perfect and the selfies were on fleek. Everyone has moments they remember fondly and wish they could go back to. And, like everyone else, paleoanthropologists wish they could go back in time, too…Just a couple of million years more!

As a species, we humans spend nearly as much effort looking behind us as we do in front of us. From an early age, we are taught the history of our communities, our countries and even, sometimes, our evolutionary history. But, our fascination with the past is not limited to education, using #Takemeback and other social trends, we idolize the thrill of hopping into another era. Why do we focus so much on things of the past? Past experience lends us insight into what may happen next. But how do we learn when there is nothing to collect or read?  

Building The Past

Paleoanthropologists have always been curious about where and how humanity all began. They strive to piece together how we, as a species, metamorphosed from small, hairy, arboreal creatures into large, hairless, gangly bipeds. While paleoanthropologists are able to use hominid fossil remains, to understand the past they can only do so to a certain extent. Hominid fossil material typically makes up less than 1% of all material discovered in at a site. Additionally, fossils will only show morphological characteristics. As a result, it becomes nearly impossible to exclusively use hominid material to research and understand why we as a species evolved. So, in order to better understand and answer questions of our evolutionary lineage, paleoanthropologists often use faunal material in addition to hominid fossil material. By doing this, paleoanthropologists are able to recreate the environment and landscape our early ancestors were living in, allowing them to better understand how certain adaptive traits, such as bipedalism, have emerged and why.  

Recreating The Past

 A tenet of Darwin’s natural selection states that if an organism is unsuited to its environment, it will reduce its overall reproductive fitness, eventually decreasing its chance to pass on its genetic material and vice versa. When observing hominin sites, paleoanthropologists often pull from Darwin’s concept of natural selection in order to create hypotheses about certain adaptations found in fossil fauna that could be related to the paleolandscape. These hypotheses are based on comparative studies built from extant living fauna in similar environments, to the fossil fauna. One such hypothesis is the savanna hypothesis. The savanna hypothesis states that extinct fauna will show a gradual increase towards adaptations for more arid and open environments in certain areas after the late Miocene (11.6-5.3 MYA). These adaptations can be seen in the form of speed and endurance.

Faunal reconstructions are incredibly common and have been made for many different sites, including the Omo, Sterkfontein, and Swartkrans. Within the Omo site region, for example, a great deal of faunal material was recovered spanning a timeline from 4-1 MYA. The material discovered, including both faunal and hominin specimens, showed clear indications of a gradual shift to a more arid/open environment (Savanna Hypothesis for the win!). Looking at the lower stratas high amounts of Tragelaphini and some species of Reduncinae are seen. These are antelope commonly seen in woodland environments. However in the upper stratas, a shift towards more digitigrade and hypsodonty mammal species like Elephantidae and Hipparion were found. Also known as Elephants and Hippos, Elephantidae and Hipparion are linked to more open environments. Even the hominid evidence suggests a gradual shift of woodlands into open grasslands in the Omo region. In lower strata Au. afarensis was found, which was thought to have inhabited a more woodlandesque environment. But, when moving up in the strata evidence of P. boisei and Homo were discovered, both of whom indicate adaptations towards a more open environment. Evidence like this helps paleoanthropologists to better define why certain adaptations came to be. So, while paleoanthropologists can’t actually #Takemeback, they can however #buildthepast.

Want to recreate your hominin evolutionary past? Explore below!

  • To Learn more about Natural Selection and Human Evolution click here.
  • To Learn more about Reconstruction of Hominins click here.
  • To Learn more about the Omo Region and its Reconstructions click here.

The Human Color Swatch: How variation affects your skin color

*A note from the Author*

We all know that the issue of race is a delicate subject and one that is unavoidably linked to skin color. This post does not focus on the subject of race, but rather on why we see differences in the color of human skin. Race is a social construct, not a biological one. The color of our skin is not determined by our race, social standing, or ethnicity, but rather by the environmental stressors our ancestors were subject to.

Have you ever found yourself in the paint aisle, staring wordlessly at the seemingly endless array of color fusion? I always find myself staring at those swatches and wondering how on earth there can be hundreds of variations of yellow. Perhaps, I’m just an unrefined savage when it comes to understanding paint color, or maybe the colors really aren’t that different and it’s simply a trick presented by paint advertisers. However, looking closer, I can see the vague tinges of shade difference. Observing this array of color all with their own name, I realize that we humans have a deep understanding of color variation. And, this ability to see color has allowed us to note the vast diversity of skin color among our own species.

Skin is humanity’s most visible characteristic. Coming in a gradient of colors, it provides us with a billboard of information regarding an individual’s health, age, and ancestry. However, our skin is more than just a walking advertisement. It is the knight of our bodies, protecting our delicate innards from physical, chemical, or microbial harm. But it is more than that. Skin also provides critical information about the ambient environment and objects we interact within our environment. So, let’s dive in and find out why the human color swatch is so variable!

What Is Skin Made Of?

The skin is divided into two main groups of layers: the dermis and the epidermis. The dermis consists of a thicker inner layer of skin, which holds the connective tissue, blood vessels, oil, sweat glands, nerves, and hair follicles. The dermis is the foundational block of your skin. It is what supports the epidermis and enables your skin to thrive. That healthy glow or occasional angry pimple you see come from the dermis. The epidermis, however, is the skin we see every day and the one that defines our color. While the dermis is the supporting actress that obviously does the most work, the epidermis is who we will be focusing on for today.

Why Does The Epidermis Determine Color?

Within the Epidermis there layers known as the melanocytes layers. These layers determine skin color since they host melanin, the primary pigment found in the body. Melanin are cytoplasmic organelles called melanosomes. They come in two different forms: eumelanin and pheomelanin. Eumelanin consists of the brown and black pigments, whereas pheomelanin consists of the red and yellow pigments. How do these affect skin color? If an individual has more eumelanin they will exhibit darker skin color compared to someone with more pheomelanin. Additionally, there are also two skin types that react differently. The first is constitutive skin color which consists of your genetically predetermined skin color in the absence of any external stimuli, like sunlight. Simply put, this is the skin color you were born with, the original #nofilter, #no makeup look. The second is known as facultative skin color which develops when exposed to any external stimuli, like sunlight. So, that killer tan you got when you went to Bali? That’s your facultative skin hard at work!

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Beach Babes

Why The Difference?

Generally, individuals with more eumelanin will exhibit a higher degree of facultative skin color and are descendants of individuals who resided in environments with high exposure to sunlight. Individuals with more pheomelanin will exhibit less facultative skin color and are descendants of individuals who resided in environments with less exposure to sunlight. This difference is strongly associated with a latitudinal signal, with darker skin being present around the poles and equator and lighter skin being present bellow the poles and equator. This latitudinal signal is directly associated with exposure to high degrees of sunlight. Both the poles and the equator have higher more intense degrees of sunlight and UV radiation. As a result, individuals living in these kinds of environments would have had to adapt to more intense and longer periods of sun exposure.

It has been proven scientifically that darker skin holds significant benefits towards prolonged and intense sun exposure. Eumelanin prevents more UV radiation from entering the body than pheomelanin. Facultative skin is also more resistant to sunburns, allowing individuals with a higher amount of facultative skin to be exposed to sunlight for longer periods of time. Compared to darker colored individuals, lighter colored individuals tend to reside away from areas of increased sunlight. As a result of not having as much sun exposure, their skin color will adaptively shift to a light color to allow for maximum absorption of solar rays. This allows them to exploit as much sunlight as possible which in certain doses can be helpful for the body and mind. Who doesn’t love a good catnap in the sun?

Why Is Sunlight Important?

Like all good tetrapod’s our skin is made to protect us from the big bad world and help us synthesize vitamin D. Vitamin D is critical in maintaining overall body function and maintenance. It manages calcium in the blood, gut, and brain and helps to provide communication between cells. Unfortunately, vitamin D is not produced within the body but instead primarily absorbed from sunlight. However, we also absorb UV light from sunlight and too much of it can cause sunburns and cancers can form. So, a balance must be made between the amount of UV penetration and vitamin D synthesis.

So what Does This All Mean?

Individuals with darker skin color have increased protection against UV radiation, but can’t absorb vitamin D as effectively as individuals with lighter skin color and vice versa. Darker-skinned individuals are able to obtain enough vitamin D if they reside in environments with adequate sunlight like in the poles and equator. However, lighter skin-colored individuals have an increased risk of obtaining diseases like skin cancer from areas with increased UV absorption, like in the poles and equator. But, lighter-skinned individuals living in areas with little to no sunlight are better adapted to that specific environment compared to darker-skinned individuals since they are able to better absorb sunlight.

As society continues to develop, it becomes easier for individuals to reside in environments for which their skin might not be best adapted. Darker-skinned individuals residing in environments with restricted sunlight may overcome vitamin D deficiency by consuming vitamin D fortified foods, like milk, multivitamins, or vitamin D tablets. Lighter skinned individuals in environments with high exposure to sunlight can overcome high absorption of UV radiation by wearing sunscreen or clothing, reducing the surface area exposed directly to sunlight. Regardless, it’s important to note that while an environment may not be “best suited” to your evolutionary biology, many many people of different skin colors are able to live in “nonideal” environments without needing outside help. You’re just a little less adapted to that specific environmental pressure. Humans are incredibly general in our biology. it’s what has allowed us to become so prolific. So, whether you can absorb vitamin D like a boss or thwart UV radiation with a flick of your wrist, each and every one of us shows amazing amounts variability. No wonder we’re able to inhabit most of the globe. Go Homo sapiens, go!

Post your photo in the comments below and join the Human Color Swatch today!

What to learn more about skin?

  • To learn more about what your dermis can do for you click here
  • To learn more about the epidermis and its layers click here
  • To learn more about the evolutionary history of skin color click here

Don’t Forget to Bring your Trowel! The 101 on Paleoanthropology

The air is hot and dry, the ground dusty. All around young graduate students are cautiously sweeping the dirt away in hopes of finding hominin fossil fragments and quenching their thirst for fame and knowledge. They are paleoanthropologists. Individuals who strive to better understand and catalog human ancestry. Defined as “the study of ancient humans,” paleoanthropology is a branch of anthropology that strives to reconstruct all aspects of human evolution. A multidisciplinary field, it combines disciplines like archaeology, anthropology, paleontology, and geology to observe the anatomy, behavior, and ecology across the human lineage with a primary focus on early human evolution known as the hominin lineage. By better understanding the hominin lineage, paleoanthropologists attempt to discover how early hominins lived and “how” and “why” certain species evolved in anatomically modern humans, or died out.

How Do Paleoanthropologists Answer These Questions?

Paleoanthropologists use early archaeological, hominin, and paleoenvironment evidence, to begin reconstructing our ancient past. Evidence often includes fossilized bone from both hominins and other animals, lithics (stone tools), plant and animal matter, footprints, evidence of hearths, butchery marks on animal bones and art. Using these materials, researchers can then establish a hypothesis and narrative to explain the physical and behavioral makeup of early hominins and how it has altered across a spatial and temporal timescale. 

How To Create A Paleoanthropologist Narrative

Let go back to our graduate students digging in the hot sun. Say for example one of them discovers an Acheulean biface tool along with an extremely “primitive” fossilized hominin hand like Australopithecus Sediba.

Left: Acheulean Biface Tool Right: Australopithecus Sediba hand

Assuming that this graduate student has adequate knowledge of hominin functional morphology, they might note that the dexterity required to create an Acheulean biface surpasses the dexterity found in the fossilized hand. As a result, the graduate student is faced with 3 potential hypotheses:

  1. the tool was not created by the hand of the “primitive” hominin found with the tool and was created by a different hominin species living at the same time.
  2. The deposit in which the tool and the hominin were found was mixed in with another deposit layer.
  3. The tool was indeed created by the hand of that hominin and all our previous understanding of hand morphology is flawed.

Where To Find Hominin Remains?

To locate fossils, paleoanthropologists typically look for areas that would have been ideal environments for hominin hundreds of thousands of years ago. This can be anything from sediments of the right time period being exposed by natural erosion to educated guesses based on the locations of previously discovered fossil specimens. One of the most common places to locate early hominin remains is in Africa. Within Africa, fossil remains are split into two groups depending on their location: East and South.

East African Fossil Specimens

Located in East Africa, East African fossil specimens are typically located throughout rift valleys. Rift valleys are caused when portions of the earth’s crusts have been pulled apart due to the movement of tectonic plates. This movement of plates causes deep valley and trench-like formations surrounded by large mountain ranges. Fossils, if found, will usually be exposed along the sides and floors of the rift valleys due to rivers and streams eroding deep into the sediment layers.

Olduvai Gorge in Tanzania, East Africa

South African Fossil Specimens

Located in the southern part of Africa, South Africa fossil specimens are typically found in caves. This is mainly due to South Africa having large limestone deposits everywhere. Since limestone is extremely porous, as rainwater runs through a limestone crack it erodes surrounding limestone, eventually expanding into caves and tunnels. While hominin fossils are located within caves there is weak evidence which suggests that early hominins used caves as habitation sites. Paleoanthropologists actually believe that the majority of hominin fossils found in caves were brought in by predators like leopards or hyenas, bone collecting animals like the porcupine, or were washed in by rain from any cave opening. Hominin fossils in South Africa are typically found when miners blast the caves in order to attain the limestone or other mineral resources. The famed Taung Child, for example, was discovered at the Buxton limestone quarry in the Northwestern Province of South Africa following a mining blast.

Sterkfontein near Johannesburg, South Africa

Why Is Paloanthropology Important?

Paleoanthropologists constantly strive to discover fossils and artifacts since they are a physical evidentiary timestamp of a particular event. Unfortunately, fossils are quite rare and often it is up to paleoanthropologists to hypothesize what occurred over the last 4 million years.  By probing into the past, researchers, like our graduate students, can begin to ask some of the broader questions surrounding our evolutionary history,  and perhaps, glean important information into who we are.

Want to dig up more on Paleoanthroplogy? Look no further!

  • To Learn more about the Paleoanthroplogy discipline click here.
  • To Better understand Human Evolution click here.
  • To Learn all about who is in Our Ancestry Tree click here.

Supervillain or Superhero? How autosomal recessive disorders affected human evolution  

Oftentimes in movies, we root for the superhero and despise the super villain. After all, who wants Dr. Evil and Mr. Bigglesworth to dominate the world by turning the moon into a death star? His success wouldn’t benefit anyone other than himself and his cohort of miscreants.  Civilization and freedom would be compromised, effectively squashing humans as individuals. But, by rooting for the devilishly carnal Austin Powers, human civilization is maintained and evil is vanquished. Using a little creative interpretation, we can find these character tropes in evolutionary biology.

A basic belief in evolutionary biology is that a gene will only survive over generations if it can provide some form of advantage to a species (the superhero). If a gene provides a disadvantage (the super villain), such as a lethal disorder or disease, it should eventually disappear from the gene pool. Basically, how many reproductive opportunities a gene provides its carrier will determine its success. However, certain genes, act as both a superhero and a supervillain. As genes combine to form traits, they can sometimes show both positive and negative assets within the trait. An example of this are autosomal recessive disorders, where the amount of negative assets present can provide either an advantage or disadvantage to the carrier. They are the superheroes and supervillains version of our genes!

Typically, humans have 46 chromosomes on which all our genes are located. Arranged into 23 different pairs, one of each chromosomes that creates the pair is passed from your mother or father. 22 of these chromosomal pairs are known as autosomal chromosome. Autosomal chromosomes decide every trait you have aside from gender. When variation within a gene results in a negative trait, and is passed from both parents this is known as a recessive mutation. An autosomal recessive disorder develops when a recessive mutation occurs on an autosomal chromosome and both parents pass the mutation. Even then there is a 25% chance of having inherited the mutated gene and developing the disorder. If only one parent passes the mutation there is a 50% chance of inheriting one of the mutated genes and becoming a carrier.

Autosomal recessive disorders are extremely harmful and deadly to the afflicted. Those burdened with an autosomal recessive disorder find themselves with complicated health issues and shorted lifespans. However, those who are carriers can demonstrate increased resistance to certain diseases. Diving into this lottery of inheritance lets look at the pros and cons of one of these disorders-Sickle Cell Anemia.

Sickle Cell Anemia

Sickle-cell anemia occurs when there isn’t a sufficient amount of healthy red blood cells to carry oxygen throughout the body. Caused by a mutation in the gene that affects hemoglobin, the usual rounded flexible shape of the hemoglobin becomes rigid and sticky, resembling sickles. Mutated hemoglobin, known as hemoglobin S., cause a wide variety of negative complications, such as anemia, pain caused by blocked blood flow, swelling of the hands and feet, delayed growth, increased infection rate, and vision problems. However, when a carrier for sickle-cell anemia, known as sickle cell trait, there is instead an increased resistance to Malaria.

An infectious disease, caused by parasitic protozoans, malaria is transferred to humans only through the female Anopheles mosquito. when infected, the protozoans move through blood vessels to liver cells and reproduce asexually, eventually releasing back into red blood cells to continue their life-cycle. If a host has the sickle-cell trait however, the defective hemoglobin S present within their body will rupture, preventing the malaria parasite from continuing its cycle. Unfortunately, anyone afflicted with sickle-cell anemia who contracts malaria become more vulnerable, since all of their red blood cells will sickle, causing a lack of oxygen throughout their body.

What Does This All Mean?

Its clear that autosomal recessive disorders are devastating and deadly and being a carrier provides protection against some pretty terrible diseases. But, most interestingly is who these particular disorders and diseases affect and why. Populations most affected by Malaria show higher rates of Sickle Cell. However, it is important to note that a higher occurrence of a specific disorder is not directly related to a particular race, nor does it indicate a certain population is at a disadvantage to others. Rather, it is directly related to the geographic region, and environmental pressures, an individual’s ancestry is adapted to. If a population group lives in an environment where potentially dangerous diseases are prevalent, the fitness of that population will select for traits that provide a genetic advantage. Over generations, that population will be more resistant and at an advantage for living in that particular environment.

When looking at sickle-cell anemia and sickle cell trait, higher percentages are found among peoples in Sub-Saharan Africa (up to 30% in Nigeria alone), the Chalkidiki district of Greece (18-32%), and on the Eastern Province of the Arabian Peninsula (20-30%) Within these geographical locations, and consequently among their populations, higher rates of malaria are seen. However, these are not the only locations in which we see sickle cell. High rates of sickle cell can also be seen among African American populations in the United States. This is attributed to the dispersal of population groups specifically associated with higher rates of sickle cell. Reviewing historical documents has enabled researchers to track these movements of large populations groups. Looking at records documenting the United States Atlantic slave trade many slaves came from the coasts of the Sub-Saharan African region. Movement of sickle cell has also been documented during the 1950’s large-scale immigration from the Arabian Peninsula into Germany of Turkish nationals.

Spread of Malaria Worldwide
Spread of Sickle Cell Trait Worldwide

While genes that result in autosomal recessive disorders negatively affect the individual who carries them, the more the common carriers of the disorders are protected from other diseases. This advantage allows the carrier to reside in environments with strong selective pressures without hindering their fitness, enabling them to effectively pass on their genes to future generations.

Though the majority of individuals will never experience the negative effects of having an autosomal recessive disorder, we must all strive to help resolve the calamity of these supervillain genes. 

  • To learn more about autosomal recessive disorders click here.
  • To learn more on how sickle cell kicks malaria’s metaphorical tooshie click here.
  • To learn more about what malaria is click here.
  • To learn more about the evolutionary link of sickle cell and malaria click here.
  • To donate to fight against autosomal recessive disorders click here.

One Dog, Two Dog, Big Dog, Small Dog: The forces of evolution

Sitting on a park bench one day, you notice a Great Dane and Chihuahua happily sniffing and circling each other in mutual greeting. Staring, you notice how different they are and wonder how it is even possible that they are still part of the same species. This difference you see is known as variation. The World Canine Organization recognizes 339 individual breeds of dogs, all of which exhibit unique forms of variation. While many of the variations we see in those 339 breeds are the result of domestication and purposeful breeding, variations within a more natural environment still occur. Differences in physical and genetic makeup exist across all organisms. These differences or variations allow for a species or population group to become better adapted to certain environmental stressors. There are four ways in which variation can occur: mutation, gene flow, genetic drift and natural selection. 


Who mutated best? Night Crawler or Andorian?

Thanks to creative sci-fi films, the word ‘mutation’ may prompt us to picture genetic monsters or creatures with two heads, one eye and an array of superpowers. However, the majority of gene mutations are subtle or even undetectable. Gene mutations occur when errors are recorded within DNA during the cellular replication process. There are two classifications of gene mutations: somatic and hereditary.

Somatic mutations are the more common of the two, and occur during the lifetime of an individual. They are typically caused by environmental factors, like UV rays from the sun, or are the result of spontaneous errors made when adult cells divide. While somatic mutations don’t directly affect the entire genome and can’t be passed to the next generation of the individual, they will be present throughout the descendants of the original mutated cell which sometimes cause cancers. Hereditary mutations are passed from parent to offspring. These occur in the cells of the sperm or egg. If either an egg or sperm cell holds a mutation, the offspring from the fertilized egg will have the mutation present in virtually all of the cells of it’s body. Although rare, by creating new genes and alleles, hereditary mutations have the ability to introduce new variants, thus potentially increasing genetic differences between populations. So, while it is highly unlikely that you are a mutant with awesome powers, it is not impossible.

Gene Flow

As humanity becomes more unified, so do our genes. When an organism migrates or moves, from one population to another, it allows its genetic material to move as well. Known as gene flow this can occur in many different ways depending on the organism itself. For example, pollen from one group of flowers may passively be transported to another group by means of insects, birds or wind, whereas humans may actively elect to move to a different region and population group.

The ability of genes to move into a new population group can be a very important source of genetic variation, especially if that gene version did not previously exist within a population. In the Amboseli basin in Kenya, mating between the yellow and Anubis baboons has allowed for the transferring of genetic makeup between the two different subspecies creating maturational and reproductive advantages. Although gene flow may seem like an easy way for organisms to transfer genetic material, barriers can block the amount of flow a population may see. There are two types of barriers that can affect gene flow: Allopatric speciation and sympatric speciation. Allopatric speciation is when gene flow is blocked by a physical barrier such as a mountain range, large body of water, or man-made obstacle. Sympatric speciation, barriers occur due to gene incompatibility. This typically arises when two different species originate from the same ancestral species but are different enough genetically to not be able to successfully reproduce. Limitations in reproductive success can be caused by incompatible genetics, fragmentation, different social behaviors or hybridization. A good example of this is the Liger.

Genetic Drift

All humans have two copies of every gene; one from their mother and one from their father. In reproduction, only one gene copy from each parent is transferred to their child. Like flipping a coin, each gene copy has a 50% chance of being inherited by you. However, the outcomes of what a child will inherit are not always the same. This is because the outcome is dependent on whether a gene pair is heterozygous (carries two different genes), homozygous (carries two of the same genes), dominant (only one gene needed to show) or recessive (both genes need to show). Known as Mendelian inheritance, certain gene pairs will be more likely to be inherited due to their physical makeup and probability. The ability to examine certain genotypic outcome probabilities can be done through by using a Punnett square.

So how can the frequency at which you receive gene pairs affect the evolution of your entire species? Well, frequencies of particular gene pairs can change from one generation to the next due to chance events that affect the reproductive success of certain individuals. Random occurrences that affect the genetic change within a population is known as genetic drift. As random occurrences continue to affect the variation of one population group, the differences between that group and another will expand creating drift. In 1811, the first specimen of the peppered moth (Biston betularia) began to appear in Manchester, England. A light bodied moth with black speckling, it was well adapted to blending in with the light colored lichen and tree bark found in the area. The majority of the moths showed this lighter dominant color, however, a darker variation of the moth existed, as well. Unfortunately for them, their dark coloration made them unable to blend into their environment, resulting in their being prone to predation . As a result, the frequency of dark coloration was about 0.01%. However, with the establishment of the Industrial Revolution, many of the trees became covered in soot resulting in a massive shift in how the environment appeared. And, like a classic underdog story, the light-colored moths became prone to predation decreasing their population, while the darker peppered moths camouflaged better in the pollution and succeeded in increasing their frequency to approximately 98%.

Natural Selection

Natural selection, a theory developed by Charles Darwin, focuses on variations which are directly caused by environmental factors relating to an individual’s fitness within a population group. While fitness may bring to mind athletic individuals, fitness from an evolutionary standpoint instead focuses on the reproductive success of an organism. For example, if humanity was all of a sudden restricted to living in caves, taller individuals might hit their heads on low ceilings, knocking themselves out and limiting mating opportunities. While, shorter individuals who were not at risk of hitting their heads, might be able to spend more time mating, increasing their overall fitness. The better suited an organism is to its environment, the higher its probability to pass on genes to its offspring, gradually increasing the amount of that particular gene within the population. As a result, our cave population would show an increase in shorter individuals compared to taller people across the next generations.

So now as you sit back on your bench all knowing, you wonder which evolutionary force created the doggie variation you’re seeing. Is it mutation? Gene flow or drift? *Gasp*…could it be natural selection?! While you may or may not ever discover which evolutionary force created all of the wonderful dog breeds we see today, remember this, you are in a dog park surrounded by happy dogs of different sizes, shapes, and colors. Now get off your bench and play with the dogs!

Want to learn more about what you just read? Look no further!

  • For a list of 339 different dog breeds click here.
  • To learn more about mutation click here.
  • Want to know more about sympatric speciation click here.
  • For more on the gene flow between yellow and anubis baboons click here.
  • To learn more about the history of the pepper moth click here and here.