Human Variation and Race

HEAT

1. Environment Stress:  Heat can negatively impact the human body in many ways.  First, it can disrupt the homeostasis of one’s body.  Homeostasis refers to the body’s tendency to seek and maintain a condition of balance or equilibrium within its internal environment. When body temperatures reach dangerously high levels it affects many parts of the body.  In the brain, the hypothalamus regulates body temperature; however, extreme heat can impair brain function, which can affect judgment and produces irritability.  The central nervous system is also affected by extreme heat.  When a body overheats, fatigue occurs, slowing down the operation of the brain, nerves, and spinal cord.  Additionally, muscles often cramp and spasm as they attempt to sweat out water and sodium as hyperthermia sets in.  Heat can also cause the heart to beat faster.  As blood vessels dilate to shed heat, blood pressure drops, which triggers the heart to beat faster in an attempt to re-regulate blood pressure.  Even the body’s kidneys are affected by heat.  Heat can cause dehydration because the body is losing moisture as it sweats.   Once dehydration sets in, the kidneys store more toxins that would usually be expelled during urination.

2. Four types of Adaptations to Heat Stress:  Fortunately, the human body has developed adaptations that allow it to stave off environmental heat stress:

Short Term Adaptation:

The human body is equipped with sweat glands that are distributed throughout the skin that allow for evaporative cooling to occur.  As one sweats, the sweat evaporates and cools the body.  This is a useful adaptation, though not foolproof.  High temperatures combined with humid conditions make it harder for the body to sweat and lose excess body heat.  The more moisture in the air, the more difficult it is for sweat to evaporate.

Facultative Adaptation:

Vasodilation is another mechanism the human body utilizes for regulating heat.  Vasodilation allows the capillaries near the skin’s surface to widen in order to increase blood flow to the skin.  This takes the heat carried by the blood away from the body’s interior and allows the heat to be emitted from the surface of the skin.  The visible effect of vasodilation is a flushing or redness of the face and sometimes body.

Developmental Adaptation:

One species-wide adaptation that occurred over numerous generations of human development is the reduction in body hair.  Less hair equates to enhanced cooling effects of sweating.  Our early hominid ancestors were covered with a greater amount of hair on their bodies, however, this adaptation made survival easier in the hot, dry climates of Africa.

Cultural Adaptations:

In addition to adaptations that occur naturally in the human body that enhance survival in excessively hot climates, there are also cultural adaptations that have arisen that make survival in heat more common.  Commercial sports drinks have been created to offset the effects of extreme heat and dehydration.  Sports drinks replenish lost mineral salts in the body and allow for rehydration to occur.  Light, loose fitting clothing has been designed to protect the body from the elements of the sun, but is light enough to allow heat to escape and evaporative cooling to occur; head coverings are also useful tools to reduce exposure to heat and sun.  Sunscreens have been developed to block out harmful UV rays.  People living in remote or undeveloped habitats must seek out shaded/covered habitats to alleviate the extent of heat exposure.  In modern cities, most new homes are built with air conditioning, insulation, and energy efficient windows, all of which allow for cooler temperatures.

3. Benefits of Studying Environmental Stresses that Affect Human Variation:

a)    By understanding our adaptations, we can better understand what mechanisms are in place to protect us when exposed to harsh or unfamiliar climates. 

b)    Studying human variations that are due to environmental stress will allow us to better understand evolution.  By learning about the adaptations that affect humans, we can better appreciate the development and differences between all species.

c)    Environmental impact on human variation also proves that there are no distinctive physical features that are based on race.  The color of one’s skin, for example, has nothing to do with race, and everything to do with melanin levels in the skin.  People who live in regions with a higher exposure to UV radiation have developed higher levels of melanin to protect their skin from ultraviolet radiation, which generally results in darker colored skin.

4. Understanding the Myths of Race Based on Physical Appearances

I could not use race to understand the variations in the adaptations I listed in question two.  The short term, facultative, and developmental adaptations are species-wide adaptations that benefit all humans, regardless of race.  Only the cultural adaptations to heat are affected by region or culture.  By understanding the environmental impact on physical variation allows one to understand that race does not explain the differences in appearance of humans.  To understand that having red skin is not a racial distinction, but rather an adaptation that is attributed to the body’s response to high altitudes allows us to extinguish racial stereotypes from our minds.  Knowledge and understanding of physical adaptations prove that humans are all surprisingly similar; the differences that have arisen are not a result of race, but instead have occurred and have sustained because they have proven to be favorable traits that increase the rate of survival in our species.

Language Blog

LANGUAGE BLOG

Part One

v For this assignment, I spent twenty minutes trying to converse with my twelve year old brother without speaking, writing or using ASL.  This was very, very difficult for many reasons. First, he was getting very frustrated with me because he could not understand what I was trying to say. Second, the conversation about a simple topic took infinitely longer than it would if we could verbally communicate.  What I noticed about his reaction to my inability to speak is that he had a very difficult time talking to me without my ability to respond.  One improvement that became apparent with this form of communication is that there is much greater eye contact; you cannot take your eyes off each other when attempting this form of communication otherwise the conversation ends, which may inadvertently increase the personal connection between people.

v My partner was definitely in control of the conversation.  I could only try to answer him, but I was unable to initiate portions of the conversation so he was the only party who could initiate and carry on the conversation.  I had to keep tapping him in order to get his attention when he looked away so that he knew I was trying to tell him something.  He definitely had the balance of power in the conversation. Admittedly, it was the longest 20 minutes of my life.

v The only culture that could communicate complex ideas within their population would be the culture that has mastered verbal communication.  There is only so much that you can communicate with bodily motions.  You can demonstrate how to do something or where to go without verbal communication, but trying to explain what, when, or why is virtually impossible without verbal communication. Therefore, a population that lacks verbal communication would be very limited in their knowledge and would be much more reliant upon one another because every instruction has to be physically demonstrated.  Cultures that can verbally communicate have the ability to be more mobile, educated, and autonomous.  A speaking culture would certainly believe that a culture that does not use symbolic language is very unintelligent, primitive, and inferior.  In the modern world, the only humans I can think of that do not speak are nuns and monks that take a vow of silence.  Unfortunately, these individuals do not represent an entire culture, but rather small religious sects within wider communities and cultures.  These individuals usually have the ability to communicate, yet they choose not to.

Part Two

v This segment of the experiment was significantly easier because the ability to communicate verbally allowed this conversation to be more relaxed and comfortable for both my partner and myself.  We both noticed, however, that there are multiple aspects that make this form of communication difficult.  First, talking without altering one’s tone is nearly impossible because it is a habitual human behavior.  Second, it is much more difficult than it seems it would be to speak without moving one’s eyebrows.  It requires complete concentration to speak without making bodily movements, eyebrow contortions, and tone fluctuations.  Neither party had difficulty understanding one another, but the conversation was altered by our inability to physically embellish our thoughts.  This second portion of the experiment was very educational and amusing because we realized how much humans take the ability to embellish speech for granted.

v I believe this experiment proves that at one time, humans relied almost exclusively on the ability to physically communicate.  Non-speech language allows humans to express excitement and emotion, which are vital components in complex communication.  With the use of non-speech language humans are able to more effectively express anger, happiness, sorrow, fear, and urgency.  Even without the utterance of a single word, a perceptive individual can read body language to comprehend how another person is feeling at any given time.

v The adaptive benefit of reading body language allows one to sense danger by gauging the reactions of other humans or animals.  This is an effective tool for hunting or escaping danger posed by nearby predators.  When competing for resources or mates, it is also helpful to read the body language of competitors to ascertain how willing they are to fight you for what they hope to gain.  You can also read body language to judge the passivity of other individuals, which allows you to know when or when not to act aggressively.

Some people are by nature very tense, while others are very shy; these kinds of people have difficulty relaxing around people they are not familiar or comfortable with.  If one were to judge this type of individual by body language alone, a false opinion of their personality and/or character would most likely be formed.  An excellent example of a situation in which people often give off unreliable body language is during interviews.  The desire to impress hiring professionals makes even the calmest individual anxious.  Times of stress and emergency situations also tend to reveal erratic temperaments and body language.

The Infamous Piltdown Hoax

            In 1912, a fossil was unearthed that scientists believed to be the missing link between man and apes.  The unusual skull remains were discovered at Barkham Manor in the village of Piltdown, England.  Amateur archeologist, Charles Dawson excavated the gravel pit in Piltdown and found a human-like jaw and numerous other skull fragments.  They also discovered primitive tools and various animal fossils.  The authenticity of Dawson’s monumental find was verified and announced by Arthur Smith Woodward of the British Museum.  Their findings showed that the remains belonged to a primitive hominid that was estimated to have lived 500,000 to 1 million years ago.  This discovery was monumental because it was the first evidence of ancient primitive ancestry that could be linked to modern humans to be found in England.  It was considered to be vital to science because this fossil purportedly proved that the large brain developed in early hominids before their ability to walk upright had developed (this theory was later falsified).  The prominence of this find was also used to further support Darwin’s Theory of Evolution.  The Piltdown fossils were kept safely locked away in England for nearly 40 years, thus suspicions were slow to arise that would oppose their authenticity.  It wasn’t until 1953 when Kenneth Oakley performed fluorine tests on the remains that he was able to discover that the remains were significantly younger than Dawson originally claimed.  Once the scandal broke, further examination and texting proved that the skull and jaw originated from two different species: a human and an orangutan.  The teeth of the orangutan were filed down to purposely cause them to resemble human teeth.  The reality was startling for the scientific world because prior to this event, scientists operated on a system of honor.  The person responsible for this shameful act of deceit not only devalued the reliability of scientific discovery, he also delayed and distorted the understanding of the origins of mankind for numerous decades.

            Like any other field, science is extremely competitive.  To be the first person to discover a new species, a cure for a deadly disease, or a new scientific methodology or tool would be a dream come true for any enthusiast of science.  Although we will never know the true motivations for this fraudulent act, it could have easily been motivated by national pride, the desire for recognition, acceptance in the scientific community, wealth, or even fame.  Wherever there is the potential for reward, there will always be the potential for dishonesty.   It is for this reason, that all experiments must be testable and precisely reproducible so that all scientific merit can be verified.

            From 1912 until 1926, scholars and scientists remained sufficiently convinced that the Piltdown fossils could authentically explain the evolutionary link between apes and humans.  However, in 1926, the Piltdown gravel was found to be less ancient than originally claimed.  Additionally, other fossils were being discovered around the world that conflicted with the findings that were produced from the Piltdown skull.  Lastly, technology improved that could be used to accurately verify the age of fossils.  When Oakley tested the fluorine levels, the tests proved that the Piltdown Man fossils were all fake.  The jaw was orangutan, the teeth were filed down to resemble human teeth, and the fossils had been boiled and stained with chemicals in an effort to make them look ancient.

            It would be impossible to remove the human factor from science.  Scientific inquiry leads to new discoveries, all of which are made possible by the hard work and dedication of scientists. Yes, this hoax was devastating to the field of science, but to quote an old proverb—you can’t let one bad apple spoil the bunch.  This hoax illustrated the need for more stringent verification of discoveries.  In the end, it was an excellent learning tool because it resulted in a better system of checks and balances to be instituted in order to prevent a future Piltdown reoccurrence.

            Piltdown teaches us all that even those who are considered experts in a field have the potential to manipulate the truth in order to reap some form of profit, so be careful what you choose to believe.  It also proves that sometimes we believe what we want to believe.  With all of the fossil evidence that was being discovered in Africa and Asia, the Europeans desperately wanted to believe that their ancestors had indeed been the first of the human race.  Sadly, it was this desire that prevented them from seeking the truths that were available all along.

Primate Locomotor Patterns

A)   Lemurs, specifically those who fall under the suborder Strepsirhini, live in the eastern rainforests of Madagascar, an island off the Southeast coast of Africa.  Although there are over 100 species of lemurs, this specific species called the Ruffed Lemur prefers to live in the crowns of large and tall trees, where they remain throughout the four seasons of the year.  This choice of elevated habitat is most suitable because this part of the rainforest receives vast amounts of rain each year.  This is an ideal location for the lemurs because fruit, flowers, and young leaves are ample and can be eaten during the warm seasons, while mostly flowers, leaves, and bark are consumed during the colder seasons.  Lemurs consume as many as 132 different plant species.  Fruit and nectar make up the highest percentage of the lemur’s diet.

B)   The most common locomotor patterns of lemurs include quadrupedalism, which refers to locomotion in which an animal uses all four legs/limbs.  Lemurs also leap, cling, suspend, bridge, and utilize bimanual and bipedal movements.  Lemurs are considered both terrestrial (on land) and arboreal quadrupeds (a primate that use their four limbs to move through trees).  Leaping is the predominant method lemurs use to move through trees.  Although some primates use their tails to grip branches, lemurs instead rely on their limbs for movement and they utilize their tails as a balancing apparatus.

C)   The lemur’s pattern of locomotion has been greatly influenced by its environment.  For example, it has had to adapt to living in trees due to the immense rainfall that occurs in their habitat each year.  Because lemurs regularly move through treetops, their limbs have developed in order to allow them to leap branch to branch, run and bound through the trees, and also walk on the ground.  Because lemurs are capable of moving seamlessly both on land and through the trees, they are able to enjoy a more diversified diet due to the large areas available for foraging.

A)   Spider Monkeys are part of the parvorder: Platyrrhini.  This order of primates includes five families, which can be found in Central and South America and also in portions of Mexico.  Spider monkeys are a type of New World Monkey, which lives high in the tree canopies of the dense tropical rain forests.  The primary diet of the spider monkey includes fruit, nuts, honey, insects, flowers, bird eggs, spiders, bark, and small mammals, most of which can be found in the rain forest treetops.   It is very rare for a spider monkey to be seen on the forest floor.

B)   The Spider Monkey pattern of locomotion is characterized by the use of the animal’s four limbs and their tail.  Even without a thumb, this arboreal (tree living) species expertly swings through the dense canopy of trees utilizing their thin arms, legs, and tail.  When standing or walking on two feet, the spider monkey uses its tail for support. 

C)   The Spider Monkey’s environment has had a great impact on its locomotor patterns.  One example of the environmental impact is the development of the species’ prehensile tail.  This adaptation aids the spider monkey in climbing and gripping quickly to enable it to avoid prey and to compete with other animals for food.  Additionally, these monkeys have developed a bare patch or gripping area on the tail known as a friction pad, which allows for safer and faster mobility. 

A)            Baboons: All of the five different species of baboons live in Africa or Arabia.  Baboons generally live in semi-arid habitats like the savanna, yet some live in tropical forests.  Baboons spend most of their time on the ground, yet they sleep, eat, and watch for predators from the safety of the trees or rocky cliffs depending on their habitat.  The baboons of the savanna live in large troops, which are governed by a system of hierarchy.  Baboons forage for fruits, grass, seeds, bark, and roots, but they also hunt for meat and are known to eat birds, rodents, and sometimes livestock.

B)            Baboons walk quadrupedally on all four limbs.  Baboons do have tails but they are not prehensile, therefore the tail cannot be used as an additional hand.  Even without the use of a prehensile tail, baboons are able to climb into tree canopies to seek out food, sleep and avoid predators. 

C)            The environment has impacted the locomotor patterns of the baboon over time.  Since baboons are very large, they had to develop strong limbs that would enable them to climb and to move fast to escape predators, while also aiding them to fight off competitors.  Since baboon tails are not prehensile, this species relies solely on their legs and their arms for movement.  Also, since baboons walk on all fours, they have no free hands to carry the food that they forage.  As a result, a cheek pouch has developed into a specialized sac, which can be used to store foraged food.

A)        Gibbons are smaller apes that live in the dense forests of southern Asia, covering the region that stretches from China to Laos, northwestern Vietnam, Borneo, and even to India.  Gibbons are predominantly tree dwellers who use the forest canopy for safety and as their source of food.  Gibbons predominantly eat fruit, but they also tend to consume flowers, shoots, insects and leaf buds. 

B)        Gibbons use an interesting variety of locomotor patterns.  Their most common form of movement is brachiating, which allows them to move with an arm-swinging motion through the jungle at up to 35 miles per hour.  Brachiating also enables gibbons to swing and reach fruits that are at the end of branches.  Gibbons have also developed the ability to move bipedally.  When they are spotted on the ground, they often walk on two feet and swing their hands over their head for balance, since they have no tails to assist with this motion.

C)        The environment has greatly impacted the Gibbons’ trait expressions.  Because gibbons are the most threatened primates on Earth, they must seek safety in the forest canopies.  To move rapidly and efficiently through the dense forests, gibbons had to develop into brachiators, which are arm-swinging primates.  Another trait that developed due to their tree-dwelling lifestyle is the gibbons’ hook-shaped hands, which are used for grasping branches.  A third trait that arose in this species is their extremely long arms used to grasp faraway limbs, and their strong legs for propelling and grasping. These various traits allow for the speed, agility, and acrobatic movements the gibbons require for their survival. 

A)        Chimpanzees are primates that generally live in the rainforests, woodlands, dry savannas, and grasslands of Africa.  They tend to live in communities with several dozen other chimpanzees and animals.  A chimpanzee’s diet consists mainly of fruit, leaves, seeds, blossoms, stems, and even bark.  They sometimes consume insects, eggs, and some meats such as other monkeys.  Chimpanzees make use of both the ground as well as the trees, where they collect most of their fruit and build the nests they sleep in at night. 

B)        Chimpanzee’s patterns of locomotion include both quadrupedal knuckle walking and bipedalism.  Although this is true, they tend to do most of their walking on all fours.  The ability of chimpanzees to walk on four or two legs is incredibly useful when they use their hands to make tools.  Sticks are used by chimpanzees to remove insects from their nests, they use stones to smash open nuts, and they use leaves to drink water from.  All of these capabilities require chimpanzees to move bipedally.  Another function of chimpanzees being able to move bipedally is their ability to swing from branch to branch through the trees, where they gather most of their fruit and do most of their eating. 

C)        Chimpanzee’s locomotor patterns, which allow them to walk on all fours as well as on two feet, are the primary reason that these animals are one of the few that employ tools.  These tools allow chimps to break into food and eat while simultaneously standing on two feet.  Chimpanzees originally developed this trait so that they would be able to carry food and see over visual barriers in order to see predators and get a better view of their surroundings.  Another function chimps adapted due to these locomotor patterns is their ability to swing in the trees while gathering fruit, so that they do not have to walk as far and as long to get food and so they can carry their food while swinging through the trees. 

It is fascinating that in each instance, the aforementioned species all underwent trait alterations, which were triggered by forces in the environment. Some developed the ability to brachiate, others were able to alter their locomotion in order to transport goods or to utilize tools.  Gibbons and chimpanzees developed the capacity to bridge, which is the ability to stretch the body across two opposing branches.  Each new trait that develops empowers the apes to overcome challenges and dangers they face on a daily basis in their natural habitats, which, of course, is the basis of the Theory of Evolution by way of natural selection.  Clearly, the environment is one of the most dominant forces that causes the evolution of species by allowing for the elimination of traits that are unnecessary, and most importantly, by allowing other traits that are vital for survival to emerge.