Week 8: Human Variation & Race

Human Adaptation: Solar Radiation

1. High levels of Solar Radiation negatively impacts our survival as humans because of the damage to skin cells and DNA within these cells by harmful UV rays. Our bodies benefit from UV radiation by the stimulation it has on the production of Vitamin D. However, overexposure can lead to a plethora of harmful conditions from sunburn to melanoma.


2.  
Short Term Adaptation: As for a short term adaptation to over exposure to solar radiation, there doesn't seem to be any for humans. Lighter skinned people readily sunburn when over exposed to harmful UV rays, while darker skinned people do not. This adaptation can't be seen as short term at all though.

Facultative: A facultative adaption to solar radiation can be seen through tanning of the skin. If we are exposed to the sun for a long period of time, then the melanin granules in our skin increase and become larger, causing skin to appear more tan. Tanning can be much more apparent in lighter skinned people than darker skinned people, while those with extremely light skin haven't adapted the ability to tan and absorb solar radiation, causing sunburning.

Developmental: As I stated above there isn't a short term adaptation to over exposure to solar radiation, there is however a developmental adaptation by those with darker skin. Darker skinned people produce a melanin pigment called eumelanin, while those with lighter skin produce pheomelanin. This adaptation of darker skin is the product of thousands of years of exposure to high solar radiation and extreme heat.

Cultural: A cultural adaptation to solar radiation is apparent in different forms of solar protection, such as clothing, and shelter. The darker skin of African cultures can be attributed partially to a a lack of large shelters and forested areas, which lighter skinned cultures in Europe and elsewhere did possess. Today the use of hats, UV protective clothing, and sunscreen, allow us to protect ourselves from over exposure the its harmful effects.

3. Studying human variation can be helpful because it can help us identify and create solutions for environmental stressors. One such environmental stressor pertaining to solar radiation is the impact of little sunlight on darker skinned people living in northern territories where the sun shines for fewer hours in a day. This circumstance can potentially lead to Rickets disease in areas such as northern Europe. Studying such complications as Rickets can help us to determine what are healthy, sufficient amounts of solar radiation.


4. I would use race as a means to organize geographically groups of people and how they are affected by environmental stressors pertaining to their geographic location. There are dark skinned people in Africa, and there are dark skinned people in Europe. To group dark skinned people as a race and not take into account their geographic location, would be a huge error in understanding and collecting data.

Week 7: Language Experiment

The first part of the experiment was definitely the easier of the two phases. While my communication was restrained to simple concepts and responses, there was little to no loss of communication as my partner understood my handicap and adjusted their form of communication to aid me so. My partners communication was wildly opposite from mine, as they used big hand gestures, and detailed, precise language to demonstrate what they wanted to communicate. There form of communication became exaggerated due to my lack of communication abilities. If this experiment were represented as two different cultures meeting for the first time and one was able to verbally communicate and the other wasn't, the culture that was able to verbally communicate would have a great advantage in communicating complex ideas. The speaking culture might feel superior to the non verbal culture because of their ability to express more complex ideas, more concisely. This can be expressed in our culture by how the deaf and mute communicate. While the deaf and mute use highly developed sign language that can express abstract and complex ideas, their communication can only be expressed with the minority of our society who know sign language. This can lead to those who don't use sign language and use verbal communication to see the deaf and mute as inferior or in lacking the proper tools for their form of communication.

Maintaining a conversation for 15 minutes and the restraints of the second phase of experiment made communication extremely difficult. I personally could not maintain the requirements of the experiment, and often burst into laughter because of the ridiculous nature of this phase. Non verbal communication signifiers and expressions are just as important as the phonetic and grammatical rules that define our language when communicating with one another. Words and phrases can take on entirely different meanings when paired with hand gestures or facial expressions. My partner had great difficulty with maintaining interest and in absorbing any sort of emotional cues from me, and any kind of joke or sarcastic remark was lost in translation. People who suffer from Aspbergers Syndrome and Autism tend to have difficulty in reading body language. This drastically hampers their social interactions because they are unable to pick up on emotionally symbolic cues and can come off as emotionally unresponsive to someone who does possess this ability in recognition.

Piltdown Hoax

The Piltdown Man otherwise known as "The Bold Hoax", was a hoax in which amateur archeologist Charles Dawson claimed to discover the fossilized remains of a jaw bone of an early human. The remains were discovered in Piltdown, East Sussex, England in the year 1912. For over 40 years after its discovery, the remains were considered to be the missing link between apes and humans, and made a strong case for Darwin's theory of evolution. It wasn't until 1953, when carbon dating had come into the realm of archeology that the Piltdown Man was proven to be a hoax. The original jawbone found by Dawson was dated to only be 100 years old, and was more than likely the product of an altered orangutan jaw, a human skull of medieval age, and Chimpanzee fossil teeth. Piltdown Man had also been forcefully stained to sell its appearance as a fossil, with an iron solution and chromic acid. Filing marks were found on the teeth with the use of a microscope, and it was presumed this had been done to give the teeth a shape more suited to human diet.

The hoax was successful for several reasons. It satisfied European expectations that the earliest humans would be found in Eurasia. British nationalism played a bias role in the hoax because the British wanted a "first Briton" to stand against hominid remains found elsewhere, in France and Germany.


Skepticism of the hoax had been apparent from the onslaught by members of the scientific community such as G.S. Miller. Miller stated that "deliberate malice could hardly have been more successful than the hazards of deposition in so breaking the fossils as to give free scope to individual judgment in fitting the parts together." Scientists also maintained that Piltdown Man didn't match up with the path of early human evolution as demonstrated by fossils found elsewhere.


Piltdown Man is a direct example of how the faults of human character can spoil the scientific process. The greedy and malicious acts of those responsible for the hoax could have greatly jeopardized years of delicate, and calculated scientific examination by dozens of scientists. Whether those responsible did it for the satisfaction of being immortalized in history books as the champions of evolution, or if money played a role in persuading the hoaxers, we will never know. However, greed and deceit are key players in the character flaws of those responsible for the hoax.

The scientific method proved to be the true champion of justice in the case of the Piltdown Man. Through consistent testing, and the furthering of scientific technology such as carbon dating, the Piltdown Man was brought down by science.

The Piltdown Man is likely not the last time the scientific community will be faced with deceit, forgery, or mistakes. These are all by products of the "human factor" in science, and will continue to exist so long as humans are conducting science. The only sure way to remove the human factor from science would be to conduct science without humans at all. An improbability unless the human race is one day taken over by advanced life forms from another planet, or by artificial intelligence created by us.

From the Piltdown Man hoax we can learn that deceit and greed have no place in science. Science has nothing to do with fame or fortune and should never be conducted in a manner that supports such desires.

Comparitive Dentition Patterns Among Primates

Lemurs(Prosimians/Strepsirhini): a. Lemurs can be found on the island of Madagascar (an island off the coast of Africa), and the neighboring Comores Islands. They are arboreal creatures and live most of their lives in trees.Lemurs live in a variety of habitats. Some live in moist, tropical rainforests, while others live in dry desert areas.

b. Lemur dentition is heterodent and derives from an ancestral primate permanent dentition of . In the toothcomb of most lemurs, the bottom incisors and canine teeth are procumbent (face forward rather than up) and finely spaced, thus providing a tool for either grooming or feeding. The toothcomb in lemurs normally consists of six teeth (four incisors and two canines), although indriids, monkey lemurs, and some sloth lemurs only have a four-tooth toothcomb due to the loss of either a canine or an incisor.

c. The toothcomb, which is specific to Lemurs is a direct expression of their environment and habitat. It is useful in grooming and can be a handy tool in the harsh and diverse climate of Madagascar.

 Spider Monkey (New World Monkey/Platyrrhini): a. Spider monkey's are found in the tropical rainforests of Central and South America. They thrive in evergreen, semi deciduous and mangrove forests and almost never come down to ground level. These monkeys live in the highest parts of the trees found in rain forests, known as the 'upper canopy'. They prefer undisturbed high forests.

b. Spider monkey dentition is similar to that of all New World monkeys. They have 2 incisors, 1 canine, 3 premolars and 3 molars in each quadrant.

c. Since these primates are found high in tree tops their dentition has developed to facilitate the easy consumption of whole fruit and leaves.

Baboon (Old World Monkey/Cercopithecidae): a. Baboons live in sub-saharan west and north Africa. This area is extremely dry and arrid.

b. Baboon dentition can be characterized by a more elongated arch form, prominent maxillary canine crowns, and second and third molar crowns of greater size than first molar crowns.

c. Baboons eat mostly vegetation consisting of grasses, roots, seeds, but are known to eat small sub-saharan mammals such as hares and birds. This diet along with the behavioral adaption of showing their teeth to demonstrate dominance, has allowed for the evolution of this specific dentition.
 

Gibbon (Lesser ape/Hylobatidae): a. Gibbons can be found in the tropical and subtropical rainforests of India on Indonesia, China, and the islands of Sumatra, Borneo, and Java. They are arborean primates and spend nearly all of their lives in treetops.

b. Gibbons possess noticeable characteristics of their dentition. They have large, dagger-like canines in both the upper and lower jaw. These canines are not sexually dimorphic.
c. Gibbon canines are adapted for eating meat and much like baboons, for showing dominance. 

 Chimpanzees (Great ape/Hominidae): a. Chimpanzees are divided into two subspecies within Africa. The common chimpanzee can be found in west and central Africa, while the Bonobo can be found in the Congo. The Congo River acts as the main dividing line between these two species, and they can be found in a diverse range of habitats from the rain forest to grasslands.
b. Chimpanzee dentition is similar to that of the Old World apes and human species. They are the most closely related to humans out of all the primates. They have 2 incisors, 1 canine, 2 premolars, and 3 molars in each quadrant.
c. Like many primates with pronounced canines, Chimpanzees most likely developed them due to the necessity for tearing and eating meat from flesh and to show dominance.

Summary: Through my findings I have found that dentition patterns in primates are mostly due to their diet. Behavioral patterns have played a key role in the development of prominent canines in some of the larger apes, and smaller, more predominantly herbivore primates developed more square flat teeth for grinding small leafs and fruits.

Homologous and Analogous Structures

1. a. Humans and horses share a common homologous structure respectively, however they are two entirely different species. They are both mammals but share many differences.
    b. The arm of a human and the forelimb of a horse are considered homologous structures. Each structure contains similar bones. A humerus, carpals, metacarpuls, and phalanges. These structures however serve different funtions. The human arm aids in lifting, climbing, use of tools, and countless other activities, while the horses forelimb is mainly used for running. This homologous trait represents a genetic similarity that is evident in all mammals.
    c. Generally all mammals derive from a similar ancestor, and this is evident in similarities in much of their bone structure.
   
    d.

2.  a. Birds and insects share an analogous structure in their wings. Birds are part of the avian family while insects belong to the family of arthropods.
    b. Both species have wings but are composed of completely different structures. Bird wings contain hollowed out bones which allow them to be light enough to fly, but still agile enough to fly at high speeds and altitudes. Insect wings don't contain bones and are mainly extensions of their own exoskeletons. Although the structure of each species' wings are different, they are still functionally similar in the aid of flight.
    c. Although the common ancestor of these two species (which is probably some sort of reptile or fish) did not share the similar analogous trait, they did most likely evolve this structure due to similar environmental necessities.
    d.

Jena Baptiste-Lamarck: Influences on Darwin

Perhaps one of the most influential thinkers and scientists to aid Darwin in his findings of the evolutionary theory was Jean Baptiste-Lamarck. Lamarck's landmark theory was known as the inheritance of acquired characteristics. This theory suggested a dynamic relationship between a species and its environment, and suggested that should a certain species' environment change, that species would change over time to acclimate to its surroundings. A common example of Lemarck's theory is hypothetically expressed through giraffes. As giraffes continually consume leaves at the bottom of trees, they try to reach leaves in higher branches. This straining force brings new tissues to the neck, elongating it and passing this new trait onto its offspring. This theory, which has since been disproved was influential to Darwin in accumulating his own theories. It helped Darwin to conclude that organisms that are better suited to their environment will benefit from its resources. Lamarck differed in that he believed organisms were constantly evolving upwards towards greater complexity and perfection, while Darwin's theory of natural selection held that natural selection acted on random variation, not a constant improvement.
Darwin's publication On the Origin of Species was and still is heavily opposed by the church. In Darwin's time the church held great precedence over all scientific and philosophical discovery, and to make any verbal or written opposition to the church could lead to ones imprisonment and or death. This heavy constraint by the church only invigorated Darwin more to publicize and educate the public of his findings.



Sources: 

Introduction to Physical Anthropology text

http://www.pbs.org/wgbh/evolution/library/02/3/l_023_01.html