Human Variation vs. "Race"

1. The stress I will discuss is heat stress, given that we all (presumably) live in sunny Southern California. Heat can have a number of negative effects on human homeostasis; some of these are obvious, and others are less so. Physically, heat can affect the body temperature and hydration level of an individual, making that person susceptible to heat-related illness and death.  Heat resulting from higher exposure to the sun (or more direct equatorial sun) can increase the risk of things like skin cancer. And, heat can limit human reproductive success in other ways: if the temperature is too high, it is difficult to be outside socializing and looking for potential mates.

2. Short-term: This might include increased radiation of heat from the surface of the skin when exposed to heat stress, in order for the body to maintain a proper temperature.

Facultative adaptation: The release of certain hormones can alter the body’s metabolism in order to assist the body in maintaining an acceptable internal temperature in heated environments.

Developmental adaptations: One theory explaining the loss of body fur in hominids posits that heat stress from the African environment in which humans developed led to an evolutionary shedding of hair for improved thermoregulation. 

Cultural adaptations: Clothing styles and air conditioning might be two of the most obvious cultural adaptations to heat. In the summer, humans tend to wear less clothing, and crank the AC up in order to make the environment artificially cool.

3. Information about human variation can be very useful. By looking at variation in adaptations across clines, it is possible to see physiologically (and culturally) where, when, and why the divergent adaptations took place. Exploring the different responses to stress across time and location is beneficial for understanding how humans (and other species, for that matter) got where they are now, and perhaps where evolution might be heading in the future.

4. The idea of race implies that there are separate “species”, if you will, of humans., when in reality, there is only one species that has adapted differently to different environmental pressures. The development of humans in various geographic locations is something that can be defined and studied scientifically much more objectively than saying something like “why did different races develop”. Defining a “race” of people precisely enough to study them as a group seems doomed from the start, since there is so much variation even within groups from similar geographic areas.   

Language Experiment

Part One: No Symbolic Language

1.     This half of the experiment was relatively easy. It was kind of like playing charades… all I had to do was remember not to speak. I felt like I wasn’t even really participating in the conversation most of the time because I couldn’t contribute any new topics and it was pretty hard to ask questions.

2.     I had the conversation with my wife. She is a sociology major who studied a lot of theory, and I think that influenced the outcome. Basically, I told her what I needed to do for this assignment, and it gave her free license to talk at me for 15 minutes about theories of symbolic and gestural communication. In that regard, yes, she changed the way she talked to me because she knew why I was only using gestural communication. She used the opportunity to tell me about a sociologist named Mead, I gave her a lot of thumbs-up.

3.     The culture using symbolic communication clearly has the advantage in communicating complex ideas. Without it, you can essentially do nothing but respond, and even that is simplistic. You cannot reason, convince someone of something, explain your logic, or describe anything that you can’t physically describe. The culture who uses symbolic communication might view the other culture as inferior, or its members less intelligent, because individuals from the culture would have no way of expressing complex or abstract ideas. Having children, I am familiar with at least one subset of the population that has trouble communicating with spoken language. Of course it affects how people interact with them! A good example is my son, who is 2 but very advanced verbally. He spoke in complete, complex sentences at 1 year old. My wife and I actually got a laugh out of this very idea. People would baby talk our son, and he would respond with a very grown-up sounding answer. Once people realized he could communicate, the way they spoke to him was a very different story. They figured that because he could speak, his intellectual development was greater than they had assumed because of his age. Children are one group who have yet to develop the ability to communicate with spoken language, and this is reflected in our culture as infantilizing “baby talk”: because a child cannot speak, he is expected also not to understand. It speaks to the way perceived intelligence is tied to our use of symbolic communication.

Part Two: No Gestural Communication

1.     This part was much harder than the first! I kept slipping up during the 15 minutes and my wife would catch me. Nonverbal communication just happens so naturally, it’s really hard to stop yourself from doing it. It requires a lot more effort to control than simply not talking.

2.     She pointed out that it was annoying to listen to me talk, and it was impossible to pick up on emotional cues. My sense of humor is fairly dry anyway, but it was hard for her to understand when I was joking.

3.     Nonverbal communication is very important, especially for giving and receiving social cues and emotion. My wife stated that it would have been hard to understand my intent if we weren’t married and didn’t know each other well. Based on that feedback, I think it’s a very valid point that nonverbal communication, or ‘signs’, are very important in being able to read the intentions or meaning of other people.

4.     I believe I am correct in saying that individuals with autism have difficulty reading and interpreting body language, which hampers their ability to pick up on social cues. Body language is very important in communicating things to other people that symbolic language may not explicitly state; one example might be asking someone if they are okay and them responding “yes” but looking like they’re about to cry. The look on their face communicates more about the real answer to the question than their words. As an adaptive benefit, humans might be able to pick up on emotions like anger, which would allow them to avoid potentially dangerous confrontations, or fear, which could alert them to hazards in the environment that they should be wary of themselves. I don’t know a way in which body language could be a negative adaptation... maybe in poker?

The Piltdown Hoax

            The Piltdown Man hoax initially began in 1912 with Charles Dawson’s supposed discovery of fossilized early human remains in Piltdown, England. Arthur Smith Woodward worked alongside Dawson upon his invitation to the site of the dig and there he was able to gather fragments of skull, which were submitted to his department of the British natural history museum. After Dawson’s death, no further fossils were found at the Piltdown site. Later discoveries of early remains in Asia and Africa seemed to contradict the findings at Piltdown. They did not paint the portrait of human evolution as occurring in a fashion consistent with the remains found by Dawson. In 1940, dating using fluoride estimated the Piltdown fossils to be only about 100,000, a very young age for the type of fossils discovered. Finally, in 1953, even more precise dating technology was available and the Piltdown Man was confirmed to be a hoax. The fossils had been altered with staining and filing to accomplish the ruse.

            One human fault that contributed to this famous hoax was pride. Dawson was interested in his own reputation and personal success, as was Woodward with the reputation of his department. Instead of being interested in furthering their profession, these scientists were self-seeking and out to prove their own value rather than the value of their discoveries to actual reality. Selfishness and pride got in the way of Dawson and Woodward’s objectivity and led to bad decision-making and a lack of foresight as to how their elaborate scheme would affect the scientific community as a whole. However, while bad science created the Piltdown mess, good science resolved it and exposed it as a hoax.

The first critical step of the scientific method involved in exposing the hoax was the asking of questions. The film assigned notes that many scientists of Dawson and Woodward’s era were scared to speak up even if they were reluctant to accept the veracity of the Piltdown man. When the technology became available to actually resolve the questions some scientists had in their minds about authenticity, it was used properly to date the fossils and provide a basis for further explanation. Background research was conducted on the origin of the fossils, a hypothesis was created questioning the dates of the fossils, and then fluoride dating was conducted in order to test the hypothesis. Importantly, the results were communicated to the rest of the scientific community, and the hoax was finally able to be debunked, allowing efforts at researching evolution to be directly properly instead of wasting valuable time and money on rabbit trails created by the ruse.

The “human factor” in science is important in that it guides the questions that are asked. Without human curiosity, the scientific method could not even begin; human interest and the quest for knowledge are therefore undoubtedly critical factors in the advancement of science. However, once scientists have advanced past the preliminary questioning phase of the scientific method, it is important to then step back and let the data do the talking. The hypothesis testing should be a totally, completely objective process whose outcomes should have had no interference by the biases or hopes of the scientists doing the testing. Additionally, I think it’s important that scientists not simply look for evidence that supports their claims, but instead acknowledge all test results and subject their hypothesis to the most thorough testing possible. While advances in technology would almost certainly prevent a 40-year hoax like the Piltdown Man from happening again, it is possible to imagine that data could be altered or concealed, leading to a perhaps less dramatic, but potentially just as serious, false conclusion.

Of course, the Piltdown Man story serves as an important reminder to always, always, always check your sources! Had more scientists asked questions about the find instead of assuming the best about the scientists reporting their data, the hoax might not have been as lastingly successful as it was. And, if more scientists had set aside their hope for an early British human fossil find, there would likely have been a greater willingness to investigate the remains from the outset. It is clearly important never to blindly assume the source you're using is accurate without verifying the data yourself, or ensuring that the origin of the material is reputable and preferably academic in nature (depending on the type of research being conducted). It's important to be reminded of this frequently, especially in an age where much research is conducted using the internet, a medium with wide access and high anonymity. 

Primate Locomotor Pattern Comparison

Lemurs: Lemurs exist only in the very limited, isolated territories of the Comoro Islands and Madagascar. They live in densely forested, jungle environments, and it isn’t hard to see how they have adapted to make the most of the space they occupy. Most lemurs’ time is spent in trees, although there are some families that spend a relatively large amount of time on the ground. Lemurs locomotor patterns include clinging and quadrupedal locomotion, and it is a testament to their isolation that lemurs possess such diverse locomotor traits. Because they face little to no competition with, and predation from, other species, they are able to occupy multiple areas within the forest, both low to the ground and high in trees. Of note are the sifakas, which have extremely large legs that allow them to easily jump between tree environments but restrict ground locomotion to hopping instead of walking; unlike other lemurs, they also have only vestigial tails. The highly specialized locomotor patterns of the lemur are well adapted to their very unique environment.

Lemur

Spider monkeys: Spider monkeys are also primarily arboreal primates. They prefer to remain in the high trees of rainforests and mangrove forests in Central and South America and spend little time on the ground. When they do, they exhibit quadrupedal locomotion; usually, they can be found climbing or using suspensory locomotive traits, like brachiating, to move among trees. The spider monkey’s development of suspensory locomotion is clearly a very useful adaptation to the densely forested habitats in which they live. Generally speaking, it seems less useful to have highly developed quadrupedal locomotion in an environment where much of an animal’s time is spent moving in and among trees (although spider monkeys still exhibit this type of locomotion during the limited times they are on the ground, and when they are eating).

Spider Monkey

Baboons: Baboons are Old World primates that can be found in various terrestrial environments within Africa. They are generally found on savannahs and hills. Baboons primarily exhibit quadrupedal locomotion, and some subspecies have even developed quite efficient bipedal locomotion, especially during feeding. They have powerful hindquarters and legs, and can move quickly across the ground. These abilities can be viewed as adaptations to their generally treeless and open environment: baboons live in relatively arid climates devoid of sheltering trees and forestation, and at the same time face predation from large cats and humans. The ability to use locomotor traits effectively on the ground in such environments is invaluable to the species.

Baboon

Gibbons: Gibbons are rainforest dwelling lesser apes that can be found in south and East Asian locations. They exhibit traits uniquely suited to brachiation, which is the type of locomotion they use most commonly. One such trait is a specialized ball-and-socket joint in the wrist that is able to allow the hand and arm a greater range of motion and agility during swinging. Brachiation is a highly efficient type of locomotion given the rainforests gibbons are native to. With little need for ground locomotion and thick groves of trees to move among, swinging is a useful adaptation for gibbons’ navigation of their environment.

Gibbon

Chimpanzees: Chimpanzees can be found throughout Africa, especially along the Congo River basin. Their primary habitat is rainforest, but they can adapt to living situations in woodlands and savannahs as well. They are highly intelligent and highly adaptable to changes in environmental structure. This is reflected in their unique locomotor patterns. Chimpanzees “knuckle walk” by dragging their knuckles along the ground and using them for support during bipedal locomotion. They can also walk fully upright in certain instances, such as when using a tool or performing a task that requires the use of both hands. Chimpanzees also brachiate when swinging and exhibit climbing and other suspensory behaviors as needed. The variation in environments the chimpanzee inhabits is reflected in the adaptation of its locomotor traits to accommodate various circumstances. The locomotion of the chimpanzee has also adapted to reflect the chimp’s use of its environment, such as upright bipedal locomotion during hand use.

Chimpanzee

Summary: The most pronounced differences in primate locomotive adaptation seemed to occur between the primarily arboreal and the primarily terrestrial primates. It also seemed that the more intelligent, and the more adaptive, primates have locomotor patterns that have adapted in response to their interaction with the environment. Clearly, the huge difference in locomotion between tree and ground primates is directly related to the habitat of each primate, and it is therefore relatively easy to see why the adaptations took place and why locomotor patterns differ so widely between primate species.

Homology Versus Analogy

     The homologous trait I have selected for discussion is hair. Two species that exhibit this homologous trait are orangutans and humans. Orangutans are orange, tree-dwelling great apes and humans are, well, us. Like the orangutans, we possess hair on our heads and bodies, but the properties and purposes of this hair differ greatly between the two species. Orangutan hair is dense and covers most of the body in an even distribution with similar texture and length. Humans, on the other hand, have a high concentration of thicker, darker hair on the scalp and a few certain other areas while having generally thin hair distribution everywhere else, in sharp contrast to the orangutan’s dense full-body covering. According to outside Internet research I conducted on this topic, there are varying theories about the reason for the homology between ape and human hair. These theories include the difference in climate experiences of apes and humans, the loss of hair by humans as a way to rid the body of pests and parasites, and even the loss of thick body hair by humans as a response to human developments in temperature regulation (such as the use of clothing and more advanced shelters). The common ancestor of both species is the early hominid, which, like other mammals, had body hair.

Human

Orangutan

     An analogous trait can be observed in the hair of orangutans versus the hair of dogs. A dog is a canine originally domesticated from wolves. As described above, orangutans possess thick, dense hair covering most areas of the body. Like the orangutan, dogs possess similar hair, which is generally thick, dense, and found on almost all area’s of the dog’s body in equal proportion. I believe that the common ancestor of dogs and orangutans must have been a mammal and therefore possessed body hair similar in at least some fashion to the hair of orangutans and dogs. 

Dog

Orangutan

Week 2 Post

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