Human Variation & Race Blog

1. Select only ONE of the following environmental stresses: (a) heat, (b) high levels of solar radiation, (c) cold, or (d) high altitude. Discuss specifically how this environmental stress negatively impacts the survival of humans by disturbing homeostasis.

The disruption of homeostasis can occur with high levels of solar radiation which is an environmental stressor. The reason High levels of solar radiation negatively impact the survival of humans is due to the fact that while UVB radiation penetrates through the epidermis layer, UVA radiation has the ability to go beyond the epidermis and penetrate straight through to the dermis layer. Although UV radiation does provide stimulation of vitamin D production through UVB waves which is beneficial to humans, overexposure of UVB and UVA rays can still cause dangerous sunburns and short-term suppression of immune systems. This type of UVB exposure becomes directly absorbed by the DNA within cells, and this absorption has the dangerous potential to cause genetic damage that could lead to skin cancer. Any genetic level damage directly disturbs homeostasis and is potentially life threatening to humans.

2. Identify 4 ways in which humans have adapted to this stress, choosing one specific adaptation from each of the different types of adaptations listed above

SHORT TERM: Humans have adapted to exposure to the sun in appropriate and measured timeframes that are unrelated to vitamin D production. Short term adaptations consist of enhancing mood and energy through the release of endorphins, melatonin regulation through the "third eye" of the pineal gland photoreceptors, regulating body temperature, UV radiation also enhances skin barrier functions and helps in treating skin diseases, such as psoriasis, vitiligo, atopic dermatitis, and scleroderma.

FACULTATIVE:  the process of developing facultative pigmentation is better known as cosmetic tanning. Facultative Pigmentation is the level of an acquired tan developed by an individual exposed to ultraviolet light. It protects us from the harmful UVB radiation waves is skin tanning.  The process of tanning occurs when exposure to sunlight activates a protective mechanism through increased melanin production in the epidermis layer.  Melanin is our body’s naturally produced sunscreen and the degree of tanning will take place until the overexposure to UV rays is reduced. 

DEVELOPMENTAL: You can see developmental changes in populations that have a higher concentration of people with darker skin.  Higher concentrations of melanin are found in individuals with dark skin which acts as a natural sunscreen that a person’s body produces.  Populations that are more exposed to the sun’s harmful rays reside in mostly in African and Tropical climates.  In this regard, geographical locations makes a difference in the number of people with darker skin however, those with darker pigmentation can tan and sunburn as well. Regardless, of where one lives, it is evident that too much exposure to solar radiation can result in skin cancer and not enough exposure can result in a Vitamin D deficiency which results in the inability to process calcium and also weakens bones.  Populations that reside in locations with limited sunlight can suffer adverse effects such as developing diseases like rickets, which is when bones are too weak and can’t support the weight of the body as it grows. 

CULTURAL: Cultural adaptations to protect a person’s body from harmful UVA /UVB rays has occurred through clothing, adequate shelter and with the development of sunscreen. Clothing and shelter gave humans the ability to protect themselves from direct exposure and in turn resulted in the reduced levels of melanin production. Even by migrating to environments that helped protect from harsh UVA/UVB elements such as forested areas also helped to reduce sun exposure.  Throughout history it is evident that skin pigmentation has become lighter in various populations more specifically northern geographical regions and darker skinned populations are more concentrated  in southern regions that are closest to the equator.

3. What are the benefits of studying human variation from this perspective across environmental clines? Can information from explorations like this be useful to help us in any way? Offer one example of how this information can be used in a productive way.

By studying the vicissitudes of diverse sample populations over time, this enables us to assess and see how environmental stressors affect various populations.  One example would be studying the high rate of sickle cell anemia in black populations. This type of research can help scientists identify and develop treatments to hopefully cure or just help other people diagnosed with sickle cell anemia and not just limit it to one population.  Also, studying the cause and effect of rickets in populations with fair skinned people can help with the understanding of the need for sunlight and how much of it is actually necessary to avoid the certain diseases.

4. How would you use race to understand the variation of the adaptations you listed in #2? Explain why the study of environmental influences on adaptations is a better way to understand human variation than by the use of race.

I believe that studying diverse races is an important aspect of understanding variations of adaptations. I think race tells us quite a bit and although it won’t answer all the questions, it would certainly give us great insight. However, going by race alone would be rather myopic and would have many limitations in regards to the information that we would be looking for. Therefore, studying environmental influences of vast populations as a whole would be more telling as to how outside stressors have influenced adaptations in humans overall.  

With or Without Language

SYMBOLIC LANGUAGE

I must admit that this experiment was immensely challenging for me especially since I'm a very social and emotive person. I grew up with people telling me "you talk too much" as well as being known for gesticulating quite a bit when I talk. So to completely eliminate any speech felt almost crippling to me. I conducted this experiment with my immediate family and my boyfriend and they were very amused at my attempt to communicate without verbalizing anything.

My boyfriend even made a crack about how I managed to control the conversation even with silence by just emoting through dynamic physical gestures. They didn't necessarily alter the way they communicated with me other than to poke fun of how the silence was driving me crazy especially when I have a tendency to get loud when I'm trying to convey a point especially when I nobody is listening.

Although in the beginning it seemed as though my family and boyfriend had control over the conversation as they had the power to speak, once they began to ask questions about why I took Anthropology and what this experiment has to do with the subject I began to really take over using my hands, pointing to things in reference to the point I was trying to convey and not letting them get a word in (a bad habit I have) when I wasn't finished emoting my points. My sister thought it was hysterical when I was getting frustrated when they all began to talk over my physical form of communication to see how I would overcome such an obstacle. It was very difficult in those moments as I couldn't raise my voice like I normally would to get my point across and I felt invisible when I couldn't use my voice.

The power balance was equal in some areas but not in others. When I was addressed one on one I had more control but when everyone began to chime in at the same time turning the focus from me unto each other, the power definitely shifted and it was uncomfortable and incredibly frustrating. However, what I've come to understand is that symbolic speech also forced me to listen more and really take in what the others were saying and I was able to pay attention to their body language more which also communicates volumes. This was a learning experience for me as it made me realize that silence is also golden and provides more power than most people realize.

In this regard, it has become apparent that although verbal speech is powerful, silence and symbolic speech can be just as powerful as it forces you to pay attention to things that you wouldn't normally do when actively talking with someone. I think in a conversation between two different cultures where one uses spoken language and the other doesn't, I would think that both cultures would have equal advantage as long as intently listening to one another is the primary focus. Even if a culture doesn't speak, the culture that does can still listen by the way the non-speaking culture communicates. Although it would be simpler to use verbal language, silent communication can be just as effective and profound as verbalization.

After researching about cultures who value silence, I found that in Japan, they've historically associated silence with truthfulness. This belief of the value of silence originated in Zen Buddhism, where verbal language was discouraged and silence was encouraged because it was believed that enlightenment could not be attained by talking about it. In this capacity, I've come to realize that silence can be just as powerful as any verbal communication.

SCIENCE BE FOOLED: THE PILTDOWN HOAX

The Piltdown Man

The Piltdown Man came during a time when scientists were desperate to find the missing link in the theory of evolution. After Charles Darwin published the origin of species in 1859, the race was on to search for evidence that would uncover the ancient ancestor that linked apes to humans. There were many sensational findings in Germany and France of ancestral fossils  that we've come to know as Neanderthals. However, British Scientists, were desperate to prove that Britain were also an integral part in the story of evolution, and the "proof" they needed came from the Piltdown Man which gave British Scientists the right to claim Britain as the birthplace of mankind.

The Piltdown fossils were found by Charles Dawson in Sussex, and he passed on his findings to Sir Arthur Smith Woodward. Dawson went on to claim that before 1910, he was handed a dark stained and thick piece of human skull by a workman during the excavation process. After closer inspection and recognizing that it might be part of an ancient human, he continued to dig until he found and collected more pieces of skull.

He corresponded with Woodward in February of 1912 informing him of his exciting discoveries where Woodward made the trip to join him in excavating additional findings at Piltdown. It was there that both found additional fragments of the supposed human skull as well as the bones of ancient animals, primitive stone tools and an ape like jaw.

After these discoveries, Woodward proceeded to construct a skull that was supposedly the missing link of evolution between humans and apes. Being that it was determined that the brain size was the same as that of modern humans, yet possessing an ape-like jaw, the Piltdown Man was born

The Piltdown Skeptics

Although Woodwards discoveries seemed exciting, not everyone was buying into the validity of his findings. Some scientific experts overseas voiced their skepticism as they didn't believe that the skull and jaw were a match. There were arguments from scientists who asserted that the fossils looked more like a mix of human and ape fossils and weren't even the same species. However, Dawson and Woodward found a canine tooth in 1913 that they claimed was additional evidence proving the link.The canine tooth was of medium size and looked a cross between an ape's and a human's tooth. To Woodward, this was confirmation that the jaw was not from an ape but an ape man creature. Dawson also claimed to have found a molar tooth and several pieces of skull not far from the original Piltdown site. They looked similar to the Piltdown man and was subsequently named the Piltdown Man II. With two supposed ancestral findings along with an endorsement from the Natural History Museum, the Piltdown Man was accepted by most scientists as the missing link between man and apes. 

The Hoax Exposed

Although the Piltdown man was generally accepted throughout the scientific community for a time, it came into question once gain in the late 1940's as new technology for dating fossils was developed. Dr. Kenneth Oakley from the Natural History Museum tested the Piltdown fossils in 1949 and concluded through his findings that the neither the skull nor jaw were as ancient as originally thought. In order to gather more evidence to prove their findings, Dr. Oakley worked with Professor Joe Weiner and Sir Wilfrid Le Gros Clark from Oxford to conduct further extensive testing of the Piltdown remains. They found that the human wear on the teeth was created artificially using a file and was done on an orang-utan jaw. In addition, the thick boned human skull was from a more recent time than originally stated. What was more surprising was that the skull was found to have been boiled and stained to give the antiquated look on the Piltdown gravels. This is not to say that all the mammal fossils weren't genuine however, it was clear that they were purposefully planted.

The news broke of the Piltdown Hoax on November 21st 1953. The headlines created much embarrassment for The Natural History Museum inspiring Weiner and Oakley to proceed in trying to expose the one responsible for the hoax.

Scientists are Human

The scientific community is a very competitive field where one's legacy is predicated upon revolutionary theories and discoveries. Like any human who is ambitious and looking to leave their mark on society, groundbreaking scientific discoveries are what last the test of time and could make the name of the discovering scientist remembered for centuries. With this being said, although the Piltdown Man was proven to be a hoax, the individual who created the hoax is still a mystery. However, the fact that many in the scientific community were actively searching for the missing link between humans and apes, it's not surprising that a scientist or scientists felt that they had found an opportune moment to make their name in the history books by deceiving the scientific world. It is reprehensible for sure however, the scientific community can be quite competitive and filled with massive ego's so it's no wonder someone would go to this extreme to fool the scientific community.

The Process of Discovering the Fraud

The process in which scientists discovered the Piltdown hoax was using scientific objection and diligently testing the original hypothesis with the help of new emerging technologies such as new fluorine testing, and new fossil discoveries being examined using advanced microscopes. These new tools helped to provide the clues to eventually determine the truth. The Fluorine tests were a key component in helping scientists test the natural level of fluorine in the fossils which in turn allowed them to calculate the real date of the fossils.

Science and The Human Factor

There really is no way to remove the "human" factor from science unless you replace human scientists with artificial intelligence. What I do believe is that with the continuous advancement of technology, it significantly help in lessening human error, the chances of future hoaxes and it provides more advanced means to conduct extensive testing to discern fact from fiction.  However human error is still always a possibility.

Lesson Learned?

I've never been one to take anything for face value however, being that I don't have a high aptitude for science; I would probably be inclined to buy into a lot of what I read in regards to scientific discoveries. This would be a huge mistake on my part and it has become clear that I need to further educate myself by continuing to research and question anything that either doesn't seem logical or that I don't truly understand. Regardless, we should never allow others to think for us but we should keep our minds open that what could be determined as fact or fiction today could be proven otherwise tomorrow.

 

Comparitive Primates

Primates to be Compared

Sifaka (Prosimians/Strepsirhini representative)

  Spider Monkey (New World Monkey/Platyrrhini representative)

Olive Baboon (Old World Monkey/Cercopithecidae representative)

 

Lars Gibbon (Lesser ape/Hylobatidae representative)

 

Chimpanzee (Great ape/Hominidae representative)

 

 

 

 

 

 

 

Environment

Sifaka (Prosimians/Strepsirhini representative):

Sifakas are beautiful primates that are on the endangered species list. They reside only in the forests of Madagascar spending most of their time in the tree's. Being that they mostly dwell in tree's,  Sifakas remain upright, and leap swiftly from tree to tree using their powerful hind legs to jump. On the ground, they use a two legged sideways hop to move swiftly as well. Sifakas are beautifully colored primates and are strictly vegetarians. They eat leaves, flowers, fruit, buds, and tree bark. Interestingly, sifakas have been known to eat hundreds of different plants that they find in the Madagascar forests. Its in the daylight hours that they forage for food and sleep prior to sunset. Their family dynamic consists of living in medium to large groups consisting of ten to thirteen animals. They remain in a firm territory, and mark it using their scent glands. Although various Sifka territories can overlap they will defend their territory by others of their own species. If territory invasions are successful, this usually results in the death of male members, group take over and even infanticide.  All sifakas living in Madagascar are threatened by the destruction of their forest habitats. In addition, they are also hunted for their meat.


Spider Monkey (New World Monkey/Platyrrhini representative):

The spider monkey is a primate that can be found in the tropical jungles from Southern Mexico to Brazil. Due to their strong dislike of mountainous terrain's, Spider Monkeys generally don't enter the deep southern regions of South America. The name spider monkey is thought to be derived from the way these primates hang from the tree's. They're often seen with all four of their hands on separate branches.The diet of the spider monkey consists of mainly eats fruits and berries and are thought to play a crucial part in spreading the seeds of various plants throughout the South American rainforests. For protein they also eat insects and small reptiles and even consume honey when they can find it. The primary threats to the spider monkey is the extensive hunting of them from both humans and larger animals such as the jaguar and the crocodile. In addition, humans have also been known to capture them and keep them as pets which has contributed to them being on the "critically" endangered list.


Olive Baboon (Old World Monkey/Cercopithecidae representative):

Olive Baboons are considered one of the largest of the Baboon species. They live in West and East Africa have the largest range of all baboons. Olive Baboons inhabit savannahs, steppes and forests and have proven to be very adaptable to their environments. They live amongst large groups called troops consisting of 20 to 50 members, and could also exceed over 100 baboons. The size of their troop is predicated upon food availability and environmental conditions. Due to them being omnivores Olive Baboons feed on grass, seeds, leaves, cereals, fruit, tubers, small mammals, invertebrates and young birds.
They forage on the ground by day and at night they retreat to the trees or up in the rocks to sleep in order avoid predators. The main predatory threat of the Olive Baboons are lions, leopards, african wild dogs, hyenas, chimpanzees and crocodiles.

Lars Gibbon (Lesser ape/Hylobatidae representative):

Lars Gibbons inhabit the rain forests of Southeastern Asia. They spend the majority of their time in the treetops of the rainforest and even sleep there. They rest in the forks of branches using thier long fingers and strong hands to help them swing high in the trees swiftly and gracefully. They also reside in isolated areas that are in close proximity to large rivers. They love to eat fruits but also partake in leaves, tree bark flowers and plant shoots. On occasion they'll also eat bird eggs, small birds, insects, frogs and other animals. The main threat to their species is loss of habitat due to deforestation.

Chimpanzee (Great ape/Hominidae representative):

 

Chimpanzees inhabit the forest belt from Southern Senegal, he Congo River to Western Uganda and Western Tanzania. They spend equal time on land and in the trees however do most of their feeding and sleeping in the trees. Chimps are very noisy, curious, intelligent, and social primates. They live in communities that range anywhere between 10 to 100 chimps. They share their home range amongst eachother to protect eachother from intruders which is why they sometimes forage for food in groups. Chimps feed on fruits as their principal diet, along with leaves, buds, and blossoms. They also eat berries and seeds directly off the stem with their lips. They eat up to 80 different plant foods, and will supplement their diets with meat from young antelopes, goats even young baboons, colobus monkeys, and blue monkeys. The main threats of the Chimpanzees are humans who hunt them for meat and the Leopard.

 

Body size and Sexual Dimorphism

 



Sifaka (Prosimians/Strepsirhini representative)

Sifaka's are significantly smaller when compared to other living primates.They are approximately 7-9 pounds and their body size is the same as an average house cat with the exception that Sifaka's have significantly longer tails. They have very little sexual dimorphism with the exception of the slight difference in canine teeth size and the difference in fur coloring.

Spider Monkey (New World Monkey/Platyrrhini representative)
Spider monkeys have very little sexual dimorphism. The male spider monkeys are slightly larger than their female counterparts averaging around 24 pounds while the females average around 21 pounds.They range from 1-2 feet with prehensile tails that are up to 35 inches long.

Olive Baboon (Old World Monkey/Cercopithecidae representative)
Baboons range from 24-56 pounds. Olive Baboons are very sexually dimorphic as the males are nearly twice the size of the females. In regards to body size, Baboons are in the middle range in comparison to other living primates.

Lars Gibbon (Lesser ape/Hylobatidae representative)
Lars Gibbons have very little sexual dimorphism. They have very elongated bodies with an arm span of 5ft. Their average height is 3 feet and are 17-26 pounds.

Chimpanzee (Great ape/Hominidae representative)
Chimpanzees are definitley sexually dimorphic. The Chimpanzee males weigh between 75 to 150 pounds. The females weigh between approximately 50-100 pounds. They have very long arms which allows for ease of movement between trees and also helps them when they travel on land.

Trait Influece on Environment

 

As global environments continue to change, these changes have had a significant impact on the body size of the various species of the primates. Depending on the availability of food sources and forests  these primates will adapt in size and physiological changes in their bodies in order to survive and defend against predators. If their primary food source and primary living environment is up in the trees, their bodies will adapt to be more agile and mobile in order to move easily in their changing environments.

 

 



 

 

 

 



Homologous and Analogous

Homologous Structures: Cat & Whale

Homologous structures can be found in the forelimbs of multiple differing mammals such as that of cats and whales. When two or more structures are essentially similar to each other in how they’re constructed but are modified through evolution to perform different functions, they are homologous. When studying the homologous structures in both cats and whales, you will find that the specific form, construction and the number of bones in their forelimbs are very similar. The cat’s forelimb (pictured below) is used for walking and climbing while the whale’s forelimb (also pictured below) is used for swimming.

In addition, although both a cat and whale both have similar vertebrae construction such as the Cervical, Thoracic, Lumbar and Caudal areas, both have unique physical functions. The function of the whales vertebrae is to assist with swimming whereas for the cat, it is used to help walk, run, jump and contort in various positions.

**Whale Image

**Cat Image

Common Ancestor

It would seem that the common ancestor that cats and whales share with with other mammals may possibly be a rat-size animal that more than likely weighed no more than about a half a pound that possessed a long furry tail and lived on insects. Recently scientists have discovered after conducting a comprehensive six-year study of the mammalian family tree, they have been able to identify and reconstruct what could be the most likely common ancestor of most mammals. It was found that the animal had numerous anatomical characteristics for live births that were similar to those of all placental mammals and led to over 5000 living species ranging from humans, elephants, bats, whales, cats and dogs. This discovery has been very insightful in shedding new light on the evolution of all mammal life.

**Possible Ancestor

** Cat and Whale

Analogous Structures: Platypus and Duck

When studying both the Platypus and duck species, both bird types look very similar with features consisting of both featherless necks and heads, and feed on carrion. However, with the exception of these similarities, both of these species belong to different families. Although the duck-billed platypus is an egg-laying mammal which is a behavioral trait that evolved dominantly in birds, it is not related to the avian family by any other characteristic. A duck can lay eggs, fly, swim and although has the same bill as the Platypus, however the duck is from reptile origin.

 

 

 

The duck-billed platypus is a subfamily of mammals. Although they feed their young with milk, they do so by having their milk ooze from glands under the skin, and their young lap it up from a patch of fur. They don’t fly and walk awkwardly on their knuckles to protect their webbing while on land. They also carry venom in their hind legs and they retract their webbing on land to reveal their claws. Ducks however, waddle because of their webbed feet and they can fly. Also their feet have no nerves of blood vessels which make them unable to feel the cold.

 

Analogous Ancestor

The Platypus seems like a hybrid of part bird part mammal and part reptile. We also know that ducks are birds and also have reptile origins as well.