Human Variation and Race

1)      Heat negatively impacts human’s survival because it causes the body to rise to dangerous temperatures. This can result in dehydration, heat syncope (fainting), heat exhaustion, and heat strokes, which can potentially cause damage to the brain or death.

    2)      Short term adaption- Sweat is a short term form of human adaptation towards heat. The human body produces sweat as a way of cooling itself down.  Studies have shown that it is easier for populations to withstand the dry heat of the dessert better than the humidity from the tropical areas. This is because the sweat we produce is easily evaporated, providing us with a quick cooling sensation, while in humid areas sweat cannot evaporate quick enough.

Facultative adaptation- An example of facultative adaptation to heat is peripheral vasodilation. This involves the dilation of blood vessels in the skin, bringing large quantities of warm blood from deep within the body closer to the skin. This is what causes your skin to become red or flushed when you are hot. The heat that was brought closer to the skin can then be removed by radiation or convection.

Developmental adaptation- One developmental adaptation humans have grown into through the help of numerous generations is bipedalism. Although this is currently just an unproven theory, it is still a possibility that we have adapted to heat overtime. Many scientists believe that our early ancestors evolved from being quadrupedal to bipedal to escape the heat that is closer to the ground. Our ancestors could have also stood on 2 feet in order to avoid the direct sunlight that would normally hit them if they were on all fours. This could also have been the reason for our tremendous loss of body hair overtime.

Cultural adaptation- Humans have relied on the use of air conditioners of over one hundred years. We use this as a mechanism to cool the body and avoid dangerously high body temperatures.

3)      One benefit of studying human variations through environmental clines is the ability to observe humans beyond race and ethnicity. Yes, information from explorations can be useful because the can provide us with ways to overcome the heat stresses. Scientists can observe how people living in hot environments deal with the heat. They can then bring this information back and use these methods to help people that are suffering from heat exhaustion in other parts of the world.

4)      The study of environmental influences on adaptations is a better way to understand human variation than by the use of race because we are all human. In my opinion, you cannot use race to understand the adaptations human have made to deal with heat. Heat affects every race, and there is no one race that was born with the ability to withstand high temperatures better than others.

Piltdown Hoax

                The Piltdown hoax refers to the findings of a human ancestor, in a small town called Piltdown, made by Charles Dawson and Arthur Smith Woodward in 1912. These two scientist dug up skull fragments, jawbone fragments, and teeth. The jawbone appeared to be similar to the jawbone of an ape, but the teeth were flat just like human teeth. This was a remarkable discovery, and many people were enthusiastic about their new findings. The findings of this hominid was the important pieces that were needed in order to connect the branches between humans and apes.

                Although many people were ecstatic about their findings, there were a few scientists who were skeptical about this. They did not understand how this could tie into the theory of evolution. Fortunately, and unfortunately, in 1949 a professor by the name of Kenneth Oakley used a method of relative dating to further analyze Dawson’s findings. This method is called fluoride absorption dating. This method can be used to determine the age of bones by measuring the amount of fluoride within it. The older the bone, the more fluoride it contains. With this new-found scientific method, Oakley took a fluoride analysis of all the bones Dawson and Woodward found at Piltdown. What he found was astonishing. He discovered that the skull and the jaw fragments did not come from the same time period. The skull was much older than the jaw fragments. After further examination, Oakley also discovered that the skull had belonged to a human, and the jaw belonged to a female orangutan. Furthermore, The National History Museum states, “scratches on the surfaces of the teeth, visible under the microscope, revealed that the teeth had been filed down to look human.” This is clear evidence that the bones and teeth have been altered in order to fool the human population into believing that Dawson found the missing branches between humans and apes.

                The reason for and the perpetrator of this hoax is not known. One can only assume that whoever is responsible did it for fame. The possibility that an ape-like jawbone with human-like skull and teeth could belong to the same being could have been an amazing finding. This could have altered our understanding of evolution. The perpetrator might have thought that he would be known world-wide for his “findings.” He might have made money off of fooling people as well. Luckily, there were skeptics who used the scientific method to put this hoax to rest. Oakley was able to ask questions about the findings. He began to do background research and found that the age of the bones did not match. Finally, he created his own hypotheses and found that the findings were a hoax.

                I believe that you cannot completely remove the human factor from science to reduce the chance of errors. Instances like the Piltdown hoax can and most likely will happen again. The only thing that we can do, is to always ensure that we are asking the right questions and question every new finding. Scientist must continue to test fossils and everything else, in order to maintain good science. If I was able to remove the human factor from science, I would most certainly do so. I just do not find that possible.  The life lesson learned here is that we must not believe everything that people tell us. Before publicizing a scientist’s work, always question and test their findings.

Homologous vs. Analogous Traits

1) Homologous Trait

Humans and Bats

     a)Humans and bats both share the same bones. They are both mammals and they both possess forelimbs which include the humerus, radius, ulna, carpals, metacarpals, and phalanges.

     b) The homologous trait of these species is the forelimb. The forelimb of a human and a bat are structured similarly. Although they seem to look alike, they are used for different purposes. Humans use their forelimbs to reach for objects and to pick up objects. Whereas, bat's forelimbs have evolved into wings, allowing the bat to fly. These mammals with similar bone structures have adapted to survive in their own environments.

     c) The common ancestor of humans and bats are a mammal that dates back to 80 million years ago.  New York Times states, "This tiny shrew like creature was the common ancestor of humans and other living mammals as diverse as horses, bats, tigers, and whales." 

2) Analogous Trait

Human Eyes and Squid Eyes

     a) Humans belong to the vertebrate family and squid belong to the cephalopod family. They live in very different environments. Humans live on land and squids live in the sea. 

     b) The analogous trait that they share are their eyes. They appear to be similar in structure. They both contain an iris, a lens, a retina, and a cornea. Although the structure is the same, they had to adapt to their environment independently. For example, a human's pupil is round and changes diameter depending on the amount of light in the environment. Whereas, a squid's pupil is square and adjusts for the level of light by changing from a square to a narrow rectangle. (http://www.thecephalopodpage.org/cephschool/CephalopodVision.pdf) Although they work differently,the eyes were still developed for the vertebrates and cephalopods because they need them in order to survive. Humans and squids alike, use their eyes to hunt or  run from prey. Since the squid victim to more prey than humans, they have developed better eyesight that does not contain any blind spots.

c) The last common ancestor for humans and squid is thought to be the acorn worm that has been around on Earth for 500 million years. The acorn worm is known to be the ancestor of humans, cephalopods, and all animals with backbones.

Protein Synthesis

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Historical Influences on Darwin

     In my opinion, Alfred Russel Wallace had the greatest amount of influence on Charles Darwin's theory of Natural Selection. According to NPR.org, Wallace spent eight years exploring wildlife in the Dutch East Indies. Evolution.berkeley.edu states, "Wallace supplied Darwin with birds for his studies and decided to seek Darwin's help in publishing his own ideas of evolution." NPR.org also states, "by 1855, [Wallace] had come to the conclusion that living things evolve." Three years later, Wallace sent Charles Darwin A copy of his own nine page theory of natural selection. Darwin was astonished by how similar Wallace's findings were to his own. Wallace's ideas were very similar to Darwin's ideas and they began working with each other. They even published a paper together about natural selection and evolution.
    NPR.org states, "[Wallace] was on the island of Halmahera, ill with a fever when it came to him: Animals evolve by adapting to their environment. "This must have greatly influenced the point, "if the environment changes, the traits that are helpful or adaptive to that environment will be different."
    I believe that Darwin indeed could have developed his theory of Natural Selection without Wallace. Darwin had already began writing his book, the Origin of Species before he started working alongside Wallace. Wallace was simple the support and reassurance Darwin needed to publish his book and release his findings to the world.
     The attitude of the church seemed to have made Darwin wait over twenty years to publish his findings. Religious scientists and almost everyone else had doubted Darwin's beliefs, so he did his best to refrain from sharing his thoughts with many people. Instead, he waited until he was able to gain more evidence and facts before he published his book.