Analogy/Homology Assignment

1A.      Humans and horses derive from a common ancestor and both species possess homologous traits such as limbs that have the same bone structure.

1B. Humans and horses are both limbed creatures.  Humans have arms and horses have legs. In humans, the arm limbs are made up of the humerus, radius, ulna, metacarpals, and phalanges.  Similarly, horses also have these components in their leg limbs.  The function of the arm trait enables humans to build, carry climb, etc..  The function of the leg trait in horses is different from that of the human arm.  A horses leg allow a horse to gallup, run, walk, pull equipment, and catapult their weight, and carry the weight of other objects.  As the two species evolved, each animal developed various uses for these traits, hence as the uses changed, the trait also changed, to form the variation in uses and appearances in the respective species we see today.

1C.  Humans are categorized under the order: primates.  Horses are grouped under the order: perissodactyla.  The commonality between horses and humans is that both orders are members of the subclass Eutheria, which are placental mammals.  Proving that the common ancestor, Eutheria, had this same homologous trait (moveable limbs) is very difficult, because the fossils that have been discovered are limited to mostly dental and skull remains.

1D. 

2A.  Bats and butterflies are both examples of analogous creatures.  They both have wings that perform the same function of flying, but both species look different and they are not derived from a common ancestor.

2B.  The wings are the analogous traits between a butterfly and a bat. The function of this trait allows both species to fly and perform aerial locomotion.  Structurally, butterfly wings lack bones and they are covered in scales. Additionally, butterflies have two pairs of wings.  In opposition to butterflies, bat wings have bones and they are covered with bare skin. Furthermore, bats only possess one pair of wings. Although the aforementioned data proves that the structure of the wings of the butterfly and the bat are significantly different, this analogous trait exhibits similarities in that both types of wings allow for aerial locomotion.

2C.  True. All organisms share some form of common ancestor, however, butterflies are categorized as insects, whereas bats are categorized as flying mammals.  There is no scientific proof or fossil records indicating that either species is closely related, therefore, wings have evolved independently in these two species. Thus the wings of both species can be considered an analogous trait.

2D.

DNA molecule:

CATUTACACCTTGTGCTAAGGGAACGCAAGCTGGTTCATCUCAT

Historical Influences on Darwin

After ample review, I have concluded that Thomas Malthus was the individual that had the greatest influence on Darwin’s development of his theory of Natural Selection.

Economist, Thomas Malthus, was born in England in 1766.  Malthus is most well known for his published work called Essay on the Principle of Population, written in 1798.  In his essay, Malthus hypothesized that populations would thrive in areas where resources were ample; as resources diminished and became strained, populations would decrease due to famine and disease.  Malthus’s ideas pertaining to overpopulation and resource shortages shaped one of Charles Darwin’s key ideas of Natural Selection, which is the concept of survival of the fittest.  Even though Malthus was not a scientist, his studies were vitally important to the work of Darwin because Darwin was able to use Malthus’s ideas to prove that similar to humans, plants and animals in nature often produce more offspring than can survive.  Overproduction of offspring combined with a shortage of resources inevitably result in a natural selection that allows only the strongest among a species to survive.  Over time, the strongest survivors of each species with the most favorable adaptations become the most competitive in the natural world.  Over millions of years these adaptations result in permanent modifications of physical/biological traits.  Charles Darwin referred to this process as evolution.

 “Resources are limited. Our planet has a limit of how much it can hold and produce.  There will not be enough resources available for all organisms to reproduces as many offspring as they can.” 

“Organisms with better access to resources will be more successful in their reproduction efforts.  The rabbits with more food and water and shelter will reproduce more offspring than those rabbits with fewer of these resources.”

The above two quotes support Darwin’s theory of natural selection.  The man originally responsible for proving these ideas is Thomas Malthus.  Malthus argued that families were producing more children than they could afford to support with their limited resources.  In his essay, Essay on the Principle of Population, Malthus stated that throughout history, human populations grew in areas that had abundant resources, once resources became strained, overpopulation would naturally be eliminated by factors that include famine, disease, and war. Darwin studied Malthus’s work and was able to see that the human population was mirroring the research he gathered from nature over the years.  Darwin concluded that the idea of “survival of the fittest” applied to both human populations and to populations in the natural world.

Just as students need to use reputable sources to support the claims they make in their work, scientists like Charles Darwin relied on the expertise and studies of influential specialists in other fields to support his ideas and/or theories.  I do not believe Darwin would have been as successful in proving or developing his idea of “survival of the fittest” and his theory of Evolution based on Natural Selection without Malthus’s contributions.  In fact, both Darwin and Alfred Russel Wallace both gave a large portion of credit to Thomas Malthus for shaping their ideas that relate to Natural Selection and the Theory of Evolution.

Darwin’s findings were extremely controversial and he was aware of this.  Fear of backlash from religious and scientific establishments in Britain were what kept Darwin from publishing his works after he completed them.  This is why it took him years to finally publish his findings, and he most likely still would not have done so if it were not for Alfred Russel Wallace, who was preparing to publish his own similar theory.  After Darwin did publish his findings, he received the animosity he had been avoiding for so long.  Some examples of the harsh responses Darwin faced included Henry Cardinal Manning’s  - England’s highest ranking official at this time – reaction to Darwin’s findings when he stated: “a brutal philosophy – to wit, there is no God, and the ape is our Adam”.  Samuel Wilberforce, one of the most highly respected religious leaders in England during this time, sarcastically asked one of Darwin’s supporters whether he was related to an ape on his grandmother’s or grandfather’s side.  There were many cartoons made of Darwin’s head on a monkey’s body that became a popular mockery of Darwin and his ideas.  When Darwin went to collect his honorary degree, Cambridge students hung monkey’s heads from the roof of the building in mockery.  Even with all of this animosity, Darwin had a great number of supporters.  Unfortunately, even today there are still many individuals who denounce evolution and mock Darwin’s proven and factual theory. 

Sources used as reference for this blog include:

http://www.ucmp.berkeley.edu/history/malthus.html

http://www.britannica.com/EBchecked/topic/360609/Thomas-Robert-Malthus/222944/Malthusian-theory

http://evolution.about.com/od/scientists/p/Thomas-Malthus.htm

http://www.pewforum.org/2009/02/04/darwin-and-his-theory-of-evolution/

If I were stranded on a desert island I would take a machete with me for protection, to kill food, and to help me build shelter.  I would also take water with me because water is absolutely essential for survival, and there is no way of knowing if a desert island would have any fresh water; it is likely that there would not be a water source available.