Analogy/Homology

1. Homologus Traits

1.     A) Two different species that have homologous trait is a monkey and human’s opposable thumbs.

B) Both species depend on their opposable thumbs for several tasks. Without opposable thumbs these species would be handicap and have a harder time getting around. When it comes to monkey they use their opposable thumbs to grasp thinks such as tree branches and picking up objects. As for humans, they have a more flexibility for manipulating small objects and they can move their thumbs across their hands much better and farther than any other primates.

C) One of the common ancestors to the human and ape species is the hominid species. Since the earliest hominid species diverged from the ancestor were shared with modern African apes. Five to eight million years ago there have been at least a dozen different species of these humanlike creatures.

2. Analogous Traits 

2.     A) Two species that have analogous traits would be a rhinoceros and an elephant’s horn

B) Both species have a horn like feature on their head. Reason being is that they use these horns to protect them selves from attack of other predators. The rhinoceros and elephant both have a thick layer which helps protect them from attacks as well.

C) As for a common ancestor for a rhinoceros would have to be a hyracodontidae, also known as “running rhinos” showed adaptations for speed, although they do not have a horn feature like the rhinoceros. As for the elephant, they diverged from a common ancestor of the Mammutidae, which includes species termed as mastodons. Unlike the rhinoceros ancestor, the elephant’s ancestor had a horn feature, mastodon being an example.

Protein Synthesis

TTATGCTACCAAGGGTATAACGTCAGTGTAACATTGTCTACTGGTACATG

Historical Influence on Darwin

Thomas Malthus has had a significant influence towards Charles Darwin’s theory of Natural selection. Malthus’s observation that impacted Darwin was that nature plants, animals, and humans are able to produce far more offspring than can survive. Unless family size was regulated, population would grow less and less due to food famine.

 What is preventing organisms from reproducing at their potential?  The reason why organisms are being prevented from reproducing at their potential is due to the lack of environment space and amounts of food.

 Resources are limited. Just like the example of the rabbits, Malthus stated that we are able to produce far more offspring than can survive. Meaning that we do have the chose to produce as much offspring as we want, but we don't because we would not be able to help support the offspring with lack of food.

 Organisms with better access to resources will be more successful in their reproductive efforts. With a bigger environment and a bigger supply of food, organisms will be able to produce offspring at their potential.

In a way Darwin might not be able to develop his theory of natural selection without the influence of Thomas Malthus. Malthus’s theory on population is basically the basis of Darwin’s theory.  Malthus’s theory is human population is going to decrease over time because there is not enough resources to keep a mas population. Therefore, the most fit will be able to survive and reproduce. Where as Darwin’s theory is scarcity of resources, territory, etc. leads to the most fit to survive from competition and thus the survivors will therefore create more babies and their genes will be passed to the next generation, thereby creating more species with those fit genes.

Darwin also wrote about Malthus in his autobiography (1876)

"In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long- continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work".

The attitude of the church did affect Darwin because back then the church had a significant power over people, when Darwin publicized his book. Many people felt like they’re religion was being questioned. Christian belief about species is that they were all created by God and started with two humans named Adam and Eve. Darwin’s theory completely disregarded the Christian belief and stated that species evolve within time. This later became a very controversial issue.

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