Assigned Problem
Our assignment was to compare and contrast the tree, bush, and ladder metaphors of organizing biodiversity and evolution. We were also asked to discuss the implications that these metaphors create. Required reading: Infinite Nature, Chapter 3 pg. 29-32.
Rational
We decided to break down and define each metaphor, following with a skit that dramatized the implications that we felt each metaphor created. We began with the tree and ladder metaphors which we felt wrongly imply that humans are superior and more evolved than all other species. Lastly, we discussed the bush metaphor which we felt was an accurate metaphor for arranging biodiversity and evolution.
Five Points
The five points made in the video that were connected to points made in class discussions and the book are as follows. The first of these was the idea of using a ladder model as a means of organizing the various levels of biodiversity. This idea places different organisms on different rungs of the ladder, increasing with complexity as you move up the ladder. Humans are placed at the top of the ladder. The second theory proposed is that of the tree. The tree demonstrates how all species originated from a single ancestor, the trunk of the tree, and the branches emanating from them are all the organisms that ever existed. The branches that abruptly stop are those that have had a particular species go extinct, and the branches that reach the outermost part of the tree that bud and have leaves are those of organisms that are present today and are still evolving. The final theory that is set forth is one that depicts a juniper bush as the best representative of how organizing biodiversity should be approached, and that is in a way which shows how the intertwined and twisted branches sprawl with no noticeable purpose representing how all organisms are related and part of a bigger, interconnected web of life. Another point that is brought up in the video is the question of why, in most of the organizational processes of biodiversity, is the human race thought of as the pinnacle of evolution. Granted there are some aspects that do place humans towards the top such as the ability to communicate through language, to reason, and to adapt to different situations and create a widespread population, but there are animals that have actually evolved more than we have such as the Bonobo chimp. This is why there is skepticism as to why humans are presumed to be at the top. A final point that was made was the opposition to the idea that all organisms are evolving into a better form. This is a misconception that many fall prey to. The fact is that evolution happens by random mutation and chance and the results of this may not necessarily be for the better for a species survival.
References
Avise, John. “Three Ambitious (and rather unorthodox) Assignments for the Field of Biodiversity Genetics”. National Academy of the Sciences. 2009. http://books.nap.edu/openbook.php?record_id=12501&page=281 5th November 2009.
Rosenberger, Alfred. “Charles Darwin lll, Descent With Modification”. Vision Learning Vol. Bio-2 (5). 2004. http://www.visionlearning.com/library/module_viewer.php?mid=112. 5th November 2009.
Baum, David. “Trait Evolution on a Phylogenetic Tree: Relatedness, Similarity, and the Myth of Evolutionary Advancement”. 2008 Nature Education. http://www.nature.com/scitable/topicpage/Trait-Evolution-on-a-Phylogenetic-Tree-Relatedness-41936. 5th November 2009.
Kull, Kalevi. “Ladder, Tree, Web: The Ages of Biological Understanding”. Department of Semiotics, Tartu University. http://www.zbi.ee/~kalevi/kull312.pdf. 5th November 2009.
Malamud, Randy. The Chronicle Review 2008. http://forum.eol.org/viewtopic.php?f=1&t=31&view=previous. 5th November 2009.
The first source was used as a reference for the tree metaphor. It argued that if you include fossils in the tree it turns more into a web.
The second source deals with Charles Darwin’s view of biological diversity. He includes a tree-like metaphor in his book “The Origins of Species”. It is the only illustration in this book.
In the third source Baum talks about how the tree metaphor can evolve and change and really goes through the mechanics of the tree metaphor.
The fourth source goes over the tree, ladder, and web models. It goes into detail on each one and even gives some background on where they came from.
The fifth source goes over how humans affect the ladder and tree metaphors. It also gives examples on how humans affect the environment.
Tuesday, December 8, 2009
Tuesday, September 29, 2009
Director's Commentary
-We as humans tend to inflate out evolutionary importance. Proof of this can be seen in the metaphors and models that we use to organize and explain species diversity.
-The ladder and the tree are two organizational metaphors that are commonly used as models for understanding biodiversity and evolution. Both of these models suggest that humans have earned a special place nearest the apex of evolution, superior to all other life forms.
-The ladder metaphor suggests that humans have marched up the ladder of progress and they are superior somehow to the life forms below them. The ladder metaphor is useful only to satisfy human egos.
-Marching up this ladder of progress is not necessarily a good thing. Many species such as mosses, fungi, sharks, and crayfish have changed very little over great expanses of time. They have remained fit enough to survive and reproduce, and this has been enough to secure their existence.
-Just because some organisms have changed and diversified a great deal over a period of time does not mean that they have gotten “better”. They have changed to survive in their current conditions. What was “better” a million years ago may not be “better” today, and what works in one location may not work in another.
-Darwin toyed with the concept of a "tree of life" to explain the evolutionary relationships between different species. -Without it the theory of evolution would never have happened. The tree also helped carry the day for evolution. Darwin argued successfully that the tree of life was a fact of nature, plain for all to see though in need of explanation. The explanation he came up with was evolution by natural selection. -Most branches eventually come to a dead end as species go extinct, but some reach right to the top - these are living species. The tree is thus a record of how every species that ever lived is related to all others right back to the origin of life.
-Unlike the "Tree of Life", the Juniper's branches twist and wind with no set form so that the trunk of the shrub is where its structure comes from. The truck represents the hearty and tough mechanisms of life which proved themselves by lasting the test of time and resulting in the species present today. As for the organization of species in the shrub; there is none. The different thickness and lengths of the branches do not single out any species as the most evolved or better than any other. Instead the species' branches are not distinguishable and with no structure showing how biodiversity is more of a sprawling web with all species intertwined in it with each as equally important as the next.
-The ladder and the tree are two organizational metaphors that are commonly used as models for understanding biodiversity and evolution. Both of these models suggest that humans have earned a special place nearest the apex of evolution, superior to all other life forms.
-The ladder metaphor suggests that humans have marched up the ladder of progress and they are superior somehow to the life forms below them. The ladder metaphor is useful only to satisfy human egos.
-Marching up this ladder of progress is not necessarily a good thing. Many species such as mosses, fungi, sharks, and crayfish have changed very little over great expanses of time. They have remained fit enough to survive and reproduce, and this has been enough to secure their existence.
-Just because some organisms have changed and diversified a great deal over a period of time does not mean that they have gotten “better”. They have changed to survive in their current conditions. What was “better” a million years ago may not be “better” today, and what works in one location may not work in another.
-Darwin toyed with the concept of a "tree of life" to explain the evolutionary relationships between different species. -Without it the theory of evolution would never have happened. The tree also helped carry the day for evolution. Darwin argued successfully that the tree of life was a fact of nature, plain for all to see though in need of explanation. The explanation he came up with was evolution by natural selection. -Most branches eventually come to a dead end as species go extinct, but some reach right to the top - these are living species. The tree is thus a record of how every species that ever lived is related to all others right back to the origin of life.
-Unlike the "Tree of Life", the Juniper's branches twist and wind with no set form so that the trunk of the shrub is where its structure comes from. The truck represents the hearty and tough mechanisms of life which proved themselves by lasting the test of time and resulting in the species present today. As for the organization of species in the shrub; there is none. The different thickness and lengths of the branches do not single out any species as the most evolved or better than any other. Instead the species' branches are not distinguishable and with no structure showing how biodiversity is more of a sprawling web with all species intertwined in it with each as equally important as the next.
Monday, September 28, 2009
Wednesday, September 23, 2009
Sunday, September 20, 2009
Current Status
This is our third meeting, however we have run into a few snags and progress is slow. We are currently taking another approach towards our podcast in hopes of better portraying the book's ideas.
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