Life As We Know It and Its Evolution
Lead: Thomas Davis

2/7/2013

Summary by Hannah Whitcomb

Origins of Life

Reading:

R. Dawkins "The selfish Gene", Ch. 2
E. Mayr "One long Argument", Ch. 4, 5
Stannard, God for the 21st Century, Part 2
Foreword of "Origins of Life

The seminar began by Professor Davis passing around various forms of life, one of which was a white-fruited strawberry.  The point in this was to see how there are many forms of life and how humans are able to help maintain some cultivated species that may not thrive on their own in the wild. 

        Next, a portion of the film Unlocking the Mystery of Life, raising the question of whether life as we know it is the result of chance happenings, random mutations occurring, or if there is any reason to believe that it could be a result of some sort of plan.

        Conversation started up about trying to define and describe the meaning of life.  It is very difficult to do so, but two ways were presented: one is describing life as a “property”, meaning a unique characteristic of living things.  The second was life as a “category”, meaning life on earth and living (animals, plants, fungi, microbes, and viruses) vs. non-living things.  This led to some conversation surrounding the topic of viruses and what a virus actually is.  We were informed that a virus is simply genetic information surrounded by a protein coating which can infect and “take over” a host cell to build new viruses; they do not reproduce on their own and do not have any sort of metabolic capacities.  Whether viruses are living or non-living is a highly contested issue.  This conversation led right into ways to define life: i.e. what criteria can be considered?  Some common defining life properties include: similar chemical composition among all living things, complex and orderly molecular structure, growth and reproduction, and Darwinian evolution.  The Darwinian evolution bit was very interesting because it’s not strictly unique to life, but can also be seen in different aspects of culture, such as language.  Over time, many little differences have been made to languages, they can evolve in many different ways, but this is one of them. 

          Once some common ways to describe life were listed, an attempt at different definitions was made.  One definition for life as a property reads as “a living thing is a structurally complex, physical entity that dynamically maintains its organic molecular structure via the internal use of chemical energy”.  A second definition was presented for life as a category: “life is the collective sum of all living things, each having arisen from a living predecessor, and having diversified into kinds (species) under the influence of Darwinian natural selection”. 

          The next section tried to account for the existence of life by means of retrodiction, i.e. using collected information to infer the past back to the theory of The Big Bang.  Based on how we understand the universe as it works today (laws, properties, explanatory paradigms, etc), we are able to retrodict how and what the universe was when everything first began.  Through these means, we are able to envision conditions within nanoseconds of the origins of the universe.  This same method used for the universe can be used to trace back lineages of species to the start of life as we know it.  Although we are unaware of the true beginnings of life, there are several models.  By means of the Darwinian evolution theory, we are able to come up with a few of these models for the origins of life on earth.  Unfortunately, the use of this paradigm does not always succeed because randomness plays a large role in the diversity of life.

          From this topic of the concept of randomness came conversation surrounding the idea that there is no such thing as a mistake in nature.  The concept of a mistake is something that was made up by humans.  Is it possible that nature does not make a mistake in the sense that we think of it?  Not every mutation can result in something bad, and instead, many times the mutation can lead to the survival of the species. 

          Once the talk of mutations was dropped, we again considered how life as we know it originated on earth.  There are three theories that were presented: earthly origins, extraterrestrial origins (panspermia), and a sort of intellectual design.  The latter two are quite possible, but still do not address the question of the ultimate origin for that life and instead just give the story from the perspective of the origin on earth. 

          To end the seminar, conversation shifted towards the idea of somehow creating synthetic life.  A synthetic genome has been made before, but that does not mean that synthetic life has been made along with it.  Just because the organic molecules can be put together does not mean life will magically be created; even the simplest cells are incredibly complex.  When talking about the protein synthesis within the cell itself, one organelle, the ribosomes, play a very crucial role.  The process of copying DNA is such that the original strand of DNA is copied over into a new strand called RNA.  This RNA is then copied into a strand called mRNA, and can then be read over many times by the ribosomes.  The “reading” of these ribosomes results in the direct synthesis of protein molecules, but not without the help of many other molecules as well.  The ribosomes are the organelles that bring codons (three nucleotides on the RNA strand) from what is called transfer RNA to the growing chain of amino acids.  The tRNA has an end that is called the anticodon, which corresponds to both a three codon segment of the mRNA and the correct amino acid.  Aminoacyl tRNA transferase is another molecule, which helps to ensure the correct amino acid is attached to the corresponding tRNA molecule for synthesis.

           Knowing this, a new question arises: if each ribosome consists of 50-80 protein molecules, each consisting further of even more amino acids, and is needed to created new proteins, how were they formed to begin with?  This bit of information then leads to the idea that either there must have been molecular evolution before cellular evolution somehow, or that life has somehow been lead by an intellectual design.