Life as We Know it and its Evolution, Lead: Thomas Davis

1/31/2005

Summary by Greg Hasevlat:

Life as We Know it and its Evolution

Readings:
"God for the 21st Century" Part 2, by Russell Stannard ed.
Foreword of “Origins of Life”
R. Dawkins “The Selfish Gene”, Ch. 2
E. Mayr “One Long Argument”, Ch. 4 & 5

The class began with this simple question: Where did we come from? This inquiry would then be the basis of discussion for our debate on the origins of life on this planet. Thomas Davis proceeded to give the class an elementary chronological outline of the universe as we know it.

           • 13.7 Billion Years Ago (BYA) - Big Bang
           • 4.5 BYA - The Age of Earth
           • 3.8-3.7 BYA - Formation of simple cell organisms discovered through fossil evidence.

This timeline served as a chronological map that outlined the ontological question of our existence. Prof. Davis then noted the short time span in which the earth both “cooled” and life began. This curious notion brought about the idea that after “Dark Earth”, “Light Earth” was not far behind; but, what was it that allowed for earth to seize the inhospitable environment and become a place where life could flourish? This notion of life beginning so rapidly brought about the next idea that life may not have originated on this planet at all. That in reality life came from outer space. This theory is called “panspermia”. This idea illustrated the notion that life came from another world, and that it is likely to have traveled via meteor that crashed into earth. If the seeds of life came from space then was the timing right or was there a transitional period? Prof. Davis then explained to the class that many of the simple, organic building blocks of life can be found in space. Scientists have discovered amino acids in interstellar gas clouds, but that there is no real proof that living cells would have been able to survive the journey to earth.

The other side of the debate is centered on the fact that Darwinian evolution denounces the idea that a “designer” created the world and that a more materialistic pattern emerged out of what was here into what is now alive. This pattern, if you will, is concurrent with the theory of survival of the fittest, whereas a “God” did not design the world and all of its natural views but that design and chance made up the vast majority of the current state of natural and physical elements. This, however, is treading in the deep end of materialism and Darwin did in fact point out that he was a God fearing man.

Other opposing views include, as stated above, that life may not have originated at all on earth and that it is merely of extraterrestrial origin. Adhering to the notion of “God” above also leads theologians to profess that life originated via special creation or the idea that life-forms were placed on earth by “super-natural or divine forces.” Furthermore, another idea is that life may have come from spontaneity, or the idea that molecules “became more and more complex over time.”

In the absence of specific knowledge about the origins of life on earth, Prof. Davis then directed us to define life as we know it. This brought about general ideas that humans have about life as a whole. Prof. Davis noted that life is a self sustaining chemical system capable of undergoing Darwinian evolution. This transitional being would then have the ability to support itself while adapting to its surroundings for a sustained period of time before death. The discussion strayed for a few minutes while we debated whether or not a computer could fit this description. We agreed it could not. Prof. Davis informed the class that life has five general characteristics.

           • Order - breakdown of cell structure
           • Sensitivity - response to stimuli
           • Reproduction - ability to replicate
           • Metabolism - ability to provide sustenance for itself
           • Homeostasis - can maintain constant internal condition

These are the five characteristics that living things must have; however, Prof. Davis then propelled the debate into the reaches of what it means to be alive: that is what it makes sense to say about the phenomena that is life. It was eventually agreed that metabolism was the most important aspect of life because an organism does not have to reproduce to be alive, but it does have to “eat” (i.e., to obtain energy and molecular building blocks from its environment)

The debate eventually came down to the appearance of metabolism and how it might have come into place. Prof. Davis described a leading theory where replication came from:

           • DNA - transcription
           • RNA - genetic code
           • Protein - translation

Each of these represents the beginning of a pre-biotic RNA world which in turn is the formula for all possible catalytic properties. These are the things that evidently came together and worked, creating a viable and sustainable system that spawned life as we know it.