Life as we know and its evolution
Lead: Thomas Davis

1/30/2006

Summary by Michael DeLone

Life as we know it

During our first meeting Doctor Davis and Professor deVries introduced themselves to the class and gave a synopsis of how the course is going to be structured. Dr. Davis continued with the lesson and asked the question, “How did we get here? What are we doing here?” and began to talk about evolution. He went on to say that if we want to discover what is in the universe and how it got there, we have to look at ourselves because we are in the universe and therefore composed of the same materials. “Why is the world the way it is? Because it got that way.” Dr. Davis listed three things that exist.
  1. Universe
  2. Life
  3. Consciousness
He posed the question, “Is there a meaning to this universe?” and then went on to say that in order for there to be a meaning, there must be a consciousness to experience the world. We are all experiencers, which “defines” us as conscious and therefore we as humans are self-aware. However, there can be things or beings that are experiencers and are conscious but are not self-aware.

Dr. Davis then asked the two questions: “Where did consciousness come from?” and “Is everything that is conscious, alive? The class briefly discussed this issue and put forth some ideas on both questions but it proved impossible to declare a definitive answer for either. We then talked about properties of life and whether or not something is alive. Is a virus alive since it has genes but no metabolism? NASA’s definition of life is a self-sustained chemical system capable of undergoing Darwinian evolution. Darwinian evolution depends on the passage of traits or characteristics from parent to offspring through reproduction. The individuals that inherit the combinations of traits that best adapt them to their environments are the ones that will live and reproduce, while less genetically fortunate individuals die or fail to reproduce and pass on their hereditary material. Hereditary variation must arise as well, and is considered to arise at random rather than to serve a need. Thus, Darwinian evolution relies on chance (random mutation) and necessity (natural selection).

Dr. Davis then took the topic in another direction by asking, “When does Human life begin?” and “When did life begin on Earth?” Unfortunately, we can only speculate about the environment when life began, so we aren’t certain. We then talked about the beginning of the Universe (≈13.7 billion years ago), the beginning of Earth (≈4.5 bya) and the earliest fossils of simple celled life (≈3.5-3.8 bya). One way of looking at how all of this began is looking at the early universe or at very distant stars to see what they are made of. The earliest stars were made of the light elements such as hydrogen and helium but made heavier elements such as oxygen, nitrogen, carbon, etc. From this Dr. Davis introduced three theories:

1. Panspermia – Life originated elsewhere in the universe in the form of simple bacteria and arrived here as spores on an asteroid, meteorite or comet.
2. Life began on Earth under the correct circumstances and conditions.
3. Intelligent Design – Supreme being

We then discussed that the atmosphere and conditions of early Earth were very violent and rapidly changing, that there was water, and magma and gasses in the air. In theory, after millions of years these conditions could have somehow lead to the creation of rRNA molecules with primitive catalytic properties. Simple cell-like compartments might also have formed. Meanwhile, simple organic chemical cycles could have been catalyzed by minerals on the surfaces of submerged rocks. For the first cellular, reproducing life forms to have originated, three key components of life had to arise and be integrated together: cellular compartments, metabolism, and a genetic system. It is not known how this happened. The difficulty in envisioning how it might have happened is that in today's cells, metabolism is catalyzed by proteins, which in turn are manufactured by ribosomes, which translate the genetic information carried by mRNA and stored in DNA. However, ribosomes are made out of proteins, and there needs to be ribosomes in order to create protein, so which one came first? This "chicken and egg' problem must be solved before we can reconstruct the origin of life.

Dr. Davis then summed up the lesson and concluded that something must have happened for life to begin. This “something” that created life could have been one of many options. The laws of nature combined with the conditions on Earth could have been right for life to be created by natural processes, or something could have been added in order for life to begin, progress and give it some sort of direction, or it could have been something else that we haven’t thought of yet. The main concept to understand is that we currently don’t have the ability to determine these things, which is why we are always asking questions in the attempt to discover the truth.