Cosmology and our View of the World
Life As We Know It and Its Evolution
Lead: Thomas Davis
Summary by Chris Carroll
Origins of Life
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 lecture began with Professor Davis proposing the contemplation of life. It is easy to decide that the person next to us is, hopefully, alive and it is easy for us to think of what life is in a general sense. A person has life; a rock does not. But to define life, that is, to give criteria that satisfies all observations and considerations, is quite difficult. In an effort to do this, Davis attempted to bring the thought process to its base levels. We must consider the questions “when do we find life?”—when do we determine when newfound things have life or not?—and “when do we create it?’’. For the latter, Davis pointed out that synthetic life has never been produced, though it doesn’t stop us from trying. Davis also suggested that there are ethical considerations when determining what life is. One might be reminded of cloning and abortion, and how these controversial topics almost always incorporate ways of trying to justify one view or the other by analyzing the aspects life. Davis, who has taught introductory biology many times, recalled that it is interesting to open any of the biology textbooks because in the very first pages the text goes something like “let’s talk about life. Well what is life? Let’s define it. Well that’s not easy…”. Defining life is not a topic best left for the starry-eyed and the purely philosophical (and sometimes political), but a real consideration for real applications. On the interaction between life and consciousness, Davis stated that life is a pre-requisite of consciousness. In order to have consciousness you must have life, and without consciousness there is no profound sense of meaning or significance. Davis presented a graphic in which circles of CONSCIOUSNESS and LIFE intersect, and also one in which LIFE enveloped CONSCIOUSNESS. A student proposed that CONSCIOUSNESS could envelope LIFE such that life itself might be dependent on consciousness, that is, life might simply be a perception of consciousness. Davis made the point that at the end of these thoughts, as it is with many things, we will come to the question “what is the meaning of life?”.Moving passed the introduction of the presentation, the next slides gave a basis on which to begin our consideration of life. Life can be seen as a property. It is an element of existence imbued in some things based on a make-up absent in those things that have no life. It can also be seen categorically, such as when the phrase “life on Earth” is spoken. Science provides a great example of this in the case of eukaryotes and prokaryotes. Different forms of life are given separate categories. However, determining the categories and what goes in them is dependent on the nature of the organism, which brings us back to life as a property. It is easily seen, then, that the ideas category and property are closely linked. As such, we tend to see things in terms of animals, plants, fungi, and bacteria. We run into an issue, though, when we consider viruses. A set of criteria in these things usually consists of the following: diversity, composition, molecular structure, complex cellular and complex sub cellular organization, metabolism, growth, reproduction, genetic system and evolution. Viruses fall short in regards to cellular organization and metabolism. Hence, Davis regards viruses as non-living. But Professor Tom Laue disagreed and thinks viruses do have life on the grounds that the above criteria are too stringent. Because viruses “hijack” their host’s metabolism, Laue is of the opinion they should count as living. However, the term normally provided to viruses is obligate intracellular parasites to account for their “hijacking” abilities. For consideration, Davis provided some established definitions. One definition states that a living thing is a structurally complex physical entity that dynamically maintains molecular structure via internal chemical energy. The thermodynamic definition states that life can be thought of as regions of order that fight entropy. There also exists a thought called the Gaia hypothesis which states that life is evident when there is an atmospheric chemical disequilibrium. This thought was put forth by James Lovelock.
This last idea will make one start to think of why things got to where they are now. Davis introduced the concept of retrodiction, which is using the powers of observation to determine the state of things now and applying them to figure out the causal steps that would have brought us to the present. Retrodiction is a form of deduction about the past that explains current situations. For our purposes, retrodiction means thinking about how life diversified. In the view of biology, this inevitably means thinking of evolution and the fossil record. The word “evolution” is forever linked with the household name Darwin. However, as Davis pointed out, Darwin’s ideas and the ideas that stemmed from his observations have a tendency to become muddled and mixed together. The concept of evolution, mutations and natural selection, while connected, are not the same. Evolution is the process by which organisms change and deviate, mutation is a change in the DNA, and natural selection is the process by which the better suited and adapted individuals outlive their competition to a point at which the lesser organisms or species exist no more. Evolution is dependent on mutations, and the effects of natural selection allow us to see which evolutionary paths took hold. Professor Laue interjected to bring up the fact that epigenetics, a new and rising field of genetics, muddles the idea of mutations because epigenetic mechanisms change and regulate gene expression without changing the primary sequence. This doesn’t change how the three main concepts interplay. Davis commented on how in textbook settings, mutations are largely referred to as mistakes. However, given that evolution is dependent on mutations, and given the complexity of Nature itself, Davis is not convinced that Nature makes mistakes, and therefore does not completely buy the idea that a mutation should be considered a mistake.
On this note, it is my opinion that considering a mutation a mistake is still valid. Replications mechanisms, such as those used in genetic systems, are “designed” and indeed act in a way to exactly replicate the previous information and employ much effort and energy in DNA repair mechanisms. In some cases, this regulation system extends to an extreme measure called cellular apoptosis, or programmed cell death. When these fail, the mutation holds. It is a deviation from the mechanistic intent. The aspect of a mutation to be beneficial in any number of ways to an organism is a matter of statistics, that is, thermodynamics, the nature of mutation and environmental circumstances determine the mutation’s influence in a manner of statistical chance. The methods of analysis for demonstrating the statistical nature of genetics were proposed by R.A. Fisher and in fact the field of population genetics is built on this idea.
Studying evolution sheds light on speciation. By analyzing genetic similarities, the branching effect of speciation can be illustrated as a tree (I think it resembles more closely an English Ivy plant, but that’s neither here nor there). Go back far enough and you will eventually find yourself at a common ancestor, aptly named LUCA for Last Universal Common Ancestor. The idea of a common ancestor is not a universally accepted one. Contenders of the design theory, sometimes grouped as Creationists (however not all design theorists believe the literal translation of book of Genesis), do not accept that LUCA ever existed. They put a spin on the concept, and say that yes, you can show species variation, but a canine was never related to an aquatic animal. The original canine begot other canines and variation, as well as controlled breeding, gave us the dogs we have now. Davis did not explicitly say that he agreed with this point of view, but he did seem to give it some credit while simultaneously saying that proposed Darwinian explanations for macroevolution were not convincing enough for him. However, Davis did admit that the current design theory doesn’t explain a beginning for life and instead introduces a straw man argument. This disappoints Davis, as he seemingly is looking for another answer, and the design theorists haven’t provided a good alternative. At this point, both Professor deVries and Professor Möbius entered into the discussion. deVries commented that in modern times, the lines that divide species have been muddled and in fact are not well defined. To say that a canine has no relation to other species defies the modern observation. Möbius questioned how design theorists think of microevolution. If they don’t believe in macroevolution in the accepted form, how can they believe in microevolution?
Möbius, I think, missed that, as far as I can tell, the design theory of variation is still dependent on microevolution. But this is not always consistent with what design theorists believe, especially Creationists. In a recent public debate, Creationist Ken Ham interviewed a Creationist microbiologist, who asserted that new functions bestowed on an organism are not caused by new genetic information being introduced but instead is the application of already existing genetic information that had not yet been expressed. This is, as any geneticist can tell you, entirely wrong.
Davis progressed with the lecture by pointing out that when talking about the origin of life, one must of course answer how life started, not just where diversification came from. DNA encodes proteins. Proteins transcribe and translate RNA, and then proteins, such as DNA polymerase, assemble new DNA. This new DNA will then, as always, encode proteins. But this begs the question: if proteins are required to form the machinery that translates genetic code to create proteins, where did the machinery come from if the mechanism to create the proteins is reliant on proteins that needed to be created in the first place? When answering how life started, one runs into this “chicken and egg” problem. First, we must go further back to see how the molecules necessary for life were introduced. Davis showed slides of an experiment by Miller and Urey in which what were thought to be the atmospheric chemicals were submerged in water which was heated to a gas, charged with electricity, condensed before starting the cycle over. This experiment replicated what were thought to be the conditions of early Earth, and demonstrated that in these conditions, specifically being recycled through water and pelted with energy, early atmospheric molecules form the molecules that can start life. In fact, these molecules almost start assembling by themselves. These are the molecules necessary for DNA and RNA. Back to the chicken-and-egg issue, recent studies have shown that RNA has the material (no longer used or functioning) that would give it the ability to replicate itself. This bypasses the DNA-protein question. Sort of. Why were DNA and proteins introduced? There’s not much difference between RNA and DNA. Changes like those could have been product of statistical chance guided by thermodynamics. And if you’re encoding for a function, in this case replication, we know that those systems with more efficient functions outlast inferior systems and take over. Proteins are much better at DNA replication than RNA could’ve been. This gives evidence for what is referred to as and RNA world.
This may seem to end things, but Davis introduced a new idea, panspermia. This states that life did not originate on Earth, but was brought here. One proposal is that a chunk of space rubble landed on Earth as a meteorite, bringing with it early examples of life. Another proposal is that intelligent, extra-terrestrials introduced life to the planet. Davis does not believe that the latter is such a dismissible notion, as there is a lot of evidence supporting contact from beyond the stars.
While I agree that it is probable other life forms contacted early civilization, I find that the RNA world hypothesis makes any design theory unnecessary.
So, when you’ve arrived at the origins of life, you run into what Davis said you were going to run into. What is the meaning of life? Better put, what is the significance of life? Is there a significance of life? Davis believes there is a significance to life, but deVries defiantly disagrees. There is no grand significance to life or anything, he says. There is no significance. Davis countered by saying that to determine that there is no significance to life, but to be able to recognize what significance is proves that significance exists somewhere, or in something. So if you recognize significance, you can’t so there is none anywhere. deVries conceded that significance is a relative term. He can state that life on Earth is significant to him, because it’s his home and he’s a swell guy. So it has significance to him. But in the grand scheme, what significance does life on Earth have to the cosmos? Why does there have to be significance? Davis asserted that in the absence of consciousness, there can be no significance. If life is a necessary condition for consciousness, and if consciousness is a necessary condition for meaning, then life must be very important, i.e. significance exists. The conversation went back and forth, and voices were lost in each other until Davis eventually said they were talking about two different things, and because of time constraints they both agreed to move to the next slide. I myself got lost in the points they were trying to make.
It is my take that they weren’t considering the whole question, or maybe they were considering the wrong question, or maybe they’re looking at it in the wrong light. As I understand, they were talking about significance in terms of the level of effect something has on another. If there was a human being that was of superhuman proportions both in physical and mental capabilities, his effect on the human population would undoubtedly be profound. He would be significant. But in the grand scheme of the cosmos, what significance does the greatest human have compared to that of the greatest ant? Then, he would have no significance. This scenario is only considering level of effect. I see significance in terms of probability, statistical significance. There are some events, as in organic chemistry, which have two pathways. One pathway will happen, say, 95% of the time and will give one product. The second pathway only happens 5% of the time, and gives a different product. This is because of thermodynamically favored events. By physical laws, the second pathway should almost never be observed (or only 5% of the time). And yet, sometimes, it is. The strictest laws of nature held to even a minute statistical difference do not deal with absolutes. These have been occasionally called “thermodynamic miracles”, events highly unlikely to occur. From a genetics standpoint, the amount of statistical variation that is possible when leading up to a given person in a given time is simply astronomical. The levels of recombination during meiosis, the de novo mutations, the epigenetic marks and variations, the chances for error, the environmental input to a mother during the first trimester, the extreme level of competition and success of the father’s individual sperm out of millions, the chance for developmental complications. And of course, the odds of romance. I would faint in an attempt to calculate the odds of Professor deVries coming out of the womb as baby deVries. To consider even more the odds that William deVries became Professor deVries, the man sitting across from me in Morse hall 401 Wednesday nights during second semester of Junior year would be incalculable. Not all life events are as special. If I am breeding out independently assorting genes in a subset of fruit flies, I will see every phenotype possible every time. You know, if I don’t mess up. I think the universe runs on statistically significant events. I think life embodies a lot of what the universe can do with those events. So in these terms, I say life holds significance.
But what does this mean? How do we derive meaning from any of this? These final considerations were left largely untouched because we ran out of time, but Davis again reiterated that if consciousness is necessary to recognize significance, and if we find consciousness in life, then life must be significant indeed.