Life Ascending Week 2: Origin of Life LoganYang

Origin of Life: Lane explains the dominant theories of how life could have arisen from the infamous primordial soup, the thermal and alkaline vents, and even the possibility of life (or at least organic molecules) having been imported from space. Lane writes well keeping concepts general enough for the public to understand but maintaining an authoritative tone that keeps the reader of overly questioning the ideas presented in the chapter. The main surprise for me was how thoroughly the subject was dealt with. I had expected a fairly surface level explanation that only touched on the specific processes required for life to originate, but was pleasantly surprised to see Lane discuss the laws of thermodynamics and explains how they govern the reactions that could have possibly governed the origin of life. 

The chapter starts with the Miller experiment which proved that simple gases can be used to make organic molecules and how this theory came to dominate until the observation of ocean vents. The black smokers that are populated by tube worms and their ilk are the next subject of conversation as Lane describes how the hydrogen sulphide reacts with oxygen to create the raw energy required for the synthesis of organic compounds in modern vents and that an analogous reaction could have occurred earlier in earth's history via hydrogen sulphide and an iron mineral catalyst like those found within the vents. The next discussion is that of alkaline vents which also use chemical energy but this time the much more familiar reaction of hydrogen and carbon dioxide. These vents seem to be a perfect place for life to arise as the chambers within the spires at these vents allow for the concentration of organic molecules increasing their chances of interaction with one another, iron for catalytic process, and and rich in energy due to hydrogen flowing into the system. 

I personally really like how Lane sets up the next part of the chapter, having described the possible theories as to what was necessary for life to evolve he now approaches the question from a different aspect asking given current life forms what should have evolved and would it have been possible in the environments the chapter as analyzed. Using LUCA (last universal common ancestor) he states that a process like the Krebs cycle i.e. one that incorporates free hydrogen and carbon dioxide into usable organic compounds must have arisen in these alkaline vent environments. Using a reaction known to produce energy when bonding hydrogen and carbon dioxide Lane concludes the reaction was possible in these vents as they supplied both a catalyst and the activation energy needed to start the reaction. The only problem then becomes how did life which through this mechanism is now able to create its own energy move from the vents to the open ocean? The answer for this the establishment of a chemical gradient such as that used mitochondria today where a proton gradient supplies enough energy to cause a net gain in atp and energy, however these gradients are established by proteins which are encoded by genes which suggests DNA evolved before life moved of the vents. 

My main issues with how Lane writes is that he makes these events seem goal driven or at least that is the vibe I received. The ending part of the chapter seems to highlight this as his statement that genes must have evolved to make proteins the must makes a chemical gradient his logic is sound and plausible, but I am wary of how directed and driven he makes it sound. One quote that really concerned me was "It is certainly true that natural selection can't work without some sort of replicator; and it is equally true that life can only evolve complexity though the auspices of natural selection" (Lane 12). I am fairly certain that this statement is straight up wrong as we have covered in class that evolution can occur without selection and I see no reason why complexity would be an exception to this, thoughts on this anyone? (Also I am reading through the DNA chapter as I post this and found another quote that concerns me when describing the errors in DNA replication Lane states "Natural Selection, by casting away all but the least of these monsters, is actually a force for stability" (Lane 37). Is it possible for Natural selection to be the subject of hero worship?