Story of Evolution, Evolution of Stories Bryn Mawr College, Spring 2004 First Web Paper On Serendip

Is Death Responsible for Diversity?

Bethany

Some of the hardest questions we struggle to answer in life surround the phenomenon of death. What happens when we die? Is there something beyond death? Is one way to go better than another? Is it possible to escape death? Why do we die, anyway? Why couldn't we just live forever? One explanation for death may come from the story of evolution. To explore this question, let us imagine a hypothetical situation, a world in which nothing dies. (We will imagine also, for now, that organisms would continue to evolve along the same trajectory as they do at present.) Every organism that has ever existed in the past would exist now, along with every organism present and every organism that has yet to exist. Not only would the world contain these organisms, but all potential organisms. "However many ways there may be of being alive, it is certain that there are vastly more ways of being dead or rather, not alive." – Richard Dawkins (p 104, Dennett) All the representations of the ways of being 'not alive' would be there, including those that we could not possibly fathom, those that are not necessarily contingent to our present environment. What this signifies, this absence of death, is a lack of natural selection. When nothing can die, everything is selected for, nothing is selected against. No death implies; no tests, no judgments of fit or unfit, no randomness or weeding-out of the genome, no consequence to anything that is potentially detrimental to the species. This hypothetical situation is a look at the unchanging set of all possible options, every combination of DNA that could potentially give rise to life. Every possibility is valid. This version of the world could only exist if we ignore three crucial points; the second law of thermodynamics, the definition of a niche as it pertains to the environment and to evolution, and the fact that without these influential factors, evolution, at least in the sense that we now know it, would not exist. The second law of thermodynamics states that energy tends to go from a state of high concentration to a state of expansion, or being spread out. In other words, there is a tendency to move away from potential energy. As we know it, the sun 'dies', gives off energy. This energy is taken in by plants, which die and fertilize more plants with that energy. They also give energy to any plant-eating animals, which in turn give energy in decomposing to more plants. Organisms give energy to other, carnivorous organisms by being eaten, by dying. There is no way to create something new if some form of work is not done. Energy must be transferred, and the manifestation of this in evolution is the process of death, and consequent creation or new life. It is not possible to acquire something from nothing, the energy must be used, given out, recycled. In the hypothesis version of the world, there is no transfer of energy; there is only accumulation of life. This would quickly exhaust the supply of energy and available space. Another enormous side effect is that evolution would cease, at least as it exists now. A driving factor for this process is the idea of competition, which relies on a loser, which implies death or extinction. "Indeed, the gist of every selection is to favor individuals that have succeeded in finding a progressive answer to current problems. The summation of all these steps is evolutionary progress." (p 215, Mayr) A situation in which there is no death is a situation in which everything is constant. Therefore there would always be the same current problems and no catalyst to inspire any changes. "Elimination does not have the 'purpose' or the 'teleological goal' of producing adaptation; rather, adaptation is a by-product of the process of elimination." (p 150, Mayr) No adaptation without elimination. Death is also vital to the evolutionary niche, and the expansion and contraction that occur within this niche. If death were non-existent, we might have niches, but they would not be necessary. Every organism would be able to live anywhere, to co-exist with any other organism. This side effect of the absence spits in the face of our current situation. According to Mayr, a niche is a "constellation of properties of the environment making it suitable for occupation by a species." (p 288) It's important to remember that an environment is partially defined by what organisms inhabit it. So a niche evolves and changes with its living constituents. "Open ecological niches or zones are often repeatedly colonized by entirely unrelated organisms that, once adapted to these niches, become by convergence, extremely similar." (p 156, Mayr) This supports the hypothesis that the definition of a niche includes the organisms to which it is home, and it also spotlights the huge influence of selection pressure; what worked then will work now, what worked there will work here. If the niches are similar, they will probably yield similar organisms and similar lineages. But if there is no selection pressure then you could have penguins in the Savanna, giraffes on the South Pole. There would be nothing barring these organisms from different environments, because there is no death, no consequence for a lack of compatibility between inhabitant and habitat. The world would be just one big niche, where anything goes, anything is possible. If we do away with natural selection, then we must consequently do away with change, with evolution, with boundaries. "Whenever a species acquires a new capacity, it acquires, so to speak, the key to a different niche or adaptive zone in nature." (p 208, Mayr) The key merited is contingent to the change only because the niche is 'locked' before the change occurs. The boundaries we see are what create the selection pressures that cause organisms to change and are often products of selection pressures themselves. There is a direct relationship between these phenomena. If we have change (evolution) and niches, then death and natural selection are mandatory. Sources - Mayr, Ernst. What Evolution Is. New York; Basic Books, 2001. Dennett, Daniel. Darwin's Dangerous Idea.

| Course Home Page | Forum | Science in Culture | Serendip Home |

Send us your comments at Serendip