Mike Ko Personal Portfolio


Home-School Education
Hong Kong

University of Durham
Bachelor of Science
United Kingdom

University of Sussex

Master of Arts
United Kingdom

Writing - Commentary

What is Life?




                        What is Life? This is one of the most fundamental questions that humans have ever asked. We have probably been doing so for as long as we can think consciously. Countless efforts were made to define what we call life, but no satisfactory definition emerged. Life is clearly different from the other structures that exist as its environment. Yet just how so exactly is hard to pinpoint. Physicist Erwin Schrödinger was one of many who had pondered upon this perplexing question. In his book, titled precisely “What is Life?”, he compared life to a growing crystal that repeats its structure. But at the same time, life is also much more than that. In their book with the same title, Lynn Margulis and Dorion Sagan present their views on life in “What is Life?”. Following the footsteps of many others, they showed what exactly the word ‘life’ meant.

Defining Life: Autopoiesis

                        The book can be divided into three notable parts. In the first part, the authors introduced a potential criterion for defining life. For something to be defined as life, the authors have cited, it must demonstrate autopoiesis. In other words, life must sustain itself. Though metabolism, life extracts various forms of energy to maintain its form. All life does so, but rocks, gases, plastics, and everything else does not. Yet to a certain extent, the Earth as a planet is also autopoietic, due to all the life that exists on its surface. Life is more or less a self-sustaining chemical process.

                        Of course, where there is life, there is death, and humans have greatly speculated on the nature of death as well. Yet from a scientific perspective, death purely marks the end of self-sustaining metabolism. Structural order of the organism breaks down, energy is dissipated as heat, and thermal equilibrium is established. Life is an autopoietic process, while death is just the consequence of the Second Law of Thermodynamics.

Life's History, Diversity, and Sentience

                        The second part shows how life manifests itself on Earth. The authors first discussed the beginning of life, an occurrence whose details nobody can be certain of. Still, life probably arose from self-sustaining chemical reactions involving RNA. RNA can store genetic information, yet it can also act as enzymes. Hence RNA molecules can reasonably self-replicate on its own. If this RNA chemical system gained a membrane, it can become a self-sustaining, self-replicating unit called a cell.

                        Regardless of the actual origins of life, it is apparent that a single ancestral cell did emerge. Over time, that common ancestor evolved into the various forms of life that exists today. These are grouped into five main categories: the bacteria, protoctists, animals, fungi, and plants. Each category’s history and special characteristics are explained, illustrating the various autopoietic forms that are defined as life.

                        Finally, in the third part, the book dealt with an abstract subject: sentience. The authors asserted that all life, be it a microbe or multi-celled, lives with a purpose. An autopoietic purpose. They strive to sustain themselves until the last moment, when they die. All life makes decisions to achieve that goal. Thus, all life is sentient.

Interesting Perspectives

                        The book for the most part was a tour of life, describing the different forms that exist on Earth. However, I think the beginning and ending chapters contained most of the interesting parts.

                        The book stated that the defining property of life is that they are autopoietic. They carry out self-sustaining metabolism. I think this captures most, if not all, of life’s essence. Even now, I still cannot come up with any non-living yet autopoietic object. However, additional criteria may be required in the future to accurately define life. Consider if humans managed to program a robot that maintains its form and replicates itself. That robot can then be defined as autopoietic; it strives to self-sustain. Yet most shall be inclined to define the robot as non-living. Hence autopoiesis by itself may be insufficient to define life in the end.

                        I also agree with the authors that all life is sentient, in the sense that they sense and react to their environment to suit their needs. However, I am wary of using the word ‘sentience’. It is mostly used to describe humans’ superior ability to think. In my view, humans are certainly different from many life forms. We can store large amounts of information in our brains and use them accordingly. Yet down to the basic level, we are biologically no different than any other form of life.

                        In addition, the book mentioned an interesting way of perceiving life. English scientist James Lovelock proposed that the Earth as a whole can be defined as a living unit. Known as “Gaia”, this unit includes Earth’s living and non-living components, organic and geochemical processes. Together they function as interlinked parts that regulate Gaia. This is analogous to how our bodies are regulated by its component cells’ activities. Although its resemblance to multi-celled organisms’ hierarchy is intriguing, I am not partial to this perspective. Planets and their non-living components do not require life to regulate their chemical cycles. Life is more like an accessory to a planet, distinct from non-living matter. I am inclined to say that life interacts with its non-living environment, but they are always different. They do not act together and strive to accomplish a particular purpose. So I do not prefer to combine a planet with life into a single, living entity.

                        Still, I think there was one important point in the tour of life section. That point is on merging bacteria. Evolution is mostly described as a linear process. Certain individuals of one species evolve to become another. Yet the first protoctists, ancestors of all eukaryotes (including animals, fungi, and plants), arose from merging bacteria. This reminded me that evolution can be non-linear. Species, at least microbes, can merge to evolve into new species.

                        Summing up, “What is Life?” certainly answers one aspect of the title question. It showed the major forms that existing life takes. Yet the author’s answer to the other aspect, on defining life, may turn out to be inconclusive. The issue is as scientific as it is philosophical and ethical. Hence we shall probably continue to ask ourselves what life is for a long time.

                                                                                                                                                                  Mike Ko
                                                                                                                                                                  ( 1,044 words )


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