About a 4 minute read.

I think I wore my pocket protector and had tape on my glasses when this was written. 🙂 

What is life? Every budding biologist learns that life must have some level of organization, be able to reproduce, regulate internal processes, respond to stimuli, and adapt to changes over time. This definition intuitively makes sense for plants, animals, and fungi because we can see them change and die. We recognize life as something that is impermanent. But what about things like rocks, bodies of water, and the atmosphere or the machines we make ourselves? We don’t think of these things as alive. Though it’s funny because as humans we do this subconscious thing and give living qualities to inanimate things. The ancient Greeks personified the Earth as the primordial god named Gaia. Primordial, meaning before all other things. Much later in the 1970s, a chemist named James Lovelock proposed a hypothesis that claimed the earth is a living organism. This idea became known as the Gaia Theory.

Many believe that we have dominion over this planet, but Lovelock was very skeptical about the human role on Earth. He once said,  “The idea that yet humans are intelligent enough to serve as stewards of the Earth is among the most hubristic ever.” Defiance of Gaia was at the root of Lovelock’s meaning of hubris. Humans are just part of this world, and our definition of life must reflect that Earth is an intelligent living organism.

The famous physicist Carl Sagan called this world a “pale blue dot” that is “suspended in a sunbeam.” earth_PNG39This comparison leaves the impression that Earth is just rock and water; made up of primordial elements. Gasses and space debris were combined with heat and pressure to first form the Earth. It was from this turmoil that life as we see it came to be. There are many theories about how life began. An experiment published in 1953 by Miller and Urey showed that early gases such as methane, ammonia, hydrogen, and water could be charged with electricity to produce amino acids. Amino acids are the building blocks for more complex biomolecules such as nucleic acids. The early conditions on earth were shown to be capable of creating life.

Nucleic acids are considered the most important biomolecule in life. DNA, or deoxyribonucleic acid, is the most well known of all nucleic acids and the chemical structure was elucidated in 1953 by Watson and Crick. Nucleic acids are used to create, store, and pass along information from one generation to the next. DNA contains genes which make nucleic acids called RNA, ribonucleic acid. RNA, in turn, makes proteins.

Central Dogma of Molecular Biology

Proteins are made of amino acids and are the workhorse of life. Life figured out a form and function for all molecules, so it’s not a surprise that different types of life use the same proteins. All green plants use a protein called Rubisco, which is involved in the transformation of carbon dioxide into plant sugars. The central dogma of molecular biology demonstrates that life has cataloged ways to adapt to changes over time.

Organisms are made up of a system of elements, both non-living and living. Humans have hair, birds have feathers, and elephants have tusks. Plants have non-functioning structures that serve to transport minerals and water, much like the vascular systems within animals. Organisms also co-exist with other organisms. The cells of the body contain smaller structures called organelles. One of these organelles is known as the mitochondria.cell-featuring-mitochondria.jpg

The mitochondria used to be a single-celled organism that was assimilated into a larger cell. Each mitochondrion has a unique DNA from that of its parent cell, suggesting a divergence at some ancient point in the past. Bacteria also form relationships with other microorganisms as well as animals, plants, and fungi. They live among animal organs, in the soil and cover most of the surface of the planet. The bacteria in the guts of animals can exchange genetic information with their host to adapt to their environment. Another example of the characteristics of life mentioned above. Even relatively simple organisms like mycorrhizae fungus live in the soil and provide water that’s deep in the ground to trees in exchange for additional food.

Humans have relied on the plants around us to live since the dawn of man. We use trees to create buildings, fibrous plants for cloth and we have cultivated plants that we use for both food and medicine. The human relationship with plants is both symbiotic and synergistic, demonstrating a co-evolution of multiple species. The great Hippocrates said, “Let food be thy medicine and medicine thy food.” Many medicines were originally derived from plants before they end up in a synthetic form. These plants were discovered by people scouring remote and familiar places alike. Some of these plants might be closer than you think. Some of the plants that grow around us even possess unknown benefits. The ones called weeds have medicinal benefits that coincide with the ailments of people living nearby. It would be curious to find out that the plants growing outside our doors contain the medicine we need. Perhaps the pale blue dot is, in fact, an intelligent organism better known as Gaia?

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