With New Horizon’s next target to be 2014 MU69, located outside of our Solar System in the Kuiper Belt, it is no doubt that we will reach further ends of our universe through advances in spacecraft technology. The chance to explore other galaxies and the possibility of finding life on other planets inches closer to becoming a reality. It’s possible that life elsewhere would be quite different, but learning about the nature of life on Earth can help us understand the possible characteristics of life on other worlds.
What are the General Properties of Life on Earth?
Defining living organisms from nonliving materials can be difficult given the multitude of characteristics defining each. Biologists have identified at least six key properties that appear to be shared by most, or all, living organisms on Earth, according to the 3rd edition of Life in the Universe by Jeffrey Bennett and Seth Shostak. The general properties defining life on Earth are: order, reproduction, growth and development, energy utilization, response to the environment and evolutionary adaptation.
Order
The internal structure of living organisms represents order. The molecules that make life possible are arranged in patterns that make cell structures, as opposed to a random order. However, order alone does not make all things living. For example, DNA has order but it’s considered a building block of life, not life itself.
Reproduction
Living organisms reproduce their own kind and subsequently copy their own DNA. Bacteria are simple life forms that contain genetic information in a single loop of DNA. They reproduce by binary fission, basically a single cell dividing into two identical daughter cells. Without reproduction, there wouldn’t be a way for life as a whole to survive.
Growth and Development
The growth and development of living organisms depend on factors such as heredity and environment. This property seems necessary to life in that all organisms grow or develop during at least some periods of their life cycles.
Energy Utilization
Living organisms wouldn’t be able to perform any activities without energy as fuel. To maintain order and survive, a living organism must have a continual source of energy like food or chemical interactions with the environment.
Response to the Environment
With changes in the environment come changes in living organisms. Swallows fly south for the winter, a Venus flytrap closes in response to an insect and an octopus squirts ink to escape from predators. However, response to the environment alone is not a sufficient requirement for life. Solar panels respond to the environment by converting sunlight to electricity, but they are not considered living organisms.
Evolutionary Adaptation
Organisms who adapt to their environment may evolve in ways that better their chances of survival. “Survival of the fittest” is a fitting phrase and is understood as “survival of the form that will leave the most copies for itself in successive generations.”
Conclusions About Life On Earth
While all six properties of life are significant, biologists today regard evolutionary adaptation as the most fundamental and unifying of all. It explains the immense diversity of life on Earth and understanding this through the theory of evolution can give future research an insight into our quest for the search of life in other worlds.
