Difference Between Spontaneous Generation and Panspermia

The key difference between spontaneous generation and panspermia is that spontaneous generation theory believed that life can arise from nonliving matter while panspermia theory believed that life on earth was transferred from somewhere else in the universe to earth.

The origin of life on earth is a very big mystery to human beings. There are several theories that attempted to explain how life on earth originated. Spontaneous generation and panspermia are two such theories. Spontaneous generation theory proposed that living creatures could arise from nonliving matter. Panspermia theory stated that life on earth did not originate from here, but it was transferred from somewhere else in the universe. Thus, panspermia theory believed interplanetary transfer of life and the distribution of life throughout the universe.

CONTENTS

1. Overview and Key Difference
2. What is Spontaneous Generation 
3. What is Panspermia
4. Similarities Between Spontaneous Generation and Panspermia
5. Side by Side Comparison – Spontaneous Generation vs Panspermia in Tabular Form
6. Summary

What is Spontaneous Generation?

Spontaneous generation is an obsolete theory regarding the origin of life on earth. According to it, life can arise from nonliving matter. In other words, organisms do not descend from other living organisms. Certain conditions in their environment should be fulfilled in order for creation to occur. Spontaneous generation theory was proposed by the Greek philosopher Aristotle. Spontaneous generation assumes the generation of complex organisms; for example, dust creating fleas, maggots arising from rotting meat, and bread or wheat left in a dark corner producing mice, etc.

Several scientists, including Francesco Redi, John Needham, Lazzaro Spallanzani, and Louis Pasteur did not accept this theory. They performed different experiments/research in order to disprove this theory. Francesco Redi showed that maggots arise from eggs of flies rather than directly from rotting disproving spontaneous generation. Later, Louis Pasteur did experiments with flasks with twisted necks (swan-neck flasks) and proved sterilized broths in swan neck flasks remained sterile. Unless microbes are introduced from outside (from the air), the broths remained sterile, and there was no growth of microorganisms. Pasteur’s experiments disproved spontaneous generation theory by proving “life only comes from life”.

What is Panspermia?

Panspermia is another theory that explains the origin of life. According to it, life on earth did not originate on our planet. It was transported here from somewhere else in the universe. The Greek philosopher Anaxagoras wrote this idea for the first time in the 5th century. According to this theory, the emergence of life began soon after the heavy bombardment period of the earth since the earth was endured a very powerful series of meteor showers during that period of time.

However, there was life on earth before this bombardment phase.  Due to these meteor showers, the living forms went extinct from the earth and then after originated again from transferring from the universe. In order to receive life from elsewhere in the universe, there should be another planet that supports living organisms. The presence of water and the presence of organic matter in space has supported this belief. But, due to the failure to test and prove experimentally, this panspermia theory has been criticized in many situations. Therefore, scientists acknowledge this panspermia theory as an untested and unproven theory regarding the interplanetary transfer of life.

What are the Similarities Between Spontaneous Generation and Panspermia?

• Spontaneous generation and panspermia are two theories that explain the origin of life on earth.
• These theories are obsolete theories.
• Both theories did not mention about the origin of life from living matter.

What is the Difference Between Spontaneous Generation and Panspermia?

Spontaneous generation theory is an obsolete theory that states living organisms can originate from nonliving matter while panspermia theory is an unproven and untested theory that states life on earth was transported from somewhere else in the universe. Thus, this is the key difference between spontaneous generation and panspermia. The Greek philosopher Aristotle first proposed spontaneous generation theory while Greek Philosopher Anaxagoras first wrote about panspermia theory in the 5th century. The spontaneous generation theory came to be preferred by science for more than two thousand years in contrast to panspermia. However, scientists disproved spontaneous generation theory while panspermia theory remained an untested, unproven theory.

Below infographic tabulates the differences between spontaneous generation and panspermia.

Summary – Spontaneous Generation vs Panspermia

Spontaneous generation theory states that living organisms develop from nonliving matter. Panspermia theory states that life on earth was not originated here. It arrived from somewhere else in the universe. So, this is the key difference between spontaneous generation and panspermia.  Scientists have disproved spontaneous generation theory, but panspermia theory remains an untested, unproven wild theory.

Reference:

1. Joshi, Sonali J. “Origin Of Life: The Panspermia Theory .” Helix Magazine, 2008, Available here.
2. Braun, Bruce. “Life Traveling In Space: A Story Of Panspermia.” Nature News, Nature Publishing Group, Available here.

Image Courtesy:

1. “Louis Pasteur Experiment” By Kgerow16 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Panspermie” By Silver Spoon Sokpop – Own work; For the proto-bacteria I used an adapted version of File:Bacteria-.svg by JrPol and for the DNA I used an adapted version of File:DNA chemical structure.svg by Madprime. Earth from File:Earth Flag.svg by Himasaram (CC BY-SA 3.0) via Commons Wikimedia