Theories of the Origin of Life

Theories of the Origin of Life

• The study of living organisms is an active area of biology, and there are six major theories that propose to explain the origin of life on Earth.

What is a Theory?

• A theory is a widely accepted explanation of a biological phenomenon based on sound evidence from rigorous empirical experiments and scientific observations.

Divine Creation Theory

• Proposes that life on Earth is created by a supernatural power, God.
• Proponent: Religion/Christian belief.
• Beliefs in this theory:
  • All living organisms were created on the same day, with no difference in their appearance.
  • They were created in their present form, with no evolution.
  • Their bodies and organs are fully developed to meet the requirements to run life, with no adaptation.

Abiogenesis Theory

• Also known as Spontaneous Generation Theory.
• Assumes that non-living material in a spontaneous manner gives rise to life.
• Proponent: Alexander Oparin & J.B.S. Haldane.
• Observations that support this theory:
  • The hair of a horse tail dipped in water gives rise to a horsehair worm, Gordius.
  • Fly larvae develop on rotten meat.
  • Van Helmont claimed that he could produce mice from a dirty shirt and handful of wheat grains kept in a dark cupboard in 3 weeks.

Biogenesis Theory

• According to this theory, life can arise from pre-existing living things.
• Proponent: Louis Pasteur.
• Note: Lazzaro Spallanzani, Francisco Redi, and Louis Pasteur performed well-designed scientific experiments to disprove the theory of spontaneous generations.

Theory of Catastrophism

• Assumes that life originated by creation and is followed by catastrophe due to geographical disturbances.
• Proponent: Bishop James Ussher & Baron Georges Cuvier.
• Note: Each catastrophe destroyed life completely, whereas each creation forms life differently from the previous one.

Theory of Cosmozoic

• Also known as Theory of Panspermia or Apore Theory.
• Assumes that life was present in the form of resistant spores and appeared on Earth from another planet.
• Proponent: Richter & Arrhenius.
• Note: This theory does not add much to the fundamental details about the origin of life, and no scientific experiments support this theory.

Theory of Eternity of Life

• Also known as Steady State Theory.
• Assumes that life has no beginning or end.
• Proponent: Hermann Bondi, Thomas Gold, & Fred Hoyle.
• Note: The main objection against this theory is that it could not explain evidence supporting the formation of Earth, and then life appeared on it.

Frequently Asked Questions

• Which of the 6 theories provided is favored most by the scientific community?
• Answer: Biogenesis theory was favored most by the scientific community. The term 'biogenesis' comes from 'bio' meaning 'life', and 'genesis', meaning 'beginning'.

The Theories of the Origin of Life

• The study of living organisms, including plants, animals, and microorganisms, is an active area of biology.
• There are six major theories proposed to explain the origin of life on Earth.

Divine Creation Theory

• Proposes that life on Earth was created by a supernatural power, God.
• Proponent: Religion/Christian belief.
• Beliefs in the theory of special creation:
  • All living organisms were created on the same day.
  • They were created in their present form, with no evolution.
  • Their bodies and organs are fully developed to meet the requirements to run life.

Abiogenesis Theory

• Also known as the Spontaneous Generation Theory.
• Proposes that non-living material can give rise to life in a spontaneous manner.
• Proponents: Alexander Oparin and J.B.S. Haldane.
• Observations that support this theory:
  • Hair from a horse tail dipped in water gives rise to a horsehair worm, Gordius.
  • Fly larvae develop on rotten meat.
  • Van Helmont claimed that he could produce mice from a dirty shirt and handful of wheat grains kept in a dark cupboard in 3 weeks.

Biogenesis Theory

• Proposes that life can arise from pre-existing living things.
• Proponent: Louis Pasteur.
• Experiments that disprove the theory of abiogenesis:
  • Redi's Experiment
  • Spallanzani's Experiment
  • Pasteur's Experiment

Theory of Catastrophism

• Proposes that life originated by creation and is followed by catastrophe due to geographical disturbances.
• Proponents: Bishop James Ussher and Baron Georges Cuvier.
• Note: Each catastrophe destroyed life completely, whereas each creation forms life differently from the previous one.

Theory of Cosmozoic

• Also known as the Theory of Panspermia or Apore Theory.
• Proposes that life was present in the form of resistant spores and appeared on Earth from another planet.
• Proponents: Richter and Arrhenius.
• Note: This theory does not add much to the fundamental details about the origin of life.

Theory of Eternity of Life

• Also known as the Steady State Theory.
• Proposes that life has no beginning or end.
• Proponents: Hermann Bondi, Thomas Gold, and Fred Hoyle.
• Note: The main objection against this theory is that it cannot explain the evidence supporting the formation of Earth and the appearance of life on it.

Quiz on the six major theories that explain the origin of life on Earth, including the Divine Creation Theory and more.