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The Molecular Origin of Life: Replication or Metabolism-First? Introductory Version

Co Authors:

Annie Prud’homme-Genereux
Continuing Studies and Executive Education
Capilano University

Rosalind H. Groenewoud
Life Sciences
Quest University Canada


This case explores both the evidence and inconsistencies in the two major hypotheses for the origins of life on Earth: Replication-First or Metabolism-First. The case has two versions published on this website - one is written at the introductory level and the other at an advanced level for instructors to choose from based on their students' background.  The introductory version is most suitable for students in a first or second year biology course while the advanced version is suited for students in a third or fourth year undergraduate evolution course with previous biochemistry knowledge.  Using a "jigsaw intimate debate" format, students will gain a clear understanding of both hypotheses. The purpose of this format is to dissuade students from agreeing with one hypothesis, solely because they learned it first. Students, separated into groups, learn and then teach one hypothesis and then they switch and argue on behalf of the other.

  • Develop a definition of life.
  • Compare and contrast the Replication-First and Metabolism-First hypotheses.
  • Describe potential locations and environments that could have fostered early life.
  • Synthesize scientific information quickly.
  • Think critically about scientific information.
  • Explain recently learned information to peers.
  • Use scientific evidence to argue a position.
  • Develop an educated opinion on a recently heard debate.
  • Evaluate the strength of scientific arguments.
  • Think creatively about scientific information.
Keywords: Origins of life; Replication-First Hypothesis; RNA World Hypothesis; Metabolism-First Hypothesis; Iron-Sulfur World Hypothesis
Topical Area: Scientific argumentation
Educational Level: Undergraduate lower division
Formats: PDF
Type/Method: Intimate Debate, Jig-Saw
Language: English
Subject Headings: Biology (General)   Evolutionary Biology  
Date Posted: 5/10/2012
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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