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 advanced version of the case is best suited for students in a third or fourth year undergraduate evolution course with previous biochemistry knowledge, while the introductory version of the case is suitable for students with less background knowledge in a first or second year biology course. 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.