THE molecule looked like a giant jellyfish. Or maybe a spider. Halfway through my organic chemistry final, the monster lay there on the page, mocking me. My task: explain how the ungainly molecule folds into a tidy package. The problem: I had no clue. Maybe if I looked at it sideways? No, that didn’t help. This was getting ugly.

Contemplating a midlife career change from science writer to doctor, I spent eight months last year at Harvard Extension School slogging through two semesters of organic chemistry, or orgo, the course widely known for weeding out pre-meds. At 42, I was an anomaly, older than most of my classmates (and both professors), out of college for two decades and with two small children. When I wasn’t hopelessly confused, I spent my time wondering what the class was actually about. Because I’m pretty sure it wasn’t just about organic chemistry. For me, the overriding question was not “Is this on the test?” but rather “What are they really testing?”

Orgo has been haunting pre-meds since 1910, when the Carnegie Foundation for the Advancement of Teaching released a landmark report calling for tougher admission standards to medical school and for medical training based on science. Hence emerged science prerequisites that have remained virtually unchanged: two semesters each of biology, physics and general and organic chemistry.

The report was meant to professionalize medicine but led to generations of doctors more grounded in science than in the humanities. This is not necessarily bad, but lately a sense has emerged that the pendulum has swung too far. Medical schools are tweaking admission protocols, looking beyond an A in orgo for future doctors who are less Spock and more Kirk.