Darwin's Rib

An evolution professor learns an important lesson in his class.

By Robert S Root Bernstein
Sep 1, 1995 5:00 AMApr 17, 2023 8:59 PM
A mock-up of a human skeleton on the background of a blackboard on the wall in a classroom for teaching.
(Credit:nik93737/Shutterstock)

Newsletter

Sign up for our email newsletter for the latest science news
 

As all good teachers know, students will work much harder for extra-credit points than at the assigned task. I like to take advantage of this convenient trait in my introductory course on evolution. Once my students — nonscience majors at a midwestern land-grant university — understand the basic terms, I offer additional points for answering the questions I really want them to investigate. Find a dozen differences between the skeletons of a chimpanzee and a human being, I challenge them; tell me how a human female skeleton differs anatomically from a male.

The male and female skeletons I display are exemplary in their difference, and since most students should be able to guess what that difference is if they don’t already know, I usually feel confident that the final answer is a giveaway. I say usually because seven years ago, the first time I taught the course, I got a surprising answer that still crops up with alarming regularity. Five minutes into the lab period, a young woman announced that she could answer the question without even examining the human skeletons.

I waited silently for her to explain that the female pelvis is shaped slightly differently from the male’s, with a larger opening for childbearing. That part was the giveaway. The real purpose of the exercise was to make her prove her conjecture with measurements — to translate the theory to practice. I also wanted her to explain why this sexual dimorphism — that is, this sexually determined physical difference — is not nearly so pronounced in nonhuman primates, such as chimpanzees.

She spoke: Males have one fewer pair of ribs than females.

I was totally unprepared for her answer. My mandible dropped. After a moment’s reflection, I realized she must be referring to the biblical story in which God creates Eve from one of Adam’s ribs. My student was someone who believed in the literal truth of the Bible, and it was her religious belief, not her previous knowledge of human anatomy, that made her so sure of her answer. This was going to be a challenge.

0 free articles left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

0 free articlesSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!

Subscribe

Already a subscriber?

Register or Log In

Stay Curious

Sign up for our weekly newsletter and unlock one more article for free.

 

View our Privacy Policy


Want more?
Keep reading for as low as $1.99!


Log In or Register

Already a subscriber?
Find my Subscription

More From Discover
Recommendations From Our Store
Stay Curious
Join
Our List

Sign up for our weekly science updates.

 
Subscribe
To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.