Which of the following organs can be considered vestigial in humans but functional in other mammals

1. Analyze the question The question asks which organ is vestigial in humans (reduced, with little or no function) but still functional in other mammals.

2. Explain the concept Vestigial organs are structures that have lost most or all of their original function through evolution. Examples in humans include the appendix, the coccyx (tail bone), wisdom teeth, and the muscles that move the ear.

In herbivorous mammals such as rabbits, horses and cows, the caecum and appendix are large and help digest cellulose with the aid of symbiotic bacteria. In humans, the appendix is small and does not play a significant digestive role.

3. Go through the options

• A. Liver: It is essential in humans (detoxification, bile production, glycogen storage), so it is not vestigial.
• B. Appendix: It is reduced in humans, but functional in herbivores for cellulose digestion. This fits the question.
• C. Rectum: It stores faeces before egestion, so it is functional in humans.
• D. Stomach: It digests food in humans, so it is functional.

4. Answer The correct option is B. Appendix.

5. Exam tip When you see "vestigial", think appendix first. Remember the pair "Appendix: small in humans, large in herbivores". Also watch for other vestigial examples such as the coccyx and wisdom teeth, as JAMB likes to rotate these.