Kerry Lynn Macintosh.
Imagine a scientist friend invites you to visit her research laboratory. She directs you to a cage. You see a small, furry creature with round ears and a long tail crouched in one corner of the cage. Based on these visual cues you assume the creature is a mouse. You quickly draw some basic inferences: the mouse is fond of cheese, afraid of cats, and none too bright.
Then your friend surprises you. She informs you that she engrafted the mouse with human brain stem cells; as a result, all the neurons in its tiny brain are of human origin. She made the mouse so she could study the function of human neurons in a living model. You ask whether the mouse thinks like a human. Your friend laughs and explains that its brain is too small for that.
You glance at the mouse again. Despite what your friend has said, the mouse’s glittering black eyes now seem to hold a spark of human intelligence. You shudder in revulsion.