News Animals

To understand the origins of pain, ask a flatworm

Experiments in planarians identify a chemical middleman that triggers the body’s ouch detectors

Schmidtea mediterranea

DANGER DETECTOR  In planarians (Schmidtea mediterranea shown), a protein called TRPA1 detects hydrogen peroxide, a molecule produced when cells are damaged. These new results give hints about the evolution of human pain.

Chris Petersen/Northwestern University

By Laura Sanders

- More than 2 years ago

Hydrogen peroxide, a molecule produced by cells under duress, may be a common danger signal, helping to alert animals to potential harm and send them scurrying.