Evolution > prey

In this simple procedure, grains of rice are used to model small organisms, and students act as predators selecting food during limited time spans. Over a number of generations, the proportion of grains of rice of each colour in each population will change if students select one colour in preference to another. This is a simple model for natural selection resulting from predation.

This involves placing baits of different colours (the ‘worms’) in a place where birds are known to search for food. Uneaten ‘worms’ are collected (or counted) regularly and the ‘worm population’ is restored with more coloured bait in the same proportions as the bait that remains. After several cycles of predation and breeding, the proportions of each colour in the population will have changed – simulating directional