Identify the type of immunity developed by the European colonists during childhood to these diseases.

The type of immunity that the European colonists developed during childhood to these diseases is known as "acquired immunity" or "adaptive immunity". This type of immunity is developed when our bodies are exposed to microbes or diseases, our immune system 'learns' and 'remembers' how to fight off these diseases.

Here are the steps of how this immunity is developed:

1. Exposure to Disease: The first step in developing acquired immunity is exposure to a disease or pathogen. This can happen through natural exposure in the environment or through vaccination.

2. Recognition: The immune system recognizes the foreign pathogen and immune cells (like T and B cells) are activated.

3. Response: The immune system responds to the pathogen by producing specific antibodies that can neutralize or destroy the pathogen. T cells also help in destroying the infected cells.

4. Memory: After the infection is cleared, some of the activated T and B cells become memory cells. These cells remember the specific pathogen and can mount a faster and stronger immune response if the same pathogen is encountered again in the future.

So, when the European colonists were exposed to diseases during their childhood, their immune system developed a memory of these diseases, which is why they were able to fight off these diseases more effectively later in life.