The mystery of blood types

Why do we have different blood types? We ponder a medical mystery.

When my parents informed me that my blood type was A+, I felt a strange sense of pride.

If A+ was the top grade in school, then surely A+ was also the most excellent of blood types — a biological mark of distinction.

It didn't take long for me to recognise just how silly that feeling was and tamp it down. But I didn't learn much more about what it really meant to have type A+ blood.

By the time I was an adult, all I really knew was