City-dwelling helped us evolve resistance to disease

摘要

Living in a crowded city doesn't sound like a recipe for good health, but it may have helped our ancestors protect their descendants from disease.rnSome people carry a genetic sequence, or allele, that provides immunity to leprosy and tuberculosis. Mark Thomas at University College London wondered whether this genetic immunity could have been gained when people began living in close proximity. Poor sanitation would have meant that disease was rife in ancient cities, but exposure tornthe pathogens would have led to resistance developing, which the inhabitants would have passed on to their descendants.