What two religions fought in Europe during the Middle Ages?

The two main religious that fought in Europe during the Middle Ages were Islam and Christianity.Islam was founded in 7th Century AD and quickly expanded.Muslim invaded Spain from North Africa and held Spanish territory for around 600 years.  

Explanation:

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.