Simplify the following text for a Grade 11 native English-speaking person.
Original: When it comes to conducting tests related to intelligence , learning , and drug abuse , rats are a popular choice due to their high intelligence , ingenuity , aggressiveness , and adaptability .
Simplified: Rats are more popular for tests relating to intelligence , learning , and illegal drugs . This is mostly because rats have a high intelligence , ingenuity , aggressiveness , and adaptability .