Modern dog breeds are largely the result of 160 years of owners crossbreeding certain dogs in order to select for particular physical appearances. Owners often say that some breeds are also more likely than others to have particular personality traits—basset hounds are affectionate; boxers are easy to train—but Kathleen Morrill and colleagues found through a combination of owner surveys and DNA sequencing of 2,000 dogs that while physical traits are predictably heritable among purebred dogs, behavior varies widely among dogs of the same breed.
Which choice best states the main idea of the text?
Explanation
Context: Dog breeds are largely the product of 160 years of selective crossbreeding for physical appearance. Owners often claim certain breeds have particular personality traits. But Morrill et al.'s study combining owner surveys and DNA sequencing of 2,000 dogs found that while physical traits are predictably heritable in purebred dogs, behavior varies widely within the same breed.
Answer: B) Research fails to confirm a commonly held belief about dog breeds and behavior.
Why? The passage sets up the commonly held belief (breed predicts personality traits) and then presents Morrill et al.'s finding that contradicts it — behavior varies widely within breeds, unlike physical traits. B accurately states that research fails to confirm the belief.
Traps:
- A) "Dog breeds would not exist without many years of human intervention in dogs' breeding" — while true, this is background context; the main point is about the behavior-breed belief being contradicted
- C) "The dog breeds most popular among owners have often changed over the past 160 years" — about popularity trends; not addressed in the passage
- D) "A study of dog breeds is notable for its usage of both opinion surveys and DNA sequencing" — the methodology is notable, but the main point is the finding about behavior variability contradicting breed-behavior beliefs