Self-study
Biologist: Support Researchers believe that dogs are the descendants of domesticated wolves that were bred to be better companions for humans. ██ ███ ████████ ████ █████ ████ ████ ██████ ██ ███ ███ ████ ████ ███████ ███████ ███████████ ██ ██████ ████ ██ ████ █████ ██████ ██ ████ ████ █████ ████ ████ ████ ███ █████████ ████ ██████ ████ ████ ████████████ ████ ████ ████████ ████ ███████
Summary
The author concludes that some dogs are descended from wolves that were domesticated much more recently than other wolves were domesticated. (In other words, dog X descended from wolves that were domesticated 1,000 years ago, whereas dog Y descended from wolves that were domesticated 5,000 years ago.)
Why does the author believe this?
Because some breeds of dog are more closely related genetically to wolves than to most other breeds of dog. (In other words, dog X is more similar genetically to wolves than dog X is to other dogs.)
Notable Assumptions
The author assumes that if dog breed X is more similar genetically to wolves than it is to dog breed Y, then dog breed X is descended from wolves that were domesticated more recently than the wolves from which dog breed Y descended.
23.
Which one of the following ██████████ █████████ ███ ███████████ █████████
a
If one breed ██ ███ ██ █████████ ████ ██████ ████ ████ ████████████ ████ ████████ ████ ████ ███ ██████ ████ █████ ████ █████ ██████ ██ ███ ███ ██████████ ███ ██████ █████ ███ ██ ████ ███████ ███████ ██ ██████ ████ █████ █████ ██████ ████
(A) both reverses the logic of the argument and twists a premise. It reverses the logic, because we want to get from a premise about how closely related a dog breed is to wolves to a conclusion about the timeline of descent. But (A) tells us that IF we know something about the timeline of descent, then that allows us to conclude something about the close relationship. We don’t know anything about the timeline of descent; that’s what we want to prove. In addition, (A)’s reference to “former [dog] breed may be more closely related to wolves than those other [dog breeds] are [related to wolves]” doesn’t capture the premise accurately. The premise compared how closely related a dog breed was to wolves than that same dog breed was to other dog breeds. It didn’t compared how closely related two different dog breeds are to wolves.
b
If one breed ██ ███ ██ ████ ███████ ███████ ██ ██████ ████ ██ ███████ █████ ██ ████ ████ ███ ██████ █████ ██ ███ ███ ████ ██████ ██████████████ ████ █████████ ████ ███ ██████ █████ ████
Builds a bridge from the premise to the conclusion. We know from the premise that some dogs (dog X) are more closely related to wolves than they are to other dog breeds (dog Y). According to (B), that former dog (dog X) has more recent undomesticated wolf ancestors than the the latter dog breed (dog Y) has. This helps establish that dog X descended from wolves that were domesticated more recently than the wolves from which dog breed Y were domesticated. (Before a wolf is domesticated, it must be undomesticated. That’s why if dog X has more recent undomesticated wolf ancestors, that supports the claim that dog X has more recent domesticated wolf ancestors, too, since we know that dogs descended from domesticated wolves. So the undomesticated wolf from which dog X descended must have been domesticated some time before dog X came about.)
c
Any breed of ███ █████████ ████ ██████ ████ ████ ████████████ ██ ████ ███████ ███████ ███████████ ██ ██ █████ ████ █████ ██████ ██ ███ ████ ██ ███████
(C) asserts that a dog breed descended from domesticated wolves is more closely related to some other breeds of dog than it is related to wolves. But the premises involve a dog breed that is more closely related to wolves than it is to most other dog breeds. Moreover, (C) says nothing about the timing of wolf domestication.
d
If one breed ██ ███ ██ ████ ███████ ███████ ██ ██████ ████ ███████ █████ ██ ███ ███ ████ ███ ██████ █████ ██ ███ ██ ████ ███████ ███████ ██ ██████ ████ ██ ███ ██████ █████ ██ ████
The “if” part of (D) doesn’t relate to anything in the argument. (D) triggers if one breed of dog is more closely related to wolves than another dog breed is related to wolves. But the premises actually told us that one dog breed is more closely related to wolves than that dog breed is related to other dog breeds. They don’t compare two different dog breeds and how closely related those breeds are to wolves. Moreover, (D) says nothing about the timing of wolf domestication.
e
Any two breeds ██ ███ ████ ███ ████ ███████ ███████ ██ ████ █████ ████ ██ ██████ ███ ████ █████████ ████ ██████ ████ ████ ████████████ ████ ████
(E) triggers if we know that two breeds of dog are more closely related to each other than to wolves. But the premises don’t establish that there are two breeds of dog more closely related to each other than they are to wolves. They tell us about how some dog breeds are more closely related to wolves than that dog breed is to other dog breeds. In any case, (E) doesn’t allow us to distinguish the timeline of descent from wolves. Placing the descent “long ago” doesn’t allow us to say that one dog descended from wolves domesticated more recently than other wolves were domesticated.