PrepTest 109, Section 1, Question 1
Marmosets are the only primates other than humans(56 more words not shown)
Which one of the following,(7 more words not shown)
- AA study conducted(8 more words not shown)
- BRight-handed marmosets virtually(9 more words not shown)
- CAccording to the(19 more words not shown)
- DNinety percent of(17 more words not shown)
- EMarmosets raised in(19 more words not shown)
Reading the argument
Are the young marmosets copying their parents, or could they have inherited the same tendency?
I can see why the researchers consider imitation. The infants imitate a lot of behavior. The researchers propose that young marmosets acquire their parents’ hand preference that way. But a parent and child can resemble each other without one learning the trait by watching the other. Think about hair color: a child's resemblance to a parent wouldn't, by itself, show that the child copied the parent's appearance.
That leaves us with two possible explanations of the marmosets' handedness. How could we separate them? Imagine young marmosets born to left-handed parents but raised by unrelated right-handed adults. Would the young animals tend to use the left hand or the right? Following the adults who raise them would give us a reason to take the learning explanation more seriously.
What we’re looking for
We're asked to support the researchers' hypothesis. I'd look for evidence that being around adults with a particular hand preference matters, even without inheriting genes from those adults. We don't need to establish that genes have no role at all. We need support for the claim that imitation helps explain the preference.
Working the answers
- A
Many adults being right-handed tells us that right-handed marmosets exist. It doesn't tell us how they acquired that preference. Both inheritance and imitation remain possible. We need evidence about where the handedness comes from, not just another count of animals with it.
- B
Siblings having different hand preferences doesn't establish imitation. We aren't told which adults raised them, those adults' preferences, or whom each infant imitated. We also shouldn't assume that siblings must share every inherited trait. This family comparison doesn't separate the explanations in the way we need.
- C
Some marmosets can use both hands equally well. That is another description of their abilities, not an explanation of how those abilities develop. The researchers' hypothesis concerns learning by imitation; the percentage of ambidextrous animals doesn't show that process happening.
- D
This concerns humans, while the hypothesis concerns marmosets. Even if we set that difference aside, a left-handed child having a left-handed parent would still leave the same question: inheritance or imitation? The parent-child resemblance doesn't distinguish those explanations.
- ECorrect
These young marmosets tend to match the right-handed adults who raise them even though they aren't related to those adults. That is close to the test we wanted: the resemblance follows the rearing environment without the usual parent-offspring genetic relationship.
It is especially useful because left-handedness is more common among marmosets generally, yet right-handedness is more common in this group raised by right-handed adults. E supports a role for the adults' behavior. It doesn't prove every young animal copied an adult or rule out all genetic influences, but it makes the imitation hypothesis more credible.
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