In an experimental study we investigated whether.twig tool use in woodpecker finches is acquired.socially. This seemed plausible since previous studies.have shown that several forms of tool use in primates.develop via social learning. We took whole broods.from the Galapagos Islands. We split each brood into.two groups: half of the chicks were reared with a tool-.using model, and the other half were reared with a.non-tool-using model. We found that young.woodpecker finches that never had the opportunity to.watch tool use develop this ability with similar.aptitude and reached distinct developmental steps.that marked the appearance of new tool-oriented.behavior at a similar age as their siblings that were.given the chance to observe tool use in adult.woodpecker finches. We concluded that, in contrast.to chimpanzees, social learning is not necessary for.the acquisition of this behavior in woodpecker.finches. Instead, the developmental process seems to.be strongly dependent on genetically fixed.components. Interestingly, New Caledonian crows.also appear to have a specific genetic predisposition.for tool use, as demonstrated by the finding that they.develop basic use of stick tools without a tool-using.model. However, in contrast to our study, a tool-.using demonstrator (a human in the study on New.Caledonian crows) stimulated faster development of.tool use in juvenile New Caledonian crows. Field.observations also show that New Caledonian crow.parents scaffold the development of wide tool.manufacture and use in juveniles for up to one year..Juveniles stay close to their parents and are provided.with discarded tools. The early exposure to this.discarded tool might help juveniles to form a mental.template of functional tool design..Information about woodpecker finches’ social.system can shed some light on the reasons for the.strong genetic predetermination of tool use in this.species. For one thing, in contrast to socially living.primates, woodpecker finches are solitary and thus.parents are likely to be the only available tool-using.models. In such a system, reliance on social.transmission from parents to offspring during an.association would be a highly risky endeavor. Where.the likelihood of encountering important social.information is uncertain, selection for a development.process based on genetically fixed components could.be advantageous, especially given that tool use.provides an important part of the woodpecker finch’s.diet and seems crucial to survival during the dry.season in the islands’ Arid Zone..Although our experiment showed that the.development of tool use is based on a very specific.genetic predisposition, we were able to demonstrate.that non-social, individual learning does play an.important role during the ontogeny [development.within an organism’s lifetime] of tool use in serving.to improve the efficiency of this behavior. Five.individuals developed tool-using techniques that.deviated from the tool use performed by birds in the.wild, most likely because our artificial crevices.differed from natural crevices and tree holes. At some.point during the study, each of these birds dropped.their tool into the artificial crevice and pulled it out.with an upward motion of their beak, thereby.levering the prey to within reach at the front of the.crevice. After initial success with this technique, the.five birds significantly increased their use of this.method. These and other observations on learning in.tool-using woodpecker finches have altered our.conception of how this behavior develops. The.ontogenetic unfolding of this complex behavior is.determined by a very specific genetic component, but.is enhanced through individual learning.Q: Based on the passage, the researchers’ conclusion that the woodpecker finches who used the novel levering technique were displaying individual learning is supported in part by the fact that Answer Choices: (A)no genetic variations were common to all those finches that were not also common to all the finches that did not use that technique. (B)those finches tended to stop using the technique after the researchers altered the artificial crevices to reduce the effectiveness of the technique. (C)the portion of that technique that deviates from typical tool-using behavior takes place inside a crevice and is therefore difficult for other finches to observe and acquire socially. (D)there is probably not a naturally occurring circumstance that would have favored the development of that technique and its prior transmission to those finches.
A: Among A through D, the answer is
(A)no genetic variations were common to all those finches that were not also common to all the finches that did not use that technique.
(B)those finches tended to stop using the technique after the researchers altered the artificial crevices to reduce the effectiveness of the technique.
(C)the portion of that technique that deviates from typical tool-using behavior takes place inside a crevice and is therefore difficult for other finches to observe and acquire socially.
(D)there is probably not a naturally occurring circumstance that would have favored the development of that technique and its prior transmission to those finches.
Answer: 3