The size of northern fur seals provides a reliable indication of their

Question

The size of northern fur seals provides a reliable indication of their population levels - the smaller the average body size of seals in a population, the larger the population. Archaeologists studied seal fossils covering an 800-year period when the seals were hunted for food by Native peoples in North America and found that the average body size of the seals did not vary significantly.

The statements above, if true, provide the most support for which one of the following?

(A) During the 800-year period studied, seal hunting practices did not vary substantially between different groups of Native peoples in North America.
(B) The body size of northern fur seals is not strongly correlated with the overall health of the seals.
(C) Before the 800-year period studied, the average body size of northern fur seals fluctuated dramatically.
(D) Native peoples in North America made an effort to limit their hunting of northern fur seals in order to prevent depletion of seal populations.
(E) Hunting by Native peoples in North America did not significantly reduce the northern fur seal population over the 800-year period studied.

Source: LSAT

DavidTutorexamPAL · Answer

We can solve this question using the  Logical  approach, since it asks us to infer a conclusion from the argument. 
The argument is such: (1) seal size indicates population size, (2) over a specific period - no big change in seal size. 
 Logical conclusion of (1) and (2): over this period, the seal size population must have also not changed significantly - exactly what (E) tells us!

As always, we can also go the  Alternative  route and use the  process of elimination , though this will probably not be as efficient:

(A) During the 800-year period studied, seal hunting practices did not vary substantially between different groups of Native peoples in North America.  We know nothing of the makeup of what happened in different places, only the total effect. Thus, there is no indication for this. 
(B) The body size of northern fur seals is not strongly correlated with the overall health of the seals. This would be indicated if (and only if) we knew that their overall health depleted during this time - but the mere fact that they were hunted does not mean this is necessarily the case  
(C) Before the 800-year period studied, the average body size of northern fur seals fluctuated dramatically.  We know nothing about what happened previous 
(D) Native peoples in North America made an effort to limit their hunting of northern fur seals in order to prevent depletion of seal populations. This is definitely possible, and could explain why the population size didn't change - but it isn't necessary! it is possible they made no such efforts (on the contrary, they tried to hunt as much as possible!) - but the result was still that the population didn't change for some reason. It's important not to jump to conlusions which are more than we can know 
(E) Hunting by Native peoples in North America did not significantly reduce the northern fur seal population over the 800-year period studied.  direct logical conclusion

PedroBodnar · Answer

I'm sorry, but I don't think E can prove that the population didn't changed significantly. It states that their hunting didn't reduce the population, but the seal population might be increasing during this period.

Answer D, however, makes one infer that if they were limiting their hunting to the point that would prevent the depletion of seal population, then certainly the population was kept at controlled minimal levels.

Can someone please enlight what am I missing?

DavidTutorexamPAL · Answer

It's the other way around - we are asked which of the  answers the text supports  -  not  which of the answers supports the conclusion in the text.

Therefore, the informaiton in the text (seal size is correlated to population size, no change in seal size)  supports  (not proves) what is written in (E): hunting didn't change the population. (D) , as I explain above, is possible - but it doesn't derive form the information.

Is this clearer?

PedroBodnar · Answer

I see. Now it is clear, thanks!

unraveled · Answer

A and E are the contenders.
A stresses on variation of hunting practices instead of on the effect these practices had on seal population. Reading A does not sparks immediate opposition to choose it as an answer.

On the other hand, as per E whatever population was 800 year ago, it remained almost at similar levels for these many years, suggesting that hunting by Native peoples in North America was such that population didn't reduce significantly.

Answer E.

nikitamaheshwari · Answer

VeritasKarishma   GMATNinja  - CAn you explain option choice A and E please?

Thanks

KarishmaB · Answer

Smaller the avg size of seals, larger the population. 
In the 800 yr period when seals were hunted for food by Native peoples, their avg size did not vary.

What can we say from this? That hunting did not affect their population much. 
Since the size did not vary, it means the population did not vary either. 
So (E) is correct.

(A) During the 800-year period studied, seal hunting practices did not vary substantially between different groups of Native peoples in North America.

nikitamaheshwari 
Did different groups of Native peoples hunt differently? We don't know. Perhaps one group used tools different from the other. Perhaps one group hunted 10 seals a week and another hunted 20, we don't know. The point is, whether their practices were same or different, we don't know. All we know is that the overall impact of all groups together was not much on the seal population. We are not given data about different regions or times during the 800 year period. We only know that throughout the period, not much had changed in the avg size of seals and hence not much has changed in the population size.

(B) The body size of northern fur seals is not strongly correlated with the overall health of the seals.

Any correlation with the health of the seals is irrelevant.

(C) Before the 800-year period studied, the average body size of northern fur seals fluctuated dramatically.

Before 800 yr period is irrelevant.

(D) Native peoples in North America made an effort to limit their hunting of northern fur seals in order to prevent depletion of seal populations.

We cannot say that the native people made a conscious effort. They may or they may not have. What we do know is that the impact was that the population did not change much. Whether native people consciously tried to keep it consistent or whether their hunting was so limited that it anyway had no impact, we don't know.

Answer (E)

scrantonstrangler · Answer

We can solve this question using theLogical

approach, since it asks us to infer a conclusion from the argument.
The argument is such: (1) seal size indicates population size, (2) over a specific period - no big change in seal size.
Logical conclusion of (1) and (2): over this period, the seal size population must have also not changed significantly - exactly what (E) tells us!

As always, we can also go theAlternative

route and use the process of elimination, though this will probably not be as efficient:

(A) During the 800-year period studied, seal hunting practices did not vary substantially between different groups of Native peoples in North America. We know nothing of the makeup of what happened in different places, only the total effect. Thus, there is no indication for this.
(B) The body size of northern fur seals is not strongly correlated with the overall health of the seals.This would be indicated if (and only if) we knew that their overall health depleted during this time - but the mere fact that they were hunted does not mean this is necessarily the case
(C) Before the 800-year period studied, the average body size of northern fur seals fluctuated dramatically. We know nothing about what happened previous
(D) Native peoples in North America made an effort to limit their hunting of northern fur seals in order to prevent depletion of seal populations.This is definitely possible, and could explain why the population size didn't change - but it isn't necessary! it is possible they made no such efforts (on the contrary, they tried to hunt as much as possible!) - but the result was still that the population didn't change for some reason. It's important not to jump to conlusions which are more than we can know
(E) Hunting by Native peoples in North America did not significantly reduce the northern fur seal population over the 800-year period studied. direct logical conclusion

agrasan · Answer

While doing this question, option D caught my attention but it is a wrong one. 
We are given  NO  cause-effect relationship between native North Americans' intentions and seal hunting so we can't say that D is supported from the given information.

The size of northern fur seals provides a reliable indication of their

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