Zoologist: Plants preferentially absorb heavy nitrogen from rainwater. Heavy nitrogen consequently becomes concentrat...

SamA on April 21, 2020

Hello @hatemz,

Let's break down this argument.

C: Prehistoric cave bears were not exclusively herbivores. (They ate some meat.)
Why?
P: Carnivores have higher concentrations of nitrogen than herbivores.
P: Samples from the prehistoric bears match the nitrogen levels of modern, carnivorous bears.

This does seem to make sense at first. If they have the same nitrogen levels, we would expect that the prehistoric bears ate meat as well. However, let's consider the testing process. Are there any possible flaws here? Bone samples are taken from the prehistoric bears, while blood samples are taken from the modern bears. What if nitrogen is primarily stored in bone? Then we could not rightfully compare these samples.

D defends the argument from this criticism. If bone samples and blood samples from the same animal are identical, then it is perfectly valid to compare either sample. This is why D is correct.

Here is the problem with B. We have no information in the stimulus about the "rate" of nitrogen accumulation. Even if we could figure out this rate from the bone sample, we have no idea if this would support the conclusion. Remember that our primary objective is to support the theory that the prehistoric bears ate meat. We don't know how the rate relates to this.

zachmorley2 on January 14, 2021

I'm not sure where the connection between the plants/herbivores to the meat eaters is coming from.

Emil-Kunkin on May 11, 2023

The connection is that herbivores eat plants, and the carnivores mostly eat herbivores.