Self-study
In the winter, ravens survive by eating carcasses; in fact, an individual raven may survive for weeks on one carcass. ████ █████████ ██ ████ ████████ ██████ ████ █████ ███████ ████ ██████ ██ ████ ███ █ ████████ ████ █████████ ██████████ ████████ ██████ █████ ████████ ██ █████ ██████ ██ ██████████████ ██ ███ ██ ███████████ ██████ ████ █████ ██ ███ █ █████ ████ ██ ██ ████ ██████ ██ █████ ██ ██████ █████ ██ █████ ████ ███ █████ ████ ██ ██████ ██ █████ █████████ ███ ██████ ███ ███████ ████ █████████ █████ ██ ███ █████ ███ ██ █████ ███████████ ████████ ████████████ ██ ███ ███ ████ █████████████████ ██ ████████ ██ ██████ █████ ██████ ██ █████ ███ ████████ ████ ████ ████ ███ █████
There were many reports that ravens often recruit more ravens to help eat a carcass. This is counterintuitive, because it seems strange that a raven would be altruistic. Heinrich investigated this phenomenon. He observed a meadow where a mated pair of ravens laid exclusive claim to meat placed by Heinrich. Juvenile ravens had to group up to drive the mated pair away from the meat. (The implication is that ravens might share a carcass not out of altruism, but out of self-interest. The ravens might need to group up in order to access food.)
Describe Method of Reasoning
Heinrich investigated reports of ravens sharing a carcass. He found that this phenomenon might be due to juvenile ravens needing to group up to help get access to food.
15.
Which one of the following ████████████ ████ ████ █████ ██████████ █████ ██ ████████ ██ ███ ███████ ██████
a
He proposed two ███████████ ███████████ ████ ██ █████ █████ ███████ █ ███ ██ █████████████
Heinrich did not propose any hypotheses. We only get a description of his experiment and the results.
b
His investigation partially █████████ █████ ████████████ ███ ███ ██ █ ███████ ████████████████ ██ █████ █████████████
His investigation confirmed prior observations (ravens indeed recruit others), but led to a radical reinterpretation (the reason ravens recruit others is not altruism, but self-interest; they need to group up to help access food belonging to older ravens).
c
He proposed a ██████ ███ ████ █████████ ██ ███████ ██ ███████ ████████████
We don’t get any theory proposed by Heinrich. If you consider “altruism” to be Heinrich’s theory, then (C) is wrong because Heinrich did not confirm that the ravens were altruistic.
d
He used different ███████ ████ █████ ████ ██ ███████ ███████ ███ ███████ ██ ███ ████ ███████████
We do not know what kinds of methods were used in earlier studies, or whether there were earlier studies. So we don’t know Heinrich used different methods.
e
His investigation replicated ████████ ███████ ███ ███████ █ ████ ███████ ███ ██ █████████████ █████
We do not know whether there were previous studies or anything about the observational data in those studies. So we don’t know whether Heinrich replicated any studies or had a more limited set of data.