The degree and relationship of some obviously correct extrapolation is described in that study;
QUOTE
4. DISCUSSION
Our results suggest that fathead minnows conditioned to
recognize the odour of lake trout generalized their
recognition to closely related species, the brook trout
and rainbow trout, but not to distantly related predatory
(pike) or non-predatory (sucker) fish. The absence of
response to the sucker odour indicates that minnows did
not rely on diet cues to generalize their recognition. The
absence of a response to pike odour indicates that the
generalization is limited to trout only, but not all fish
predators. As expected, minnows responded with the
highest response intensity to the odour of lake trout,
the species they were conditioned to recognize as a threat.
The level of generalization was dependent to some extent
on the degree of relatedness of the other potential
predators to the reference predator. Minnows did not
respond differently to lake trout and brook trout, but the
p values for both behavioural measures (0.065, 0.067)
indicate that we may have weak support to say that
minnows chemically differentiated the two species. We
also have evidence suggesting that minnows responded
with less intensity to rainbow trout odour than brook trout
odour, hence displaying a graded response to other
trout odour, reflecting the taxonomic closeness of these
trout species to the reference predator.
The proximate mechanism behind this response
pattern may be a difference in the suite of molecules that
form the trout odour. In this case, odour molecules among
the trout species are probably similar as they are
recognized by the minnows, but are not identical as the
minnows clearly differentiate the odours. Alternatively, the
graded responses could be explained by the existence of a
concentration gradient of specific chemicals. Fathead
minnows have been demonstrated to adjust the intensity
of their antipredator response according to the concen-
tration of predator odour they are exposed to (Ferrari et al.
2006).
UNQUOTE
So, some extrapolation is obviously useful. Other types of extrapolation and especially assumptions, are not. Because an insect can see in the UV spectrum can not be extrapolated to trout for instance. Indeed, it may not safely be extrapolated even to other insects.
Science is not there to "prove" things, but to discover how they work.
May also be of interest;
http://en.wikipedia.org/wiki/Scientific_theory
QUOTE
Assumptions to formulate a theory
This is a view shared by Isaac Asimov. In Understanding Physics, Asimov spoke of theories as "arguments" where one deduces a "scheme" or model. Arguments or theories always begin with some premises—"arbitrary elements" as Hawking calls them (see above)—which are here described as "assumptions". An assumption according to Asimov is...
...something accepted without proof, and it is incorrect to speak of an assumption as either true or false, since there is no way of proving it to be either (If there were, it would no longer be an assumption). It is better to consider assumptions as either useful or useless, depending on whether deductions made from them corresponded to reality. ... On the other hand, it seems obvious that assumptions are the weak points in any argument, as they have to be accepted on faith in a philosophy of science that prides itself on its rationalism. Since we must start somewhere, we must have assumptions, but at least let us have as few assumptions as possible.
UNQUOTE
http://www.arachnoid.com/theory/index.html
http://www.arachnoid.com/wrong/index.html
http://www.arachnoid.com/reader_exchang ... ience.html
TL
MC