What does ‘Konrad Lorentz’s observation was “one sentence”’ mean?

Question

New York Times (May 20) introduces a study of Dr. Johanna H. Meijer at Leiden University Medical Center in the Netherlands that proves mice are really enjoying wheel-running in the article titled, “Mice run for fun, not Just work, research shows.” I was drawn to the phrase, “the Lorenz observation ‘was one sentence’” in the following sentence:

As a “brain electrophysiologist” studying biological rhythms in mice, she relished the chance to get out of the laboratory and study wild animals, and in a way that no one else had.

She said Konrad Lorenz, the great-grandfather of animal behavior studies, once mentioned in a letter that some of his caged rats had escaped and then returned to his garden to use running wheels placed there. But, Dr. Meijer said, the Lorenz observation “was one sentence.” - Source

I surmise 'Lorenz observation “was one sentence”' means his observation scratches only an aspect of whole, imcomplete, or just superficial, but I’m not sure. What does observation (view, remark, conclusion) is “one sentence” mean?

Is the phrase, “one sentence” used very often in this way? For instance, can I say “It’s one sentence of the politician, we cannot conclude he is nationalist.”

Answer 1

This is very literal.

It is saying that the observation that Lorenz made, that some rats came back, was only one sentence.

The inference is that it is simply an anecdote and not an extended experimental study controlling for confounding variables. That is, a great scientist only made a minor remark, so not necessarily a pronouncement of universal truth.

The point is that it is misleading to say 'research shows' when there is only 'one sentence' in a letter to support it.