You're hitting on a pretty interesting concept here. There's been an awful lot of ink spilt on the increased (and generally characterised as over-specialisation) of academic studies. "An expert is someone who knows more and more about less and less, until they know everything about nothing."

Contrasting with earlier times -- generally prior to the Industrial Revolution, though somewhere between the 19th and 20th century seems to be where the shift occurred -- I'm wondering what the factors are.

Preindustrial societies couldn't support a great many independent researchers, and those almost always had specific patronage (with its own sets of advantages and pitfalls). The goal was to become known as "that clever person" without much limitation as to what it was you were clever about.

The fruit hung lower. There's much been made of areas in which obvious principles were waiting to be plucked.

In a professional research environment, there are many curious path-dependent and self-reinforcing tendencies. "Publish or perish" means you must publish even where you've got little to report. The fact of publishing is often more important than the content. We have those who've published hundreds or thousands of papers, and dozens or hundreds of books (Asimov comes to mind). And those who've published two, but revolutionised thought (Wittgenstein).

Organisation and regimentation of inquiry tends to lead to a cloistering of concepts. An institution or discipline is started with a specific point in mind.

There's the close-mindedness of specific disciplines, one instance noted by Herman Daly in a recent book review, pointing to a footnote in his book Beyond Growth:

"I sent MIT Press, at their solicitation, a collection of essays on sustainable development, an earlier incarnation of this book. They sent it out for review, and on the basis of three positive reviews, wrote a contract to publish, subject to my doing further editing work. This I did, and sent in the revised manuscript. Some months later I was informed that a distinguished economist on their editorial advisory committee was not happy with the book and wanted more reviews. Did the distinguished economist have specific criticisms? No, I was told, he had not read the manuscript, but just wanted more reviews as a matter of procedure. Not to worry, MIT Press was still committed to publishing the book. So they sent the manuscript out for two more reviews. One was positive, the other was extremely negative. That made a total of five reviewers, all of MIT Press's own choosing, of which four said publish, and one said do not publish. The negative review "trumped" the four positive reviews, and the press broke its contract. The basic thrust of the negative review, leaving aside ad hominem irrelevancies, was "That is not the right way to look at it." All of this was the more surprising because I had recently published a collection with MIT Press that was well received (Valuing the Earth: Economics, Ecology, Ethics, ed. H. Daly and K. Townsend [Cambridge, Mass.: MIT Press, 1993])."

H. Daly, Beyond Growth, fn. 5 on p. 225.

Mentioned in Daly's review of Collision Course:

"It is also refreshing to me that MIT Press published her book. This indicates the welcome likelihood that some anonymous member of the MIT department of economics no longer has a veto over the decisions of the MIT Press."

http://www.resilience.org/stories/2015-04-02/collision-cours...

A rather striking instance of Plank's observation that "Science advances one funeral at a time". (Or non-funereal loss of veto power, possibly.)