Scientific method has a long and tortured (literally) history. When you consider what education was available and how it was available to only a select few of privilege until very recently (and in a lot of ways it still is) you might appreciate the great many obstacles that preceded more modern scientific discovery.
Rejecting empirical evidence has always been a root cause for science. Although scientific progress has been greatly hindered over the centuries by religious dogma, little stood to be gained by contradicting it. The Catholic Church imprisoned Galileo for suggesting that the earth was not the center of the universe, which only contradicted precepts of the church. Imagine what would have been done to anyone suggesting that humans arose from more humble beginnings than the creation fable of Genesis purports?
Galileo may seem like ancient history today over four and a half centuries later and Newton who followed in the next century may not seem any more modern but they and the scientists that built on their work had to rely on their ability construct theories from the rudiments of knowledge. That is to say each following scientist had to rely on their ability to understand every fundamental that the preceding scientist expounded on. Even today, eking out just one more preponderance of data to add to the body of mathematical theory relies on as just as vast amount of knowledge.
So right there is where the attention of most of the available scientific minds went for the eons leading up to the eighteenth century. They were preoccupied with proving what they could, leaving speculation as to the circumstance of life up to the philosophers, while they maintained focus on irrefutable truths. Notice the trend away from empirical data.
Let's not forget that while scientists may be smart, they still aren't all knowing or perfect. Aside from handily avoiding ridicule and possibly disenfranchisement from the society that allowed them to pursue their hunger for knowledge, scientists too, could and still can be drawn to the comfort that religion offers.
A century or so after Newton, Darwin makes his compelling observation that life may have arrived at it's current state from a more primitive form. Made sense to a lot of scientists at the time and a large percentage of scientists since.
It is really rather obtuse to conjecture about the relevance time has to any argument but to decry the progress of human intellect as anything other than potential denied for all but the most infinitesimal portion of it's capability is ignorance and there can't really be any furtive discussion.