...it would seem logical to conclude that a "sensitivity to visual words'" [quoting one of the researchers] would have evolved after the advent of writing. And yet, it seems highly improbable that the human brain could have evolved such a specialized ability within a period of a few thousand years--an extremely short period of time on the (supposed) evolutionary timeline.
But, what if human beings had actually begun to use a kind of proto-writing prior to the earliest known writing systems? Would this have provided enough time for a specialized ability to recognize written signs to evolve?
In an August 2015 TED talk, paleoanthropologist Genevieve von Petzinger talks about her discovery of a set of 32 geometric signs appearing in ancient caves across Europe. These signs appear among other types of cave art, some of it dating back 40,000 years. While some of these signs disappeared over time, about 65% of them remained in use until the end of the Ice Age--about 10,000 years ago. She stresses that these signs do not constitute a full writing system--representing all the words in a spoken language--nor are they an alphabet. Nevertheless, they do seem to represent the beginning of human communication in graphic form.
If this is the case, we might be tempted to speculate that human beings evolved an ability to recognize graphic symbols even before the first full writing system emerged. However, the problem of time still remains. Even if we assume that human beings began to develop a capacity to recognize graphic symbols closer to 40,000 years ago than 5,000 years ago, this would still be extremely short on an evolutionary timescale.
In short, it seems highly unlikely that human beings evolved an ability to recognize written language. This suggests, in turn, that any evolutionary explanation for human language as a whole must be suspect. However, if a capacity to use language was "built in" by the Creator, a specialized human ability to read should not be so surprising.
Image of cave art from Wikimedia Commons