This is a fascinating story. A newly published research paper argues that 37,000-year-old cave paintings include the earliest writing system known to date.
An Upper Palaeolithic Proto-writing System and Phenological Calendar
Here's a quote from the Abstract:
Quote: Using a database of images spanning the European Upper Palaeolithic, we suggest how three of the most frequently occurring signs—the line <|>, the dot <•>, and the <Y>—functioned as units of communication. We demonstrate that when found in close association with images of animals the line <|> and dot <•> constitute numbers denoting months, and form constituent parts of a local phenological/meteorological calendar beginning in spring and recording time from this point in lunar months. We also demonstrate that the <Y> sign, one of the most frequently occurring signs in Palaeolithic non-figurative art, has the meaning <To Give Birth>. The position of the <Y> within a sequence of marks denotes month of parturition, an ordinal representation of number in contrast to the cardinal representation used in tallies.
The lead author of the paper, Bennett Bacon, is not a professional archaeologist. According to
this article on the Fatherly Website (via MSN), Bacon is a furniture restorer. He "spent evenings looking over and analyzing photographs of cave paintings of prehistoric animals and a series of lines and dots."
There is some pushback from the scientific community (as is to be expected). This article
from Gigazine quotes a couple of academics who point out there are alternative interpretations of the markings. One of them also says "it seems to me that there are a number of unproven assumptions in this study."
Still, it's an intriguing theory and obviously attracted some support in the scholarly community. It will be interesting to see what further research and anslysis lead to.