India, Nov. 8 -- If you wanted to know when the bison were returning, and when to expect the next hearty steak, you likely checked the latest cave update, in Ancient Lascaux, France.

For nearly a century, ever since the caves were discovered in 1940, anthropologists have struggled to decode the lines, dots and Y-shaped marks carved into the rock here.

Now, in a study published last year, researchers from Durham University and University College London, analysed 800 such sequences and found that they contained 13 types of marks (sets of lines, dots and Y symbols), in patterns consistent with the 13 months in a lunar year.

Suddenly, the message of the marks became clearer: they could represent the mating, migration and birthing patterns ...