LONDON, ENGLAND—Independent researcher Bennett Bacon, Paul Pettitt and Robert Kentridge of Durham University, Tony Freeth of University College London, and their colleagues analyzed more than 800 sequences of three specific abstract marks in Europe’s Paleolithic cave art, according to a Live Science report. Those marks, positioned near images of animals, include varying combinations of dots, lines, and a Y-shaped sign. The researchers note that none of the sequences contain more than 13 marks, and suggest that the marks could convey information about the 13 months in the lunar calendar. They then found strong correlations between the number of marks near the image of an animal and the time of year in which that animal mates. The Y-shaped signs, they added, could signal a particular event, such as the animal’s birthing season. Bacon said that such information on seasonal migration, mating, and birth would be valuable to Paleolithic hunters because the animals would be more vulnerable during these times. Critics note that many more signs recur in the region's rock art than the researchers have studied, and that the marks they analyzed could be interpreted in other ways. Read the original scholarly article about this research in Cambridge Archaeological Journal. To read about rock art elements that hunter-gatherers living in Texas and Mexico may used to depict speech, go to "Speak, Memories."