Justeson, as well as Houston, argued once again that the "emblem glyphs" were the titles of Maya rulers with some geographical association. The debate on the nature of "emblem glyphs" received a new spin in . The authors demonstrated that there were many place-names-proper, some real, some mythological, mentioned in the hieroglyphic inscriptions. Some of these place names also appeared in the "emblem glyphs", some were attested in the "titles of origin" (expressions like "a person from Lubaantun"), but some were not incorporated in personal titles at all. Moreover, the authors also highlighted the cases when the "titles of origin" and the "emblem glyphs" did not overlap, building upon Houston's earlier research. Houston noticed that the establishment and spread of the Tikal-originated dynasty in the Petexbatun region was accompanied by the proliferation of rulers using the Tikal "emblem glyph" placing political and dynastic ascendancy above the current seats of rulership. Recent investigations also emphasize the use of emblem glyphs as an emic identifier to shape socio-political self-identity. Numerical system The Mayas used a positional base-twenty (vigesimal) numerical system which only included whole numbers. For simple counting operations, a bar and dot notation was used. The dot represents 1 and the bar represents 5. A shell was used to represent zero. Numbers from 6 to 19 are formed combining bars and dots, and can be written horizontally or vertically. Numbers over 19 are written vertically and read from the bottom to the top as powers of 20. The bottom number represents numbers from 0 to 20, so the symbol shown does not need to be multiplied. The second line from the bottom represents the amount of 20s there are, so that number is multiplied by 20. The third line from the bottom represents the amount of 400s, so it's multiplied by 400; the fourth by 8000; the fifth by 160,000, etc. Each successive line is an additional power of twenty (similar to how in Arabic numerals, additional powers of 10 are added to the right of the first digit). This positional system allows the calculation of large figures, necessary for chronology and astronomy. History It was until recently thought that the Maya may have adopted writing from the Olmec or Epi-Olmec culture, who used the Isthmian script. However, murals excavated in 2005 have pushed back the origin of Maya writing by several centuries, and it now seems possible that the Maya