Shovel-shaped incisors are commonly cited as evidence for regional continuity in China.   Stringer (1992) however found that shovel-shaped incisors are present on >70% of the early Holocene Wadi Halfa fossil sample from North Africa, and common elsewhere.  Frayer et al . (1993) have criticized Stringer's method of scoring shovel-shaped incisor teeth. They discuss the fact that there are different degrees of "shovelled" . trace (+), semi (++), and marked (+++), but that Stringer misleadingly lumped all these together: "...combining shoveling categories in this manner is biologically meaningless and misleading, as the statistic cannot be validly compared with the very high frequencies for the marked shoveling category reported for East Asians."  Palaeoanthropologist Fred H. Smith (2009) also emphasizes that: "It is the pattern of shoveling that identities as an East Asian regional feature, not just the occurrence of shoveling of any sort".  Multiregionalists argue that marked (+++) shovel-shaped incisors only appear in China at a high frequency, and have <10% occurrence elsewhere.