title: Dental evidence for ontogenetic differences between modern humans and Neanderthals.
abstract: Humans have an unusual life history, with an early weaning age, long childhood, late first reproduction, short interbirth intervals, and long lifespan. In contrast, great apes wean later, reproduce earlier, and have longer intervals between births. Despite 80 y of speculation, the origins of these developmental patterns in Homo sapiens remain unknown. Because they record daily growth during formation, teeth provide important insights, revealing that australopithecines and early Homo had more rapid ontogenies than recent humans. Dental development in later Homo species has been intensely debated, most notably the issue of whether Neanderthals and H. sapiens differ. Here we apply synchrotron virtual histology to a geographically and temporally diverse sample of Middle Paleolithic juveniles, including Neanderthals, to assess tooth formation and calculate age at death from dental microstructure. We find that most Neanderthal tooth crowns grew more rapidly than modern human teeth, resulting in significantly faster dental maturation. In contrast, Middle Paleolithic H. sapiens juveniles show greater similarity to recent humans. These findings are consistent with recent cranial and molecular evidence for subtle developmental differences between Neanderthals and H. sapiens. When compared with earlier hominin taxa, both Neanderthals and H. sapiens have extended the duration of dental development. This period of dental immaturity is particularly prolonged in modern humans.
authors.affiliation: Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA. tsmith@fas.harvard.edu
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Smith
authors.forename: Paul
authors.initials: P
authors.lastname: Tafforeau
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Reid
authors.forename: Joane
authors.initials: J
authors.lastname: Pouech
authors.forename: Vincent
authors.initials: V
authors.lastname: Lazzari
authors.forename: John P
authors.initials: JP
authors.lastname: Zermeno
authors.forename: Debbie
authors.initials: D
authors.lastname: Guatelli-Steinberg
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Olejniczak
authors.forename: Almut
authors.initials: A
authors.lastname: Hoffman
authors.forename: Jakov
authors.initials: J
authors.lastname: Radovcic
authors.forename: Masrour
authors.initials: M
authors.lastname: Makaremi
authors.forename: Michel
authors.initials: M
authors.lastname: Toussaint
authors.forename: Chris
authors.initials: C
authors.lastname: Stringer
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Hublin
mesh_terms: D000366:Age Determination by Teeth / Q000379:methods*; D000818:Animals; D049690:History, Ancient; D015186:Hominidae / Q000033:anatomy & histology / Q000254:growth & development*; D006801:Humans; D009805:Odontogenesis / Q000502:physiology*; D010161:Paleodontology / Q000379:methods*; D014070:Tooth / Q000254:growth & development