Short and long period growth markers of enamel formation distinguish European Pleistocene hominins

Abstract

characterizing dental development in fossil hominins is important for distinguishing between them and for establishing where and when the slow overall growth and development of modern humans appeared. Dental development of australopiths and early Homo was faster than modern humans. The Atapuerca fossils (Spain) fill a barely known gap in human evolution, spanning ~1.2 to ~0.4 million years (Ma), during which H. sapiens and Neandertal dental growth characteristics may have developed. We report here perikymata counts, perikymata distributions and periodicities of all teeth belonging to the TE9 level of Sima del Elefante, level TD6.2 of Gran Dolina (H. antecessor) and Sima de los Huesos. We found some components of dental growth in the Atapuerca fossils resembled more recent H. sapiens. Mosaic evolution of perikymata counts and distribution generate three distinct clusters: H. antecessor, Sima de los Huesos and H. sapiens. Dental enamel microstructure provides a timescale for dental development in the past. It also has the power to resolve taxonomic attribution when morphological character complexes and the timing of tooth formation are combined. Studies on dental enamel growth and relative dental development have been carried out in different hominin populations, from australopiths 1-4 , to early Homo 5 , H. naledi 6 , a Chinese specimen of the early Late Pleistocene 7,8 , Neandertals 9-12 , and archaic/modern H. sapiens 13-16. However, some of these works focused exclusively on the anterior dentition 1,2,5,6,10 while others employed crude estimates to reconstruct missing portions of the worn crown 17. These studies suggest that australopiths and early Homo shared dental development that was faster than in modern humans, with suggestions that the shift toward fully modern human dental development appeared some time after H. erectus or relatively late in human evolution 5. This potential shift was observed from a relatively reduced number of teeth, as KNM-ER 15000 and Sangiran S7-37. However, caution is claimed because substantial intraspecific variation in aspects of dental development (such as long-period line periodicity) within early hominin taxa has subsequently been demonstrated 4. Later Neandertals appear not to have an identical dental development with H. sapiens, as some aspects of their dental development tend to be more advanced 9,10,12. However, a recent study of a single Neandertal from El Sidrón (Spain) suggests that this hominin, with some

An inconstant biorhythm: The changing pace of Retzius periodicity in human permanent teeth

“…The combination and regional patterning of neural crest derived cells, homeobox genes, and signaling molecules are thought to play major roles in tooth specification, which correspond with the concept of developmental modules (Mitsiadis & Smith, 2006; Townsend et al, 2009). It has been suggested that it is via these distinct development regions, or modules, that evolutionary selection can operate independently on different tooth groups (McCollum & Sharpe, 2001; Modesto‐Mata et al, 2020). The changes we observed in RP between tooth types suggests that modularity may be a useful approach to understand the shifts in RP along the tooth row.…”

“…Other applications of RP within anthropology might be similarly affected. Perikymata on the external surface of teeth reflect the same time interval as RP, and as such are used to estimate the pace of lateral enamel formation as well as to assess inter population and species variation in perikymata counts (Bocaege & Humphrey, 2016; Dean et al, 2001; Dean and Reid, 2001; Guatelli‐Steinberg et al, 2005, 2009, 2014, 2018; Guatelli‐Steinberg et al, 2007; Guatelli‐Steinberg et al, 2012; Guatelli‐Steinberg & Reid, 2010; Mann et al, 1991; McFarlane et al, 2014; Modesto‐Mata et al, 2017, 2020; Ramirez Rozzi, 1993; Ramirez Rozzi & Bermudez de Castro, 2004). Furthermore, perikymata are used in the identification and timing of stress episodes evident as linear enamel hypoplasia (Bocaege et al, 2010; Cares Henriquez & Oxenham, 2020; Cunha et al, 2004; Guatelli‐Steinberg et al, 2004; Guatelli‐Steinberg et al, 2014; Hassett, 2014; Hillson, 1992; King et al, 2002; King et al, 2005; Nava, Frayer, and Bondioli, 2019; Temple, 2016; Temple et al, 2012).…”

[Retracted] Research on the Application of Multimedia Elements in Visual Communication Art under the Internet Background

“…e dynamic effect (Dynamic Effect) gradually appeared. e form of motion animation is the design of time and space, which is beyond the static scope [22]. However, in the digital environment based on computers and networks, the new media has twoway interactive features that greatly support the new environment's interaction.…”

The Sima de los Huesos Middle Pleistocene hominin site (Burgos, Spain). Estimation of the number of individuals

“…Regarding the age at death of the SH individuals, we are aware that the rate of dental tissue formation in Middle Pleistocene populations may be significantly faster than in recent populations (Modesto-Mata et al, 2020) and that there is a certain variability in recent humans concerning dental development (e.g., Braga & Heuzé, 2007;Liversidge, 2003;Tompkins, 1996). It is very possible that the age of death of immature individuals is overestimated, so the figures obtained are only indicative and should be taken with caution.…”

“…In order to estimate the chronological age of the individuals we have employed the data for the mean age of attainment of mineralization stages published by Anderson, Thompson, and Popovich (1976) for a Caucasian population. We are aware that the rate of dental tissue formation in Middle Pleistocene populations may be significantly faster than in recent populations (Modesto-Mata et al, 2020) and that there is a certain variability in recent humans concerning dental development (Tompkins, 1996). It is very possible that the age of death of immature individuals is overestimated, so the figures obtained should be taken with caution.…”