Dental cementum virtual histology of Neanderthal teeth from Krapina (Croatia, 130–120 kyr): an informed estimate of age, sex and adult stressors

Abstract

The evolution of modern human reproductive scheduling is an aspect of our life history that remains vastly uncomprehended. The present work aims to address this gap by validating a non-destructive cutting-edge methodology to infer adult life-history events on modern teeth with known life history and then applying it to fossil specimens. We use phase-contrast synchrotron X-ray microtomography to visualize the dental cementum of 21 specimens: nine contemporary humans; 10 Neanderthals from Krapina (Croatia, 130–120 kyr); one Neolithic Homo sapiens from Ajmana (Serbia); and one Mesolithic H. sapiens from Vlasac (Serbia). We were able to correctly detect and time (root mean square error = 2.1 years; R 2 = 0.98) all reproductive (menarche, parturition, menopause) and other physiologically impactful events in the modern sample. Nonetheless, we could not distinguish between the causes of the events detected. For the fossil specimens, we estimated age at death and age at occurrence of biologically significant events. Finally, we performed an exploratory analysis regarding possible sexual dimorphism in dental cementum microstructure, which allowed us to correctly infer the sex of the Neolithic specimen, for which the true value was known via DNA analysis.

Life history in primate teeth is revealed by changes in major and minor element concentrations measured via field-emission SEM-EDS analysis

“…Details regarding the methods are reported in the electronic supplementary material. Histological thin sections were prepared following a previously published protocol [11]. To be suitable for high-vacuum SEM imaging, sections were uniformly carbon-coated using a Denton Desk V (Denton Vacuum, Moorestown, NJ, USA).…”

“…Intrinsic and extrinsic events leave a permanent record in all calcified tissues, which are formed according to an internal biological rhythm [7]. Events correlating with AGLs include: reproduction [8,9], weaning [10], menopause [11], changes in diet [12] and climate [13][14][15][16]. Within mammals, teeth are the recording structure of choice as they are not remodelled during life [17].…”

Synchrotron X-ray Studies of the Structural and Functional Hierarchies in Mineralised Human Dental Enamel: A State-of-the-Art Review

“…The data were extracted from Endnote software in ‘.txt’ format and manually edited to arrange the studies by techniques. In total, 31 terms were considered based on these studies [ 11 , 31 , 39 , 56 , 57 , 77 , 78 , 89 , 90 , 121 , 169 , 170 , 171 , 172 , 173 , 175 , 193 , 195 , 247 , 266 , 286 , 294 , 299 , 303 , 304 , 305 , 306 , 307 , 308 , 309 , 310 , 311 , 312 , 313 , 314 , 315 , 316 , 317 , 318 , 319 , 320 , 321 , 322 , 323 , 324 , 325 , 326 , 327 , 328 , 329 , 330 , ...…”

“…The data were extracted from Endnote software (Clarivate) in ‘.txt’ format and manually edited to match the reading format and correlation of words; for example, British spelling was applied when translating non-English titles and acronyms were generally written in full length. The minimum number of occurrences of a term was set to four, and in total 140 terms were used based on these studies [ 11 , 31 , 39 , 56 , 57 , 77 , 78 , 89 , 90 , 121 , 169 , 170 , 171 , 172 , 173 , 175 , 193 , 195 , 247 , 266 , 286 , 294 , 299 , 303 , 304 , 305 , 306 , 307 , 308 , 309 , 310 , 311 , 312 , 313 , 314 , 315 , 316 , 317 , 318 , 319 , 320 , 321 , 322 , 323 , 324 , 325 , 326 , 327 ,…”

Elemental composition of primary lamellar bone differs between parous and nulliparous rhesus macaque females

“…These tissues act as recoding structures [ 1 ], keeping track of the physiological changes experienced by an organism in the form of accentuated growth lines and changes in elemental composition. A large body of work spanning several decades has shown that a variety of both intrinsic and extrinsic events, including birth [ 2 , 3 ], reproduction [ 4 ], weaning [ 5 ], menopause [ 6 ], illnesses [ 7 ], dietary changes [ 8 ] and climate variation [ 9 – 11 ], leave a permanent record in calcified tissues which is preserved even in fossil specimens [ 12 ]. The microstructural organization of teeth is not altered during life [ 13 ].…”