Association between ancient bone preservation and dna yield: a multidisciplinary approach.

Ancient molecular typing depends on DNA survival in archaeological bones. Finding valuable tools to predict DNA presence in ancient samples, which can be measured prior to undertaking a genetic study, has become an important issue as a consequence of the peculiarities of archaeological samples. Since the survival of DNA is explained by complex interrelations of multiple variables, the aim of the present study was to analyze morphological, structural, chemical, and biological aspects of a set of medieval human bones, to provide an accurate reflection of the state of preservation of the bony components and to relate it with DNA presence. Archaeological bones that yielded amplifiable DNA presented high collagen content (generally more than 12%), low racemization values of aspartic acid (lesser than 0.08), leucine and glutamic acid, low infrared splitting factor, small size of crystallite, and more compact appearance of bone in the scanning electron micrographs. Whether these patterns are characteristic of ancient bones or specific of each burial site or specimen requires further investigation.

Exploring the relationship between weaning and infant mortality: an isotope case study from Asikli Höyük and Çayönü Tepesi.

We measured stable nitrogen isotope ratios in bone collagen of 60 individuals from the early Neolithic (9th-8th millennium Cal. BC) sites of Çayönü Tepesi and Asikli Höyük. Our aim was to identify the duration of exclusive breastfeeding (EBF), compare this with juvenile mortality at each site, and assess whether there was a relationship between them. The isotope analysis suggests that weaning commenced at about 1 year at Asikli Höyük and around 2 years at Çayönü Tepesi. The mortality data show equal numbers of infant deaths up to 24 months; however, after 24 months, the mortality rate increases at Çayönü Tepesi, and a Student's t-test confirms a significant difference in infant mortality between the sites. Weaning foods prepared in the early Neolithic from agricultural crops would have had low-iron content, poor nutritional value, and would have been prepared in nonsterilized containers. Therefore, later weaned infants in early Neolithic farming settlements, although capable of some immunological response, were probably undernourished putting them at a disadvantage when encountering bacteria in their weaning food. Our results suggest that infant feeding regimes that introduced infants to weaning foods in the first year of life may have had a positive effect on their survival.

Moose teeth as monitors of environmental isotopic parameters.

The radiocarbon activities of amino acids isolated from crown first molar dentin of moose born between 1948 and 1984 on Isle Royale National Park, USA closely follows the bomb radiocarbon signal generated from atmospheric nuclear weapons testing. This demonstrates that these amino acids are metabolically inert and have recorded the isotopic parameters of the environment during the first year or two of the animal's life. The moose teeth amino acids provide both carbon and nitrogen isotopic chronologies for Isle Royale for a period of nearly four decades. The carbon isotopic record reflects both anthropogenic alterations of the global atmospheric carbon cycle (the "Suess" effect), and changes in forest ecology and moose feeding habitat. The nitrogen isotopic chronology is more variable than the carbon record and is the result of environmental and biological factors which are poorly understood.

Isotopic evidence for breastfeeding and possible adult dietary differences from Late/Sub-Roman Britain.

Historical documents indicate that breastfeeding and weaning practices have fluctuated in England through history. In order to obtain evidence for general breastfeeding patterns in Late/Sub-Roman Britain, stable carbon and nitrogen isotope values were measured in juvenile and adult skeletons (n = 87) from the cemetery of Queenford Farm, Dorchester-on-Thames, Oxfordshire. As the site contained few individuals between 0-1.5 years of age, it was not possible to determine the initial timing for the introduction of weaning foods. Between ages 2-4 years, the mean +/- SD delta(13)C results (-20.2 +/- 0.3 per thousand) are significantly more negative (t = -4.03, P < 0.001) compared to adult females (-19.7 +/- 0.3 per thousand). This is interpreted as evidence of a different diet being fed to children during weaning. After age 2, the delta(15)N values gradually decline, indicating complete cessation of breastfeeding by 3-4 years. Among adults, stature (males = 1.68 +/- 0.06 m; females = 1.58 +/- 0.07 m) and sexual dimorphism (106) were low, suggesting that the population was possibly under environmental stress. The delta(13)C results for adults are similar, but females show a small but statistically significantly (t = -2.86, P < 0.01) lower mean delta(15)N value (9.9 +/- 0.9 per thousand) compared to males (10.6 +/- 0.5 per thousand). These lower female delta(15)N values possibly reflect the different physiology of the sexes (pregnancy and/or lactation) or the reduced consumption of animal/fish protein by women, and this may have been influenced by individual preference, family needs, or societal values of the era.

Detection of breastfeeding and weaning in modern human infants with carbon and nitrogen stable isotope ratios.

Carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope ratios were longitudinally measured in fingernail and hair samples from mother-infant pairs where infants were exclusively breastfed (n = 5), breast- and formula-fed (n = 2), or exclusively formula-fed (n = 1) from birth. All exclusively breastfed infants had a dual enrichment in carbon ( approximately 1 per thousand) and nitrogen ( approximately 2-3 per thousand) when compared to maternal values. In contrast, breast- and formula-fed subjects had reduced enrichments compared to exclusively breastfed subjects, and the exclusively formula-fed infant showed no increase in delta(13)C or delta(15)N values. This finding of a carbon trophic level effect in breastfeeding infants suggests that (13)C-enrichments of approximately 1 per thousand in archaeological populations are not necessarily the result of the consumption of C(4)-based weaning foods such as maize or millet. During the weaning process, the delta(13)C results for breastfed infants declined to maternal levels more rapidly than the delta(15)N results. This suggests that delta(13)C values have the potential to track the introduction of solid foods into the diet, whereas delta(15)N values monitor the length of time of breast milk consumption. These findings can be used to refine the isotopic analysis of breastfeeding and weaning patterns in past and modern populations.