Climate change, genetics or human choice: why were the shells of mankind's earliest ornament larger in the pleistocene than in the holocene?
BACKGROUND: The southern African tick shell, Nassarius kraussianus (Dunker, 1846), has been identified as being the earliest known ornamental object used by human beings. Shell beads dated from approximately 75,000 years ago (Pleistocene era) were found in a cave located on South Africa's south coast. Beads made from N. kraussianus shells have also been found in deposits in this region dating from the beginning of the Holocene era (<10,000 years ago). These younger shells were significantly smaller, a phenomenon that has been attributed to a change in human preference. METHODOLOGY/PRINCIPAL FINDINGS: We investigated two alternative hypotheses explaining the difference in shell size: a) N. kraussianus comprises at least two genetic lineages that differ in size; b) the difference in shell size is due to phenotypic plasticity and is a function of environmental conditions. To test these hypotheses, we first reconstructed the species' phylogeographic history, and second, we measured the shell sizes of extant individuals throughout South Africa. Although two genetic lineages were identified, the sharing of haplotypes between these suggests that there is no genetic basis for the size differences. Extant individuals from the cool temperate west coast had significantly larger shells than populations in the remainder of the country, suggesting that N. kraussianus grows to a larger size in colder water. CONCLUSION/SIGNIFICANCE: The decrease in fossil shell size from Pleistocene to Holocene was likely due to increased temperatures as a result of climate change at the beginning of the present interglacial period. We hypothesise that the sizes of N. kraussianus fossil shells can therefore serve as indicators of the climatic conditions that were prevalent in a particular region at the time when they were deposited. Moreover, N. kraussianus could serve as a biomonitor to study the impacts of future climate change on coastal biota in southern Africa. (+info)
Navel jewelry artifacts and intravertebral variation in spine bone densitometry in adolescents and young women.
Young adult populations (18-25 years of age) throughout the world have latched onto the mainstream trend of body piercing. Best health care practices for these individuals involves the knowledge of proper procedural techniques, postsite care, common complications, and treatment modalities. (+info)
Persistent nodular contact dermatitis to gold: case report of two cases.
Ulcerated plaque under a ruby ring in an immunosuppressed patient.
We report a primary inoculation fungal infection in a 76-year-old man with acute myeloid leukemia. The patient presented with a painful red plaque located where he routinely wore a ruby ring. Histopathology revealed multiple branching septate hyphae. Cultures confirmed Fusarium and Candida parapsilosis infection. A short discussion of these organisms follows. (+info)
Lead poisoning of a child associated with use of a Cambodian Amulet --- New York City, 2009.
Lead poisoning in children is a preventable public health problem that can adversely affect the developing nervous system and result in learning and behavior problems. The most common source of exposure for lead-poisoned children aged <6 years in the United States is lead-based paint. However, nonpaint sources have been identified increasingly as the cause of lead poisoning, particularly in immigrant communities. This report describes a case of lead poisoning in a child aged 1 year that was investigated by the New York City Department of Health and Mental Hygiene's (NYC DOHMH) Lead Poisoning Prevention Program in 2009. The likely source of exposure was an amulet made in Cambodia with leaded beads that was worn by the child. Health-care providers and public health workers should consider traditional customs when seeking sources of lead exposure in Southeast Asian populations. Health-care providers should ask parents about their use of amulets, especially those in Southeast Asian families and those with children found to have elevated blood lead levels (BLLs). Educational efforts are needed to inform Southeast Asian immigrants that amulets can be a source of lead poisoning. (+info)