THE BODY IN THE CELLAR.......Part IV * Continuing......Having now established that the skeleton found in the cellar area, of a 17th century property called Leavy Neck, was both (A) Human and (B) Male. We next need to determine his approximate age and ancestry. Skeletons are good age-markers, because bones and teeth mature at fairly predictable rates. Teeth are an ideal source for age-related information. With the first permanent molar erupting at approximate 6yrs., to complete permanent dentition at about 21yrs. [see:#1 picture] The cranium (skull) of an infant is actually in several bone -pieces at birth. The bones that enclose the brain, fuse/meld (grow) together through out childhood along jagged lines of separation, these lines are known as suture lines.[see:#2 picture] This fusing is so widely variable, it is best used with additional indicators, to estimate age. The long bones (arms/legs) also have a similar like growth. At birth each end of the diaphysis (shaft- the midsection of the long bone), there is a rounded piece called a epiphysis. It is separated from the shaft by a growth plate area of cartilage, called a metaphysis. This leaves a noticeable jagged line.The cartilage will ossify (change into bone) slowly throughout childhood, and at maturity become a solid long-bone by about 25yrs. [see:#3 picture] Using these standard procedures, Dr. Owsley determined that they belonged to a male, who at the time of his death was: (C) Age- 15 or 16 yrs.old. The next thing to determine is his ancestry. Had he been born and raised in the colony of Maryland, or some place else? Our bones have features that can be clues to a persons ancestry. Ancestral origins can be assessed by looking at the skeleton itself, especially the skull and teeth. The bones of the skull show inherited features from one generation to the next. By comparing a skulls measurements with data from populations world wide, scientists can evaluate the relationship to a particular group of people. For example: - African ancestry generally show, greater facial projection in the area of the mouth, front of the jaw projects forward of the chin; a wider distance between the eyes; a wider nasal cavity. - European ancestry tend to have, a straight facial profile, front of jaw aligned with the chin; a narrower face; a narrow nasal opening. -Native American ancestry have, proportionately wider faces; with cheekbones that project farther forward; shorter, broader cranial vaults.[see: #4 picture] Bone cells retain biogeographical information found in our DNA. One kind of laboratory test, critical to forensic anthropology, is the stable isotope analysis. This test can supply information about a persons birthplace or, how long they had lived in the Maryland colony. Through a plants process of photosynthesis, the plant absorbs varying amounts of a chemical element called Carbon. This carbon comes in three Isotopes (forms), carbon-12, carbon-13 and carbon-14. Carbon-12 and13 are stable, that is they do not decay, (break-down overtime) like carbon-14. All three of these isotopes are absorbed in the bones when people consume the plants. [see: #5 picture] Carbon-13 is of particular interest for two reasons. First, the amount of carbon-13 that the bones absorb varies depending on the type of plant consumed. Second, as a stable isotope, carbon-13 remains in a persons bones after death and can be measured even centuries later. Since teeth do not remodel (mature bone tissue is replaced with new bone; this continues until death) like the other bones of a person, they are more reliable in conducting a stable isotope test. The main plant used for food and grown in the new colony of Maryland, was corn. In Europe, the main grains were: wheat, barley and rye. Corn holds a higher amount of carbon-13 then the three other grains. So when the colonists started eating corn, their levels of carbon-13 increased. Scientists believe that it takes about 20 years for a bones carbon-13 content, to be completely replaced by dietary change. This test is done to determine a number known as, the carbon-13 value. This value is written as a negative number, that is a number less then zero. Example: A person born in England would have a carbon-13 value of -21 to -18. A person born in the new Maryland colony; and on a diet that included corn, would have a carbon-13 value of -15 to -9. And, it is thought, a person born and raised in England, then immigrating to the Maryland colony;an having lived less then 20 years in the colony, would have a carbon-13 value of -18 to -16. When Dr. Owsley evaluated the skull of the Leavy Neck skeleton, it showed a similarity to other skulls of a 17th century colonist from Europe. When the stable isotope test was conducted, it showed a carbon-13 isotope value of -19.39. This indicated, at the time of his death, the Leavy Neck young boy, had not lived in the Maryland colony long. So this young boys ancestry was: (D) European-more likely English/Irish. So now, the last two questions we need to ask are: Had, he been an indentured servant? And, how did he die? To continue.... .....Shirley R. Spear Reed..... * Written in Bone by: Sally M. Walker Forensic Anthropology Training Manual by: Karen R. Burns The Smithsonian Institution
Posted on: Tue, 18 Mar 2014 20:52:24 +0000