Abstract
Analysis of taphonomic change to human skeletal remains helps forensic anthropologists estimate time since death and evaluate whether the discovery location was the actual crime scene. This thesis examines aqueous taphonomic changes such as bone staining, abrasions, completeness, and aquatic life activity observed within in the forensic anthropology casework of partially and completely submerged human skeletal remains from Florida. The objective of this research was to determine whether any taphonomic differences between three aqueous environments (marine environments, fluvial environments, and still freshwaters) were present. I predicted that taphonomic changes from marine environments would be associated with less skeletal material being recovered, increased frequency of abrasion and aquatic life modifications, and lighter bone color when compared to still freshwaters, which would produce the inverse taphonomic modifications.I conducted statistical analyses to determine the results of these objectives and hypotheses. Methods and procedures included reviewing Forensic Anthropologist Dr. Heather Walsh-Haney’s previous forensic redacted reports of partially and fully submerged skeletal remains recovered from across the state of Florida. I evaluated these reports following methods outlined by Higgs and Pokines (2014), Sorg et al. (1997), and Buikstra and Ubelaker (1994).
Statistical analyses were conducted to test for significance of the identified taphonomic variables within each aqueous environment (marine, fluvial, and still freshwater environments). Multinomial regressions revealed significance for incomplete skulls (p<0.05, Wald test statistic = 5.856, odds ratio = 4.412) and postcrania (p<0.05, Wald test statistic = 7.878, odds ratio = 5.780) in marine environments when fluvial systems were the reference category and these findings were also supported by a chi-square test (χ2 (4) = 29.293, p<0.05; χ2 (4) = 18.633, p<0.05). There was significance between incomplete skulls (p<0.05, Wald test statistic = 5.623, odds ratio = 4.098), postcrania (p<0.05, Wald test statistic = 10.053, odds ratio = 0.156), and limbs (p<0.05, Wald test statistic = 7.254, odds ratio = 0.151) in marine environments when compared to still freshwaters. These findings were also supported by a chi-square test (χ2 (4) = 29.293, p<0.05; χ2 (4) = 18.633, p<0.05; χ2 (4) = 14.173, p<0.05). The statistical analysis also revealed significance in light brown and yellow bone staining in marine environments when compared to fluvial environments (p<0.05, Wald chi-square = 6.049, odds ratio = 0.024). The chi-square test supported the findings of the multinomial logistic regression (χ2 (8) = 18.116, p<0.05). The final model revealed a higher likelihood of modifications made by aquatic organisms for skeletal remains recovered from marine environments than still freshwaters (p<0.05, Wald test statistic = 6.789, odds ratio = 0.111). This finding was supported by a chi-square test (χ2 (2) = 7.904, p<0.05).
Overall, I found marine environments were marked by the most taphonomic change. Specifically, skull and postcrania remains recovered from marine environments tended to be incomplete, less likely to evidence light brown or yellow coloration, more evidence of abrasion, and modifications from aquatic organisms than by remains recovered from fluvial systems and still freshwaters, respectively. The frequencies of each variable were slightly lower in fluvial environments, followed by still freshwaters. Additionally, skeletal remains from still freshwaters had a lower likelihood of evidencing aquatic organism modifications when compared to marine environments. These results contribute to the current literature and assists forensic anthropologist to calibrate their understanding of the type of environment the human remains were exposed to and can assist in the estimation of time since death for the recovered remains.