Chloe P. McDaneld 1 , Timothy P. Gocha 1 , Courtney C. Siegert 1 , Ryan M. Strand 1 , Lori E. Baker 2 , M. Katherine Spradley 1 1 Forensic Anthropology Center at Texas State, Department of Anthropology, Texas State University; 2 Department of Anthropology, Baylor University Understanding the Degree of Craniometric Variation in South Texas Migrants Introduction • A humanitarian crisis continues to unfold in South Texas due to the increase in migrant deaths. In 2012, Texas surpassed Arizona in the number of migrant deaths and has continued to surpass every year since (USBP 2016). • Public perception often holds that the majority of migrants are from Mexico, however the data do not bear that out. In 2014 the number of Central Americans apprehended by US Border patrol surpassed, for the first time, the number of Mexicans apprehended. In 2016 it happened again. • Further, data from the South Texas Human Rights Center (STHRC) indicate 40.5% of those missing in South Texas are from Mexico, while 41.7% originate from Central America, mostly El Salvador, Honduras, & Guatemala (Figure 1). • Brooks County, TX represents the epicenter of this crisis, where many migrants perish trying to circumvent the Border Patrol checkpoint. Historically, most of these individuals were buried as ‘unknown’ without any scientific attempt at identification. • In response to this crisis, Operation Identification (OpID) aims to facilitate the identification and repatriation of human remains found along or near the South Texas border through community outreach, scientific analysis, and collaboration with governmental and non- governmental organizations. • The purpose of this research is to learn more about the South Texas migrants through biodistance analysis of craniometric data. TOO MUCH WHITESPACE! Results • The natural log of the DCVM indicates the Guatemalan group is the most homogeneous, followed by OpID, and the American White group is the most variable (Table 2) • In reference to the OpID sample, the Hispanic group is the most similar, followed by the Guatemalan group, with the American Black and American White being the most dissimilar (Table 3; Figure 2). • Inter-individual D 2 values from the OpID sample were analyzed against the Defrise- Gussenhoven statistic, resulting in 8.05% significant inter-individual pairwise comparisons (n=1,522 out of 18,906) at the 0.05 level. Acknowledgements We would like to acknowledge and thank the student volunteers at Texas State University, Baylor University led by Dr. Lori Baker, and at the University of Indianapolis led by Dr. Krista Latham for contributing countless hours to the project, the continued collaboration and support from the Brooks County Sheriff’s Office and surrounding community, the Equipo Argentino de Antropología Forense, the South Texas Human Rights Center, the Colibrí Center for Human Rights, and all of our partners in the Forensic Border Coalition, as well as the University of North Texas Center for Human Identification. Conclusion • Despite public perception that most migrants are Mexican nationals, identification of migrants entering the US via Texas are predominantly from Central America. • The OpID sample displays relative homogeneity compared to other groups used in the analyses. However, it is comprised of individuals from various countries of origin. Once more positive identifications have been made and more reference data from Latin America have been collected, then a more thorough investigation of biological variation will be possible. • Craniometric databases could conceivably combine the OpID sample with traditional ‘Hispanic’ data to better represent the variation potentially encountered in individuals considered ‘Hispanic’ within a forensic context. Discussion • Discriminant function analysis, and the resulting DCVM, indicates the Guatemalan group is the most homogeneous. Since this group is mostly indigenous Guatemalan Mayan, a homogenous population structure is not surprising. The OpID sample is the second most homogenous, followed by Hispanics. • The distance plot (Figure 2) demonstrates the OpID sample clusters with the Hispanic sample from the FDB, which is largely made up of Mexican migrants from Arizona. Considering the shared population history and probable gene flow between Mexico and Central America, this result was expected. • The observed within group variation based on the Defrise-Gussenhoven statistic demonstrates the OpID sample exhibits similar levels of homogeneity as geographically and temporally isolated population groups as reported by Hefner et al. (2016). • Positive identifications from the OpID sample (n=22) corroborates the missing persons data from the STHRC, and apprehensions by US Border Patrol, all of which indicate more Central Americans entering Texas than Mexican individuals (Figure 4) Figure 1. Google map of known migrant routes from Central America through Mexico (modified from Amnesty International 2011) References Figure 4. Bar chart showing country of origin for positive identifications from OpID Materials & Methods • Craniometric interlandmark distances (ILDs) were collected for OpID using a Microscribe® G2 3D digitizer in conjunction with 3Skull software (Ousley 2010). Data for other groups was obtained from the Forensic Anthropology Data Bank. OpID: 57 female, 99 male Guatemalan Mayan: 77 male Hispanic: 59 female, 255 male American White: 202 female, 388 male American Black: 55 female, 100 male • AD 2 matrix was obtained in SAS 9.3.2 using 16 ILDs (Table 1) representing overall craniofacial morphology and to maximize sample size. The log of the determinant of the covariance matrix (DCVM) was used to assess homogeneity among samples. • Eigenvectors were generated using the EIGEN function in NTSyS 2.2r • DISPOP (Jantz, no date) was used to calculate inter- individual D 2 and the Defrise-Gussenhoven statistic was used to assess overall homogeneity of the OpID sample. The reference groups Zuni, Mexican American, AmWhite, and AmBlack were used to generate the covariance matrix. A total of 51 ILDs were utilized due to missing data (Table 1). Table 1: ILDs used to calculate inter-individual D 2 in DISPOP and D 2 matrix in SAS 9.3.2 *GOL *BPL *DKB IML PAS PRR LAR NOL *NPH WNB XML PAF DKR OSR *BNL *NLH ZMB MLS *OCC ZOR BAR *BBH JUB SSS WMH OCS FMR *XCB *NLB FMB *FRC OCF EKR XFB MDH NAS FRS FOL ZMR *ZYB OBH *EKB FRF NAR BRR *AUB *OBB DKS *PAC SSR VRR Figure 2. Plot of Eigenvectors from D 2 matrix American Black Guatemalan Hispanic OpID American White -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 DIM- 2 (29%) DIM- 1 (69%) Figure 3. Examples of crania from the OpID sample Table 3: Squared distance to group pooled by sex From Group AmBl Guate Hisp OpID Guate 9.100 Hisp 5.614 3.613 OpID 6.806 5.028 0.611 AmWh 6.471 17.715 3.946 7.295 Table 2: Log of the determinant of the covariance matrix Group Ln of the DCVM Guate 33.047 OpID 34.718 Hisp 38.192 AmBl 38.521 AmWh 39.332 Pooled 38.812 USBP 2016. United States Border Patrol Southwest Family Unit Subject and Unaccompanied Alien Children Apprehensions Fiscal Year 2016. https//www.cbp.gov/newsroom/stats/southwest-border-unaccompanied- children/fy-2016 Jantz RL. No Date. DISPOP. Computer program. Hefner JT, Spatola BF, Passalacqua NV, Gocha TP. 2016. Beyond Taphonomy: Exploring Craniometric Variation Among Anatomical Material. Journal of Forensic Sciences 61: 1440-1449. * All ILDs listed in Table 1 were used in DISPOP calculations. Only those denoted with * were used in SAS. n=6 n=5 n=1 n=1 n=9 4.5% 4.5% 23% 27% 41% 0 2 4 6 8 10 Honduras Ecudaor Mexico Guatemala El Salvador COUNT Country of Origin for Positive Identifications Facilitated by OpID