Accurate gender attribution has always been a priority in forensic casework and has always concerned the archeologists. Characteristics of forensic DNA samples analysis are similar to that of ancient DNA, small quantities of workable molecules being the main resemblance. The most frequently used markers for molecular sex attribution are the single copy gene for amelogenin located on X (AMELX) and Y (AMELY) chromosomes. Worldwide used sex determination kits were designed based on amelogenin genes amplification, especially useful in forensic casework. Sometimes these sex tests fail due to allelic dropout. New molecular markers for sex identification are constantly developed to overcome this problem. Another issue characteristic for ancient DNA studies is the contamination of samples with modern molecules of DNA. The accuracy of sex tests for ancient DNA studies depends on the possibility to discriminate between authentic ancient DNA and modern contaminant DNA.
Keywords: physical anthropology, sex attribution, molecular sex attribution, AMELX, AMELY, ancient DNA.
Correct sex identification has always been preoccupying archeologists or anthropologists and has major importance in forensic casework for nowadays population. In past populations, the status of man and woman significantly varied and the dynamics of relations between sexes changed during time. Physical anthropology may work out identifying with a higher degree of certainty the gender of skeletal remains by analyzing a few markers that indicate the sex.
The most common physical markers are the skull and the pelvis. Skull features tend to be more robust in the man than the female and the sub pubic region presents important differences due to the fact that females are capable of giving birth (Buikstra, 1994). The pelvic region markers are more reliable in sex attribution compared to those on the skull. These protocols however show no results when infant remains are analyzed. Alternative methods regarding tooth crown diameter in deciduous (Black, 1978) or permanent teeth (Cardoso, 2008) were developed for sex identification of immature individuals.
All anthropological data tend to be influenced by the observer’s subjectivity and cannot be obtained when fragmentary remains are analyzed. Considering these limitations, a molecular sex test can provide additional information. Of course molecular methods have their own limitations regarding DNA’s status of preservation or its contamination with modern molecules, but, in connection with traditional anthropological methods can offer a bigger picture, more complete picture.
Sex tests based on the amelogenin gene
The interest in ancient human DNA extraction and molecular analysis begins at the end of the 1980’s, when ancient Egyptian mummy DNA was cloned (Pääbo, 1985). Since then, new extraction techniques were developed in order to overcome the degradation process that DNA suffers over time and the contaminants...