It is well-known that sex determination of the skeleton is an essential feature

It is well-known that sex determination of the skeleton is an essential feature, as a prerequisite for obtaining other key identifying components, such stature, ancestry, and age at death in forensic and archaeological contexts.1,2 Obtaining accurate sex estimation is crucial for studying ancient populations to get valuable data and to reconstruct their life conditions: demography, identity, and epidemiology, and is also important for identifying individuals in medico-legal situations. 3–6
Sex, in adults, can be estimated at 75–95% depending on the sample and its expression of sexual dimorphism and skeletal preservation.6 The osteometric methods are considered the most reliable due to their repeatability and often high accuracy of sexing however expressing limitations due to inability to reliably determine the sex of individuals from skeletal features before age 18 year7 as the fixed biological boundary when the synostosis of the spheno- occipital synchondrosis is complete. Numerous methods have tried to do so, usually applying studies of the morphological and metrical attributes of the infant and juvenile mandible, tooth, and ilium8–10 ; however, no approach has demonstrated adequately reliable when tested on recorded skeletal samples,11 which can be great sources of information for the development of methods that can provide a high degree of certainty and offer an optimal capacity for discrimination.
The development of novel methods for the identification of skeletal remains of fetuses and newborns have been restrained by the lack of documented osteological collections.12 However, several studies have attempted to provide reliable methods that allow the construction of the biological profile of fetuses.13–26 Frequently, based on anthropological examination, estimated age (gestational age) in fetal remains is the unique attainable character of the biological profile.12,25,27 A recent study using geometric morphometrics analysis, on a subadult age group,28 composed of 58 individuals for the pubis and 83 for the ischium aged between birth and 1 year of life, from the San José’s juvenile collection (Granada Spain), 29 concluded that it is difficult to develop such an approach and found a non significant difference between male and female at these ages.
Great expectation was built on ancient DNA analysis, however due to problems of con- servation, contamination, and expense, has shown to not be the adequate response to this issue.4,30,31 Despite, advances in the field of molecular genetics has provided more sensitive methods for sex determination, the method based on the amplification of the human amelo- genin gene (AMEL), found on both chromosomes X and Y, is the most widely used. Several DNA studies attempted, with disputable results, to determine the sex of infants.32,33 It is difficult to determine sex from degenerated or fragmented DNA samples or from limited sample quantities because DNA testing depends highly on the quantity and quality of DNA samples. Ancient DNA and postmortem samples are frequently constituted by small frag- ments and are small in quantity because DNA is easily degraded by environmental factors and microbial attack at archeological sites34 ; It is also the case in forensic samples, as de- graded or fragmented DNA samples, make it problematic to obtain accurate results for the investigation.
On the other hand, the last two decades have seen the development of paleoproteomics, used to identify and/or characterize proteins in the archeological and paleontological record. Ancient proteomic studies have extended the age for which biomolecules and phylogenetically informative molecular sequences can be recovered to well beyond the hypothesized limit for DNA preservation,35 while, proteins have been shown to resist alteration for hundreds of thousands of years,36,37 as demonstrated in Siberia, on a 43,000-year-old mammoth more where more than 100 different proteins were found from its femur. The analysis of ancient proteins could provide a useful indicator of disease, starvation, and other kinds of stress information such as osteogenic sarcoma and prostate carcinoma38,39 or osteocalcin analysis for detecting stress.40
While parts of the skeleton or DNA have decayed, more often the tooth enamel survives burial conditions. The Amelogenin (AMEL) is a major matrix proteins found in the human enamel involving Amelogenesis. Developing human enamel has about 30% protein, 90% of which are AMELs. Thus, paleoproteomics holds promise to a reliable sex determination method of any age using the most likely survival tissue and it is minimally destructive and inexpensive.