Estimating sex from skeletal remains

Sex is one of the first biological characteristics estimated from the adult skeleton. This is because some of the methods of estimating other identifying characteristics, such as age-at-death and stature, are sex-dependent. In addition, in the forensic field, knowing the sex of a deceased individual immediately rules out a large proportion of possible identifications. Although a number of macroscopic methods for determining the sex of infant and juvenile skeletal remains have been developed, current standards generally recommend that this is not attempted. This is because the methods have been shown to have a low level of reliability when applied to skeletons from different periods and places. DNA analysis and peptide analysis can be used to determine the sex of children (discussed in Week 5).

Sex is determined through an examination of the sexually dimorphic features of skeletal size and shape. Differences between male and female skeletons arise from the interplay between genetics, hormonal variation, culture and environment. For individuals who have completed skeletal maturity, sex determination of skeletal remains is considered to be reliable. It is important to note, however, that skeletal features are not polarised in terms of sexual dimorphism – the skeletons can’t always be placed into two neat categories. Instead, the traits relevant for sex determination exist on a spectrum from very feminine to intermediate to very masculine. As a consequence, five categories of sex determination are generally used in anthropological analysis as follows:

• Female
• Probable Female
• Intermediate
• Probable Male
• Male

The range of sexual dimorphism expressed may vary between skeletal samples. For example, skeletal samples from different time periods or geographical locations can vary in the extent to which particular ‘masculine’ and ‘feminine’ traits are expressed. These differences arise due to the interaction between social, environmental and genetic factors.

The American Academy of Forensic Sciences has produced an Approved American National Standard for sex estimation in forensic anthropology.

After watching this video, continue on to the following steps, which describe methods for estimating sex from the pelvis (os coxae) and the skull in further detail.

A note on transgender, transsexual and intersex

Last time the course ran we had a lot of questions regarding transgender, transsexual and intersex individuals. This course has cited and discussed methods that enforce the assumed biological sex binary (male and female). Please note that biological sex is complicated and is not as clear cut as what has been previously described as ‘male’ and ‘female’. The forensic community has started to adapt and there is a need to review methods to be more inclusive and representative of the population. This is an ongoing process and may take years to redefine what is seen as biological sex and the research behind estimating biological sex in forensics.