When determining the sex of a deceased person from the skull, you are looking at degrees of emphasis on certain aspects of said skull. In general, females are gracile and males are robust, meaning that females tend to be closer to a neonatal form, and that is why we are so damn cute! Okay, the last part is my own opinion. For instance, the mastoid process is usually larger in males and protrudes out more, and the glabella is also larger in males while females are usually small and petite. What tends to happen therefore is that different features are scored on a five point system of most female to most male to get an idea of the sex of the skull.
However, sexing a skull is not so straightforward. As you can see in the above picture, it is rather down to opinion, as well as skulls being variable i.e. a female may have a robust glabella or a male may be quite petite. In life it is usually very easy to tell a woman from a man, especially with the added benefit of gender social cues, such as short or long hair. In death, it is a lot harder and it is much more advisable to use the pelvis to sex a skeleton than the skull. If you are wondering why the pelvis, it is because women have the ability to have babies and men do not, thus changing the shape of the pelvis between the sexes, as a woman has to be able to fit a human through hers…scary!
Spradley & Jantz (2011) actually advise using postcranial elements over the skull to estimate sex correctly when the pelvis is unavailable as they are more reliable, while White & Folkens (2005) advise that if using skulls to estimate sex, the entire population should be used (entire population meaning the group of individuals you have under study believed to be from the same living population e.g. a cemetery from Canterbury for instance). This is because populations vary, for instance, Australian Aboriginal skulls tend to be extremely robust compared to say, a European skull.
Now onto what I think is very interesting and the paper I wanted to discuss. Walker (1995) looks at sexism in sexing, whereby often than not, “There are nearly always more males than females in skeletal collections from archaeological sites. This is not consistent with what we know about the sex ratios of extant human populations” (Walker 1995: 36). Like I said above about the sexing being the opinion of the scorer, Walker (1995) argues that cultural stereotypes are prevalent for the scorer, whereby the scorer will unconsciously think of females as petite and small, and males as robust and strong (just think of nearly every film ever!).
Now you may be thinking at this point; “Hold on a minute, you were just saying gracile for females and robust for males” and yes, that is a general rule (I also said though that females can be robust and males gracile) but what Walker (1995) is highlighting is that osteologists and forensic anthropologists are not considering the the human life cycle when they do not have access to post-crania. Walker (1995) also says this lack of consideration is due to the majority of craniofacial development literature stating that cranial morphology “…remains essentially stable after adolescence…[yet] this static view of adult cranial morphology is unwarranted” (Walker 1995: 36).
What this means is that post-menopausal females have more robust features than younger women, such as heavier supraorbital ridges and may therefore be sexed as male, contributing to the male skeletal abundance. At the same time, young males under the age of 30 tend to be more gracile than their older counterparts, such as having less developed supraorbital areas, and the differences between the two groups (<30 and 30>) are statistically significant. Younger men may therefore be more likely to be placed in the female category or undetermined category if the rest of their body, especially the pelvis is not well preserved (Walker 1995). If you are confused by this paragraph, you should know that bone constantly remodels itself during life, it is not static and hormones will have a part to play in this.
To conclude, sexing using skulls is possible but is not the best method, and one should use the pelvis if possible. This is because typical female or typical male traits can be found in both sexes, although in general, females are more gracile and males more robust. However, as Walker (1995) points out, life cycle is not usually thought about when sexing and a cultural bias may be at play. Both sexes get more robust as they age, although at different ages, and this may cause the observer to mis-sex a skull. Age should therefore be taken into account when sexing so that sexism is not introduced while sexing.
Spradley, M. K. & Jantz, R. L. (2011). Sex Estimation in Forensic Anthropology: Skull versus Postcranial Elements. Journal of Forensic Sciences 56 (2)
Walker, P. L. (1995). Problems of Preservation and Sexism in Sexing: Some Lessons from Historical Collections for Palaeodemographers. In Saunders, S. R. & Herring, A. (eds.) Grave Reflections, Portraying the Past through Cemetery Studies. Canadian Scholars’ Press: Toronto
White, T. D. & Folkens, P. A. (2005). The Human Bone Manual. Elsevier Academic Press: London