No, it is impossible to distinguish between male and female skull until late adolescence, I would say until 16-18 years. And before the age of 20-25 it is usually risky since many traits like the browridge or mastoid process are still underdeveloped in male  

It may be possible, but the research has not yet be performed.  In the attached paper, you will see that ontogeny of the craniofacial architecture of the chimpanzee separates males and females from the stage of having the complete deciduous dentition.  In this paper we speculated that the differences were manifest from birth.  There was one later attempt to determine if these principles also separated male and female humans, but the study was performed on children with facial growth deficiencies, and the results were equivocal.  

Until that time, no research was performed trying to distinguish them. However, it is know that only after adolescence that the craniofacial architecture is distinguished male from female.

Without conducting destructive analyses (such as DNA), the morphological features that distinguish male vs. female physical traits do not present themselves until post-adolescence (age depending on the demographic and time period you are studying).

sorry friend, it is impossible to distinguish between male and female skull, maybe until +18 years old 

Accurate sexing infant skeletal crania, impossible.

There are a number of methods that have been developed for estimating sex in human subadults, but the reliability of these methods are dubious. As a bioarchaeologist dealing with skeletal populations that are clearly not comparable with the modern samples used in these studies, I never use them. Scheuer & Black (2001) "The Juvenile Skeleton" (pages 19-21) provide a good overview of these issues.

Every once in a while bits of research are done in this field. There are quite a few studies giving discriminant functions based on metrics of the skull and tooth dimensions (which will only be feasible when you have general populational background). But these approaches usally are prone to big errors and correct classifications are in the range of 60-70 %. Which is better anyhow than pure chance. But in a forensic context this is probably not good enough.

So far no method to sex infants has proven solid enough and honestly... there is little hope someone will come up with a good one. The ones based on metrics will fail due to the plasticity of the bones in process of growing, questions related to nourishment and genetic background of the sample. Trying to infer human sex through studies on Pan are really risky. Although genetically close to us, chimps mature much faster and are a lot more dimorphic: we can assume sexual attributes will develop earlier and will be more marked at any given stage. 

I suspect that bioarchaeologists are generally overly conservative in their wholesale rejection of all "bits of research" done on this problem.   How many of these rejected "dubious" methods have been independently tested, and what were the findings?    Has this been explored comprehensively in an overview study?

I wonder about the efficacy of one such study, generally ignored by bioarchaeologists, viz. Schutkowski's (1993) "morphognostic" method of sex estimation from infant mandibles.   This method was independently tested by Ridley in a 2002 thesis, who found the method to be reliable for estimating sex in fetal and infant remains.  The Ridley study is all but ignored (as well), it seems.

It would be good to hear from bioarchaeologists and forensic osteologists who reject the Schutkowski method (and Ridley follow-up), as to their particular objections.

Ref. cited:

Ridley, J. 2002 Sex estimation of fetal and infant remains based on metric and morphognostic analyses. Master’s Thesis, Department of Geography and Anthropology, Louisiana State University and Agricultural and Mechanical College.

Schutkowski, J. 1993. Sex determination of infant and juvenile skeletons: I. Morphognostic features. American Journal of Physical Anthropology 90:199-205.

Hi Professor Heathcote,

If someday a method is developed that is shown to be broadly applicable I’d be happy to use it! Schutkowski’s method, however, has been tested by a number of researchers with less than encouraging results (e.g. Cardoso & Saunders 2008; Vlak et al. 2008). Even those researchers who achieved positive results expressed caution about applying the method to different populations (Sutter 2003; Wilson et al. 2008; 2011).

I work with archaeological skeletal populations from Greco-Roman Egypt, Meroitic Sudan and Neolithic Turkey. As such, I don't think it would be appropriate to use Schutkowski's method, which is based on a skeletal sample from Victorian England, when it is difficult to unravel the confounding effects of environment, genetics, nutrition and other growth factors on the subadult skeleton. Admittedly, this debate is not my area of expertise, but I have yet to see any method for sexing subadults broadly adopted by my bioarchaeological peers. I think it is unnecessary (and potentially detrimental) to use inappropriate methods on archaeological skeletal populations as it may lead to erroneous interpretations of cultural behavior. It is for this reason, I think, that we are so conservative!

best regards,

Scott

References:

Cardoso HFV & SR Saunders 2008. Two arch criteria of the ilium for sex determination of immature skeletal remains: a test of their accuracy and an assessment of intra- and inter-observer error. Forensic Sci Int 178: 24–29.

Sutter, RC 2003. Nonmetric subadult skeletal sexing traits. I. A blind test of the accuracy of eight previously proposed methods using prehistoric known sex mummies from Northern Chile. J. Forensic Sci. 48: 1–9.

D. Vlak, M. Roksandic, M.A. Schillaci 2008.Greater sciatic notch as a sex indicator in juveniles, Am. J. Phys. Anthropol. 137 (3): 309–315.

Wilson, LA., N. MacLeod, LT Humphrey 2008. Morphometric criteria for sexing juvenile human skeletons using the ilium. J. Forensic Sci. 53: 269–278.

Wilson, LA, HFV Cardoso, & LT Humphrey. 2011. On the reliability of a geometric morphometric approach to sex determination: A blind test of six criteria of the juvenile ilium. Forensic Sci Int 178: 24–29.

I don't think that it has ever been demonstrated to be possible (using known sex and age material) with any level of accuracy, greater than 50:50 chance. You might be able to do something with the tooth crowns, depending upon how far they have developed. Otherwise, just a guessing game.

It is also my opinion, gathering from the literature (most of it already cited in the above comments), that it is not possible to accurately estimate sex on infant skulls. At least, not with a level of certainty that would leave me confortable using it in my analysis.

Maybe tooth crowns could be an interesting option, but I must admit I never delved into that aspect myself.

Gonçalves et al. (2014; link bellow) among others have proposed it is possible to sex Neolithic individuals using odontometrics of the lower canines. Considering that LC crowns around 5-6 yrs old, this could be one possibility. The authors provide a good review on the topic (page 186), but metrics is not my thing. 

Best,

Claudia

https://www.researchgate.net/publication/282292468_Rozdzia_3._Rozwj_koci_dugich_koczyn_czowieka_w_yciu_podowym._A.Malinowski_O.Nowak_B.Modziejowski_R.Asienkiewicz__Chapter_3._Development_of_long_bones_in_human_extremities_in_the_foetal_period._%28in_polish%29

...in this book is also a chapter about development of foetus skull...maybe it would be useful in answer of your question ?

Chapter Rozdział 3. Rozwój kości długich kończyn człowieka w życiu p...

I am a forensic anthropologist. The identification of sex in human infant skulls is limited by the lack of skeletal development reflective of male-female differences. Combined with limited sample size so characteristic of studies of infant skeletal material, the estimation of sex of infant crania is, to my knowledge, currently without much merit, if any. Also, I caution the use of archaeological or fossil data which is generally not only undocumented but also deficient as far as sample size is concerned. Not to mention the effect that temp[oral and spatial (geographical) differences that make these samples largely inappropriate for comparison to modern samples. 

It is with good reason that "experts" do not offer "conclusive" estimates.

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