Get Caught

Art-heavy personal blog of mostly Homestuck and Ninja Turtles. Also bones, cats, the human body, SCIENCE!, politics, Star Trek, and Watchmen. Occasionally NSFW but everything's tagged.










Probably the greatest burn I’ve ever seen on tumblr


Sherlock, is that you?

Science: 1. Hipsters: 0.

And i guess Sally left Anderson




And using cranial sutures on top of everything FUCKING HELL you can’t evaluate fucking cranial fucking sutures from a FUCKING X-RAY THE SCORING METHOD DOESN’T FUCKING WORK LIKE THAT (seriously what are you going to even fucking base it on, from this angle?  just one part of the coronal suture? you’re just going to ignore the sagittal, lambdoid, and palatine sutures?), and even if you could it is one of the least reliable methods of aging seriously what a fucking joke.

Cut and pasted from my original rant so some of the quoted bits referred to that first user who tried to go all Bones on this image, so just replace “African American decent” and “Caucasian” as relevant:  

Going to have to call bullshit on the “likely European” just from looking at profiles and x-rays like this.  Determining ancestry and likely social race from skulls is a sticky area, anthropology wise:  it can be important to identification in forensic contexts so it’s still used, but there’s a lot of racist bullshit pseudoscience that goes mostly unexamined and is still pushed as fact.  Most of the people (even very experienced, very famous anthropologists) who claim to be able to tell just by looking at a skull what social race an individual would likely have been identified as (self-identification is a whole ‘nother ballgame) fail to acknowledge that they’re actually using a lot of non osteological factors in their determination.  Stuff like knowing the population demographics of the area where the skull came from or even the demographic distribution of the individuals you see most often in your casework (like an anthropologist I met who proudly proclaimed that they could correctly assign race at just a glance in 95% of cases… and then two minutes later admitted that since they worked near the US border with Mexico 95% of their cases were undocumented workers who had died in the while attempting the desert crossing; so even just guessing “Hispanic” 100% of the time they would have appeared to have a very high rate of successful identification without having ever looked at a skull). 

Off the top of my head I can only think of one method that just looks morphological traits (shape and physical features of a skull) that has any sort of statistical validation to it at all, and that method is limited to “white”, “black”, or “Hispanic” classifications (most methods also sidestep the fact that Hispanic is an ethnic identity, sooooo).  The method with the most statistical validation requires careful measuring different points of the skull and then plugging those metric measurements into FORDISC, a program that uses descriminate function analysis to assess the degree to which a particular skull matches measurements taken from skulls from different known populations around the world. 

FORDISC itself isn’t perfect and has it’s own biases when it comes to what groups it includes in its reference samples (it’s been a few months since I’ve used it but IIRC the “Chinese” sample isn’t all that big and doesn’t take into account the fact that a country with over a billion people is going to have loads of internal diversity and variation) and it can’t really account for individuals of mixed background, but it at least gives you a statistical output that you can use to judge the validity of the program’s sorting. 

Also going to have to call bullshit on the biological sex identification.  When attempting to establish biological sex just from a skull alone you look at a specific grouping of traits (nuchal crest, mastoid process, supraorbital margin, supraorbital ridge/glabella, and the mental eminence if you’ve got the jaw are the most standard features used) and score the individually in an attempt to reduce bias.  I’ve not tried it with just an x-ray and I’d have to look up the literature to see if you can even attempt it with any sort of validity, but just looking at this image at this scale and quality (and with that hand blocking the mastoid process and some of the jaw’s goinal angle [corner of the jaw] on the individual on the right) I wouldn’t put too much stock in it for this case. 

The backs of both skulls are cropped out of the image, meaning you can’t use nuchal crest.  Not only is the mastoid process (muscle attachment site just behind the ear) difficult to see here, but you can only see one side (you need to use both if possible) and you can’t really get a good idea at the true size and shape of it in this flat 2D slice.  Supraorbital margin (the shape of the edge of the upper rim of your eye socket) is also out (maybe with enough magnification and a clear x-ray you could make a call, but I’ve always found it easier to feel with my own fingers).  You CAN at least look at the shape of supraorbital ridge/glabella (where your frontal bone/forehead meets your nasal bones/the upper part of your nose).  You can’t look at mental eminence (how your chin looks face-on) at profile at all. 

So for this x-ray, that’s one trait out of five.  Pretty piss-poor for an any osteology-based attempt at sexing. 

As for age, they’re adults and have all of their teeth in (looks like the person on the left has had their third molars out, while the person on the right still has theirs, partially erupted), and maybe with the full-size ex-ray you could narrow things a bit by looking at their tooth roots, the shape of their pulp chambers, and the amount of wear to their tooth cusps (or you could get creative and look for evidence of arthritis in the bones of the hand), but other than that?  Adult, early to mid twenties and up, but who knows how far up, much less whether their age falls into what they would culturally identify as their “prime”. 

We are all different inside, shaped by our genetic histories, our environments, and the lives we’ve lived.  That diversity is beautiful and fascinating and why I went into anthropology in the first place.   There are some trends and patterns within that variation that make it possible to look at bones and infer some things about the person in life, but we have to be careful in our observations, measurements, and interpretations lest we fall back into the same tired, biased, non-scientific, biologically essentialist bullshit that’s characterized much of anthropology’s past (mostly to the benefit of the privileged white, upper-class, educated men writing out all of those supposed “rules”).

(via cmyblack)