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>> Good morning everybody.
My name is Ashley Humphries.
Like Doctor Ross mentioned
before, some of this might --
information might be
a little generalized
for more experienced
individuals, but we wanted
to make sure we -- to
accommodate everybody.
My discussion will be on the
determination of biological sex
from the human skeleton.
>> So just a general
anthropological protocol
that we go over.
First of all is the bone human.
What context is it in?
Is it even a forensic context?
Is it prehistoric?
How many individuals
are present?
And then we go into
the biological profile,
which will be the
most important to us
in our discussions
throughout the day.
And since I am discussing
biological sex determination,
there are two main means
for -- for determining sex,
and those are through visual
assessment or anthroposcopic,
and measurements
-- anthropometric.
And then again, as you go
through the anthropological
protocol,
you have these other areas
that narrow down the field
of missing persons, so we
can identify an individual,
and also provide information
on perhaps how they
ended up where they were.
Kind of a big deal in
anthropology is the difference
between biological
sex and gender.
And anthropology will
prefer to use biological sex
because it is the
actual physical
and anatomical difference
between males and females.
And this is based on the type of
gametes produced by the gonad,
so ova in the female and
spermatozoa in the male.
Gender, on the other hand, is
more of a social construct,
and it's -- specifies
a socially --
socially and culturally
prescribed roles men
and women are to follow.
And these roles can
be influenced
by an individual's sex.
So one of the main areas,
or main reasons why
we can determine sex
from the skeleton is
because of sexual dimorphism
between males and females.
There -- we look at size,
and then architecture.
Males are generally larger,
have more muscle markings,
are stronger, and then females
tend to be more gracile.
And then we also
look at architecture.
And the female pelvis is the
most architecturally different
area that we look at, because
the female pelvis is designed
to bare children, and
so it obviously needs
to be a lot wider to let
the baby come through.
When we're determining sex,
we have to be very careful
of population differences,
because there are gonna
be different levels
of sexual dimorphism
across populations.
Here I just have a
photograph of a European female
and a European male -- or
an Asian male, excuse me,
to try to show that the Asian
male appears a little bit more
graphile, and perhaps some
people may resemble more
female morphology.
But we just need to keep in
mind that when we're looking
across populations,
that the sex --
the levels of sexual
dimorphism could be different.
When it comes to determining
sex from juvenile skeletons,
it can be very difficult.
There are methods to use, but
sometimes they're no better
than chance, and you quite --
you don't want to go
to court with that.
So it's a realm that
we sometimes stay away
from a little bit.
But as -- well, Doctor Ross
had mentioned to use the 3-D ID
for determining ancestry
for -- for juveniles.
You can't really quite do
that with the -- the sex.
So with our visual
indicators, the skull
and the pelvis together can
provide fairly great accuracy --
between 90 to 100%.
The pelvis alone would
be better than the skull
because of the morphological
differences,
because of bearing children.
And then the skull alone
can also provide fairly
great accuracy.
And then as we go down
to the long bones,
it gets a -- a lot less.
And so I'll go over the sex
differences of the pelvis first.
Here I have a photograph
of the anterior, superior,
and inferior views of the
male and female pelvis
to show the differences.
The first photo on the left is
indicating the sub-pubic angle.
And for the females you can
see that it's much wider
than the male's on the bottom.
The center pictures are showing
the position of the sacrum.
And for the females
it's tilted back.
And then when you're looking
into this pelvic
inlet you can see
that the female pelvis
has a lot more space.
Again, related to childbirth.
And then the picture
on the right is just showing
the positioning of the ilia,
and males are more
narrower and taller,
and then the females are wider
and a little bit
shorter and broader.
One of the features that is very
commonly used is the greater
sciatic notch, which
is located right here.
We use a set of standards
by Buikstra & Ubelaker
that shows the -- a range of
width, and you choose from one
to five the -- whether it's
female or intermediate or male.
So the wider it is, the more
likely it is to be female,
and the narrow, the
more likely male.
And that's again,
related to childbirth.
And you can see in
this picture up here,
the female is much
wider than the male --
greater sciatic notch.
The preauricular sulcus
is located inferior
to the auricular surface, where
the sacrum articulates with --
with the two halves
of the pelvis.
And these traits
are very important,
because we don't find the
pelvis just fully intact,
all articulated.
It's generally going to
be in -- in sections.
So two halves of the
pelvis -- so two off coxae,
and then the sacrum
that lies in the middle.
So the pre -- the preauricular
sulcus, if it's present,
it's -- it's probably female.
>> If it's absent,
then it's mostly male.
This one, I don't like
to necessarily say
that if it's absent it's
-- it's definitely male,
because you can have a female
that does not have this groove,
or depression inferior
to the auricular surface.
And so here the male, you
cannot see a depression,
and here the female,
you see a slight groove.
The ishciopubic ramus is
located inferior to the pubis,
right here on -- if
you see this photograph
at the top right corner.
And on males this
is wider or blunt,
and then on females it's
more narrow or sharp,
and just related to the overall
-- or that males are larger.
The pubic body, which is located
here in the front, males this --
this area tends to be
more triangular in shape,
and then on females it's
rectangular or square.
And this is related to
the sub-pubic angle.
If you see this picture,
you can see the differences
between the angles.
And so the female is
more of a square shape,
because the sub-pubic
angle or concavity is going
to be larger than the male.
So here I have a radiograph.
Can somebody please
tell me what --
based on the greater
sciatic notch,
what sex you believe
this individual will a --
and b to be.
Anybody? Okay.
>> [Inaudible].
[ Laughter ]
>> Both are female,
are they not.
>> Thank you.
It's -- they're both
-- they're both female.
So I -- I believe it is the
right and the -- the -- it's --
this is a little difficult
because you're not handling it,
you know, the angle
could be a little off.
But they are both female.
This one obviously yes,
that would be an extreme
example of a female.
So this is the -- the
pubic bone, or the pubis.
And based on that
photograph can you tell me?
If that's all you had?
>> [Inaudible].
>> It's female.
>> Yes, correct.
So this is more of a -- a --
more of a square or
rectangular shape.
And you can see the
concavity right here
for the sub-pubic angle.
If you had more of a
photograph, I'm sure it --
it would have been easier.
Okay. How about this one?
This is, like I said, is a
little tough from the angles.
I don't blame you on this one.
But I see a slight
depression here.
If maybe the photograph were
turned a little bit there,
we could see it more --
the preauricular sulcus.
But I do believe this
individual is female.
Now I'll go over
some of the visual,
or morphological
differences between males
and females using the skull.
Here I have the photographs that
we used from the standards book
by Buikstra & Ubelaker.
The nuchal crest, or --
is located on the posterior
aspect of the skull.
And I'll go through all
of these individually.
And we have the mastoid process,
and supraorbital margin,
the glabella region,
or supraorbital ridge,
and the mental eminence,
and these are related
to robusticity, so males are
more robust than females.
The nuchal area, located here,
you can see the difference
between the male and the female,
where the female is more smooth,
has less apparent
muscle markings,
and then the male will have
more prominent muscle markings.
And sometimes this
area will have a hook.
Here's another angle.
The mastoid process,
which is located here --
if you feel behind your
head, you can feel it --
females it's smaller and less
projecting, as you can see
on the right side, and
on males it's thicker,
larger, or more projecting.
Sometimes it might not be
projecting, but it may be wider.
So that's one thing
to keep in mind.
The supraorbital margin,
which is located on the --
the superior portion
of the eye orbit,
on males this area will be thick
and rounded, and this one I --
I have to feel it to
actually assess this one.
And then on females this area
will often be a sharp ridge.
Brow ridges -- you can
often just see this
by looking anybody.
The males typically
have a large,
or a pronounced brow
ridge, but not always,
especially between populations.
So one thing to keep in mind.
And then females
it's often small,
or there -- there is none.
We can also look at the
shape of the frontal bone,
right here in this area.
On the males it --
it's more slanted,
and then on females
it's higher or rounder,
or more bulbous, projecting.
You can see that difference.
And then we also look at
the shape of the mandible.
Males tend to have a
more square shape here,
and females more
rounded or pointed.
I like to flip the -- the --
the mandible over and look
at the inferior aspect,
as shown in this picture, and
then here's the superior view.
So looking at this photograph,
can you tell me male
or female, and why?
[ Silence ]
>> Yes.
>> Male.
>> Correct.
>> Cause the brow ridge
is straight up and down
and the very little [Inaudible]
in the mastiod looks
kind of small.
>> Mm-hmm.
Exactly. And it's pretty smooth
back here, and there is a --
a little bit of an
occipital bud.
But other than that, the muscle
markings are very smooth.
How about this photograph?
>> Okay, so it's -- it's
-- this individual is male,
large brow ridges, a rough
nuchal area, and large mastoids.
So then we also have metric
approaches to determining sex,
and these are quantified
approaches.
And early comparisons were
based on single measurements
or indices from numerous
areas of the body,
both cranial and post-cranial.
Recent analyses have
taken advantage
of the multivariate statistics,
which can allocate an individual
to the sex or ancestry.
And accurate measurements
require knowledge
of the skeleton and
its various features,
and how to locate the --
the landmarks properly.
>> So an example
of metric analysis
of the postcrania would be
the femoral head diameter,
located here.
So you just measure this
with a sliding caliber.
And here's an example
of a European-American.
If the measurement
is less than 42.5,
then the individual
is likely female.
And as you look down the list,
you can have probable female,
then intermediate, probable
male, and then if it's greater
than 47.5 it is likely male.
>> This is a similar
method, used for the --
the humeral head
vertical diameter.
And again, once you take this
measurement using the sliding
calibers, if it's less
than 43 millimeters,
then likely female, and so on.
>> The ischio-pubic index
uses the measurements
of the pubic length, from here
to where the point of fusion
between the three bones of
the ossa coxae, the ilium,
the pubis, and the ischium, and
then uses the ischium length
from here to the
point of fusion.
And so you enter --
you divide pubic length
by ischium length times 100, and
males tend to be less than 84,
and females greater than 94.
However, this is one of those
where ancestry is good to know
when applying this method,
because they will vary.
>> Cranial measurements
allows researchers
to summarize the dimensional
elements of sexual dimorphism,
and it uses size and shape
analysis that's based
on the linear distances
between two landmarks.
And these linear
measurements are then plugged
into discriminate functions
of function equations,
and then it produces
sectioning points.
And then from there, you can
determine if it's greater
than the sectioning point, or
less than a sectioning point,
whether the individual
is male or female.
This is very much
ancestry-dependent,
and so therefore you need
to be aware of standards
that are based
on the inappropriate
reference population.
And so you would measure, for
example, here's bregma tibasion
for cranial height,
and urion's urion
for cranial breadth, and so on.
And as an example
here, you can plug them
into the discriminate functions,
and the sum of all values comes
to 90 76, and since
it's greater than 81 71,
it's likely that
the person was male.
[ Silence ]
>> And then we move on to 3-D
ID, which takes the linear --
takes the landmarks that we use
for the linear measurements,
and it provides information
about the relative
position of those landmarks.
With the traditional
linear measurements used
for traditional craniometrics,
you don't get the information
about where they're
actually positioned.
You're only getting how
wide the cranium is,
or how long the cranium is.
But we know that the actual
positioning of the landmarks
in -- in 3-D space provides --
can provide a little
more information.
So with the 3-D measurements,
we then use a geometric
morphometrics,
which Doctor Ross will discuss
more later, and we'll use size
and shape analysis that uses
the Cartesian coordinates, x, y,
and z of the anatomical
landmarks to give us --
to allocate the individual male
or female, or the ancestry.
So then the x, y, and z
coordinates are then compared
to a known reference population.
If the reference
population isn't there,
it will try to assign it to --
to the closest population
it can, but obviously
if it's not there, it might not
be as strong or as accurate.
And those are the
cited references.
I flew right through that.
I'm -- any questions?
So we just want --
you want to be able
to recognize these things
before you go applying the 3-D
analyses, to have
an understanding
of where we're coming from,
and to have prior knowledge,
because you need this
prior knowledge of well,
could the individual
be male or female
when you're using the program.
Okay? Alright.
[ Applause ]
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