What a Skeleton Can Tell Us: Age Gender How?

As a person ages: n The cartilage that we a born with ossifies (turns into bone) n The skull changes shape n Sexual distinctions on the skeletons become more apparent in adult than in children n Bones become less dense from age 30 on

2 1/2 year old child skull

5 year old child

10 year old child

Adult Skull

Differences Between Males and Females (Feminists be darned; women really are different from men…well, at least their skeletons are...)

Why do these differences exist? n Why do these differences exist? Because of estrogen/ testosterone; these affect musculature as well n Why are they not 100% reliable? Because there is overlap in what is considered normal (average ranges due to size of the adult)

Accuracy of Sex Distinction n 95% using the pelvis alone n 92% using the skull alone n 90% using the mandible alone n 80% using the legs alone Data is for caucasians; lower success for other ethnic groups-

General Differences Male Male n heavier bones n rougher bones n larger bones n broader shoulders n larger ribcage n more angular bones Female Female n lighter bones n smoother bones n smaller bones n more narrow shoulders n smaller ribcage n more rounded bones

Male Female

Legs Male n greater diameter n longer length n markings more prominent n heavier Female n smaller in diameter n shorter in length n markings are less prominent n lighter

Cranium Male n cranial mass larger and blockier n supraorbital ridge rounder and more smooth n zygomatic more pronounced n forehead slopes more n larger teeth n pointier mandible Female n cranium mass smaller and rounder; tapers at the top n supraorbital ridge sharper n zygomatic less pronounced n forehead slopes less n smaller teeth n rounder mandible

Cranium Continued n Male n mastoid process (bone behind ear) larger n back of jawbone is straight n Zygomatic process extends out further to the side n external occipital protuberance present n Female n mastoid process small n back of jawbone slants n zygomatic process pushes out less to the side n external occipital protuberance absent

Male skulls

Female Skull

Face n Differences in the n chin n jaw n cheekbones n as noted in the cranium section

Which is which? Why?

Site 1 Forensic Artistry: Using the Skull to Get an Image of the Person start by marking the skull with depth markers add clay to flesh out the face add finishing touches: hair, eyes- these may not be accurate Site 2 The Technique

Male pelvis

Female pelvis

Pelvis Male n More massive, rougher, heavier n Upper end of pelvis less tilted n Deeper “bowl” n Longer, more narrow and curved sacrum n Coccyx more vertical, less moveable Female n lighter, smoother, more delicate, thicker n upper end of pelvis more tilted n more shallow “bowl” n sacrum shorter, less of a curvature n coccyx less vertical, moveable, tilted backward

Pelvis, continued Male n less flared n heart shaped and smaller pelvic inlet n longer, less moveable pubic symphosis n angle of pubic arch less than 90 degrees n acetebulum more under hips Female n more flared n oval/ round pelvic inlet, larger n shorter more moveable pubic symphosis n angle of pubic arch over 100 degree n acetebulum more out to the side

Which is which? Why?

Activity Level Active/ athletic people n heavier bones with more pronounced ridges for muscle attachment; less likely to be round and smooth Inactive People n lighter, less dense bones with less pronounced ridges; much more likely to be smoother and more rounded bones

Bone structure

Bone function n Support/ framework n Protection –Hard surface –Makes WBC’s that fight off infection n Make blood (RBCs) n Movement –Attachment sites for muscles