Pubic Symphysis Morphology

Morphological changes of the articular surfaces of the innominate provides an excellent postcranial age indicators for adult remains.  Variation in the face of the pubic symphysis, the anterior-most point of articulation between the two innominates in the pelvic girdle, is a common region analyzed for age determination. Todd (1920) outlined a 10-stage method for assessing this surface, based on a large sample of male innominates.  Changes in the symphyseal surface over time proceed in a predictable pattern from a heavily contoured face, to one delimited by a rim in the mid 30s, to a surface marked by increasing porosity after 40 years.  Analysis by Meindl and coworkers (1985) has shown the Todd method to be the most accurate of the pubic symphyseal methods available.  It should be noted however, that a tendency to over-age individuals has been found after age 40 by some (BROOKS, 1955), while others claim under-aging of the 45+ year old individuals is problematic (Aiello and Molleson, 1993).

Below are the methods of Todd (1920) and Suchey/Brooks (in Brooks and Suchey, 1990).  The diagrams of each method were adapted from Buikstra and Ubelaker (1994), the descriptions associated with each drawing taken from the original publications.


Phase 1: Symphyseal face rugged, traversed by horizontal ridges separated by well-marked grooves, there being no distinction in size between the upper and lower ridges.  None of the following structures are present: nodules fusing with the surface, a delimiting margin, or definition of extremities.  (Age, 18-19)

Phase 2:  Symphyseal surface still rugged.  Horizontal grooves are becoming filled near their dorsal limit with new, finely textured bone.  Bony nodules may be present, fusing with upper symphyseal face.  Dorsal delimiting margin begins to develop.  No delimitation of the extremities.  Ventral bevel commences.  (Age, 20-21)

Phase 3: Symphyseal face shows progressive obliteration of ridge and furrow system.  Commencing formation of a dorsal platform.  Bony nodules may be present.  Definition of dorsal margin, with sharp lipping.  Ventral bevel more pronounced.  Extremities not delimited.  (Age, 22-24)

Phase 4: Great increase of ventral beveled area.  Corresponding diminution of ridge and furrow formation.  Complete definition of dorsal margin through the formation of the dorsal platform.  Commencing delimitation of lower extremity.  (Age, 25-26)

Phase 5: Little change in symphyseal face and dorsal platform.  Margin more clearly defined and more sharply lipped.  Lower extremity better defined.  Upper extremity forming with or without the intervention of a bony nodule.  (Age, 27-30)

Phase 6: Increasing definition of extremities.  Development and practical completion of ventral rampart.  Retention of some granular appearance of symphyseal face indicating that activity has not yet ceased.  Failure of ventral aspect of pubis adjacent to ventral rampart to become transformed into a compact surface.  The rampart may therefore be somewhat undermined.  Retention of the pectinate outline of the dorsal margin and slight ridge and furrow system.  No lipping of ventral margin and no increased lipping of dorsal margin.  (Age, 30-35)

Phase 7: Face and ventral aspect change from granular to fine-grained or dense bone.  Slight changes in symphyseal face and marked changes in ventral aspect from diminishing activity.  No formation of symphyseal rim.  No ossification of tendinous and ligamentous attachments.  (Age, 35-39)

Phase 8: Symphyseal face and ventral aspect of pubic bone generally smooth and inactive.  Oval outline complete.  Extremities clearly defined.  No distinct "rim" to symphyseal face.  No marked lipping of ventral or dorsal margin.  Development of ossification in tendinous and ligamentous attachments, especially those of sacro-tuberous ligament and gracilis muscle.  (Age, 40-45)

Phase 9: Symphyseal face presents a more or less marked rim.  Dorsal margin uniformly lipped; ventral margin irregularly lipped.  (Age, 45-49)

Phase 10:Ventral margin eroded at a greater or lesser extent of its length, continuing somewhat onto the symphyseal face.  Rarefaction of face and irregular ossification.  Disfigurement increases with age.


Phase 1: Symphyseal face has a billowing surface composed of ridges and furrw which includes the pubic tubercle.  The horizontal ridges are well-marked.  Ventral beveling may be commening.  Although ossific nodules may ocur on the uper extremity, a key featuer of this phase is the lack f delimitation for either extremity (upper or lower).

Phase 2: Symphyseal face may still shw ridge development.  Lower an dupper extremities show early stages of delimitation, with or witout ossific nodules.  Ventral rampart may begin formation as extension from either or both extremities.

Phase 3: Symphyseal face shows lower extremity and ventral rampart in process of completion.  Fusing ossific nodules may form upper extremity and extend along ventral border.  Symphyseal face may either be smooth or retain distinct ridges.  Dorsal plateau is complete.  No lipping of symphyseal dorsal margin or bony ligamentous outgrowths.

Phase 4:  Symphyseal face is generally fine-grained, although remnants of ridge and furrow system may remain.  Oval outline usually complete at this stage, though a hiatus may occur in upper aspect of ventral circumference.  Pubic tubercle is fully separated from the symphyseal face through definintion of upper extremity.  Symphyseal face may have a distinct rim.  Ventrally, bony ligamentous outgrowths may occur in inferior portion of pubic bone adjacent to symphyseal face.  Slight lipping may appear on dorsal border.

Phase 5: Slight depression of the face relative to a completed rim.  Moderate lipping is usually found on the dorsal border with prominent ligamentious outgrowths on the ventral border.  Little or no rim erosion, though breakdown possible on superior aspect of ventral border.

Phase 6:  Symphyseal face shows ongoing depression as rim erodes.  Ventral ligamentous attachments are marked.  Pubic tubercle may appear as a separate bony knob.  Face may be pitted or porous, giving an appearance of disfigurement as the ongoing proecss of erratic ossificaiton procededs.  Crenelations may occur, with the shape of the face often irregular.


Literature Cited:

AIELLO, L and T. MOLLESON, (1993).  "Are Microscopic Ageing Techniques More Accurate than Macroscopic Ageing Techniques", JAS 20:689-704.

BROOKS, S.  (1955).   "Skeletal Age at Death: The Reliability of Cranial and Pubic Age Indicators", AJPA 13:567-597.

BROOKS, S and J SUCHEY  (1990).  Skeletal age determination base on the Os Pubis:  A Comparison of the Acsádi-Nemeskéri and Suchey-Brooks Methods." Human Evolution, 5:227-227-238.

BUIKSTRA, J and DH UBELAKER.  (1994).  Standards for Data Collection from Human Skeletal Remains.  Proceedings of a Seminar at the Field Museum of Natural History,  Fayetteville:  Arkansas Archaeological Survey Research Series, No. 44.

MEINDL, R, C. LOVEJOY, and R. MENSFORTH. (1985).  "Skeletal Age at Death:  Accuracy of Age Determination and Implications for Human Demography", Human Biology 55:73-87.

TODD, T  (1920).  "Age Changes in the Pubic Bones, I:  The White Male Pubis", AJPA 3: 285-334.


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  auricular surface
  bone growth and development
  dental attrition
  epiphyseal closure
  dental eruption

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