Historical Research (A. D. 100-1890)

Todd and Lyon (1924:327) present the following historical account of cranial sutures. Cranial sutures were viewed as controlling both the growth of the brain and, therefore, the shape of the skull. Although classical authors, like Hippocrates, Aristotle and Galen, had observed that some human crania exhibit open sutures, whereas others are almost or entirely devoid of them, the fact that union occurred during life did not appear in the anatomic literature until the works of Gabriele Fallappia (1523-1562), in the middle of the 16th century (Todd and Lyon 1924:327).

Additionally, it was assumed that the condition of the sutures were indicative of racial background (Todd and Lyon 1924:328). For example, in the 1st century A. D., Celsus, in his compendium of medical learning, stated that crania devoid of sutures occur more readily in warm climates [in reference to Ethiopians] (ibid.). Fallappia, best known for his ?identification? of the fallopian tubes, was encouraged by his teacher, Andreas Vesalius (1514-1564), to challenge the classical view that sutures had a close relation with skull morphology (ibid.). One hundred years later, other anatomists had come to agree that this relationship could only be found in rare instances (Todd and Lyon 1924:327).

In 1641, Thomas Bartholin (1616-1680) proposed the following ?uses? for cranial sutures (Todd and Lyon 1924:326): 1) to permit the free transpiration of the vapours in the brain; 2) for the attachment and suspension of the dura matter; 3) for the transmission of fibers of the dura through to the pericranium; 4) for the transmission, in both directions, of vessels carrying nourishment and life to the parts; 5) to diminish the likelihood of fracture of the bones of the skull [Interestingly, Hershkovitz et. al. (1997:397) have once again suggested that open sutures may increase skull efficiency in absorbing related mechanical stresses]; and 6) to permit the penetration of applications from the exterior.

Bartholin asserted that the number and location of the sutures was the same in males and females, and were rarely changed by the shape of the cranium (Todd and Lyon 1924:327). It was proposed that these ?cranial deformations? occurred during fetal development or at birth (ibid.). In the 18th century, anatomists emphasized the analogy between sutural membranes and the diaphyso-epiphseal plane (Todd and Lyon 1924:328). The Hippocratic idea of the relationship between cranial form and suture condition was revived in the 19th century. Since the middle of the 19th century, the growth of the brain has been viewed as a cause, rather than effect, of suture closure (ibid.).

During the 19th century, it was observed that cranial union first occurs in the sagittal suture, and that it occurred earlier within the cranium than upon the exterior (Todd and Lyon 1924:328). In 1856, the anatomist Louis Pierre Gratiolet (1815-1865) proposed a sequence for suture closure and stated that union occurred earlier in ?negroes?. It should be noted that Gratiolet made this distinction in order of cranial closure between ?higher and lower races of mankind?, with negroid races belonging to the lower group (Todd and Lyon 1924:342). [Note: current, politically incorrect terminology has been retained within this paper since its usage is employed within the context of the historic period in which the original studies were carried out]. Gratiolet, observed that ectocranial suture closure progressed sequentially (Todd and Lyon 1924:353): sagittal, lambdoid, then coronal.

Other anatomists began to try to establish an age related sequence for cranial suture closure. For example, in 1861, the physician Paul Broca observed visible sutures in males over the age of 50, and developed a 4 point rating system for cranial suture closure (Todd and Lyon 1924:353). Over time, it came to be accepted that, in the ?white stock?, union began between the ages of 40 and 45 (ibid.). However, in 1869, F. Pommerol noted that the period of union, for each suture, varied across individuals but followed the general pattern (Todd and Lyon 1924:328-329). Pommerol identified the following sequence (ibid.): 1) individuals under 35 years of age had open cranial sutures; 2) around 40 years, the sagittal suture begins to close; 3) around 50 years, the coronal suture begins to close; and 4) by 65 years or more, the temporal suture has finished closing.

In 1885, F. C. Ribbé examined 50 skulls of known age, 40 of which were of ?white stock? , the other 10 presumably non-white (Todd and Lyon 1924:329). He found that the earliest occurrence of cranial suture union was at 21 years and the latest at 55 years. Taking the mean, Ribbé concluded that closure commenced between the ages of 40 and 45, with a standard deviation of 15 to 20 years (ibid.). He stated that ectocranially, sagittal and lambdoid sutures closed before the coronal (Todd and Lyon 1924:355).

In 1888, Schmidt proposed that the basal suture untied between 18 to 21 years, but possibly between 25 and 40 years, and was complete between 40 and 60 years (Krogman 1962:77). In 1890, T. Dwight proposed that before the age of 30, all of the cranial sutures were open (ibid.). Krogman (1962:77) states that Dwight also observed that suture closure began endocranially and occurred later in females than in males (Todd and Lyon 1924:329). Dwight concluded that closure was irregular and, as such, not of value as an indicator of age (Krogman 1962:77). However, his samples consisted of street urchins of indeterminate ages and he did not indicate whether his conclusions referred to internal or external suture closures (Todd and Lyon 1924:329).