August 17, 2011

Solving the Mystery of Conjoined Twins at Angel Mounds

Conjoined twinning is a rare congenital abnormality.  We know of old historical cases, of course, like Chang and Eng, whose birthplace gives us the term Siamese twins.  Going back further, Moche ceramics seem to depict conjoined twins as early as the turn of the first millennium.  But even though conjoined twins undoubtedly existed in antiquity, no conclusive bioarchaeological evidence has ever been found.

In 1941, an archaeologist named Glenn Black and his crew of WPA workers uncovered an unusual single burial of two infants, both about three months old, at a Middle Mississippian site (11th-15th c AD) called Angel Mounds near Evansville, Indiana.  Because of the positioning of the skeletons, Black suggested the burial might be that of conjoined twins.


Diagram of skeletons W11A60 and W11A61 from Angel Mounds


In order to shed light on this mystery, Charla Marshall, Patricia Tench, Della Collins Cook, and Frederika Kaestle undertook aDNA analysis, with the idea that conjoined twins would share mitochondrial genotypes because they have the same mother.  In a brief communication to AJPA, Marshall and colleagues (2011) report that their DNA sequencing clearly showed no maternal relationship.  It is still possible the infants were related, but they were not twins, conjoined or otherwise.  The question remains: why were these two infants buried in this manner?

This study, of course, would have been more interesting had the authors found conjoined twins, but they showed that certain interpretations about burials are now better made in a laboratory setting through the addition of chemical analysis of osteological data.


Reference:

Marshall C, Tench PA, Cook DC, & Kaestle FA (2011). Brief communication: Conjoined twins at Angel Mounds? An ancient DNA perspective. American Journal of Physical Anthropology, Early View. PMID: 21834072.

3 comments:

George Myers said...

In 1999 I excavated as part of a team in New York City's City Hall Park, a double burial in what is believed to be the "First Almshouse" cemetery between City Hall and the so-called Tweed Courthouse, now the Dept. of Education headquarters, though at one time considered for the Museum of New York City located uptown. They were in the vicinity of the Horace Greeley statue and a planned water fountain was to go there. Asked to excavate for "clearance" the small footprint I was disappointed when my knee impacted one of the two adults skulls in the fairly shallow burial, atop one another. One, as I recall had some perhaps ribbon on its wrist and a tiny piece of wood which appeared to have an outline of the "proverbial" two stone tablets of Moses. I'd ask if anyone else has seen anything similar?

These two in the article are apparently ceremonially placed in the ground, perhaps in respect, whereas many in City Hall, next to an infamous prison "blacker than any Black Hole of Calcutta" (NY Times 1903) and British Army barracks in the American Revolution, and the aforementioned almshouse, appeared often in shallow multiple burials in some cases and without artifacts.

Anonymous said...

Sorry I'm confused, surely any siblings would share mtDNA? So the fact they didn't share the same mitochondrial genotype means that not only are they not twins, but they do not have the same mother at all and are even less likely to be related?

Kristina Killgrove said...

@Anon - If two half-siblings shared a father rather than a mother, no, they wouldn't share mtDNA. The authors of this paper therefore couldn't say for certain that the two infants were not related, as they could have had the same father (or been cousins, etc.). They do not appear to have been full siblings, so they were neither twins nor conjoined twins.

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