After the MSA: The knowledge of deadly poison during the Late Stone Age in South Africa ?

This is an elongated MSA-“point” from Kwa Zulu Natal in South Africa.  The most important site for the MSA/LSA transition in this region is the Border Cave, situated  about 400 m from the border of Swaziland. The cave’s mouth opens west towards the Lembobo Mountains. These mountains are 650 meters in height and stretch north and south along 35 km wide Loweld plain. First excavations at Border Cave were conducted in 1940 by the bat guano miner W. E. Horton, followed by archeologists including K. W. Butzer and Peter Beaumont. The stratigraphic sequence contains a Howiesons Poort industry and pre- and post-Post-Howiesons Poort layers.   Recent examination of dates from several sites in South Africa by Jacobs and colleagues found that Howiesons Poort is dated from 66-58 k.a. BP .

Border cave includes approximately 4 m of deposits, dated between 200k.a. ago and the present. Environmental analysis suggests that at the time of the earliest occupation of the cave, the area was well woodedwhile later occupations experienced open savannah woodland. A long debate and attempts at several different dating chronologies (particularly electron spin resonance (ESR) and amino acid racemization) were mostly resolved in the early 21st century, with most scholars accepting the current chronology:

  • Layer 1BS, Early Later Stone Age, 44 k.a. BP
  • Layer 1WA, white ash deposit ~38-40 k.a. BP
  • Layer 2BS, Middle Stone Age 3, 60-47 k.a. BP
  • Layer 2WA, white ash deposit ~59 k.a. BP
  • Layer 3BS, Howiesons Poort, 79-60 k.a. BP. Here several remains of Homo sapiens were found mainly during the early excavations
  • Layer 3WA, white ash deposit
  • Layer 4BS, Middle Stone Age I

D’Errico and colleagues recently showed that at Border Cave two assemblages, dated to 45–49 and >49 k.a., show a gradual abandonment of the MSA-technology and can be considered transitional industries.

The early LSA technocomplex, dated to 44-42 k.a cal. BP is based on an expedient technology dominated by bipolar knapping, with microliths hafted with pitch from Podocarpus bark. Organic artifacts, which are similar in form to those used by San hunter-gatherers, include bone and ostrich shell beads, bone projectile points, wooden digging sticks, a supposed  poison applicator and notched bones. These assemblages mark the beginning of the LSA in South Africa. The wooden “poison applicator”, from the LSA levels, dated to ∼24 k.a. BP and clearly intrusive according to the  C-14 dates, retains residues with ricinoleic acid, derived from  Castor beans.

Ricinoleic acid (12-hydroxy-9-cis-octadecenoic acid) is an unsaturated omega-9 fatty acid that naturally occurs in mature Castor beans. By gross weight, a castor bean also contains approximately 0.6 percent ricin, a toxic glucoprotein.

Ricin is one of the most potent naturally occurring toxins and is among the deadliest poisons available. Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis. As little as 500 μg can kill an adult if given parentally.  One case of fatality (assassination) following intramuscular injection of a small ampoule containing ricin has been described*. The person developed fever, glandular swelling, hematemesis and leukocytosis followed by renal failure and a clinical picture resembling sepsis and multi-organ failure. Upon autopsy hemorrhagic necrosis were found in the intestinal wall, the heart muscle and in lymph glands. Similar clinical and pathological findings were observed in pigs injected with ricin.

Oral exposure to ricin is far less toxic and a lethal dose can be up to 20–30 milligrams per kilogram.  It is resistant, but not impervious, to digestion by peptidases. By ingestion, the pathology of ricin is largely restricted to the gastrointestinal tract where (hemorrhagic gastroenteritis). The meat of animals killed by poisoned projectiles can be eaten by humans without danger if properly heartened above 85o C, because the poison is destroyed at these temperatures.

There remain some statements and questions:

  • The evidence of Ricinoleic acid should not confused with the evidence of Ricin (!)
  • Ricin was not reported to be evidenced from the  “poison applicator”.
  • Therefore the findings remain ambivalent.  Castor beans preparations may contain Ricinoleic acid but no Ricin and in this case lack the properties of a deadly poison.
  • Please read  also a critical comment by A.A Evans at http://www.pnas.org/content/109/48/E3290.full
  • How was ricin extracted from Castor beans?
  • Was the poison known elsewhere?
  • Was there a continuity of its use until recent times?
  • Was the principle of using poisoned projectiles used elsewhere?

A meticulous analysis of upper Paleolithic organic projectiles may help to answer these questions in the future

Suggested Readings:

http://www.pnas.org/content/early/2012/07/23/1204213109.full.pdf

http://www.ncbi.nlm.nih.gov/pubmed/22847432

http://en.wikipedia.org/wiki/Ricin

http://www.redorbit.com/news/science/1112666399/later-stone-age-south-africa-pnas/

*Bulgarian dissident Georgi Markov was killed by a poison dart filled with ricin and fired from an umbrella in London in 1978
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