Idea

We anecdotally noted genera (e.g. Artemisia) that are used to repel unwanted spiritual forces in several regions (SW China, North America), and which can be also used to repel insects. We propose that this reflects, at least in part, a process of metaphorical extension whereby plants (usually aromatic) that have material repellant properties are more likely to be added to the repertoire of plants utilized for an analogous function in the non-material realm.

To see if a broader pattern might exist as evidence of this process, we turned to the Moerman Native American Ethnobotany database, as an example of a large, standardized compendium of ethnobotanical information which includes species-use-records for both plants used to repel insects and other pests, and for plants used for a variety of spiritual and symbolic purposes, including repelling spiritual forces.

Orou pointed out that this is a nice fit into the literature on theory of why certain plants end up in use reperetoires, and he could suggest some introduction refs and text around this.

Methods -- data extraction

NAEB originated in the mid 1970s as a database of medicinal plants used by Native Americans. Currently the database contains information about plant uses by 291 Native American groups, and includes plants used for food, drugs, dyes and fibers. Each record is drawn from a cited, published source, usually from primary literature (Moerman 1998). NAEB now comprises 44,691 species use records of a given plant (or fungal) taxon used by a given tribe for a given use, usually with additional details on the use noted.

To populate the first list, Jasmine searched NAEB for use records that contained the strings “insect”, “pest”, “bug”, “flies”, “mosquito”, which included plants coded in the database as insecticidal. We did not include records that contained the search string but as part of the species name or another unrelated word (e.g. results with “pestle” or “...campestris” for the search string “pest”). We were left with 396 results, which we then manually reviewed. To ensure that the set of use records met our intentions (plant with potential chemical activity against insects, including those cited as repelling, preventing, or killing insects or other pests), we dropped from further analysis use records for which the species was only noted as used to treat insect bites/stings or other irritation, and use records in which the use was clearly non-repellant (e.g. used to attract insects). Records in which the manner of use could not be determined (e.g. “used for fleas”), were assigned to an indeterminate category.

To populate the second list, Jasmine searched NAEB for use records that contained the strings “ghost” and “spirit”. This returned 172 results (representing 90 total species), which we also manually reviewed to ensure that they met our criteria. For the remaining analyses, we dropped species where the use record contained the string but was not clearly related to repelling unwanted spiritual forces: as part of the species name or another unrelated word in the record text (including treatment of ‘ghost sickness’ or use in ‘ghost dances’), or because the use was non-repellant (e.g. used to attract or appeal to spiritual forces).

In this list, there were 130 records that met these criteria as material repellents, representing 54 species of 44 genera, and 90 records that met the critera as spiritual repellants, representing 46 species of 36 genera.

There were 7 species found in both lists (i.e. dual-use):

dual-use species
Juniperus scopulorum Sarg.
Artemisia douglasiana Bess.
Thuja occidentalis L.
Umbellularia californica (Hook. & Arn.) Nutt.
Heracleum maximum Bartr.
Achillea millefolium L.
Artemisia ludoviciana Nutt.

There were 9 genera found in both lists:

species of dual-use genus records (spiritual) records (material)
Achillea millefolium L. 1 2
Artemisia absinthium L. NA 2
Artemisia douglasiana Bess. 2 1
Artemisia dracunculus L. NA 10
Artemisia frigida Willd. NA 6
Artemisia ludoviciana Nutt. 3 4
Artemisia vulgaris L. 2 NA
Fomes igniarius (L. ex Fries) Kickx NA 2
Fomes sp. 2 NA
Heracleum maximum Bartr. 3 3
Juniperus monosperma (Engelm.) Sarg. 2 NA
Juniperus scopulorum Sarg. 2 2
Monarda fistulosa L. NA 2
Monarda sp. 1 NA
Pinus rigida P. Mill. NA 1
Pinus strobus L. 1 NA
Thuja occidentalis L. 3 1
Thuja plicata Donn ex D. Don 1 NA
Umbellularia californica (Hook. & Arn.) Nutt. 1 5

Methods, analysis approach #1

In our first attempt to quntify whether this observed overlap (species used for this dual purpose) was greater than we might expect 'by chance', Robbie tried a Monte Carlo approach, in which we picked a set of 46 (the same number as species used against spirits) random species from the entire list of 4,251 NAEB species, and calculated the number of species shared between this control list and the list of species used against insects (dual-use species).

In the figure above, we run this analysis 1,000 times (pale histogram) and saw that our observed number of dual-purpose species (dark vertical lines) is high in comparison to the random samples. This is particularly true for exact-species matches.

Concered that this control set might be overdispersed (as species that are rarely reported are just as likely to be picked for our control sets as species that are commonly reported, making it less likely that they would include species also in the insect species set). So, we re-ran the analysis selecting from species present on each of the the 44,692 NAEB records, making it (e.g.) much more likely that the controls sets would include Thuja plicata (368 records) as they would Zamia pumila (1 record).

In the figure above, we run this second analysis 1,000 times and can see a small rightward shift in the distributions of # dual-purpose taxa (pale histograms). As before, our observed number of dual-purpose species (dark vertical lines, unchanged) is high in comparison to the random samples. This is particularly true for exact-species matches.

Finally, if we include the 70 additional records that we categorized as "indeterminate", there are 182 records that met the expanded criteria as material repellents, representing 86 species of 67 genera, and 108 records that met the expanded critera as spiritual repellants, representing 55 of 44 genera.

With this expanded dataset, there were 13 species found in both lists (i.e. dual-use):

dual-use species
Juniperus scopulorum Sarg.
Artemisia douglasiana Bess.
Thuja occidentalis L.
Umbellularia californica (Hook. & Arn.) Nutt.
Heracleum maximum Bartr.
Hierochloe odorata (L.) Beauv.
Achillea millefolium L.
Artemisia ludoviciana Nutt.
Picea glauca (Moench) Voss
Juniperus monosperma (Engelm.) Sarg.
Abies lasiocarpa (Hook.) Nutt.
Heterotheca villosa var. villosa
Tsuga heterophylla (Raf.) Sarg.

and there were 14 genera found in both lists:

species of dual-use genus records (spiritual) records (material)
Abies lasiocarpa (Hook.) Nutt. 3 2
Achillea millefolium L. 1 2
Artemisia absinthium L. NA 2
Artemisia douglasiana Bess. 2 1
Artemisia dracunculus L. NA 10
Artemisia frigida Willd. NA 9
Artemisia ludoviciana Nutt. 3 7
Artemisia vulgaris L. 2 NA
Fomes igniarius (L. ex Fries) Kickx NA 2
Fomes sp. 2 NA
Heracleum maximum Bartr. 3 3
Heterotheca villosa var. villosa 1 1
Hierochloe odorata (L.) Beauv. 1 2
Juniperus monosperma (Engelm.) Sarg. 2 1
Juniperus scopulorum Sarg. 4 3
Juniperus virginiana L. NA 1
Monarda fistulosa L. NA 2
Monarda sp. 1 NA
Monarda sp. 1 NA
Picea glauca (Moench) Voss 2 2
Pinus rigida P. Mill. NA 1
Pinus strobus L. 1 NA
Thuja occidentalis L. 3 1
Thuja plicata Donn ex D. Don 1 NA
Tsuga heterophylla (Raf.) Sarg. 2 1
Umbellularia californica (Hook. & Arn.) Nutt. 1 5

Although all the sets are slightly larger in this analysis, the # of observed dual-use species is, again, higher than most of the distribution of randomly selected sets:

The same is true of the record-weighted method:

Methodology, approach #2

Orou suggests that this could also be done with a binominal logit model, which would let us include some other factors that we think to be relevant (e.g. aromatic family or not, life form, horticultual value). This would also let us build in a PGLS to look for phylogenetic signal for versatile use (spiritual / material).

y_i~Bin(p_i,n_i)

logit(p_i)=b

logit(p_i)=b1+b2X_i

p_i=exp(b)/(1+exp(b))

X=aromatic family or not

X2=life form

X3=horticultural value

logit(p_i)=b1+b2X1+b3X2+b4X3+epsilob

My notes say that our next step would be for Robbie and Jasmine to reshape the data and add a couple of columns to makea table with X1, X2, X3 (lifeform, aromatic, decorative), and two columns of use for binary repelling insects vs. repellinng spirits.

Other next steps

If we could find other regional ethnobotanical databases that included spiritual plants and pest-control, it would be very powerful to run this analysis in a different region. Unforunately, these are hard to find. Long Chunlin reports that this does not actually exist for China, but he had a student take a look through the literature for us, and they were able to pull out a few examples (discussion points of plants with this dual use). These include certain Artemisia species, as well as Pinus and Cupressus.