PONE-D-21-22127Ostrich eggshell beads from Ga-Mohana Hill North Rockshelter, southern Kalahari, and the implications for understanding social networks during Marine Isotope Stage 2.PLOS ONE

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Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: There are very few systematic studies on ostrich eggshell beads, so these findings are a welcome addition to current research. I therefore suggest publication with minor changes. However, I recommend addressing a few issues in order to improve the paper.

Four main issues concern the analysis and interpretation of OES:

First, in the supplementary tables you mention the presence of OES in the DBSR stratigraphic aggregate. Considering the age of DBSR levels, the presence of one bead with possible ochre residues, three preforms and 44 ostrich eggshell fragments is very interesting. Why were they omitted from the analysis? Did you suspect their presence results from post-depositional mixing?

My second observation concerns the stages of bead manufacturing and interpretation of the material. All manufacturing stages are present but you did not mention that stages V to VII are much more frequent. This could be an interesting observation and should be taken into account in the interpretation of the material. Additionally, the fact that fragments are outnumbered by worked OES (lines 371-372) does not necessarily mean OES was used in a conservative manner. Maybe finished beads were produced at the site and then taken elsewhere.

Thirdly, the different types of usewear that were identified and recorded are not defined, resulting in a lack of clarity. I would therefore advise the authors to clearly define each type of usewear in the methods section.

Finally, the presence of ochre residues is mentioned throughout the text. How did you characterize these residues as ochre? You should specify in the methods section if it is a visual characterization, and which criteria were taken into account (colour, texture, etc). In order to use the term “ochre”, you should conduct chemical analyses to confirm the presence of goethite or hematite (or other iron oxides). As there are no elemental or mineralogical analyses to support this, I would advise using more general terms such as “red / yellow / coloured residues”.

Please find other minor comments and suggestions listed by page number below.

OES beads section

(1) Line 87. Perhaps it would be interesting not to restrict this section to beads and mention other ostrich eggshell occurrences. For instance, engraved ostrich eggshell from Diepkloof, dating back to 60 ka (Texier et al 2010) should be mentioned somewhere.

Context section: Ga-Mohana Hill North Rockshelter

(2) Lines 154-169. Although you cite Wilkins et al 2020, figures including the location, stratigraphy and plan of the excavated areas of the site would be welcome here.

(3) Line 170. In the supplementary tables there are pieces from the surface and the DBSR deposits. Do you omit those pieces in your study?

Methods

(4) Line 178. In the supplementary tables you added pieces from DBSR and surface layers. Here you should clearly explain why these pieces were omitted from the analysis (see main issues above).

(5) Line 183. Which criteria did you use to identify pigmentation? See comments above concerning the identification of ochre.

(6) Lines 184-185. See comments on the definitions of usewear above.

(7) Lines 186-189. It would be useful to the reader if you described each manufacturing stage rather than explaining them by groups (II-V and VI-VII)

(8) Lines 207-208. Data on the horizontal distribution does not appear in the supplementary tables.

Results

(9) Lines 230 and 234, and table 1. In supplementary table 2, there is one bead and one preform from DBAS. Do you mean DBGS? If it’s a typo, you should correct the numbers in the text and table 1 (20 beads and 10 preforms from DBGS).

(10) Line 234. “This layer”, do you mean DGBS? Again, you should clearly indicate in the methods section that you omit the pieces from DBSR and surface layers from the analysis although they appear in the supplementary tables.

(11) Lines 234-235. See comments on the stages of bead manufacturing above.

(12) Lines 241 and 260. See comments on the characterisation of ochre residues above.

(13) Lines 241 and 260. It would be interesting to show detailed photos of these residues as they are not clearly visible in figure 1.

(14) Line 244-246. How many preforms show these “pathway 1” features? Maybe a figure showing a couple of detailed photos of the “pathway 1” and “pathway 2” features could be useful here.

(15) Line 255. “The shape of each fragment was recorded following Miller”: this should be moved to the methods section.

(16) Line 259. “Each fragment was examined for residue using a hand lens”. This was already said in the methods section.

(17) Lines 262-265. The definition of “scratches” and criteria used to identify non-anthropogenic marks should be moved to the methods section.

(18) Lines 266-267. “OES colour is a useful tool for understanding whether a shell might have been exposed to heat and the temperature of the heat source […] OES becomes yellow, red, iridescent and grey when heated under oxidising conditions [48,53,62], while reducing conditions are more likely to produce blackening of the shell. Blackening of OES has not been replicated in experimental studies but is relatively common in the archaeological record [48,50,63]”: Perhaps this section should also be moved to the methods section.

(19) Lines 332-333. Maybe it would be better to specify “modern” ostrich here.

Discussion and conclusions

(20) Line 370. Again, the fact that stages V to VII are much more frequent could be an important observation.

(21) Lines 373-374. “Assuming that ostrich distribution has not changed drastically over the last 15 ka”: is there any reference that supports this?

(22) Lines 399-403. See above comments on the use of the term “ochre”.

Supplementary Tables:

(23) You could add a column with the horizontal provenance of the pieces. Do they all come from area A?

(24) The different types of usewear shown in the tables should be clearly defined in the methods section.

Please find below additional comments on the supplementary tables:

Supplementary table 2:

- Why is the bead ID column empty?

- Stratigraphic aggregates column: DBAS? This stratigraphic aggregate is not mentioned in the description of the stratigraphy, or in Wilkins et al 2020: I suppose it’s a typo? You probably mean DBGS.

- Width column: (mm) instead of (g)

- “Striae”, “smoothing”, “patina”, “chip”…: all use-wear types should be defined in the methods section. Perhaps locations should also be clearly explained.

- Staining column: what kind of staining is it when you indicate “yes” instead of “ochre”? You should be more specific here.

- Staining and comments columns: ochre was not identified using chemical analysis. You should either conduct elemental and mineralogical analysis to identify these residues as ochre or simply describe them without interpreting their composition (for example: red residues).

- Correct the Orton stage numbers: some of them are not in capital letters.

Supplementary table 3:

- Observations column: see comments on the use of the term “ochre” above.

- What do you mean by “surface modification”, as opposed to “human modification” and “non-human modifications”? This should appear in the material and methods section.

Reviewer #2: Thank you for allowing me to review the paper “Ostrich eggshell beads from Ga-Mohana Hill North Rockshelter, southern Kalahari, and the 2 implications for understanding social networks during Marine Isotope Stage 2.” This is a fantastic paper. The methodology is thorough, and the writing is clear. It is amazing to see the way that researchers are getting at use and manufacture of beads to look at population interactions. I really do not have any critiques. If the authors wish, they could tie the paper to the recent Nature article by Miller and Wang (2021). I recommend accepting the paper.

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Reviewer #1: No

Reviewer #2: Yes: Jamie Hodgkins

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Ostrich eggshell beads from Ga-Mohana Hill North Rockshelter, southern Kalahari, and the implications for understanding social networks during Marine Isotope Stage 2.

PONE-D-21-22127R1

Dear Dr. Hatton,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Enza Elena Spinapolice, Ph.D

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: I reviewed this manuscript very positively the first time, and my opinion has not changed. This is a scientifically sound article, that adds insight to the field.

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Reviewer #2: Yes: Jamie Hodgkins