Bone Diagenesis and Extremes of Preservation in Forensic Science

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Overal, the review drafted by the authors is a welcome addition to the current literature, however I do have some thoughts to share and suggestions for improvement.

General:

- references to the figures do not work, most likely because the authors used an automated reference mechanism, it shows ERROR in the text.

Introduction:

The authors write that less research has been performed on bone for longer burial/postmortem intervals. However, there is a lot of archaeological research done, perhaps the authors can specify what kind of research they are referring to, i.e. longitudinal experimental work? 

At the end of the introduction the authors write "There remains a need to pull apart the chemical and microbial 40 nexus of diagenesis when producing". This results in the question how do the bacteria then alter the bone matrix, specifically the inorganic phase? I believe through a chemical reaction mechanism. If that is correct, how can we pull apart these two?

About figure 1: Not everything has been mentioned in the text before the figure, I believe it would be beneficial to elaborate or at least introduce all the content of the figure in the text in the § the figure is referred to.

2. on chemical changes

The example of iron does not fit well with the topic of the paper, why are the authors focussing on iron?

About figure 2. Fig 2. I wonder whether aubergines are a standard pictogram for bacteria? And it is left to the reader to interpret the red cross in front of the aubergines.

About figure 3 and accompanying text, for some reason the focus lies on geospheric taphonomy, aquatic taphonomy (fresh or salt water) is left out, howcome?

4. Long term microbial activity

At the end of 4.2 the authors wrote "Bioerosion is limited in extreme conditions but chemical 246 processes of acidic dissolution or alkaline degradation will still proceed" this part if a bit difficult to follow, since bioerosion seems to be chemical in the base reaction. However, Soil pH is here presented as a stable variable, however soil pH can change over time, especially when dealing with longer burial intervals. 

In 4.5; line 295, reference 58, please check the citation style and be consistent. a reference to the author et al. with a year seems more appropriate here. 

Chapter 6.

The so-called extremes in this chapter don't really cover the extremes expected (what kind of casework are the authors referring to?), instead this chapter seems to be a continuation of the previously covered topics with just highlighting a few extremes in my eyes. For example, cases involving dissolution of humans in strong acids and bases (even archaeological examples can be used like the peatbog bodies). This topic is barely touched opon.  Burned bone is also barely touched upon. The effect of freeze/thaw cycles for glacial environment is not covered. There is a lack of depth here.

The authors wrote "Light and porous soils such as sand generally facilitate diagenesis whereas 385 dense soils such as clay and wetlands slow diagenetic change for excellent preservation 386 [72,82]" My response here is that this seems highly variable. This statement is not substantiated with my own experiences, in which bones extracted from soils with high clay content generally showed poor preservation, poorer than from sandy soils, however this also always went hand-in-hand with wet conditions in the soils with high clay content.

Going into the conclusion:
Although the information seems to be in there, the authors to not cover the topic of reburial or a change in taphonomic context. The effect of such a change is of current debate and of importance for both archaeology and ethics for funeral practices. I do consider this a loss.
From the start, bone has been the focus, and the authors have, as it seems, chosen to view bone as a material being composed from bioapatite and collagen, it seems logical to start with an introduction into the chemical composition of bone (there is a recent review on that matter) and a thorough description of what is considered when discussing whole bone, since there is (for example) also a lot of adipose/grease within the porous structure of the bone which also influences or delays the decomposition/taphonomy differently in different context. 

Author Response

Thank you for reviewing our manuscript, your comments were invaluable for improving the paper. Please find attached a Word document with response to each comment and corresponding line number.

In the main file upload, we have attached a marked copy of the amended manuscript, and a clean copy (no track changes remaining) in the additional file upload.

Many thanks for your time and review!

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

General comments:

This review article provides a review of bone diagenesis research of relevance to both forensic science and archaeology.  It is an impressively comprehensive summary of research from forensic science, archaeological, taphonomic and diagenetic research and heritage conservation science, highlighting the importance of understanding burial environment and decay processes for correct interpretations of past events. The extensive bibliography will be of great use for researchers and professionals within a range of specialized fields. I appreciate the simple illustrations of complex processes. I am happy to recommend the publication, but I do have some suggestions and comments I hope can be of use to the authors.

 

Specific comments:

The bibliography is extensive, but citations with missing references has already been noted and these must of course be added.

Citation in a sentence is sometime done with author names, other times with just the reference number in brackets (e.g. line 85, ‘Gordon and Buikstra (19)…’). This should perhaps be made consistently one or the other.

The section 2.3 about Recrystallisation mainly talks about demineralization. I suggest explaining this process briefly, as crystallinity is an important diagenetic parameter.

Short-term vs Long-term microbial diagenesis – could you please explain in the two section what you mean by short vs long-term?

In the section Short-term microbial diagenesis there are several terms that should perhaps be defined and explained for the reader: histological structures (microanatomy, microstructure?), haversian systems (blood channels, vascular canals?), osteocyte lacunae (bone cell cavities?).

Line 143-144: Bones on the ground surface are exposed and quickly degrade by a range of bacteria, fungi and insects…. Could you please add references to this statement as the references at the end of the sentence as far as I can see only talk about decay once submerged or buried. Regarding bone bioerosion by microorganisms, this is found to be less in surface exposed remains (e.g. Yoshino et al 1991) so it should also be explained what is meant here exactly.

Line 153-154 ‘..by accessing the histology via the planes of decomposing soft tissue…’ Seems a difficult way to say this, it may not be clear what is meant. Consider re-phrasing, for example: By accessing the interior of the bone..? Utilizing the natural porosity/the blood vessels/channels in bone to access the interior...? Furthermore, as you mention in a following paragraph, not all researchers agree that this is an early diagenetic process where soft tissue must be present.

Line 160-161: ..biological material can also delay decomposition and diagenesis by coating the bone surfaces and passivating the chemical mechanisms occurring in these areas…

I’m confused as to what you mean. You refer to Collins et al that describe organic molecules passivating mineral surfaces, referring to the fact that the strong bond between collagen and bioapatite provide protection for both phases. Here it sounds as if some biological material (what?) coat the bone surfaces to protect it. Please clarify/explain.

Table 1: Common methods for determining bioerosion and diagenesis

This table is in my opinion unclearly structured. Microscopy (light and scanning electron) and FTIR are methods not parameters. Thus, I think this should be a column of it's own. I wouldn’t call MFD a parameter, it’s a feature observed during microscopy and the parameter semi-quantifying it is OHI. For FTIR the most used parameter, crystallinity, or the splitting factor, and a central reference for this method, Weiner and Bar-Yosef 1990, is missing. For SEM, studies using the method for characterizing histotaphonomy, such as by Bell and Turner-Walker, could be added.

Line 177: This states there is consensus that diagenetic bacteria causing bone bioerosion is endogenous, coming mainly from the decomposing body itself and not the soil.

As the authors themselves mention, there is not complete consensus (and it is not just the work of Turner-Walker alone that question this, see for example Morales et al 2018 on bioerosion of faunal assemblages in Argentina), and I recommend you to include a recent publication, probably published after the current manuscript was considered, that may constitute a game changer regarding this question:

E. M. J. Schotsmans, B. H. Stuart, T. J. Stewart, P. S. Thomas and J. J. Miszkiewicz

PLOS ONE 2024 Vol. 19 Issue 9

Line 181: Mein and Williams observed more diagenetic markers in whole carcass samples…

Yes, but the critique in a comment in QI by J. J. Miszkiewicz, J. M. Andronowski and E. M. J. Schotsmans should be mentioned as they point to some significant shortcomings of this study.

Line 190-191: The stage of diagenesis is also more advanced in adult human bone than in animals or juvenile humans (ref Jans et al) or in newborn and stillborn remains due to dietary differences creating a simpler and less efficient microbiome.

I have a couple of comments regarding this sentence: Jans et al’s study did not include juveniles or age as a factor as far as I can see, it only compared human and animal bones. ‘The stage of diagenesis’ should also be specified to clarify that one is talking about bioerosion. The way this whole sentence is phrased suggests that this is an established fact. I suggest to rephrase e.g. ‘was in one study found to…’ and ‘suggested by these researchers to be due to..’. And again, you may consider mentioning Morales et al that found extensively bioeroded animal bones.

Line 254: The direct influence of soil type on diagenesis is insignificant.

Here you could consider also referencing the following study:

Contextualising the dead – Combining geoarchaeology and osteo-anthropology in a new multi-focus approach in bone histotaphonomy

D. Brönnimann, C. Portmann, S. L. Pichler, T. J. Booth, B. Röder, W. Vach, et al.

Journal of Archaeological Science 2018 Vol. 98 Pages 45-58

Section 6 with all the cases is a really useful and fascinating read – thank you!

Author Response

Thank you for reviewing our manuscript, your comments were invaluable for improving the paper. Please find attached a Word document with response to each comment and corresponding line number.

In the main file upload, we have attached a marked copy of the amended manuscript, and a clean copy (no track changes remaining) in the additional file upload.

Many thanks for your time and review!

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

A part from a single erroneous reference that was still in the text (that can be taken out during the proofing stage), the reaction of the authors and subsequent changes to the manuscript have improved my understanding and the quality of the work in my opinion. 

Author Response

Thank you for reviewing our revisions and comments throughout, we very much appreciate it. We have now reviewed and fixed the erroneous reference ready for the proofing stage.