A Pilot Study of Microbial Succession in Human Rib Skeletal Remains during Terrestrial Decomposition

Area of Science:

• Forensic Science
• Microbiology
• Bioinformatics

Background:

• Vertebrate bone decomposition involves sequential microbial colonization.
• Understanding microbial succession in human bone is crucial for estimating postmortem interval (PMI), especially for skeletal remains discovered long after death.
• Current methods for PMI estimation with skeletal remains have significant error margins.

Purpose of the Study:

• To characterize the human bone microbial decomposer community.
• To determine if microbial succession in bone can serve as a reliable marker for PMI.
• To develop a data-driven model for quantitative PMI estimation from skeletal remains.

Main Methods:

• Six human cadavers were subjected to outdoor decomposition in spring and summer.
• Rib samples were collected at eight time points (3-week intervals) over 9 months.
• Bone microbial communities were analyzed, and random forest models were built to predict PMI.

Main Results:

• A core bone decomposer microbiome, dominated by Proteobacteria, was identified.
• Microbial community composition showed significant seasonal differences.
• The developed model predicted PMI with an accuracy of approximately ±34 days over a 9-month period.

Conclusions:

• Microbial succession in human bone is a repeatable and predictable process.
• This study provides the first quantitative, data-driven PMI estimate for terrestrial skeletal remains using bone microbiome data.
• The findings offer a potential new tool for forensic investigators to estimate time since death from skeletal remains.