SIT to employ isotope analysis to trace geographical origin of skulls found in Dharmasthala

Bengaluru 

The Special Investigation Team (SIT) probing the findings at Bangle Gudde hillock, to employ the isotope analysis method to trace the geographical origin of the skulls. The investigation team during the search found at least seven human skulls and hundreds of bones at the hillock.  

A highly placed source in the Home Department revealed to blrpost.com the SIT will be taking assistance of experts to conduct this sophisticated analysis on the teeth of the skulls. The SIT has already collected tooth samples from a local dental facility in Ujire in Dakshina Kannada. 

The SIT has already sent the skulls to a forensic laboratory and is also awaiting DNA analysis to identify the deceased. This is a long-drawn sophisticated investigation, probably first of its kind in the state of Karnataka. 

The sources said the controlled sample will be used for comparison of teeth discovered at the hillock. The SIT recovered the skulls which they found during Mahajar. The Mahajar was conducted after finding the source of the skull that was presented as evidence by the accused C N Chinnayya in the court. During the probe the SIT discovered that the skull was picked up by Sowjanya activist Vittal Gowda and then handed over to the accused.

What is isotope analysis ?

Isotope analysis of teeth is a powerful scientific method used to reconstruct details of an individual’s early life, including diet, geographic origin, migration history, and environmental conditions. This technique relies on the study of stable isotopes—particularly carbon (C), nitrogen (N), oxygen (O), and strontium (Sr)—that become chemically locked into tooth enamel during childhood. Because tooth enamel forms early in life and does not remodel or change over time, it preserves a permanent chemical record of infancy and early growth, often described as a biological “time capsule.”

Each isotope provides specific types of information. Strontium isotopes are especially valuable for determining geographic origin. The ratio of different strontium isotopes in tooth enamel reflects the local geology of the region where a person spent his/her early years, as strontium enters the body through food and water. Since geological formations vary from place to place, strontium signatures can act as a geographic fingerprint. Carbon and nitrogen isotopes, on the other hand, reveal dietary patterns. Carbon isotopes distinguish between different plant types, such as C3 and C4 plants, while nitrogen isotopes indicate the level of animal protein in the diet and can differentiate between marine and terrestrial food sources. Oxygen isotopes provide environmental information by reflecting the isotopic composition of drinking water, which is influenced by climate, temperature, altitude, and latitude.

The analytical process involves several precise steps. First, very small amounts of tooth enamel are sampled using drilling or micro-milling techniques. These samples are then chemically pretreated to remove contaminants that may have accumulated after burial or death. Next, a mass spectrometer measures the ratios of stable isotopes, such as carbon-13 to carbon-12, oxygen-18 to oxygen-16, or strontium-87 to strontium-86. Finally, the results are interpreted by comparing them to established isotopic baselines derived from regional geology, local water sources, and known food webs.

Teeth are ideal for this type of analysis because of their durability and stability. Enamel is the hardest substance in the human body and is highly resistant to post-mortem alteration, preserving isotopic signals better than bone. This makes tooth enamel especially valuable in archaeological, forensic, and paleontological contexts.

The applications of tooth isotope analysis are wide-ranging. In forensics, it helps identify unknown individuals and narrow down their place of origin. In archaeology and bioarchaeology, it sheds light on ancient diets, migration patterns, and population movements. In paleontology, it provides insights into the behavior, ecology, and environments of extinct animals, contributing to a deeper understanding of the past.