Deepak Kumar Jha, Geologist, Biogeochemist, Geoarchaeologist

Deepak in the field and holding an archaeological stone tool in a field area.

Hi!! I am Deepak, a final year PhD student. I have recently submitted my thesis for evaluation at the Indian Institute of Science Education and Research (IISER) Kolkata, India. I am quite passionate about my research work as a scientist, exploring and digging the Earth’s surface to answer some of the curiosity-driven questions such as “the role of climate instability in human evolution”.

What is your favorite part about being a scientist, and how did you get interested in science?
The most important aspect of being a scientist “who deals with sediment and rock records” is that you get the opportunity to explore scientific questions that have a broader implication in understanding the past climate under which hominins evolved to become Homo sapiens. As a scientist, I get the opportunity to visit archaeological sites that have fossilised records of stone tools and artefacts used by prehistoric humans. Seeing archaeological samples and working on them to unravel human history feels exhilarating, and the realisation of holding artefacts used by humans thousands of years ago gives me goosebumps. The experience of working in the field and digging the sediment sequences to understand the past environment feels like time travelling. This excitement and curiosity have been the source of motivation for exploring the relationship between the past climate and prehistoric humans evolution.

Deepak working in the laboratory and analysing soil samples for charcoals under a stereomicroscope.

It all started during my undergraduate coursework in Geology, where I was introduced to various topics ranging from the Vertebrate Paleontology, Earth Climate, Quaternary Geology, and Evolution of Life through time etc., which built the foundation of my research career. The Quaternary period due to its association with human evolution fascinated me a lot. The research papers that correlate the fall of Harappan Civilisation with climate instability, particularly to the Indian summer monsoon weakening at ~4.2 ka and the collapse of well-known 8th or 9th century’s old Maya civilisation was linked to the arid climate, and excessive deforestation attracted my attention in this field.

Curiosity to unravel the mechanisms through which climate has shaped the evolution of Homo species brought me closer to my PhD project. My PhD research work at the stable isotope laboratory of IISER Kolkata, India, was oriented towards the understanding human-environment relationship. With the help of my supervisor Prof. Prasanta Sanyal, I was able to formulate my PhD project, which utilises stable isotopic tools to decipher changes in climatic conditions and their resultant effects on the prehistoric human population. Throughout this project, I thoroughly enjoyed every aspect of my research work.

Deepak operating the Dionex Accelerated Solvent Extraction (ASE 350) to extract the total lipids from the sediments.

What do you do?
I try to reconstruct the environmental conditions using multiple proxies to understand the relationship between climate and culture changes. By doing this, we would be able to understand the climatic situations through which human evolution took place.

How does your research contribute to the understanding of climate change, evolution, paleontology, or to the betterment of society in general? 
My graduate research work aimed to understand the course of human evolution during the Late Quaternary period in the Indo-Gangetic region. The Quaternary period encompasses numerous key advancements in human evolution such as early migration, brain size development, typo-technological evolution, adaptation to an extreme environment, hunting to sedentism lifestyle, agriculture and domestication of animals. However, any advancement in human evolution cannot be deciphered in isolation without understanding the prevailing climatic conditions, since humans like every other organism also respond and adapt to their changing environment. To comprehend the complex research questions of Late Quaternary in the Indian subcontinent, I have used the multidisciplinary (Geology, Organic and Stable Isotope Geochemistry, Archaeology and Anthropology) approach to decode the early-human environment and their behaviour in extreme climate scenario. I have employed a multi-proxy approach that includes compound-specific isotopic analysis of n-alkanes and soil carbonates from paleosols to understand the past climate and vegetation in the Belan River Valley situated in north-central India. My research highlights the vital linkage between the prehistoric human populations and climate variability.

Deepak presents a scientific poster at a conference (INQUA 2019) held in Dublin, Ireland.

At the same archaeological sites, further research work on the study of macroscopic charcoal particles suggests the controlled use of fire by hominins during the Middle Paleolithic phase dated around ~55 ka BP. This charcoal record provides the oldest evidence of fire use by hominins from the Indian subcontinent. Additionally, I aim to decode the provenance of sediments deposited in the Indo-Gangetic plains during the Late Quaternary period. To achieve this, we have planned to measured Strontium (87Sr/86Sr) – Neodymium (143Nd/144Nd) isotopes to understand the provenance of fluvial sediments and stone tools from archaeological sites. Therefore, through this project, I have targeted novel questions and used the latest measurements techniques to provide an overall idea of climate, vegetation, fire and provenance and its linkage to prehistoric phases in India. The results of my project have helped in filling a scientific void by presenting results from the Indian subcontinent, which will lead to an improvement in the understanding global-scale picture of human evolution.

What advice do you have for aspiring scientists?
I would say to them, “The only way to achieve your dream is not to give up”. The journey is not easy, but the curiosity in you will find a path that will lead you to success.

Learn more about Deepak and his research on his website and ResearchGate profile, and follow him on Twitter @Deepak_Geoarch

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