Ivan Đaja

Ivan Đaja (also known as Jean Giaja, Serbian Cyrillic: Иван Ђаја; 21 July 1884 – 1 October 1957) was a Serbian physiologist, professor, and author, renowned for his research on hypothermia, animal hibernation, and the physiological effects of low temperatures.

Đaja was born in Le Havre, France, to a Serbian father and a French mother. He completed his early education in France before studying at the University of Belgrade, where he later became a professor. He held the chair of Physiology at the University of Belgrade from 1910 until his death.

Đaja's research focused on the fundamental biological processes of thermoregulation and metabolic adaptation to cold. His work on the "survival minimum" temperature – the lowest temperature an organism can withstand and still recover – was particularly significant. He developed specific methods and equipment for studying hypothermia and its effects on various organ systems. His experiments often involved inducing hypothermia in small mammals like rats and ground squirrels, allowing him to meticulously observe the physiological changes that occurred during cooling and rewarming.

Đaja was a prolific writer, publishing numerous scientific papers and several influential books, including "Hypothermie et vie ralentie" (Hypothermia and Slowed Life) and "L’homéothermie" (Homeothermy). His work had a significant impact on the development of cryobiology and contributed to our understanding of the physiological limits of life. He was a member of the Serbian Academy of Sciences and Arts. His work laid the groundwork for later research in cryopreservation and the medical management of hypothermia.