His De Fibra Motrice advanced the "solidist" theory that the solid parts of organs are more crucial to their good functioning than their fluids,[6] against the traditional belief in four humors.

His mother was Croatian, while his father was possibly[8] of Armenian descent[1][b] His parents were respectable but poor merchants who both died in 1670, after the birth of Giorgio's younger brother Jacob (Latin: Jacobus).

[8] He attended Lorenzo Bellini's lectures in Pisa[8] and worked in hospitals in Padua and Venice, Florence, and Bologna and travelled to the Dutch Republic and England from 1688 to 1692.

[citation needed] As early as 1685, Baglivi began experimenting with animals, injecting different substances into dogs' jugular veins and examining the life cycle of tarantulas.

[8] He continued his observations by microscope as professor of theoretical medicine at the Sapienza, as well as examining the properties of saliva, bile, and blood.

For a time he was surrounded in controversy following charges of plagiarism by Antonio Pacchioni, but Baglivi successfully defended the primacy of his own work.

[8] Being inclined towards mathematics and quantification in medicine, Baglivi viewed the physiological processes in mechanical terms, behaving like the parts of a machine.