Outwardly, Gallifreyans closely resembled humans, though were in fact more directly related to Terileptils (a reptilian-humanoid species) and Chelonians. Many biological and physiological traits of the Gallifreyan species were due in part to extended exposure to the Time Vortex.

In terms of genetics, Gallifreyans possessed Triple Helix DNA, within which the DNA of all an individual’s regenerations, both past and future, lay dormant. 98% of their genes were shared with the Great Vampires. Bio-Data Extracts for every member of the species were stored in the Matrix and Archival Office, serving as easy identification, and were colour-coded by Chapter.

Gallifreyans were far more resilient than humans, and were able to withstand extreme weather conditions and temperatures, electric shocks, Röntgen radiation and various other circumstances or accidents that usually proved fatal to humans. They could survive in a vacuum for up to six minutes, and were immune to the effects of certain poisons. The skin of Gallifreyans was honey-scented and had additional layers that enhanced its protective qualities, and while the temperature of the skin was almost indeterminable from that of a human, they had a core body temperature of between 15-16°C. Typically, Gallifreyans had twice as many organs as humans have, i.e. two hearts rather than one, four lungs rather than two, etc., and they had full conscious control over all organs. The presence of two stomachs enabled them to live for at least 40 days without food or water. Hallucinogenics or alcohol used by humans had little effect on Gallifreyans, due to their rapid metabolism of drugs and toxins. The ability to reduce metabolic activity and enter a trance-like state for several days negated the need for prolonged periods of sleep.

The left shoulder was a vulnerable area as it contained a cluster of nerves that, if dealt a strong blow, would disable the Gallifreyan. Toxic substances included Aspirin and Arsenic, and Ginger Beer could act as an intoxicant.

Wait, so Time Lords have reptilian biology?

But this just shows that they’re better than humans in every way. Apart from where feelings or aspirin are involved.