One can assume that the association between the kidneys and urine production has been known since the first time pre-historic man, or woman, killed an animal and ate the kidneys. There has however been considerable discussion through the ages what the relative roles of the kidneys, the urethers and the bladder actually are.
Around 360 B.C. Plato wrote in "Timaeus" that:
“The outlet for drink by which liquids pass through the lung under the kidneys and into the bladder, which receives and then by the pressure of the air emits them...” (from the Internet Classics Archive at MIT, translated by Benjamin Jowett.)He then goes on to describe the use of the actual outlet in sexual intercourse.
Somewhere around the same time Aristotle has a surprisingly correct description in "On the parts of animals":
"A pair of stout ducts, void of blood, run, one from the cavity of each kidney, to the bladder; and other ducts, strong and continuous, lead into the kidneys from the aorta.However, even though some dissection must have taken place, neither Plato nor Aristotle describe the methods behind their conclusions. I have read somewhere that it was not fashionable to refer too closely to the real world at the time. The world of ideas (platonic) was thought to exist independently of the real world and all important conclusions could be arrived at through contemplation and deduction.
The purpose of this arrangement is to allow the superfluous fluid to pass from the blood-vessel into the kidney, and the resulting renal excretion to collect by the percolation of the fluid through the solid substance of the organ, in its center, where as a general rule there is a cavity.
From the central cavity the fluid is discharged into the bladder by the ducts that have been mentioned, having already assumed in great degree the character of excremental residue." (Part 9. Also from the Internet Classics Archive, translated by William Ogle.)
Quite a bit later Galen or Claudius Galenus describes what I believe is the oldest surviving description of a scientific experiement in renal physiology. Seeking to show that the urine is produced in the kidneys and passed through the urethers to the bladder, Galen writes:
"Now the method of demonstration is as follows. One has to divide the peritoneum in front of the ureters, then secure these with ligatures, and next, having bandaged up the animal, let him go (for he will not continue to urinate). After this one loosens the external bandages and shows the bladder empty and the ureters quite full and distended- in fact almost on the point of rupturing; on removing the ligature from them, one then plainly sees the bladder becoming filled with urine." ("On the Natural Faculties", book 1, chapter 13, from the Internet Classics Archive, translated by Arthur John Brock).It is ofcourse not a very humane experiment given that anaesthesia was not developed for another 1600 years or so. I have not found any date of publication, but given that he lived from year 129 to year 200 it is the oldest fairly solid experimental description in nephrology I have been able to find.
Do you know of any older records?
Please chime in,