Body temperatures and sterilization points fall near the phi points between freezing and boiling.
Body temperatures vary, even within humans. The body temperatures of mammals range from around 97° to over 103° Fahrenheit. Birds have average temperatures of around 105° Fahrenheit.
The phi point between the freezing temperature (32° F) and the boiling temperature (212° F) of water is 100.8° F, or 38.2° Centigrade.
Take the phi point from the other end of the scale of temperature and you arrive at 143°, which is about the temperature required to kill bacteria. (Generally rounded and stated as 140° in most literature.)
Interestingly enough, if you take the phi point or 0.618 of 37 degrees centigrade, which is the average human body temperature, you get 23 degrees centigrade or 73 degrees Farenheit, a “room” temperature that many would consider to be just about perfect for indoor comfort and outdoor enjoyment.
Water has a very unusual property in that it reaches maximum density in the liquid state at 4° C, instead of in the solid one. This allows ice to float, which is vital to sustaining life beneath its surface in cold climates. The kilogram is defined as the mass of water filling one liter at 4° C. If this critical temperature is regarded instead of 0° C, we find that the phi point is 105.2° F, and this defines the upper end of body temperatures.
Thus even key temperatures for body heat and comfort reflect the phi points in the property of water, of which we largely consist!
| Description of key temperature point | Fahrenheit | Centigrade |
| Freezing point of water | 32° | 0° |
| Middle of range of typical body temperatures of mammals | 100.6° | 38.1° |
| Phi point 2 (0.618 down from water’s boiling point to freezing) | 100.8° | 38.2° |
| Average body temperature of birds | 105° | 40° |
| Phi point 2 (0.618 down from water’s boiling point to maximum density) | 105.2° | 40.7° |
| Phi point 1 (sterilization point) (0.618 up from water’s freezing point to boiling) | 143.2° | 61.8° |
| Boiling point of water | 212° | 100° |
| Average Body Temperatures | ||
| Animal | Fahrenheit | Centigrade |
| Elephants | 97.7 | 36.5 |
| Humans | 98.6 | 37.0 |
| Whales | 98.6 | 37.0 |
| Bat | 98.6 | 37.0 |
| Horse | 100.4 | 38.0 |
| Seal | 100.4 | 38.0 |
| Baboon | 100.6 | 38.1 |
| Rabbits | 101.0 | 38.3 |
| Cows | 101.5 | 38.6 |
| Dogs | 102.0 | 38.9 |
| Cats | 102.2 | 39.0 |
| Goats | 103.4 | 39.7 |
| Midpoint of extremes | 100.6 | 38.1 |
Insight on body temperatures in relation to phi was contributed by Stephanie Miller.
She also notes that average human body temperatures are above freezing by a number that appears in the book of Revelation – 66.6 degrees!
Insight on phi in relationship to comfort level “room” temperatures phi was contributed by Mark Gabriel.
Insight on maximum density of water and 4° C adjustment was contributed by Albert Poch Huguet.