Heat ledgers: What happens to the body, exactly, in extreme heat?

Find out. Plus, meet the climatonauts trekking through deserts to answer the question: What will survival look like, in a climate we have not evolved for?

The human body can take a fair amount of cold. It is heat it cannot withstand.

For millennia, humans have lived in a narrow climatic zone. The human body itself has a narrow temperature range of 36 to 38 degrees Celsius (the ideal of 98.6 degrees Fahrenheit being the equivalent of 37).

The brain itself is so susceptible to heat that the head retained all its original hair, even as we lost this protective cladding across the rest of our