As a deadly heat wave continues to ravage the U.S., new evidence suggests the human body may stop functioning optimally when outside temperatures climb to 104 to 122 degrees Fahrenheit. Research presented at the recent annual Society for Experimental Biology conference in Edinburgh, Scotland, suggests that temperatures in that range raise a person's resting metabolic rate — the amount of energy needed to function at rest. Michael Sawka, adjunct professor and professor of the practice in the School of Biological Sciences, is quoted in the article.