Teori penuaan dan radikal bebas pertama kali digulirkan oleh Denham Harman dari University of Nebraska Medical Center di Omaha, pada tahun 1956 yang menyatakan bahwa tubuh mengalami penuaan karena serangan oksidasi dari zat-zat perusak.
The theories of aging and free radical were first issued by Denham Harman of University of Nebraska Medical Centre in Omaha in 1956 saying that the body got aging because of the oksidant attacks from destroying substances.