Louis Ahrens was born in Pietermaritzburg, South Africa in April 1918 and a descendant of Lutheran missionaries to the country.
[1][2] Barely obtaining a matric, he attended the University of Natal and graduated with a Bachelor of Science degree in geology and chemistry in 1939.
[1][2][3]: 816 He would start his career in Johannesburg in 1940 at the National Institute of Metallurgy (then Government Metallurgical Laboratory) as an analytical chemist with emphasis on optical spectrochemical analysis.
[3]: 816 In 1949, he published a paper in the Bulletin of the Geological Society of America the establish the method of using Rubidium–strontium dating as a viable means of geochronology.
[2] During the Apollo program, Ahrens and his research team at the University of Cape Town received Moon rock samples for geochemical analyses.