In the era of `Precision Cosmology' remarkable advances have been made in the determination of cosmological parameters from the Cosmic Microwave Background and Big Bang Nucleosynthesis, with spectacular concordance between these two pillars of the Standard Cosmological Model. While much exposure has been given to the impressive results from the WMAP and Planck missions, perhaps less attention has been paid to the equally striking advances made in the last ten years in the measurements of the abundances of the light elements forged in the first few minutes of our Universe history. In this talk I shall focus in particular on the determination of the primordial abundance of deuterium, in an overview that spans almost 80 years, from the first seeds of the idea sown in the 1940s to the most recent results and forward look to the era of Extremely Large Telescopes and next generation Wide Field Surveys of the sky. To arrange a visit with the speaker during the visit, please contact their host: Eduardo Banados