It remains uncertain whether life originated in a hot environment or a cold environment, although many studies have been done from several different perspectives. The theory of the hot origin of life is based on the presence of hyperthermophiles near the root of the phylogenetic tree, the discovery of unique environments for life surrounding hydrothermal vents, the greenhouse effect of a dense CO₂ atmosphere, and the isotopic fluctuation of oxygen. However, bioorganic molecules are rather unstable at high temperatures. Here, I review previous studies concerning the hot and cold origins of life and re-assess which is more plausible.