2 Animals exposed to hypoxia, triggers a physiological response via Hypoxia Inducible Factors (HIF1). In this study, we have evidenced the existence of genetic events that caused the loss of most of the bHLH domain in HIF1A proteins borne by Alpaca and other members of the Cetartiodactyla superorder. In these truncate domains, some stop codons are found at identical nucleotide positions in both, Artiodactyls and Cetaceans, indicating that mutations originating the truncated domains occurs before their divergence about 55 million years ago. The relevance of this findings for adaptation of Alpacas to hypoxia of high altitude conditions are discussed.