A 2-million-year-old protein sequence (later abbreviated to Ma) has just been successfully sequenced and analyzed! This is the conclusion of an article published on the bioRxiv server, which allows articles to be put online before the peer review process is completed on July 3, 2023. These protein sequences come from several teeth of individuals belonging to the Paranthropus robustus species. These teeth were found in a cave in South Africa. This is an exceptional discovery. In fact, studies on ancient DNA do not allow us to go back as far as 2 Ma, as DNA does not keep well over time and is particularly sensitive to heat. For example, the oldest sequenced hominin DNA is dated to around 430,000 years ago in Europe. We’re a long way from 2 Ma!
In recent years, the study of protein sequences has emerged as an alternative to the difficulties encountered in paleogenetics. Proteins are better preserved over time and directly reflect the genome, since they are made from our DNA sequence. In this study, the researchers succeeded in determining the sex of the Paranthropus individuals studied. In fact, they found traces of a protein called Y-amelogenin on 2 teeth. This protein is produced by a gene on the Y chromosome, indicating that these two individuals are male. In contrast, the other two teeth do not display this protein, but rather a protein present only on the X chromosome, suggesting that the teeth belong to females. Such a breakthrough in paleoproteomics looks promising. However, care must be taken, as this article is not “officially” published in a journal, as it has not yet passed the peer review stage, i.e. verification by other researchers of the quality of the study carried out.