New clues to the enamel of the teeth of two million people tell us more about a former parent of humans

For almost a century, scientists have perplexed on the fossils of a strange and robust distant parent of the first humans: Strong paranthropus. It was walking straight and was built for heavy chewing with relatively massive jaws and huge teeth with a thick dental enamel. It is believed that it lived between 2.25 million and 1.7 million years.

Humans today have a diverse range of parents and ancestors far from hominin from millions of years ago. The South African fossil record ranges from first hominines such as Australopithecus Prometheus,, A. Africanus (Talented child), A. SEDIBA And A. Robustusto the first members of the genre Homo (H. Erect / Ergaster,, H.), to subsequent hominines as H. Naled And Homo sapiens (Humans).

Fossils show how these first relatives have evolved from further away than A. Africanus3.67 million years ago. They also document milestones in evolution, in particular the transition to walking on two legs, the manufacture of tools and the increase in brain development. In the end, our species –Homo sapiens– Published in South Africa 153,000 years ago.

Fossil A. Robustus were discovered for the first time in South Africa in 1938. But crucial questions have remained. What variation was there within the species? Were the size differences linked to sex, or did they reflect the presence of several species? How was A. Robustus linked to other homilies and early Homo? And what, genetically, made it distinct?

Until now, the answers to these questions have been elusive. As a team of African and European researchers in molecular sciences, chemistry and paleoanthropology, we wanted to find answers, but we could not use old DNA to help us. The old DNA has changed the situation in the study of subsequent hominins such as Neanderthals and Denisovans, but it does not survive well in the climate of Africa because of its simple structure.

We have experienced a breakthrough when we decided to use paleoproteomic – the analysis of ancient proteins. We extracted them from the email of the teeth of four million years of four A. Robustus The fossils of Swartkrans cave in the cradle of humanity in South Africa.

Fortunately, proteins that have millions of years preserve well because they stick to the teeth and bones and are not affected by hot weather. One of these proteins tells us the biological sex of fossils. This is how we found that two of the individuals were men and two were women.

These results open up a new window on human evolution – that which could reshape the way in which we interpret diversity in our first ancestors by providing some of the oldest human genetic data in Africa. From there, we can better understand the relationships between individuals and potentially even if the fossils come from different species.

More than one type of Paranthropus?

The protein sequences have also revealed other subtle but potentially significant genetic differences. A remarkable difference was found in a gene that makes the move, a critical enamel training protein. We found that two of the individuals shared an amino acid with modern and first humans, chimpanzees and gorillas. The other two had an amino acid that among the great African apes Paranthropus.

What is even more interesting is that one of the individuals had the two distinct amino acids. This is the first documented period that we can show heterozygotia (a state of having two different versions of a gene) in proteins aged 2 million years.

During the study of proteins, we think that specific mutations indicate different species. We were quite surprised to discover that what we initially thought was a unique mutation to Strong paranthropus was in fact variable within this group – some individuals had it while others did not do so. Again, it was the first time that someone has observed a protein mutation in old proteins (these mutations are generally observed in old DNA).

We realized that instead of seeing a single variable species, we could examine a complex evolving puzzle of individuals with different ancestors. This shows that the combination of analyzes of morphology (the study of the form and structure of organisms) and the study of ancient proteins, we can create a clearer evolving image of these first hominin individuals.

However, to confirm that A. Robustus Fossils have a different ancestry, we will have to take dental enamel protein samples from more teeth. To do this, we plan to sample permanently more A. Robustus Other South African sites where they were found.

Preserve the fossil heritage of Africa

Our team has taken care to balance scientific innovation with the need to protect irreplaceable heritage. The fossils were sampled at least and all the work followed the South African regulations. We have also involved local laboratories in the analysis. Many authors came from the African continent. They helped guide the research program and the approach of the first stages of the project.

Making this type of high -end science on African fossils in Africa is an important step towards the transformation and decolonization of paleontology. It strengthens local capacity and guarantees that discoveries benefit from regions from which fossils come.

By combining data on molecules and morphology, our study offers a plan for future research, which could clarify whether the first hominines were more or less diverse that we did not know it.

For the moment, the Paranthropus Puzzle has become a little more complex – and much more exciting. As paleoproteomic techniques improve and more fossils are analyzed, we can expect more surprises from our former parents.

This article is republished from the conversation under a Creative Commons license. Read the original article.