Researchers from the University of Copenhagen and the University of Cape Town have achieved a remarkable feat by predicting genetic relationships among early hominins using proteins extracted from 2-million-year-old fossilized teeth. As per Science Alert, this breakthrough DNA analysis is expected to greatly aid in tracing the extensive family tree of human beings.
The tooth fossils, most likely belonging to the African hominid species Paranthropus robustus, contain the earliest preserved human genetic material ever discovered, shedding light on our ancient ancestors.
Proteins More Robust in Predicting Genetic Relationships
Answering questions about genetic relationships over thousands and millions of years can be challenging due to the fragility of DNA, which deteriorates quickly. While nuclear DNA has been deciphered from 430,000-year-old hominin remains, the process has limitations and is not highly productive.
On the other hand, proteins are more durable, and their amino acid sequences can be used as a rough estimation of the genetic code that produced them, serving as a proxy for genetic relationships when gene sequencing is not feasible.
In this study, titled "Oldest Genetic Data From a Human Relative Found in 2-Million-Year-Old Teeth" published in Nature, researchers analyzed the enamel on teeth found in Swartkrans cave, a significant archaeological site located approximately 40 kilometers (25 miles) northwest of Johannesburg.
These fossilized teeth were linked to an early human relative known as Paranthropus robustus. By comparing the protein data to DNA information from other fossils and modern hominids ranging from orangutans to humans, the researchers hypothesized that P. robustus is an "outgroup" in the evolutionary line, similar to distant cousins like Homo sapiens, Neanderthals, and Denisovans.
The research team noted that the teeth's exceptional preservation is attributed to flash floods in an otherwise arid area. While this may limit the number of similar fossils that can be found, the techniques employed in this study can potentially be applied in other locations.
The work demonstrates the viability of retrieving relevant enamel proteins from African Early Pleistocene hominins. The researchers believe that this method may be broadly used at analogous geological locations in South Africa, and that it might be expanded to other parts of the continent.
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More About P. robustus
According to Smithsonian Magazine, P. robustus is a type of robust australopithecine that possessed distinct anatomical features. These included large cheek teeth with thick enamel, wide and dish-shaped faces facilitated by prominent cheekbones called zygomatic arches, and a prominent ridge on the top of the skull known as a sagittal crest, which allowed them to effectively grind tough and fibrous foods, indicating a specialized diet.
The discovery of P. robustus was made by scientist Robert Broom in 1938. After acquiring a fossil jaw fragment and molar that differed from other known fossils of the time.
Broom explored the Kromdraai site in South Africa, where the fossils were found. Subsequent collection of additional bones and teeth further supported the identification of a new species, which Broom named Paranthropus robustus. The term "Paranthropus" indicated its relationship to human ancestors.
The classification of P. robustus as "robust" referred specifically to the size of its teeth and face, rather than its overall body size. These distinct features and Broom's discovery contributed to our understanding of human evolutionary history and the diversity of hominin species that existed in the past.
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