Almost Human

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The latest discovery of an extinct species down in South Africa’s Gauteng province has completely remodeled our understanding of human evolution. Termed Homo naledi, this human ancestor possesses primitive but undeniable similarities to modern humans.

In 2013, recreational cavers Steven Tucker and Rick Hunter entered the Rising Star, a popular and thoroughly mapped cave. The pair was determined to uncover some fossils after hearing about a scientist in Johannesburg who was searching the area for ancient remains.

Tucker and Hunter discovered the bones in a chamber called Dinaledi (chamber of stars), which is only accessible by crawling through a series of narrow passageways. After wriggling through a constriction less than ten inches high and climbing a wall of jagged rocks, the two reached the top of a cavity, where Tucker discovered that there was empty space underneath them. The cavers entered a narrow, vertical chute and descended until they found themselves in a cavity that had the bones of 15 individuals scattered everywhere.

Lee Berger, a paleontologist of South Africa’s University of the Witwatersrand, led the excavation team funded by the National Geographic Society and the University of Witwatersrand. The excavation yielded a total of 1,550 pieces of bones.

Homo naledi appears to have a mixture of modern and primitive characteristics. Modern characteristics, like its flat feet, suggest that it walked like modern humans. Scientists believe that H. naledi’s curved fingers allowed it to wield tools and climb trees. It has apelike shoulders, but its teeth are similar to those of the earliest-known human ancestors. Other ancient traits include an apelike pelvis and a brow ridge. Ultimately, H. naledi’s anatomical features differentiates it from any previously known species.

Junior Globiella Evangelista commented, “The progression of the Homo genus is fascinating. Over the course of millions of years, after all these evolutionary changes, we end up as this intelligent and inventive species.”

Scientists are still unsure of when exactly Homo naledi lived, as three different methods of dating have resulted in inconclusive results. It is believed that the species originated near the beginning of the Homo genus, which comprises of H. habilis, H. erectus, H. neanderthalensis, and H. sapiens.

Biology Teacher Sarah Oberlander agrees with these findings, stating that “[Homo naledi] probably [lived] somewhere before Homo habilis, who used their hands and tools more, but after Homo erectus.”

Homo habilis inhabited the Earth around 2.8 to 1.5 million years ago; it had primitively long arms and saw the development of larger braincases and smaller teeth. H. erectus lived at most 1.9 million years ago; it had a smaller brain in comparison to that of modern humans, but its physique was almost identical to ours. H. neanderthalensis came after H. erectus, around 200,000 to 40,000 years ago; it was shorter and more muscular than modern people. Our current species is called H. sapiens, distinguished by its heightened intelligence and self-awareness.

The most pressing question of the discovery is how the remains ended up in the cave. One hypothesis among researchers is that this species practiced ritualistic burials, meaning they intentionally and repeatedly disposed of the dead. Previously, they had always thought that only H. sapiens were compassionate enough to bury the dead, but H. naledi has broken this boundary. However, the chamber does not hold any evidence of symbolic rituals, leaving this topic a complete mystery to scientists.

naledi had brains one-third the size of that of H. erectus. Despite its significantly smaller brain, it was knowledgeable enough to bury the dead. Queens College graduate student Sue Tees, who is currently pursuing a PhD degree in biology, concluded, “[This finding] tells me not to base intelligence on the size of the brain.”

Tees added, “There’s definitely more to discover about humans and their ancestry.” Endless questions about Homo naledi still remain, but it is indisputable that its discovery has filled in gaps of human evolution.