Washington/Johannesburg/London, Sep 11: As the world woke up to welcome a new member of the human species on Friday, scientists kept working in the wee hours to uncover more about Homo naledi -- a broad-chested fellow who walked upright and had a face with a smile that was probably more human than ape-like years ago.
Apart from a tiny brain, hunched shoulders and thin limbs, it also had powerful hands which means it was also a good climber and built for long-distance walking. Fully grown, it stood about five feet tall and weighed about 45 kg.
"The fossils, which are yet to be dated, laid in a chamber about 90 meters from the cave entrance, accessible only through a chute so narrow that a special team of very slender individuals was needed to retrieve them," said researchers from University of the Witwatersrand in South Africa.
Consisting of more than 1,550 numbered fossil elements, the discovery is the single largest fossil hominin find yet made on the continent of Africa.
The initial discovery was made in 2013 in a cave known as Rising Star in the Cradle of Humankind World Heritage Site, some 50 kms northwest of Johannesburg by Wits University scientists and volunteer cavers.
The fossils -- which consist of infants, children, adults and elderly individuals -- were found in a room deep underground that the team named the Dinaledi Chamber or "Chamber of Stars".
So far, the team has recovered parts of at least 15 individuals of the same species, a small fraction of the fossils believed to remain in the chamber.
"With almost every bone in the body represented multiple times, Homo naledi is already practically the best-known fossil member of our lineage," said Lee Berger, research professor in the evolutionary studies institute at Wits.
H naledi was named after the Rising Star cave -- "naledi" means "star" in Sesotho, a South African language.
"Overall, Homo naledi looks like one of the most primitive members of our genus, but it also has some surprisingly human-like features, enough to warrant placing it in the genus Homo," noted John Hawks from University of Wisconsin-Madison in the US.
H naledi had a tiny brain, about the size of an average orange (about 500 cubic centimeters), perched atop a very slender body
H. naledi's teeth are described as similar to those of the earliest-known members of our genus, such as Homo habilis, as are most features of the skull.
The shoulders, however, are more similar to those of apes. The hands suggest tool-using capabilities
"Surprisingly, H. naledi has extremely curved fingers, more curved than almost any other species of early hominin, which clearly demonstrates climbing capabilities," added Dr Tracy Kivell from University of Kent in Britain who was part of the team that studied this aspect of H naledi's anatomy.
This contrasts with the feet of H naledi, which are "virtually indistinguishable from those of modern humans," pointed out Dr William Harcourt-Smith of Lehman College from City University of New York who led the study of H. naledi's feet.
Its feet, combined with its long legs, suggest that the species was well-suited for long-distance walking.
"The combination of anatomical features in H. naledi distinguishes it from any previously known species," Berger stressed.
Perhaps most remarkably, the context of the find has led the researchers to conclude that this primitive-looking hominin may have practiced a form of behaviour previously thought to be unique to humans.
The team notes that the bones bear no marks of scavengers or carnivores or any other signs that non-hominin agents or natural processes, such as moving water, carried these individuals into the chamber.
The finds are described in two papers published in the scientific journal eLife and reported in the cover story of National Geographic magazine.