Nearly 150 years ago, Charles Darwin had written in his then-controversial volume The Descent of Man: “In each great region of the world the living mammals are closely related to the extinct species of the same region. It is, therefore, probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man’s nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere.”

It was an astonishing position to take back then, almost as heretical as evolution itself, and it helped spawn the cheapened, dumbed-down version of Darwin’s theory – that humans were descended from monkeys. For many decades after Darwin wrote that statement, virtually none of his scientific colleagues would have supported such a view about Africa. Africa was the ‘Dark Continent’, largely uncivilised, largely without the ancient remains of human activity.

By contrast, for most scholars, it was absolutely clear that whatever had happened to bring about the rise of homo sapiens, they had come onto the scene where they would develop into the species – us – that could create tools, craft those astonishing cave paintings in France and Spain, and thereby fall neatly in line with more primitive progenitors like the Neanderthals, Peking and Solo Man and even Piltdown Man – until the latter was finally unmasked as a clever forgery, designed so as to locate the so-called ‘missing link’ between apes and humans firmly on British soil where it belonged.

In 1924, Raymond Dart had described the first indisputable, solid evidence of very ancient hominids in South Africa from a site at Taung – naming those fossil remains, Australopithecus africanus. But Dart’s discovery – and then those of a growing list of other researchers – was largely ignored by the leading global figures of palaeontology for many decades yet to come. One of the great fossil discoveries of the 20^th century, the fossil sites at the Flaming Cliffs of Mongolia, was made by palaeontologists under the direction of the American Museum of Natural History’s Roy Chapman Andrews – the real person who was the likely inspiration for the fictional film character of Indiana Jones. Andrews and his team were convinced Central Asia had to be the origin point for human evolution. Ultimately, they found vast fields of exceptionally well-preserved dinosaur fossil bones and the first petrified dinosaur eggs – but there were no ancient hominid remains there at all.

Even after the Leakey family and still others began their discoveries of yet other hominin and hominid remains in Kenya, Tanzania and Ethiopia, many in the scholarly community continued to doubt, despite this growing ‘mound’ of startling discoveries backing up Darwin’s early insight, that Africa was humankind’s place of origin – and thus the real origin of a long line of precursors to humans going back millions of years. The writer can still remember, when he was a child, listening to a presentation by the internationally regarded doyen of the field, Professor Carleton Coon. That scholar remained convinced until his death that Africa was the afterthought in human evolution and that the real origins for humans would eventually be uncovered in Asia.

Photo: A handout image made available by Wits University and dated 07 September 2015 shows the skull of a new human relative ‘Homo Naledi’, in Johannesburg, South Africa. EPA/Brett Eloff / WITS UNIVERSITY.

But eventually, all of those astonishing finds throughout Southern and Northeast Africa, along with rapid, startling advances in genetics and geology, have helped tip the scales in favour of a near-universal acceptance of the ‘Out of Africa’ thesis for the origins of humanity from earlier hominids and the dispersal of true modern humans around the world, beginning around 70,000 years ago. The most contentious issues that were part of this new scientific consensus included whether the line from humanity ran back to those ancient denizens in South Africa or to those further to the north, as well as the need for much more clarity on how the connections from modern homo sapiens to those early hominids and hominins ran; that is, which fossil discoveries fit into that lineage, versus which were competing, collateral branches that eventually died out?

In recent years, the area around Sterkfontein and other nearby areas, around 40km kilometres from downtown Johannesburg, including numerous caves and dig sites has now been official labelled ‘The Cradle of Humankind’. It includes a museum together with sites that continue to be actively searched for yet more discoveries. In 2008, in the Malapa Cave, University of the Witwatersrand Professor Lee Berger (well, actually his pre-teen son and their dog) made an astonishing discovery of a substantially complete skeleton of one early hominid, now dubbed Australopithecus sediba.

Photo: A handout image dated 13 November 2014 and made available by Wits University shows the hand of a new human relative ‘Homo Naledi’, in Johannesburg, South Africa. EPA/Wits University.

Besides being an excellent scientist, Berger seems to be a very lucky one – clearly an essential attribute for success in this field, something virtually every other palaeontologist will attest to. But that earlier discovery has now been overtaken by a truly breath-taking one, made in 2013, of an entire chamber of the remains of at least 15 individuals – and at least 1,500 fossil bones – all clustered together in a small sub-chamber of the Rising Star Cave. An amateur geologist and caver had brought a jawbone to Berger and he instantly knew that this was a big, big deal.

The fruits of the research, excavation and analytical team, supported by, among others, the American National Geographic Society and various South African agencies, and led by Berger, made a huge international splash on Thursday, 10 September, when they were announced. There was the public release of findings, the unveiling of actual fossil remains and the simultaneous release of a detailed open-source scientific paper (the first of many undoubtedly) on the internet. This paper describes the discoveries and allows others to comment on it or dispute the descriptions and information in it.

Photo: A handout image made available by Wits University and dated 10 September 2015 shows the lower jaw of a new human relative ‘Homo Naledi’, in Johannesburg, South Africa. EPA/Wits University.

This early release of a scientific paper on this discovery is one of the important new elements of this development. Heretofore, it has been much more usual for detailed findings in palaeontology to be rolled out very slowly, often at a leisurely pace years after the initial discoveries were made – rather than the way this set of excavations has been handled. Beyond this first scientific paper, National Geographic Channel documentary television broadcasts have been scheduled for airing shortly on it. And within hours of the public announcement of the findings, there was a tsunami of reports on the findings on national and international television, in global print media, and on the internet and in social media.

Another unusual aspect of the discovery was Berger’s recruitment of a corps of what were termed ‘underground astronauts’. He had originally sent out a call via social media for physically fit, lithe, slender, scientifically literate people and cavers totally unfazed by working in extremely tight, close quarters. These would be the actual excavators of the fossils because only they could fit through the very narrow aperture of the small chamber where the fossilised remains were to found. (Just by the way, Berger’s university secretary admitted to having been initially very startled when their office’s e-mail address started receiving notes from individuals, male and female, giving the lead scientist their precise body measurements, to tout their suitability for his new field project.)

Photo: A handout image released by Wits University and dated 07 November 2015 shows Prof Lee Burger at the cave entrance where the fossil remains of Homo Namledi where found. Prof Burger 10 September revealed a new human relative ‘Homo Naledi’ at a media event in Johannesburg, South Africa. The new species was announced by an international team of more than 60 scientists, led by Lee R. Berger. EPA/Brett Eloff / Wits University.

The fossil remains have yet to be dated precisely – something that may be key to helping figure out where, precisely, in a complex, still-confusing prehistoric hominid universe Homo naledi will fit in. Current estimates are that these remains may be as much as 2.5-million years old, but a range of sophisticated dating tests and measurements have yet to be carried out to verify such a guesstimate.

In his comments on Thursday, Berger explained that Homo naledi seems like a confusing mix of much earlier and more advanced, more recent features. For example, Homo naledi’s brain case is much smaller than a modern human’s, but its jaw structure seems more modern – even though its teeth seem less so. Moreover, the head sits atop a relatively tall body – relative to that skull. Or, in Berger’s exuberant description, Homo naledi seems like it is a mixed up “Mister Potato Head” children’s puzzle toy, with the parts all scrambled oddly. “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,” commented John Hawks of the University of Wisconsin-Madison, one of the senior authors of the scientific papers released on Thursday.

But perhaps the most puzzling and astonishing feature of these discoveries is that from the placement of the fossils in that one small, hard-to-access chamber of the larger, overall cave structure, it seems as if these remains had been put there deliberately. It was as if an ancient band of hominids had reached some sense of honouring their dead, or perhaps even – very speculatively – a sense of some kind of afterlife.

Berger told CNN: “There is no damage from predators, there is no sign of a catastrophe. We had to come to the inevitable conclusion that Homo naledi, a non-human species of hominid, was deliberately disposing of its dead in that dark chamber. Why, we don’t know. Until the moment of discovery of ‘naledi’, I would have probably said to you that it was our defining character. The idea of burial of the dead or ritualised body disposal is something utterly, uniquely human.”

At the minimum, from this aspect of the discovery, it seems likely these creatures had a sense of self as well as a comprehension of a need to honour the deceased. Scientists have long debated the question of how or when the latter came about. That some Neanderthal remains appear to have been buried with flowers (there were significant amounts of pollen grains found in close proximity to those fossil remains) and thus were actually part of a burial ceremony still remains contested territory. And in any case, those Neanderthal remains date to much more recent times than these newly described Homo naledi fossils. There are going to be lots and lots of scientific fights about this aspect of things, along with everything else about Homo naledi. At a minimum, as Berger said on one of his television appearances, the remains already excavated will be providing scientists with decades and decades of material for study, debate and analysis. This must surely be a glorious moment to be a palaentologist. DM

Photo: A handout image dated 13 September 2014 shows a Homo naledi skeleton in the Wits bone vault at the Evolutionary Studies Institute at the University of the Witwatersrand, Johannesburg, South Africa. The fossils are among nearly 1,700 bones and teeth retrieved from a nearly inaccessible cave near Johannesburg. The fossil trove was created, scientists believe, by Homo naledi repeatedly secreting the bodies of their dead companions in the cave. EPA/JOHN HAWKS / UNIVERSITY OF WISCONSIN-MADISON

For more, read:

• Homo naledi: New species of human ancestor discovered in South Africa at CNN
• Dinaledi Chamber South Africa at eLife
• Geological and taphonomic context for the new hominin species Homo Naledi from the Dinaledi Chamber South Africa at eLife (the actual scientific paper)
• New species of extinct human found in cave may rewrite history at the New Scientist
• Rising Star Expedition reveals new species: Homo naledi at the University of the Witwatersrand website
• Australopithecus sediba at the Smithsonian Institution website