DNA analysis gives clues to how the ancient hominin’s population split and how they interacted with modern humans.
Researchers describe H. naledi, an ancient human ancestor of unknown age that may have buried its dead.
September 10, 2015|
JOHN HAWKSThere are numerous different species for nearly every type of animal alive today—dozens of different whale species and thousands of ant varieties for example, yet there’s only one species of human. That wasn’t always the case, of course. In the distant past there were at least nine animals in our genus, Homo, including H. erectus, H. habilis, and Neanderthal. Now scientists have discovered a new species to add to our family tree, H. naledi.
From deep inside a nearly inaccessible cave, researchers in Southern Africa excavated 1,550 bone fragments belonging to H. naledi—more hominin fossils than had been discovered in the previous 90 years of exploration in the region. The bones come from at least 15 individuals, male and female, of various ages. “If you are an anthropologist this is as good as it gets,” said John Hawks, a professor of anthropology at the University of Wisconsin and a collaborator on the excavation. The findings are published today (September 10) in eLife.
Hawks and his colleagues describe the shoulders, chest, and pelvis of H. naledi as primitive in morphology, similar to Australopithecus and other early hominin species that existed up to 4 million years ago. H. naledi’s cranial capacity is between 465 and 560 cubic centimeters, roughly a third of the brain size of modern humans and the smallest in the genus, the researchers wrote.
However, other features of this new species appear more modern. H. naledi is similar in overall size and weight to small-bodied H. sapiens. Study coauthor Lee Berger of University of the Witwatersrand in Johannesburg, South Africa, told The Scientist: “the feet are practically indistinguishable from modern humans. This is a walker.”
“H. naledi possesses a combination of primitive and derived features not seen in the hand of any other hominin,” the authors wrote, but Carol Ward, a professor of pathology and anatomical sciences at the University of Missouri who was not involved with the study said she was disappointed by the lack of empirical data presented in the paper. “There are only tiny composite pictures of the fossils, so you can’t see them and there are no comparative data comparing it to anything else,” said Ward. “There’s nothing we can use to make our own judgments about the validity of what they are saying.”
The team has not yet been able to determine an approximate age for the fossils. Ward said this information will be key to interpreting their significance to human evolution. “It’s an amazing collection of fossils, unprecedented and stunning,” she said, “but without a date, they don’t tell us much other than there was another kind of hominin out there.”
In an associated paper also published in eLife today, Paul Dirks of James Cook University in Townsville, Australia, and his colleagues described the remote cave in which the H. naledi fossils were found. To reach the ancient specimen-rich chamber, researchers had to squeeze through a tiny gap just 7.5 inches wide. The remains appear to have arrived in the cave fully intact and decomposed after deposition. Researchers found no indication of predation.
The researchers suggested that the nearly inaccessible location of the fossils, plus their abundance and intact condition, all point to one explanation—purposeful burial, something only modern humans are known to do.
William Jungers, chair of anatomical sciences at Stony Brook University in New York who was not involved with the study, cautioned against attributing too much meaning to the notion of intentional burial. “Dumping conspecifics down a hole may just be better than letting them decay around you,” he said. Jungers added that there may once have been another, easier to access, entrance to the cave.
Ward is also skeptical of the intentional burial explanation. “If it’s really that hard to get to the cave, how do you get to that long dark cave carrying your dead grandmother?” she asked.
The significance of H. naledi is likely to remain controversial until an approximate age for the fossils can be determined. No matter their age, Berger is confident that “this fossil will be probably one of the best known hominin species discovered in the history of this science,” he said.
L.R. Berger et al., “Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa,” eLife, doi:10.7554/eLife.09560, 2015.
P.H.G.M. Dirks et al., “Geological and Taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa,” eLife, doi:10.7554/eLife.09561, 2015.
September 10, 2015
Then, Cro-Magnon is not part of the Homo genus? I noticed you mentioned Neanderthal but not Cro-Magnon
September 10, 2015
Looking at it from a religious perspective, the entrance looks a lot like the vaginal opening, so I would say that this cave may have been used as a representative of the Mother's womb...in putting the dead here, they are returning them to the mother goddess' womb for rebirth... Of course that is all supposition, but that is how I looked at it when I saw the images in other articles that showed the images of the cave and the entrance.
September 10, 2015
"there’s only one species of human". Welllllll, that depends. We've got 'sapiens for sure, but then we've got crosses between sapiens and neanderthalensis and between sapiens and denisovans and it's beginning to look like we'll find additional hybrid species between pure "out of Africa" sapiens and similar species they encountered elsewhere. These hybrid species were geographically isolated and remain identifiable today. To what degree is a stable original hybrid maintained for hundreds of generations as a pure hybrid population now a new species? Is sapiensxneanderthalensis a species distinct from sapiens? Hard to call them sub-species as they've got DNA/genes from outside the species.
September 10, 2015
The idea of "purposeful burial" is very unrealistic, of course. The bones were flushed or washed into the cave apparently (erosion: mudflow?).
AFAICS they belong to Homo rather than to the South-African australopiths. They look most like H.ergaster (Turkana) or perhaps H.georgicus (Dmanisi) IMO, more than like H.erectus s.s. (SE.Asia).
The curved phalanges suggest vertical climbing: probably their locomotion was "aquarboreal": bipedal wading, vertical climbing etc. In any case, this find is not "controversial": it confirms the theory that early-Pleistocene Homo dispersed along coasts & rivers (e.g. Munro 2010, Cunnane 2005 etc.).
Google e.g. aquarboreal, econiche Homo, researchGate marc verhaegen.
September 10, 2015
It is my proposition that Sapiens evolved in a HOSTILE ENVIRONMENT, It is easy to demonstrate that illogical thinking and action together with a high repreduction rate has distinct survuval value, Neadnerthat evolved in a HARSH ENVIRONMENT where logical thinking , and low birth rate had high survuval value.
Neadnerthal ahd wide shoulders and big skulls where they interbred I suggest Sapiens women had a high mortality rate due to birth difficulties.
I do not suggest one is better tha n others However it would explain the high level of irrationality in today's world where we now need rationality, When we have the power to mass destroy ourselves.
It sould also explain the high level of psychopaths and sociopaths which appear to dominate our corporate and command structures. In an environment dominated by Key Performance Indicators (KPI) these people survive and multiply.
Uncontrolled and lgnred this cold well set the scene for species extinction.
If interested aspbergers2.tripod.com will provide more information
Mervyn K. Vogtr
September 14, 2015
"there’s only one species of human" Well there is now. The fact that some human populations have a small amount of introgressed DNA from related sibling/semi/sub species (Neanderthals, Denisovans) does not alter the fact of "one current species". Whether Neanderthals were a different species to H. sapiens depends on how you define species. Speciation is usually a slow accumulation of genetic-molecular and genetic-behavioural differences that render intermating less frequent and less successful, and a lot of interbreeding should be expected where related homonid species came into contact. There is evidence for introgression of a few large segments of chromosomes from ancestral chimps to ancestral humans perhaps as late as a million years after the two lines first "split".
September 29, 2015
I have to adjust my first impressions about naledi (Sept.10): although nalebi seems to have had low skull-cap & small front teeth (partly due to wearing down), they look generally a lot more like bonobos or like South-African australopiths than like H.erectus, and prof.Dirks says there were no traces of great water movements. The curved phalanges (vertical climbing) + flat humanlike feet (cf plantigrade flamingo vs digitigrade ostrich) suggest bipedal wading + climbing arms overhead in the branches above the swamp forest or wetland (google aquarboreal), not unlike bonobos or lowland gorillas wading for sedges, floating herbs, hard-shelled invertebrates, waterlilies etc., but a lot more frequently. They seem to have lived there in great densities (google gorilla bai). When they died, their bodies sank in the mud, and when later the underground eroded (cave formation), the mud(stone) ended up in the cave. IOW, (1) they was no intentional burial but a natural accumulation, (2) they were no endurance runners as prof.Berger believes but bipedal waders-climbers, and (3) they were no Homo (google Homo econiche) but Australopithecus IMO (google researchGate marc verhaegen).