Homo naledi

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Homo naledi
Bones of Homo naledi from the Dinaledi chamber (originals)

Bones of Homo naledi from the Dinaledi chamber (originals)

Temporal occurrence
Middle Pleistocene
approx. 0.3 million years
Locations
Systematics
Human (Hominoidea)
Apes (Hominidae)
Homininae
Hominini
homo
Homo naledi
Scientific name
Homo naledi
Berger et al. 2015

Homo naledi is an extinct species of the genus Homo . The species wasintroduced into the literaturein 2015 bya working group led by Lee Berger using fossils from the Rising Star Cave ( South Africa ). The cave is located in the " cradle of mankind ", southwest of Swartkrans and almost 50 kilometers northwest of Johannesburg .

In 2015, fossil bones and teeth from at least 15 individuals were found, which is why this find is the largest collection of evidence to date for an early species of hominini . The fossils had been recovered since November 2013, but were initially not assigned to a specific species.

Naming

The name of the genus Homo is derived from the Latin homo [ ˈhɔmoː ], dt. Human. The epithet naledi is a reference to the place where it was found in the Rising Star Cave: naledi (with an emphasis on the e) means “star” in the Sotho Tswana languages . Homo naledi therefore means “man from the star cave”.

Initial description

A group of cranial bones has been identified as the holotype of Homo naledi , which is designated as Dinaledi hominin 1 (DH1); In addition, the skull fragments DH2, DH3, DH4 and DH5 and some long bones - including the femur UW 101-1391 and the tibia UW 101-484 - were added to the species definition as paratypes. In total, the find comprises 137 individual teeth and 1,413 bones, of which 737 were included in the first description of the species.

All Homo naledi fossils are kept in the collection of the Evolutionary Studies Institute of the University of the Witwatersrand in Johannesburg .

Holotype DH1 skull bones


A and B: Two views of the skull fragment UW 101-1473
C to F: Four views of the upper jaw fragment UW 101-1277
G: Skull fragment UW 101-1473, upper jaw UW 101-1277 and lower jaw UW 101-1261 (in anatomically correct arrangement)
H. to K: lower jaw UW 101-1277 in four views
Scale: 10 cm. Originals.

More finds

The LES1 skull (original)

As early as 2013, around 100 meters away from the Dinaledi chamber, in a second chamber - called the Lesedi chamber - further fossils were found, which were also assigned to Homo naledi in 2017 . These are the remains of at least three individuals (two adults and one child), including the broken but well-preserved skull LES1 of an adult, the internal volume of which, according to the reconstruction, was 610 cm³; he was given the nickname Neo ("gift" in Setswana ). Other finds include a. a toothed lower jaw, various vertebrae , a thigh bone and bone fragments from the area of ​​the shoulders and arms.

Dating

An absolute dating of the finds or the surrounding rock had not yet been carried out at the time of the first description . Instead, it was derived from anatomical features that an age of up to 2.5 million years is conceivable. However, a detailed comparison of the characteristics of Homo naledi with other, surely dated hominin fossils revealed a “highly probable” age of only 912,000 years in 2016.

A uranium-thorium dating and additional paleomagnetic analyzes were finally interpreted in 2017 to mean that the fossils are 335,000 to 236,000 years old.

features

Computer-aided reconstruction of the skull using the findings DH3 and DH4

The average height of Homo naledi was about 1.50 meters, the weight 40 to 55 kg.

In the first description from 2015 it is said that the species is characterized on the one hand by a very small internal skull volume of only 560 cm³, which is comparable to the dimensions usual for Australopithecus (for comparison: chimpanzees approx. 400 cm³, humans approx. 1400 cm³); on the other hand, a body whose proportions below the head are comparable to small populations of the genus Homo . The morphological features of the skull are unique, but most comparable with finds of the early homo species Homo rudolfensis , Homo habilis and Homo erectus . In 2018, additional findings based on a digitally created " skull cast " were published, according to which the surface of the brain shows common original features of australopithecins and non-human great apes as well as derived ("modern") features that are characteristic of the homo genus .

The teeth (especially the large molars ) were referred to as “original” in the first description, but the incisors and canines are relatively small compared to Homo rudolfensis , Homo habilis and Homo erectus . In contrast to these “modern” features, the rib cage, shoulder, pelvis and the end of the femur facing the knee joint have “original” features, such as those found in Australopithecus afarensis and Australopithecus africanus . According to the researchers' analyzes, the hand and wrist show changes in comparison to older fossils of the hominini that were interpreted as "human-like adaptations". In a study published in October 2015, however, it was also pointed out that the finger bones are longer and more curved than in most of the Australopithecus finds and that the thumb bones are widened, which indicates frequent climbing. At the same time it was concluded from the arrangement of the hand bones that Homo naledi was capable of precision gripping and could therefore possibly also manufacture and use stone utensils; Stone utensils have not yet been found in connection with the fossils related to this species.

The analysis also showed that the leg and foot exhibit a mixture of primal and inferred traits, in a combination that has been described as “unique”. Nevertheless, the foot is undoubtedly adapted to walking upright over long distances.

nutrition

On the basis of the texture of the teeth (for example size, tooth enamel thickness) it can often be reconstructed which food the individuals of a fossil species specialized in: “Mammals that eat mainly leaves and grass have sharper and more complex molars with more Tooth bumps and combs. With this they can cut up the food. In contrast, species that have to grind their hard vegetable food have duller molars. ”Researchers at the Max Planck Institute for Evolutionary Anthropology therefore compared the molars of Homo naledi with those of Australopithecus africanus and Paranthropus robustus and came to the conclusion that Homo naledi Consumed food with mechanical properties similar to those of the other two species; However, the molars of Homo naledi are higher crowned, larger and more resistant to wear and tear. It was concluded from this that Homo naledi either frequently fed on plants that were particularly rich in hard biominerals or that they also consumed a lot of dust and sand when they consumed the plant-based diet - similar to today's living, grass-eating antelopes . These features also distinguish the species from the early representatives of the genus Homo , so that it was argued that Homo naledi had colonized a special ecological niche .

Finding circumstances

The site, which is almost inaccessible today, was apparently not inhabited. The bones from the Dinaledi chamber, with the exception of those on the surface of the deposits, were anatomically correct and also show no bite marks, which rules out that the bones were washed up or the bodies of predators were dragged to the place of discovery. Therefore, the researchers speculate that the dead may have been deliberately placed there. However, it is unclear who - individuals of what kind - put away the bodies; also it cannot be ruled out that the group entered the chamber on their own and died there. The ritual of the funeral of deaths write many scientists previously only anatomically modern humans ( Homo sapiens ) and Neanderthals ( Homo neanderthalensis to).

Some bones show black, dot-shaped deposits of iron / manganese oxyhydroxide, which are regularly formed on rock in the find region as a result of colonization by lichen . If these deposits were actually caused by lichen growth, this would indicate a temporary incidence of light and thus a second entrance to the cave, which is no longer recognizable today.

Tribal classification

Comparison of the naledi skull DH1 (right) with skulls of early homo species

Immediately after the publication of the first description of Homo naledi , the assignment of these fossils to a new, separate species was criticized by several paleoanthropologists as being premature. As long as their age is not known, it was said that these fossils could not be reliably located in the family tree of the hominini. The Swiss anthropologist Christoph Zollikofer , for example, objected that some of the original characteristics used for definition also occur in other already known early species and are therefore unsuitable for establishing an additional species. Tim White and William L. Jungers argued that the finds could be, for example, early South African specimens of Homo erectus . And Chris Stringer wrote in an article accompanying the first description: "In my opinion the material most closely resembles the short individuals of Homo erectus from Dmanissi , Georgia , which were dated to an age of 1.8 million years."

The American paleoanthropologist Jeffrey H. Schwartz, however, objected in Nature that individual finds are so different that they may belong to two species; The British Ian Tattersall said the same thing to New Scientist .

The absolute dating published in 2017 (335,000 to 236,000 years ago) finally placed the finds in an era in which very early anatomically modern humans may have existed in Africa . If the dates are correct, Homo naledi turns out to be a contemporary of the "archaic" Homo sapiens , from whom he differs significantly due to his very small brain. Homo naledi is thus also proof that - like Homo floresiensis in Asia - a variant of the genus Homo was able to survive in Africa for hundreds of thousands of years despite a brain size comparable to Australopithecus . In this context, Bernard Wood referred to the " modern " looking hands and feet of Homo naledi , so that this homo variant - comparable to Homo floresiensis - may have reduced a previously enlarged brain volume.

gallery

  • Skull bones (A) DH2, (B) DH5, (C and D) DH4. Scale = 10 cm

  • Lower jaw UW 101-377

  • Hand bones

  • Femur UW 101-1391
    in four views

  • Shin UW 101-484
    in four views

  • Foot bones

  • Some bones in situ
    (before recovery)

  • Schematic representation of the cave system

literature

  • Shara E. Baileya et al .: The deciduous dentition of Homo naledi: A comparative study. In: Journal of Human Evolution. Volume 136, 2019, Article No. 102655, doi: 10.1016 / j.jhevol.2019.102655 .
  • Paul HGM Dirks et al .: Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa. In: eLife. 2015; 4: e09561, doi: 10.7554 / eLife.09561 .
  • Kate Wong: Who Was Homo Naledi? In: Spectrum of Science. No. 7/2016, pp. 20–29.

Web links

Commons : Homo naledi  - collection of images, videos and audio files

Individual evidence

  1. ↑ Lee Berger et al .: Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. In: eLife. 2015; 4: e09560, doi: 10.7554 / eLife.09560 .
  2. ^ Johannes Dieterich: Mobile relationship. In: Berliner Zeitung . from September 11, 2015 → Science p. 12.
  3. ^ John Hawks et al .: New fossil remains of Homo naledi from the Lesedi Chamber, South Africa. In: eLife. 2017; 6: e24232, doi: 10.7554 / eLife.24232
  4. ↑ Darryl J. de Ruiter et al .: Homo naledi cranial remains from the Lesedi chamber of the rising star cave system, South Africa. In: Journal of Human Evolution. Volume 132, 2019, pp. 1–14, doi: 10.1016 / j.jhevol.2019.03.019 .
  5. ^ Jamie Shreeve: This Face Changes the Human Story. But how? On. nationalgeographic.com of September 10, 2015.
  6. Jump up ↑ Mana Dembo et al .: The evolutionary relationships and age of Homo naledi: An assessment using dated Bayesian phylogenetic methods. In: Journal of Human Evolution. Volume 97, 2016, pp. 17-26, doi: 10.1016 / j.jhevol.2016.04.008 .
  7. ^ Paul HGM Dirks et al .: The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa. In: eLife. 2017; 6: e24231, doi: 10.7554 / eLife.24231
  8. ↑ Homo naledi - a new relative of modern man. On: mpg.de from September 10, 2015
  9. ↑ a b Crowdsourcing digs up an early human species. On: nature.com from September 10, 2015
  10. ↑ Ralph L. Holloway et al .: Endocast morphology of Homo naledi from the Dinaledi Chamber, South Africa. In: PNAS. Online advance publication of May 14, 2018, doi: 10.1073 / pnas.1720842115
    Where hominid brains are concerned, size doesn't matter. On: eurekalert.org from May 14, 2018
  11. ↑ Caroline VanSickle et al .: Homo naledi pelvic remains from the Dinaledi Chamber, South Africa. In: Journal of Human Evolution. Volume 125, 2018, pp. 122-136, doi: 10.1016 / j.jhevol.2017.10.001
  12. ↑ Tracy L. Kivell et al .: The hand of Homo naledi. In: Nature Communications. Volume 6, Article No. 8431, 2015, doi: 10.1038 / ncomms9431
  13. ^ William EH Harcourt-Smith et al .: The foot of Homo naledi. In: Nature Communications. Volume 6, Article No. 8432, 2015, doi: 10.1038 / ncomms9432
  14. ↑ Christopher S. Walker et al .: Morphology of the Homo naledi femora from Lesedi. In: American Journal of Physical Anthropology. Volume 170, No. 1, 2019, pp. 5-23, doi: 10.1002 / ajpa.23877
  15. ↑ Homo naledi had tough molars. On: mpg.de of March 7, 2018
  16. ↑ Michael A. Berthaume, Lucas K. Delezene and Kornelius Kupczik: Dental topography and the diet of Homo naledi. In: Journal of Human Evolution. Volume 118, 2018, pp. 14–26, doi: 10.1016 / j.jhevol.2018.02.006
  17. ^ New human species discovered. On: sciencemag.org of September 10, 2015, doi: 10.1126 / science.aad1728
  18. ^ John Francis Thackeray : The possibility of lichen growth on bones of Homo naledi: Were they exposed to light? In: South African Journal of Science. Volume 112, No. 7/8, 2016, Art. # A0167, 5 pages, doi: org / 10.17159 / sajs.2016 / a0167 , full text ( Memento from September 6, 2016 in the Internet Archive )
  19. ↑ Homo naledi: New species of ancient human discovered, claim scientists. On: theguardian.com of September 10, 2015
  20. ↑ Chris Stringer : Human evolution: The many mysteries of Homo naledi. In: eLife. 2015; 4: e10627, doi: 10.7554 / eLife.10627
  21. ↑ Colin Barras: Deep cave yields a new human. In: New Scientist. Volume 227, No. 3038, pp. 8–9, full text (with a different title to the print version)
  22. ↑ Lee R. Berger et al .: Homo naledi and Pleistocene hominin evolution in subequatorial Africa. In: eLife. 2017; 6: e24234, doi: 10.7554 / eLife.24234
  23. ↑ This mysterious human species lived alongside our ancestors, newly dated fossils suggest. On: sciencemag.org of May 9, 2017
  24. ↑ Jessica C. Thompson: Human evolution: New opportunities rising. In: eLife. 2017; 6: e26775, doi: 10.7554 / eLife.26775
  25. ^ Meet 'Neo', the most complete skeleton of Homo naledi ever found. On: newscientist.com on May 9, 2017