Paleoantropología: novedades 2º trimestre 2018

Comenzamos julio repasando una selección de novedades del segundo trimestre del año, con enlaces a los estudios en que se basan. Echando un vistazo a estas series trimestrales de recopilaciones de noticias, realmente ningún trimestre decepciona…

El poblamiento de América

  • Se refuerza la hipótesis del primer poblamiento de América del Norte a través de una ruta costera del Pacífico, frente a la alternativa por una ruta interior del oeste de Canadá. Así lo indica un conjunto de puntas de arpón estriadas procedentes de Alaska y Canadá, que guarda relación con la tecnología Clovis que venía utilizándose en la zona media de América del Norte. Los fabricantes de esas herramientas hace 12.000 años no estaban migrando hacia el sur, sino que procedían de pueblos ancestrales del sur y se movían hacia el norte [+info]. La hipótesis del poblamiento por la ruta costera toma cada vez más fuerza de acuerdo a los análisis genéticos y al hallazgo de yacimientos en Canadá anteriores a la creación del corredor interior libre de hielo. Los patrones migratorios hace 12-14 ka eran por tanto más complejos que un simple movimiento constante hacia el sur.
America

Credit: Smith H.L. and Goebel T. (2018) Origins and spread of fluted-point technology in the Canadian Ice-Free Corridor and eastern Beringia.

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A new Homo naledi… and very recent!

Since Homo naledi was presented in 2015 [see related article], a global project has been carried out with 150+ scientists involved in the analysis of the anatomy, behavior, diet, geology and chronology, but also a massive exploration project in the field, inside the Rising Star cave system and other cave systems in the area.

The result is astonishing: this project has yielded more hominin fossils in the last 3 years than in the rest of history in Africa. And the exploration is far from finished: this will surely be followed by a number of further projects and discoveries in the following years.

Back in 2015, it was announced the Dinaledi chamber of the Rising Star cave, containing 1500+ hominin remains corresponding to 15 individuals of Homo naledi, which became one of the most famous species. But thousands of other remains were there still to be discovered and analysed.

Reconstruction of Homo naledi. Photo: Lee R. Berger

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El cráneo impreso de Homo naledi

He esperado un tiempo hasta lanzarme a probar la impresión 3D con un fósil de hominino. Para empezar, lógicamente se necesita disponer del modelo deseado y, por el momento, el número de modelos publicados con acceso abierto no es muy numeroso, aunque tampoco despreciable.

Creo observar una tendencia cada vez mayor a compartir el conocimiento científico producido con fondos públicos, facilitando el acceso libre y gratuito para todo el mundo (Open Access). Por cierto, hay un importante debate sobre las oportunidades y retos que plantea el Open Access en cuanto a derechos de explotación y nuevos modelos de negocio, y eso merecerá otro artículo. Hoy voy a contaros mi primer proyecto de impresión 3D, que me ha llevado tiempo y del que me siento muy satisfecho.

¿Por dónde empecé?

Desde 2014 conocía la existencia de modelos 3D publicados por African Fossils, de tres tipos: Hominids, Animals [sic] y Tools. Entre los “hominids” destaco 12 Homo ergaster y 6 Australopithecus anamensis. Como curiosidades, existe la posibilidad de descargarse también el modelo para fabricarlo montando capas de cartulina de 4 mm de espesor, y también están disponibles varios de los líticos de Lomekwi (antigüedad 3,3 Ma) presentados en 2015.

Modelos 3D Homo ergaster

Catálogo de modelos 3D de Homo ergaster. Imagen tomada de Africanfossils.org

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Quick summary about Homo naledi

A major announcement happened on Sep 10th 2015: the publication of Homo naledi, a new species of the genus Homo found in the Dinaledi Chamber of the Rising Star cave, South Africa.

Naledi‘ is an African name that originates from the Sesotho tribe in southern Africa. It means ‘star‘.

Homo naledi. Photo: Lee R. Berger

Homo naledi. Photo: Lee R. Berger

About the hominid

  • 1,550 fossils from at least 15 individuals. Full range of ages, from birth to old age.
  • They are the most complete assemblage of fossils from a candidate of human ancestor. All part of the bodies are represented in the assemblage. The comprehensive sample of Homo naledi bones is richer than in any other early humans species such as Homo rudolfensis, Homo habilis and Homo erectus.
  • Average height 1.5 m, weight 45 kg.
  • Skull: Primitive, similar to Homo habilis. Between 466 and 560 cc, in comparison to H. habilis 510 to 700 cc, H. erectus 550 to 1100 cc, H. floresiensis 426 cc.
  • Dentition: Many teeth representing many ages from young to old individuals. They look primitive in the increasing size towards the back of the tooth row, but they look modern in their small size and they are simplified, set in lightly built jawbones.
  • Post cranial: The wrist, hands, legs and feet are similar to those in neandertals and modern humans. The hands have curved fingerbones, suggestive of climbing behavior. The legs were made for long distance walking. The feet reflect effective walking. The body has similarities to the Dmanisi’s Homo erectus.

About the place

  • Only hominins reached the Dinaledi Chamber. The quality of the fossil preservation is extraordinary. They show no cut marks nor breakage. No animals broke the bones.
  • There is no archeological evidence showing that the hominins lived in the chamber. There is no sign of habitation. This chamber was never opened to the outside world. The route to the chamber was never any easy, not other animals could have reached it.
  • The fossils were not moved by water. There is no signs of a catastrophe nor scavenges.
  • Conclusion: the bodies were disposed there by purpose. This species could have some capacity to do some kind of burials or rituals. This shows a similar scenario to that proposed for the Sima de los Huesos (Atapuerca, Spain, 430 Ka.). But the Sima hominins have c. 1000 cc brain capacity, while Homo naledi was a tiny-brained hominin, a creature we would never have suspected of complex thought.

Doubts

  • On April 25th 2017 the first dating of naledi is published: between 300-200 Ka, hence much recent than the first estimations made by the discoverers (c. 2 Ma. in the roots of the Homo genus).
  • The location. For the moment Homo naledi is currently only known from this one site, the Dinaledi Chamber. Was it restricted to southern Africa?
  • How did the hominins get to the chamber? Did the cave have another entrance in the past? Could they use fire?

Slideshow