Inicio » Sin categoría

Archivo de la categoría: Sin categoría

001. Evolució Humana: convencions taxonòmiques al voltant d’Homo sapiens

No és un caprici que qualsevol nom taxonómio d’una espècie, com Homo sapiens, s’hagi de escriure en cursiva. L’obra Sistematica Naturae (1735) de Carolus Linnaeus va definir les normes de nomenclatura taxonòmica i classificació científica dels organismes en classes, ordres, gèneres i espècies. Les convencions faciliten la comprensió del procés evolutiu. En la classificació científica, cada espècie rep un nom binomial, on primer se n’indica el gènere i després l’espècie utilitzant els dos termes (gènere i espècie) en llengua llatina, en cursiva o subratllats. Així, els humans pertanyen al gènere Homo i a l’espècie Homo sapiens, que es pot abreujar com H. sapiens o H. sapiens.

Les noves tecnologies dificulten el respecte a aquestes normes bàsiques. Sense anar més lluny, el títol d’aquest blog no permet itàliques ni subratllat, per defecte el meu oridnador inserèix majúscula després d’un punt (H. Sapiens) i la prensa escrita és reticent a escriure el nom especific en cursiva i preferèixen utilitzar cometes: ‘Homo sapiens’. És una pràctica obligada utilitzar itàliques per noms en llatí i subratllat en l’escritura a mà (per raons obvies).

Earliest burial of a modern human in Africa

by M. Martinón Torres, Nature May 2021

The origin and evolution of hominin mortuary practices are topics of intense interest and debate. Human burials dated to the Middle Stone Age (MSA) are exceedingly rare in Africa and unknown in East Africa. Here we describe the partial skeleton of a roughly 2.5- to 3.0-year-old child dating to 78.3 ± 4.1 thousand years ago, which was recovered in the MSA layers of Panga ya Saidi (PYS), a cave site in the tropical upland coast of Kenya. Recent excavations have revealed a pit feature containing a child in a flexed position. Geochemical, granulometric and micromorphological analyses of the burial pit content and encasing archaeological layers indicate that the pit was deliberately excavated. Taphonomical evidence, such as the strict articulation or good anatomical association of the skeletal elements and histological evidence of putrefaction, support the in-place decomposition of the fresh body. The presence of little or no displacement of the unstable joints during decomposition points to an interment in a filled space (grave earth), making the PYS finding the oldest known human burial in Africa. The morphological assessment of the partial skeleton is consistent with its assignment to Homo sapiens, although the preservation of some primitive features in the dentition supports increasing evidence for non-gradual assembly of modern traits during the emergence of our species. The PYS burial sheds light on how MSA populations interacted with the dead.

New Hybrid Bone Reveals that Neanderthals and Denisovans Mated

The closest known extinct relatives of modern humans were the thick-browed Neanderthals and the mysterious Denisovans. Now, a bone fragment from a Siberian cave, perhaps from a teenage girl, has revealed the first known hybrid of these groups, a new study concludes. The finding confirms interbreeding that had been only hinted at in earlier genetic studies.

Archaeological excavations have revealed that Neanderthals and Denisovans coexisted in Eurasia, with Neanderthal bones ranging from 200,000 to 40,000 years old unearthed mostly in western Eurasia and Denisovans so far only known from fossils ranging from 200,000 to 30,000 years old found in eastern Eurasia. Prior work unearthed Neanderthal remains in Denisova Cave, raising questions on how closely they interacted.

The Denisovan father of the individual Denisova 11 had at least one Neanderthal ancestor, possibly as far back as 300 to 600 generations before his lifetime. In addition, the teenage girl’s Neanderthal mother was genetically more similar to the Neanderthals of Western Europe than to a different Neanderthal that lived earlier in Denisova Cave. This find suggests that Neanderthals migrated between western and eastern Eurasia for tens of thousands of years.

Viviane Slon, Fabrizio Mafessoni, … Svante Pääbo

Nature (2018) The genome of the offspring of a Neanderthal mother and a Denisovan father.

13 million-year-old infant ape skull discovered in the Turkana Basin

The discovery in Kenya of a remarkably complete fossil ape skull reveals what the common ancestor of all living apes and humans may have looked like. The find, announced in the scientific journal Nature on August 10th, belongs to an infant that lived about 13 million years ago. The research was done by an international team led by Isaiah Nengo of the Turkana Basin Institute and De Anza College, USA.