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Homo sapiens and Their Cousins

Started by Recusant, October 31, 2015, 01:52:11 AM

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Recusant

Fragments of a Homo naledi child's skull found deep in the Rising Star Cave may indicate some sort of burial practice.

"A child's partial skull adds to the mystery of how Homo naledi treated the dead" | Science News

QuoteA child's partial skull found in a remote section of a South African cave system has fueled suspicion that an ancient hominid known as Homo naledi deliberately disposed of its dead in caves.

An international team led by paleoanthropologist Lee Berger of University of the Witwatersrand, Johannesburg pieced together 28 skull fragments and six teeth from a child's skull discovered in a narrow opening located about 12 meters from an underground chamber where cave explorers first found H. naledi fossils. Features of the child's skull qualify it as H. naledi, a species with an orange-sized brain and skeletal characteristics of both present-day people and Homo species from around 2 million years ago.

"The case is building for deliberate, ritualized body disposal in caves by Homo naledi," Berger said at a November 4 news conference held in Johannesburg. While that argument is controversial, there is no evidence that the child's skull was washed into the tiny space or dragged there by predators or scavengers.

[Continues . . .]

The paper is open access (click on the red PDF button at the link).

"Immature Hominin Craniodental Remains From a New Locality in the Rising Star Cave System, South Africa" | PaleoAnthropology

QuoteAbstract:

Homo naledi is known from the Rising Star cave system, South Africa, where its remains have previously been reported from two localities: the Dinaledi Chamber (U.W. 101) and Lesedi Chamber (U.W. 102). Continued exploration of the cave system has expanded our knowledge of the Dinaledi Chamber and its surrounding passageways (the Dinaledi Subsystem), leading to the discovery of new fossil localities.

This paper discusses the fossil assemblage from the locality designated U.W. 110. This locality is within a narrow fissure of the Dinaledi Subsystem approximately 12 meters southwest of the 2013–2014 excavation. Fossil remains recovered from this locality include six hominin teeth and 28 cranial fragments, all consistent with a single immature hominin individual. The dental morphology of the new specimens supports attribution to H. naledi.

This is the first immature individual of H. naledi to preserve morphological details of the calvaria in association with dental evidence. This partial skull provides information about the maturation of H. naledi and will be important in reconstructing the developmental sequence of immature remains from other H. naledi occurrences. This is the third locality described with H. naledi material in the Rising Star cave system and represents a depositional situation that resembles the Lesedi Chamber in some respects.

[¶ added. - R]
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Recusant

A likely Denisovan fossil tooth has been found in Laos--it confirms they had a wider range than previously known. This is not all that surprising; it's been known for several years that there is a significant level of Denisovan DNA contribution in modern East Asian populations. 

"A fossil tooth places enigmatic ancient humans in Southeast Asia" | The Conversation

QuoteWhat do a finger bone and some teeth found in the frigid Denisova Cave in Siberia's Altai mountains have in common with fossils from the balmy hills of tropical northern Laos?

Not much, until now: in a Laotian cave, an international team of researchers including ourselves has discovered a tooth belonging to an ancient human previously only known from icy northern latitudes – a Denisovan.

The find shows these long-lost relatives of Homo sapiens inhabited a wider area and range of environments than we previously knew, confirming hints found in the DNA of modern human populations from Southeast Asia and Australasia.

[Continues . . .]

The paper is open access:

"A Middle Pleistocene Denisovan molar from the Annamite Chain of northern Laos" | Nature Communications

QuoteAbstract:

The Pleistocene presence of the genus Homo in continental Southeast Asia is primarily evidenced by a sparse stone tool record and rare human remains. Here we report a Middle Pleistocene hominin specimen from Laos, with the discovery of a molar from the Tam Ngu Hao 2 (Cobra Cave) limestone cave in the Annamite Mountains.

The age of the fossil-bearing breccia ranges between 164–131 kyr [thousand years], based on the Bayesian modelling of luminescence dating of the sedimentary matrix from which it was recovered, U-series dating of an overlying flowstone, and U-series–ESR dating of associated faunal teeth.

Analyses of the internal structure of the molar in tandem with palaeoproteomic analyses of the enamel indicate that the tooth derives from a young, likely female, Homo individual. The close morphological affinities with the Xiahe specimen from China indicate that they belong to the same taxon and that Tam Ngu Hao 2 most likely represents a Denisovan.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Recusant

A paper on climate and hominin evolution.  8)

"Early human habitats linked to past climate shifts" | EurekAlert


QuoteA study published in Nature by an international team of scientists provides clear evidence for a link between astronomically-driven climate change and human evolution.

By combining the most extensive database of well-dated fossil remains and archeological artefacts with an unprecedented new supercomputer model simulating earth's climate history of the past 2 million years, the team of experts in climate modeling, anthropology and ecology was able to determine under which environmental conditions archaic humans likely lived.

The impact of climate change on human evolution has long been suspected, but has been difficult to demonstrate due to the paucity of climate records near human fossil-bearing sites. To bypass this problem, the team instead investigated what the climate in their computer simulation was like at the times and places humans lived, according to the archeological record. This revealed the preferred environmental conditions of different groups of hominins. From there, the team looked for all the places and times those conditions occurred in the model, creating time-evolving maps of potential hominin habitats.

"Even though different groups of archaic humans preferred different climatic environments, their habitats all responded to climate shifts caused by astronomical changes in earth's axis wobble, tilt, and orbital eccentricity with timescales ranging from 21 to 400 thousand years," said Axel Timmermann, lead author of the study and Director of the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea.

To test the robustness of the link between climate and human habitats, the scientists repeated their analysis, but with ages of the fossils shuffled like a deck of cards. If the past evolution of climatic variables did not impact where and when humans lived, then both methods would result in the same habitats. However, the researchers found significant differences in the habitat patterns for the three most recent hominin groups (Homo sapiens, Homo neanderthalensis and Homo heidelbergensis) when using the shuffled and the realistic fossil ages. "This result implies that at least during the past 500 thousand years the real sequence of past climate change, including glacial cycles, played a central role in determining where different hominin groups lived and where their remains have been found", said Prof. Timmermann.

"The next question we set out to address was whether the habitats of the different human species overlapped in space and time. Past contact zones provide crucial information on potential species successions and admixture," said Prof. Pasquale Raia from the Università di Napoli Federico II, Naples, Italy, who together with his research team compiled the dataset of human fossils and archeological artefacts used in this study. From the contact zone analysis, the researchers then derived a hominin family tree, according to which Neanderthals and likely Denisovans derived from the Eurasian clade of Homo heidelbergensis around 500-400 thousand years ago, whereas Homo sapiens' roots can be traced back to Southern African populations of late Homo heidelbergensis around 300 thousand years ago.

[Continues . . .]

The paper is open access:

"Climate effects on archaic human habitats and species successions" | Nature

QuoteAbstract:

It has long been believed that climate shifts during the last 2 million years had a pivotal role in the evolution of our genus Homo. However, given the limited number of representative palaeo-climate datasets from regions of anthropological interest, it has remained challenging to quantify this linkage.

Here, we use an unprecedented transient Pleistocene coupled general circulation model simulation in combination with an extensive compilation of fossil and archaeological records to study the spatiotemporal habitat suitability for five hominin species over the past 2 million years. We show that astronomically forced changes in temperature, rainfall and terrestrial net primary production had a major impact on the observed distributions of these species.

During the Early Pleistocene, hominins settled primarily in environments with weak orbital-scale climate variability. This behaviour changed substantially after the mid-Pleistocene transition, when archaic humans became global wanderers who adapted to a wide range of spatial climatic gradients.

Analysis of the simulated hominin habitat overlap from approximately 300–400 thousand years ago further suggests that antiphased climate disruptions in southern Africa and Eurasia contributed to the evolutionary transformation of Homo heidelbergensis populations into Homo sapiens and Neanderthals, respectively. Our robust numerical simulations of climate-induced habitat changes provide a framework to test hypotheses on our human origin.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken