Homo sapiens and Their Cousins

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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

A 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.

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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

Abstract:

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.

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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

What 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.

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The paper is open access:

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

Abstract:

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.

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A paper on climate and hominin evolution. 

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

A 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.

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The paper is open access:

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

Abstract:

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.

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Ancient DNA brings us closer to unlocking secrets of how modern humans evolved


Advances in studying ancient DNA from prehistoric remains provides us with new insight into the life of our African ancestors and the emergence of the modern human.


"Humans all share a common African ancestry, making African history everyone's history. Yet little is known about the genetic evolution of people living on the continent in the distant past.

Thanks to advances in genome sequencing technology, scientists are now able to compare the DNA of people alive today with DNA extracted from very old skeletons, giving us a unique snapshot of life in Africa from many thousands of years ago."

The more evidence we gather the more complex the picture becomes.

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A recent specific example:

"A Strange Fossil in South China Reveals an Intriguing Link With The First Americans" | Science Alert

Remains recovered from a cave in the Chinese province of Yunnan more than 10 years ago have finally given up their secrets, with a DNA analysis revealing not just who left them, but ultimately where their ancestors would go.

Researchers from the Chinese Academy of Sciences evaluated nuclear and mitochondrial sequences extracted from a 14,000-year-old skull, discovering the woman it once belonged to – dubbed Mengzi Ren – was closely related to populations who would eventually be the first to set foot in the Americas.

Since their discovery in 2008, the dozens of late Paleolithic human bones left behind in Malu Dong (Red Deer Cave) in China's south-west have left anthropologists scratching their heads over just who they might have belonged to.

Without sufficient collagen to base a carbon dating analysis on, their age can only be estimated from surrounding features of their grave site. It's not even clear if the mix of bones that includes a skull fragment and the top end of a femur all come from the same individual.

What is clear is whoever left them behind represented a unique mix of archaic and modern characteristics.

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A close look at her nuclear DNA verified Megzi Ren's close ties with anatomically modern humans, all but ruling out her heritage among a more ancient stock.

"Ancient DNA technique is a really powerful tool," says Bing Su, an archaeologist with the Chinese Academy of Sciences.

"It tells us quite definitively that the Red Deer Cave people were modern humans instead of an archaic species, such as Neanderthals or Denisovans, despite their unusual morphological features."

Although Mengzi Ren is more closely related to today's southern Chinese populations than those in the north, she has less in common with people who now live across Asia's southeast, suggesting there were already well structured, diversified populations in the region thousands of years ago.

That's not to say Asia was populated from the bottom up. There's strong evidence that a relatively small population of humans also ventured down from the north to settle the east, a group that would split to venture across the ice-covered stretch of the Bering Strait to settle the vast wilderness of the Americas.

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The paper is behind a paywall.

Summary:

Southern East Asia is the dispersal center regarding the prehistoric settlement and migrations of modern humans in Asia-Pacific regions. However, the settlement pattern and population structure of paleolithic humans in this region remain elusive, and ancient DNA can provide direct information. Here, we sequenced the genome of a Late Pleistocene hominin (MZR), dated ∼14.0 thousand years ago from Red Deer Cave located in Southwest China, which was previously reported possessing mosaic features of modern and archaic hominins. MZR is the first Late Pleistocene genome from southern East Asia. Our results indicate that MZR is a modern human who represents an early diversified lineage in East Asia. The mtDNA of MZR belongs to an extinct basal lineage of the M9 haplogroup, reflecting a rich matrilineal diversity in southern East Asia during the Late Pleistocene. Combined with the published data, we detected clear genetic stratification in ancient southern populations of East/Southeast Asia and some degree of south-versus-north divergency during the Late Pleistocene, and MZR was identified as a southern East Asian who exhibits genetic continuity to present day populations. Markedly, MZR is linked deeply to the East Asian ancestry that contributed to First Americans.

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Taking another look at an ancient jawbone found in Spain, interesting findings were the result.

"This May Be The Oldest Fragment of Modern Humans in Europe, Or Something Even Rarer" | Science Alert

An ancient jawbone previously thought to have belonged to a Neanderthal may force a rethink on the history of modern humans in Europe.

A new analysis of the broken mandible reveals that it has nothing in common with other Neanderthal remains. Rather, it could belong to a Homo sapiens – and, since it's dated to between 45,000 to 66,000 years ago, might be the oldest known piece of our species' anatomy on the European continent.

The bone itself was found in 1887 in the town of Banyoles in Spain, for which it is nicknamed. Since then, scientists have studied it pretty extensively, dating it to a timeframe in the Late Pleistocene when the region that is now Europe was predominantly populated by Neanderthals (Homo neanderthalensis).

This, and the archaic shape of the bone, led scientists to the conclusion that Banyoles in fact belonged to a Neanderthal.

"The mandible has been studied throughout the past century and was long considered to be a Neandertal based on its age and location, and the fact that it lacks one of the diagnostic features of Homo sapiens: a chin," says palaeoanthropologist Brian Keeling of Binghamton University in the US.

Keeling and his colleagues undertook a thorough investigation of the bone using a process called three-dimensional geometric morphometric analysis. This is a non-invasive protocol that involves going over the shape of a bone in exhaustive detail, mapping its features and comparing them to other remains.

They took high-resolution 3D scans, and used these not just to study the bone, but to reconstruct the missing pieces. Then they compared Banyoles to the mandibles of Neanderthals and modern humans.

"Our results found something quite surprising," Keeling says. "Banyoles shared no distinct Neanderthal traits and did not overlap with Neanderthals in its overall shape."

It seemed more consistent with the jawbones of our own branch of the family tree, except for one detail: the absent chin.

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The paper is partly available:

"Reassessment of the human mandible from Banyoles (Girona, Spain)" | Journal of Human Evolution

Abstract:

Since the discovery of a human mandible in 1887 near the present-day city of Banyoles, northeastern Spain, researchers have generally emphasized its archaic features, including the lack of chin structures, and suggested affinities with the Neandertals or European Middle Pleistocene (Chibanian) specimens. Uranium-series and electron spin resonance dating suggest the mandible dates to the Late Pleistocene (Tarantian), approximately ca. 45–66 ka.

In this study, we reassessed the taxonomic affinities of the Banyoles mandible by comparing it to samples of Middle Pleistocene fossils from Africa and Europe, Neandertals, Early and Upper Paleolithic modern humans, and recent modern humans. We evaluated the frequencies and expressions of morphological features and performed a three-dimensional geometric morphometric analysis on a virtual reconstruction of Banyoles to capture overall mandibular shape.

Our results revealed no derived Neandertal morphological features in Banyoles. While a principal component analysis based on Euclidean distances from the first two principal components clearly grouped Banyoles with both fossil and recent Homo sapiens individuals, an analysis of the Procrustes residuals demonstrated that Banyoles did not fit into any of the comparative groups.

The lack of Neandertal features in Banyoles is surprising considering its Late Pleistocene age. A consideration of the Middle Pleistocene fossil record in Europe and southwest Asia suggests that Banyoles is unlikely to represent a late-surviving Middle Pleistocene population. The lack of chin structures also complicates an assignment to H. sapiens, although early fossil H. sapiens do show somewhat variable development of the chin structures.

Thus, Banyoles represents a non-Neandertal Late Pleistocene European individual and highlights the continuing signal of diversity in the hominin fossil record. The present situation makes Banyoles a prime candidate for ancient DNA or proteomic analyses, which may shed additional light on its taxonomic affinities.

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There were seagoing hominins before H. sapiens, it seems. 

"Ancient Humans May Have Sailed The Mediterranean 450,000 Years Ago" | Science Alert

Archaic humans may have worked out how to sail across the sea to new lands as far back as nearly half a million years ago.

According to a new analysis of shorelines during the mid-Chibanian age, there's no other way these ancient hominins could have reached what we now call the Aegean Islands. Yet archaeologists have found ancient artifacts on the islands that pre-date the earliest known appearance of Homo sapiens.

This suggests that these ancient humans must have found a way to traverse large bodies of water. And if reliance on land bridges was not necessary for human migration, it may have implications for the way our ancestors and modern humans spread throughout the world.

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The islands of the Aegean are, today, considered among the world's most beautiful places. They consist of hundreds of islands making up an archipelago scattered across the Aegean Sea between Turkey, Greece, and Crete. And they've been inhabited for a long time; artifacts have been dated to potentially as early as 476,000 years ago.

These ancient tools on Lesbos, Milos, and Naxos, moreover, have been linked to the Acheulean style developed some 1.76 million years ago, associated with Homo erectus across Africa and Asia. Several such tools have been found in Turkey, Greece, and Crete dating back to 1.2 million years ago, so their appearance in the nearby archipelago does make some sense.

Previous studies suggested that ancient humans crossed to the islands on foot during ice ages. When the world freezes, the sea level drops, and humans can make crossings that would be covered by water in more temperate times.

To determine whether this is a possibility, Ferentinos and his colleagues reconstructed the geography of the region, including a reconstruction of the shoreline around the Aegean Islands dating back to 450,000 years ago. For this, they used ancient river deltas, which can be used to infer sea level, and rates of subsidence driven by tectonic activity.

And they found that previous reconstructions were incorrect. At its lowest point over the last 450,000 years, the sea level was approximately 225 meters (738 feet) lower than it is today.

This means that, while some of the Aegean Islands were connected to each other when sea levels were lower, over the last 450,000 years, the islands have remained consistently insular from the surrounding land masses. At the sea level's lowest point, there still would have been several kilometers of open water to traverse to reach the nearest of the Aegean Islands.

Other evidence, the researchers point out, suggests that this was not the earliest sea crossing. Sometime between 700,000 and a million years ago, archaic humans were thought to have been traveling the sea around Indonesia and the Philippines.

These combined crossings suggest that sea travel was a skill developed not by Homo sapiens, but the human ancestors and relatives that came before.

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The paper is behind a paywall, with some snippet material avaiable.

Abstract:

When archaic hominins started sea-crossings and whether or not seas were barriers to their dispersal, is highly debated. This paper attempts to provide insights into these issues, focusing on the Aegean Sea.

The study shows that the Central Aegean Island Chain was insular from the surrounding landmasses over the last 450 ka and contests previously available Aegean Sea palaeo-geography. This, in association with the spatiotemporal patterning of Lower and Middle Paleolithic assemblages in the margin of the Mediterranean Sea, implies that pre-sapiens, as early as 450 ka BP: (a) were sea-crossing the Aegean Sea; (b) were encouraged by the favorable land/seascape configuration to attempt sea-crossings and (c) spread to the Circum-Mediterranean basin sourcing from the Levant, following two converging routes, the one via the Aegean Sea and/or the Bosporus land-bridge and the other via the Gibraltar straits. Furthermore, the above presented findings provide substantial evidence that the archaic hominins had developed sea-crossing behaviours as early as 450 ka BP.

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That was a fascinating article.

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Yeah, our ancestors got up to more than we suspect. It's entertaining to think of them paddling out onto the water. What an exhilarating adventure to be one of the earliest navigators on the planet.  Though maybe the very first were just hungry, and canny enough to imagine crossing the sea.