Tag Archives: #ancestors

Climatic Conditions Reconstructed During the Migration of Homo sapiens From Africa (Paleontology)

Climate reconstruction of the last 200,000 years from East Africa illustrates the living conditions of Homo sapiens when he emigrated from Africa / Homo sapiens was supraregional mobile during the humid phases and withdrew to high altitudes during the dry phases

An international research team led by Professor Dr. Frank Schäbitz has published a climate reconstruction of the last 200,000 years for Ethiopia. This means that high-resolution data are now available for the period in which the early Homo sapiens, our ancestor, made their way from Africa to Europe and Asia. Schäbitz and his colleagues obtained the data from a drill core from lake sediments that had been deposited in the Chew Bahir Basin in southern Ethiopia, which is located near fossil sites of our species. The temporal resolution of the samples, accurate to a maximum of 10 years, showed that from 200,000 to 125,000 years before our time the climate there was relatively humid and offered enough water and thus abundant vegetable and animal food sources in the lowlands of East Africa. From 125,000 to 60. 000 years ago it gradually became drier, particularly dry between 60,000 to 14,000 years ago. The data that have now been determined fit well with the genetic findings known so far, according to which our direct genetic ancestors (“African Eve”) left Africa “successfully” – in a wet phase – around 70,000-50,000 years ago. The article “Hydroclimate changes in eastern Africa over the past 200,000 years may have influenced early human dispersal” appeared in Nature Communications.

The scientists collect information about the environment from the lake sediments, since in the best-case scenario sediments enter the lakes relatively continuously through erosion in the catchment area. In addition to the mineral components, organic material and residues of organisms living in the lake belong to the deposits. If it is possible to drill lake sediments from suitable lakes, these “proxy data” (English proxies) can be used to draw conclusions about former environmental conditions and thus reconstruct the climate of the past.
In November to December 2014, the researchers were able to recover an approx. 300 m long drill core from the Chew Bahir Basin in southern Ethiopia, which dried up during the dry season. In its entirety, the drill core goes back to around 620,000 years ago. “This enables us to cover the entire history of the development of Homo sapiens in Africa. The work that has now been published over the last 200,000 years of this drill core documents very well the environmental and climatic history during the expansion of our ancestors, ”explains Professor Schäbitz.

“Some of our proxies allow a decadal time resolution in large sections of the core, something that has not yet existed for this part of Africa. We use it to record very brief climatic changes that represent less than a human life, ”says Schäbitz. It can be seen that the climate in East Africa was essentially influenced by changes in the amount of solar radiation, which led to either humid or dry climatic conditions. From 200,000-125,000 years ago the climate was generally relatively favorable, ie the low-lying areas offered enough water and thus plenty of vegetable and animal sources of food for our ancestors. Under such conditions, people were able to move relatively easily and even reach the Arabian Peninsula, which is documented by the oldest fossil finds there (approx. 175,000 years ago). From 125,000 to 60,000 years ago, however, it gradually became drier, particularly dry then between 60,000 to 14,000 years ago, with the lake drying up completely several times. 

“However, it is precisely during this period that very striking, short-term fluctuations in humidity can be observed, whose temporal patterns are reminiscent of cold-warm climatic fluctuations that are known from the Greenland ice cores. The people who lived in East Africa at the time were exposed to extreme changes in their environment, ”said Schäbitz. “It is interesting that in the period from 60,000 to 14,000 years, in which the lowlands of East Africa were repeatedly particularly dry, numerous archaeological findings in the high elevations of the Ethiopian mountains prove the presence of our ancestors at greater heights During this period the weapons and tools of these people were further developed (transition from the Middle to the Late Paleolithic in Africa). “We suppose,

It is also interesting that the last major wet phase, which can be seen in the examined core, fits well with the genetic findings: according to this, our direct genetic ancestors (“African Eve”) are said to have “successfully” left Africa about 70,000-50,000 years ago . Their descendants probably reached southeast Europe 50,000-40,000 years ago and met the Neanderthals there.

“We suspect that the evidence found in our drill core for dry-wet climatic fluctuations in East Africa had a significant influence on the development and mobility of our ancestors,” said Schäbitz. “The“ Out of Africa ”was possible several times over the last 200,000 years under humid conditions and contributed to the spread of our ancestors to Europe. During the particularly dry phases of the recent past, from around 60,000 years on, Homo sapiens groups have repeatedly managed to survive in the high altitudes of mountainous Ethiopia. “

The publication with 20 international co-authors grew out of the A3 subproject of the Collaborative Research Center (SFB) 806 “Our way to Europe”, which has been carried out successfully in Cologne since 2009 in close cooperation with the Institute for Prehistory and the Universities of Bonn and Aachen . The aim of this CRC is to understand the reasons for the history of the spread of our ancestors (Homo sapiens) from Africa to Europe. The Chew Bahir deep drilling project is also internationally involved in the “Hominin Site and Paleolakes Drilling Project” (= HSPDP) project.

Reference: Schaebitz, F., Asrat, A., Lamb, H.F. et al. Hydroclimate changes in eastern Africa over the past 200,000 years may have influenced early human dispersal. Commun Earth Environ 2, 123 (2021). https://doi.org/10.1038/s43247-021-00195-7

Provided by University of Cologne

Ancestors May Have Created ‘Iconic’ Sounds as Bridge to First Languages (Language)

The ‘missing link’ that helped our ancestors to begin communicating with each other through language may have been iconic sounds, rather than charades-like gestures – giving rise to the unique human power to coin new words describing the world around us, a new study reveals.

It was widely believed that, in order to get the first languages off the ground, our ancestors first needed a way to create novel signals that could be understood by others, relying on visual signs whose form directly resembled the intended meaning.

However, an international research team, led by experts from the University of Birmingham and the Leibniz-Centre General Linguistics (ZAS), Berlin, have discovered that iconic vocalisations can convey a much wider range of meanings more accurately than previously supposed. Listen to a selection of sounds: ‘Cut‘; ‘Tiger‘; ‘Water‘; and ‘Good‘.

The researchers tested whether people from different linguistic backgrounds could understand novel vocalizations for 30 different meanings common across languages and which might have been relevant in early language evolution.

These meanings spanned animate entities, including humans and animals (child, man, woman, tiger, snake, deer), inanimate entities (knife, fire, rock, water, meat, fruit), actions (gather, cook, hide, cut, hunt, eat, sleep), properties (dull, sharp, big, small, good, bad), quantifiers (one, many) and demonstratives (this, that).

The team published their findings in Scientific Reports, highlighting that the vocalizations produced by English speakers could be understood by listeners from a diverse range of cultural and linguistic backgrounds. Participants included speakers of 28 languages from 12 language families, including groups from oral cultures such as speakers of Palikúr living in the Amazon forest and speakers of Daakie on the South Pacific island of Vanuatu. Listeners from each language were more accurate than chance at guessing the intended referent of the vocalizations for each of the meanings tested.

Co-author Dr Marcus Perlman, Lecturer in English Language and Linguistics at the University of Birmingham, commented: “Our study fills in a crucial piece of the puzzle of language evolution, suggesting the possibility that all languages – spoken as well as signed – may have iconic origins.

“The ability to use iconicity to create universally understandable vocalisations may underpin the vast semantic breadth of spoken languages, playing a role similar to representational gestures in the formation of signed languages.”

Co-author Dr Bodo Winter, Senior Lecturer in Cognitive Linguistics at the University of Birmingham, commented: “Our findings challenge the often-cited idea that vocalisations have limited potential for iconic representation, demonstrating that in the absence of words people can use vocalizations to communicate a variety of meanings – serving effectively for cross-cultural communication when people lack a common language.”

An online experiment allowed researchers to test whether a large number of diverse participants around the world were able to understand the vocalisations. A field experiment using 12 easy-to-picture meanings, allowed them to test whether participants living in predominantly oral societies were also able to understand the vocalisations.

They found that some meanings were consistently guessed more accurately than others. In the online experiment, for example, accuracy ranged from 98.6% for the action ‘sleep’ to 34.5% for the demonstrative ‘that’. Participants were best with the meanings ‘sleep’, ‘eat’, ‘child’, ‘tiger’, and ‘water’, and worst with ‘that’, ‘gather’, ‘dull’, ‘sharp’ and ‘knife’.

The researchers highlight that while their findings provide evidence for the potential of iconic vocalisations to figure in the creation of original spoken words, they do not detract from the hypothesis that iconic gestures also played a critical role in the evolution of human communication, as they are known to play in the modern emergence of signed languages.

Featured image: ‘Tiger’ – one of the concepts vocalised by scientists © University of Birmingham

Notes to editors:

  • ‘Novel Vocalizations are Understood across Cultures’ – Aleksandra Ćwiek, Susanne Fuchs, Christoph Draxler, Eva Liina Asu, Dan Dediu, Katri Hiovain, Shigeto Kawahara, Sofia Koutalidis, Manfred Krifka, Pärtel Lippus, Gary Lupyan, Grace E. Oh, Jing Paul, Caterina Petrone, Rachid Ridouane, Sabine Reiter, Nathalie Schümchen, Ádám Szalontai, Özlem Ünal-Logacev, Jochen Zeller, Bodo Winter, and Marcus Perlman is published in Scientific Reports.

Provided by University of Birmingham

Discarded Ostrich Shells Provide Timeline For Our Early African Ancestors (Paleontology)

Uranium-series dating shows South African midden is world’s oldest

Archeologists have learned a lot about our ancestors by rummaging through their garbage piles, which contain evidence of their diet and population levels as the local flora and fauna changed over time.

One common kitchen scrap in Africa — shells of ostrich eggs — is now helping unscramble the mystery of when these changes took place, providing a timeline for some of the earliest Homo sapiens who settled down to utilize marine food resources along the South African coast more than 100,000 years ago.

Geochronologists at the University of California, Berkeley, and the Berkeley Geochronology Center (BGC) have developed a technique that uses these ubiquitous discards to precisely date garbage dumps — politely called middens — that are too old to be dated by radiocarbon or carbon-14 techniques, the standard for materials like bone and wood that are younger than about 50,000 years.

In a paper published this month in the journal Proceedings of the National Academy of Sciences, former UC Berkeley doctoral student Elizabeth Niespolo and geochronologist and BGC and associate director Warren Sharp reported using uranium-thorium dating of ostrich eggshells to establish that a midden outside Cape Town, South Africa, was deposited between 119,900 and 113,100 years ago.

That makes the site, called Ysterfontein 1, the oldest known seashell midden in the world, and implies that early humans were fully adapted to coastal living by about 120,000 years ago. This also establishes that three hominid teeth found at the site are among the oldest Homo sapiens fossils recovered in southern Africa.

The technique is precise enough for the researchers to state convincingly that the 12.5-foot-deep pile of mostly marine shells — mussels, mollusks and limpets — intermixed with animal bones and eggshells may have been deposited over a period of as little as 2,300 years.

The new ages are already revising some of the assumptions archeologists had made about the early Homo sapiens who deposited their garbage at the site, including how their population and foraging strategies changed with changing climate and sea level.

“The reason why this is exciting is that this site wouldn’t have been datable by radiocarbon because it is too old,” Niespolo said, noting that there are a lot more such sites around Africa, in particular the coastal areas of South Africa.

“Almost all of this sort of site have ostrich eggshells, so now that we have this technique, there is this potential to go and revisit these sites and use this approach to date them more precisely and more accurately, and more importantly, find out if they are the same age as Ysterfontein or older or younger, and what that tells us about foraging and human behavior in the past,” she added.

Because ostrich eggshells are ubiquitous in African middens — the eggs are a rich source of protein, equivalent to about 20 chicken eggs — they have been an attractive target for geochronologists. But applying uranium-thorium dating — also called uranium series — to ostrich shells has been beset by many uncertainties.

“The previous work to date eggshells with uranium series has been really hit and miss, and mostly miss,” Niespolo said.

Precision dating pushed back to 500,000 years ago

Other methods applicable to sites older than 50,000 years, such as luminescence dating, are less precise — often by a factor of 3 or more — and cannot be performed on archival materials available in museums, Sharp said.

The researchers believe that uranium-thorium dating can provide ages for ostrich eggshells as old as 500,000 years, extending precise dating of middens and other archeological sites approximately 10 times further into the past.

“This is the first published body of data that shows that we can get really coherent results for things well out of radiocarbon range, around 120,000 years ago in this case,” said Sharp, who specializes in using uranium-thorium dating to solve problems in paleoclimate and tectonics as well as archeology. “It is showing that these eggshells maintain their intact uranium-series systems and give reliable ages farther back in time than had been demonstrated before.”

“The new dates on ostrich eggshell and excellent faunal preservation make Ysterfontein 1 the as-yet best dated multi-stratified Middle Stone Age shell midden on the South African west coast,” said co-author Graham Avery, an archeozoologist and retired researcher with the Iziko South African Museum. “Further application of the novel dating method, where ostrich eggshell fragments are available, will strengthen chronological control in nearby Middle Stone Age sites, such as Hoedjiespunt and Sea Harvest, which have similar faunal and lithic assemblages, and others on the southern Cape coast.”

The first human settlements?

Ysterfontein 1 is one of about a dozen shell middens scattered along the western and eastern coasts of Western Cape Province, near Cape Town. Excavated in the early 2000s, it is considered a Middle Stone Age site established around the time that Homo sapiens were developing complex behaviors such as territoriality and intergroup competition, as well as cooperation among non-kin groups. These changes may be due to the fact that these groups were transitioning from hunter-gatherers to settled populations, thanks to stable sources of high-quality protein — shellfish and marine mammals — from the sea.

Until now, the ages of Middle Stone Age sites like Ysterfontein 1 have been uncertain by about 10%, making comparison among Middle Stone Age sites and with Later Stone Age sites difficult. The new dates, with a precision of about 2% to 3%, place the site in the context of well-documented changes in global climate: it was occupied immediately after the last interglacial period, when sea level was at a high, perhaps 8 meters (26 feet) higher than today. Sea level dropped rapidly during the occupation of the site — the shoreline retreated up to 2 miles during this period — but the accumulation of shells continued steadily, implying that the inhabitants found ways to accommodate the changing distribution of marine food resources to maintain their preferred diet.

The study also shows that the Ysterfontein 1 shell midden accumulated rapidly — perhaps about 1 meter (3 feet) every 1,000 years — implying that Middle Stone Age people along the southern African coast made extensive use of marine resources, much like people did during the Later Stone Age, and suggesting that effective marine foraging strategies developed early.

For dating, eggshells are better

Ages can be attached to some archeological sites older than 50,000 years through argon-argon (40Ar/39Ar) dating of volcanic ash. But ash isn’t always present. In Africa, however — and before the Holocene, throughout the Middle East and Asia — ostrich eggshells are common. Some sites even contain ostrich eggshell ornaments made by early Homo sapiens.

Over the last four years, Sharp and Niespolo conducted a thorough study of ostrich eggshells, including analysis of modern eggshells obtained from an ostrich farm in Solvang, California, and developed a systematic way to avoid the uncertainties of earlier analyses. One key observation was that animals, including ostriches, do not take up and store uranium, even though it is common at parts-per-billion levels in most water. They demonstrated that newly laid ostrich shells contain no uranium, but that it is absorbed after burial in the ground.

The same is true of seashells, but their calcium carbonate structure — a mineral called aragonite — is not as stable when buried in soil as the calcite form of calcium carbonate found in eggshell. Because of this, eggshells retain better the uranium taken up during the first hundred years or so that that they are buried. Bone, consisting mostly of calcium phosphate, has a mineral structure that also does not remain stable in most soil environments nor reliably retains absorbed uranium.

Eggshell structures exert a primary control on the distribution of secondary U and Th, so spatial characterization of key elements and careful sampling are required to produce accurate ages by 230Th/U dating. Scale bars are 1 mm. A. Thin section photomicrograph of a modern ostrich eggshell in cross section, and corresponding eggshell structures denoted by V (vertical layer), P (palisade or prismatic layer), and C (cone layer). Pores serving as oxygen pathways for incubating chicks are visible as open holes penetrating through the eggshell. B. Epoxy-mounted fragment of an ancient eggshell from Ysterfontein 1 in cross section, showing the same eggshell structures are well preserved in deep time. Analyses from laser ablation are evident along pitted lines and track concentrations of U and Th. A pore is apparent in the center of the mounted fragment. 230Th/U burial ages of eggshells from this layer are ~118 thousand years old. © Images courtesy of E. Niespolo.

Uranium is ideal for dating because it decays at a constant rate over time to an isotope of thorium that can be measured in minute amounts by mass spectrometry. The ratio of this thorium isotope to the uranium still present tells geochronologists how long the uranium has been sitting in the eggshell.

Uranium-series dating relies on uranium-238, the dominant uranium isotope in nature, which decays to thorium-230. In the protocol developed by Sharp and Niespolo, they used a laser to aerosolize small patches along a cross-section of the shell, and ran the aerosol through a mass spectrometer to determine its composition. They looked for spots high in uranium and not contaminated by a second isotope of thorium, thorium-232, which also invades eggshells after burial, though not as deeply. They collected more material from those areas, dissolved it in acid, and then analyzed it more precisely for uranium-238 and thorium-230 with “solution” mass spectrometry.

These procedures avoid some of the previous limitations of the technique, giving about the same precision as carbon-14, but over a time range that is 10 times larger.

“The key to this dating technique that we have developed that differs from previous attempts to date ostrich egg shells is the fact that we are explicitly accounting for the fact that ostrich eggshells have no primary uranium in them, so the uranium that we are using to date the eggshells actually comes from the soil pore water and the uranium is being taken up by the eggshells upon deposition,” Niespolo said.

Working with UC Berkeley professor of integrative biology Todd Dawson, Niespolo also analyzed other isotopes in eggshells — stable isotopes of carbon, nitrogen and oxygen — to establish that the climate rapidly became drier and cooler over the period of occupation, consistent with known climate changes at that time.

Niespolo, now a postdoctoral fellow at the California Institute of Technology but soon to be an assistant professor at Princeton University, is working with Sharp to date middens at other sites near Ysterfontein. She also is developing the uranium-series technique to use with other types of eggs, such as those of emus in Australia and rheas in South America, as well as the eggs of now extinct flightless birds, such as the two-meter (6.6-foot) tall Genyornis, which died out some 50,000 years ago in Australia.

The work was supported by the Leakey Foundation, Ann and Gordon Getty Foundation and National Science Foundation (BCS-1727085).

Featured image: Ancient ostrich eggshells from Ysterfontein 1, a Middle Stone Age midden in South Africa. Shown are selected eggshells from the top layer of the midden dated by Uranium-Thorium (U-Th, or 230Th/U) geochronology, with their outer surfaces facing up. Scale bar is 1 cm. With new 230Th/U burial ages of ostrich eggshells, Ysterfontein 1 is the oldest well-dated marine shell midden, indicating humans adapted to systematically utilize coastal resources such as shellfish by ~120 thousand years ago.© Image courtesy of E. Niespolo.

Reference: Elizabeth M. Niespolo, Warren D. Sharp, Graham Avery, Todd E. Dawson, “Early, intensive marine resource exploitation by Middle Stone Age humans at Ysterfontein 1 rockshelter, South Africa”, PNAS April 20, 2021 118 (16) e2020042118; https://doi.org/10.1073/pnas.2020042118

Provided by University of California Berkeley

Early Humans in the Kalahari Were as Innovative As Their Coastal Neighbours (Archeology)

Archaeological evidence in a rockshelter at the edge of the Kalahari Desert, South Africa, is challenging the idea that the origins of our species were linked to coastal environments

An international team including the geologist Michael Meyer provided the oldest proof for modern humans in the Kalahari Desert in Africa. The archaeological finds are more than 100,000 years old, as constrained by Optically Stimulated Luminescence (OSL)-dating in the Innsbruck laboratory. The study is challenging the idea that modern human behaviour was linked to coastal environments.

The origins of modern humans and modern human cognition are thought to lie in southern Africa, as suggested by numerous archaeological findings from the southern tip of the continent. Many of these archaeological sites are located near the coast. This led to the widespread view that the evolution of complex symbolic and technological behaviour of Homo sapiens presupposing cognitive abilities very similar to ours today, were linked to the sea and it´s rich marine resources such as shellfish, fish and and marine mammals. However, new archaeological findings in the Kalahari Desert in South Africa (the “African Outback”) now shed new light on human prehistory and the evolution of modern human behaviour. The current archaeological thinking is that behavioural innovations in early human history are tied to coastal landscapes, and particularly to the south coast of South Africa that is particularly rich in natural resources and offered plenty of marine food year-round, hence served as an evolutionary hotspot for our species. And indeed, archaeological evidence for early behavioural innovations are clustering along South Africa´s coast line. “In the present study we analysed findings from a rock shelter more than 600 kilometres inland and determined an age of 105,000 years for the archaeological layers and artefacts. They prove behavioural patterns equivalent to those found near the coast at the same time,” explains Michael Meyer. The geologist is head of the OSL Laboratory at the Institute of Geology at the University of Innsbruck and was responsible for dating the sediment samples from the South African archaeological excavations together with Luke Gliganic, a former post-doctoral researcher at the University of Innsbruck. The results were published in the journal Nature.

Geologist Michael Meyer in the luminescence laboratory at the University of Innsbruck. Optically Stimulated Luminescence (OSL) dating allows the natural light signals in quartz and feldspar grains to be measured and depositional ages of archaeological sediment layers to be accurately determined. Thousands of measurements on “miniaturized clocks”: Light stored in individual grains of sand is used for constraining the age of the archaeological finds and provided new insights into the history of modern human evolution. Credit: Robbie Shone

Rock shelter as a spiritual place

Given the paucity of known stratified archaeological sites in the interior of Africa, the rich archaeological assemblage unearthed by this study can be regarded as a stroke of luck. “There have been very few well-preserved, datable archaeological sites in the interior of southern Africa that can tell us about Homo sapiens occupational and evolutionary history deep inside the continent rather than from the coast. The rock shelter on Ga-Mohana Hill, a visually striking rock formation that stands above an expansive savannah landscape in the Kalahari is one such site. Our findings from this rock shelter show that overly simplified models for the origins of our species are no longer acceptable. Evidence suggests many regions across the African continent were involved, the Kalahari being just one,” says the study’s lead author, Jayne Wilkins from Griffith University in Australia. In the Kalahari Desert, the climate was wetter at the time of human presence and experienced a period of increased rainfall. The Ga-Mohana rock shelter was used as a spiritual site more than 100,000 years ago and continues to be used so today. Hence, the excavation team was conscious to minimise their impact on the local indigenous communities and on the site and back-filled the excavation pit after each season. The team found 22 white calcite crystals and fragments of ostrich eggshells, which were used by early humans as water containers. “Our analysis indicate that the calcite crystals were not introduced into the deposits via natural processes, but were deliberately collected objects likely linked to spiritual beliefs and rituals of early Homo sapiens,” adds the archaeologist.

Sand grain as miniaturized clocks

The chronology of the Ga-Mohana rock shelter was determined by the research team using Optically Stimulated Luminescence (OSL) dating. OSL dating is based on the measurement of light stored in grains of sand and is one of the most important dating techniques currently available in the earth sciences and in archaeology. “This method exploits natural light signals that accumulate through time in sedimentary quartz and feldspar grains. You have to think about each grain as a miniaturized clock. Under controlled laboratory conditions we can read out this natural light or so-called luminescence signal, which in turn informs us about the age of the archaeological sediment layers. The more light the older the sediment,” Michael Meyer describes the procedure. In the OSL laboratory at the University of Innsbruck, a broad range of geological and archaeological research questions have been investigated over the past years, with spatial research foci ranging from Africa to Australia, the Tibetan Plateau and the European Alps. The team in Innsbruck follows a particularly thorough dating approach: “We measure each sample on the single-grain level using dedicated laser equipment and statistical models to calculate sediment ages from hundreds of individual sedimentary quartz grains. This approach is labour-intensive and time-consuming and requires a high degree of methodological skill, but pays off, because of the enhanced robustness of the resulting OSL chronology. And it allows us to make much more precise statements about human-environment dynamics and interlinkages than would otherwise be possible with conventional dating approaches,” says the geologist. This was also the case at the Ga-Mohana rock shelter, where OSL single-grain dating matched perfectly with the age of independently dated climate archives, providing a much more detailed insight into human evolutionary history and concurrent climatic and environmental changes.

Featured image: The archaeological site at a rock shelter in South Africa’s Kalahari Desert: More than 100,000 years ago, people used the so-called Ga-Mohana Hill North Rockshelter for spiritual activities. (Credit: Jayne Wilkins)

Provided by University of Innsbruck

Ancient Skeletal Hand Could Reveal Evolutionary Secrets (Paleontology)

A 4.4 million-year-old skeleton could show how early humans moved and began to walk upright, according to new research led by a Texas A&M anthropology professor.

Evolutionary expert Charles Darwin and others recognized a close evolutionary relationship between humans, chimps and gorillas based on their shared anatomies, raising some big questions: how are humans related to other primates, and exactly how did early humans move around? Research by a Texas A&M University professor may provide some answers.

Thomas Cody Prang, assistant professor of anthropology, and colleagues examined the skeletal remains of Ardipithecus ramidus (“Ardi”), dated to 4.4 million years old and found in Ethiopia. One of Ardi’s hands was exceptionally well-preserved.

The researchers compared the shape of Ardi’s hand to hundreds of other hand specimens representing recent humans, apes and monkeys (measured from bones in museum collections around the world) to make comparisons about the kind of locomotor behavior used by the earliest hominins (fossil human relatives).

The results provide clues about how early humans began to walk upright and make similar movements that all humans perform today.

This discovery is described in a study published in the current issue of Science Advances.

“Bone shape reflects adaptation to particular habits or lifestyles – for example the movement of primates – and by drawing connections between bone shape and behavior among living forms, we can make inferences about the behavior of extinct species, such as Ardi, that we can’t directly observe, Prang said.

“Additionally, we found evidence for a big evolutionary ‘jump’ between the kind of hand represented by Ardi and all later hominin hands, including that of Lucy’s species (a famous 3.2 million-year-old well-preserved skeleton found in the same area in the 1970s). This ‘evolutionary jump’ happens at a critical time when hominins are evolving adaptations to a more human-like form of upright walking, and the earliest evidence for hominin stone-tool manufacture and stone-tool use, such as cut-marks on animal fossils, are discovered.”

Prang said the fact that Ardi represents an earlier phase of human evolutionary history is important because it potentially shines light on the kind of ancestor from which humans and chimpanzees evolved.

“Our study supports a classic idea first proposed by Charles Darwin in 1871, when he had no fossils or understanding of genetics, that the use of the hands and upper limbs for manipulation appeared in early human relatives in connection with upright walking,” he said. “The evolution of human hands and feet probably happened in a correlated fashion.”

Since Ardi is such an ancient species, it might retain skeletal features that were present in the last common ancestor of humans and chimpanzees. If this is true, it could help researchers place the origin of the human lineage – in addition to upright walking – into a clearer light.

“It potentially brings us one step closer to an explanation for how and why humans evolved our form of upright walking,” Prang said.

He added that the big change in hand anatomy between Ardi and all later hominins occurs at a time, roughly between 4.4 and 3.3 million years ago, coinciding with the earliest evidence of the loss of a grasping big toe in human evolution. This also coincides with the earliest known stone tools and stone cut-marked animal fossils.

He said it appears to mark a major change in the lifestyle and behavior of human relatives within this timeframe.

“We propose that it involves the evolution of more advanced upright walking, which enabled human hands to be modified by the evolutionary process for enhanced manual manipulation, possibly involving stone tools,” Prang said

This research was funded by the Wenner Gren Foundation.

Featured image: The skeletal fragments of “Ardi.” © Wikimedia Commons

Reference: Thomas C. Prang, Kristen Ramirez, Mark Grabowski and Scott A. Williams, “Ardipithecus hand provides evidence that humans and chimpanzees evolved from an ancestor with suspensory adaptations”, Science Advances  24 Feb 2021: Vol. 7, no. 9, eabf2474 DOI: 10.1126/sciadv.abf2474

Provided by Texas A&M

On the Origin of Our Species (Archeology)

New research suggests that genetic and fossil records will not reveal a single point where modern humans originated

Experts from the Natural History Museum, The Francis Crick Institute and the Max Planck Institute for the Science of Human History Jena have joined together to untangle the different meanings of ancestry in the evolution of our species Homo sapiens.

Most of us are fascinated by our ancestry, and by extension the ancestry of the human species. We regularly see headlines like ‘New human ancestor discovered’ or ‘New fossil changes everything we thought about our ancestry’, and yet the meanings of words like ancestor and ancestry are rarely discussed in detail. In the new paper, published in Nature, experts review our current understanding of how modern human ancestry around the globe can be traced into the distant past, and which ancestors it passes through during our journey back in time.

Co-author researcher at the Natural History Museum Prof Chris Stringer said: “Some of our ancestors will have lived in groups or populations that can be identified in the fossil record, whereas very little will be known about others. Over the next decade, growing recognition of our complex origins should expand the geographic focus of paleoanthropological fieldwork to regions previously considered peripheral to our evolution, such as Central and West Africa, the Indian subcontinent and Southeast Asia.”

The study identified three key phases in our ancestry that are surrounded by major questions, and which will be frontiers in coming research. From the worldwide expansion of modern humans about 40-60 thousand years ago and the last known contacts with archaic groups such as the Neanderthals and Denisovans, to an African origin of modern human diversity about 60-300,000 years ago, and finally the complex separation of modern human ancestors from archaic human groups about 300,000 to 1 million years ago.

The scientists argue that no specific point in time can currently be identified when modern human ancestry was confined to a limited birthplace, and that the known patterns of the first appearance of anatomical or behavioural traits that are often used to define Homo sapiens fit a range of evolutionary histories.

Co-author Pontus Skoglund from The Francis Crick Institute said: “Contrary to what many believe, neither the genetic or fossil record have so far revealed a defined time and place for the origin of our species. Such a point in time, when the majority of our ancestry was found in a small geographic region and the traits we associate with our species appeared, may not have existed. For now, it would be useful to move away from the idea of a single time and place of origin.”

“Following from this, major emerging questions concern which mechanisms drove and sustained this human patchwork, with all its diverse ancestral threads, over time and space,” said co-author Eleanor Scerri from the Pan-African Evolution Research Group at the Max Planck Institute for the Science of Human History. “Understanding the relationship between fractured habitats and shifting human niches will undoubtedly play a key role in unravelling these questions, clarifying which demographic patterns provide a best fit with the genetic and palaeoanthropological record.”

The success of direct genetic analyses so far highlights the importance of a wider, ancient genetic record. This will require continued technological improvements in ancient DNA (aDNA) retrieval, biomolecular screening of fragmentary fossils to find unrecognised human material, wider searches for sedimentary aDNA, and improvements in the evolutionary information provided by ancient proteins. Interdisciplinary analysis of the growing genetic, fossil and archaeological records will undoubtedly reveal many new surprises about the roots of modern human ancestry.

Featured image: This cranium from Jebel Irhoud in Morocco is often called a modern human ancestor. The meaning of that ancestry is discussed and disentangled in a new study by Bergstrom and colleagues © Chris Stringer

Reference: Anders Bergström, Chris Stringer, Mateja Hajdinjak, Eleanor M. L. Scerri & Pontus Skoglund, “Origins of modern human ancestry”, Nature, 2021.
DOI: 10.1038/s41586-021-03244-5

Provided by Max Planck Institute for the Science of Human History

Newly Discovered Receptor Helps to Sneak a Peek at Evolution (Biology)

What mammals and yeasts can do, plants can do, too: inserting proteins into membranes via a specific pathway. A legacy of their last common ancestor.

Certain proteins call for unusual ways to get incorporated into membranes, because the signal sequence required for this process is located at their rear end instead of at the front. The relevant mechanism and its components are well-known and well-studied in yeast and mammals. Scientists have already hypothesised that it also occurs in plants, but there was no evidence of an indispensable receptor, until now. Existence of the receptor was now proven experimentally by the team headed by Professor Christopher Grefen from the Chair of Molecular and Cellular Botany at Ruhr-Universität Bochum (RUB). The researchers published their report on the 5. January 2021 in the journal Proceedings of the National Academy of Sciences PNAS.

Dietmar Mehlhorn and Christopher Grefen (back) are on the trail of the previously undiscovered receptor. © RUB, Marquard

GET pathway for specific proteins

Together with lipids, membrane proteins are a central component of all biological membranes and fulfil important functions in transport and information transfer within and between cells. The majority of membrane proteins are recognised by a signal recognition particle on the basis of signal sequences at the front end of the protein and are incorporated into the membrane of the endoplasmic reticulum during their synthesis. From there, the proteins are transported to most of the important cellular membranes.

However, there is a functionally important family of membrane proteins whose signal sequence is located at the end of the protein. “Therefore, these proteins can’t be integrated into the membrane the usual way,” explains lead author Lisa Yasmin Asseck. These so-called tail-anchored (TA) proteins use a mechanism known as GET pathway. GET stands for Guided Entry of TA proteins.

Transport and insertion

The central component of the pathway is a vehicle within the cell fluid, the cytosolic ATPase GET3. It transfers the newly synthesized TA proteins to the receptors GET1 and GET2, which are bound to the endoplasmic reticulum and ensure their membrane insertion.

While the pathway with all its components has been thoroughly described in mammals and their more closely related yeasts, it remained puzzling in plants. “Some components could be identified in plants based on sequence similarities, but there was no trace of the receptor protein GET2,” says Christopher Grefen.

An ancient legacy

His team has now successfully identified this previously undiscovered receptor in the model plant Arabidopsis thaliana. By specifically eliminating the receptor – using for example the Crispr/Cas9 genetic scissors – the researchers were also able to study its function more closely. “The only difference between wildtype and Arabidopsis mutants lacking the GET2 receptor is that the latter develop shorter root hairs,” explains Grefen. “This does not restrict the growth of the plants under laboratory conditions, it could, however, pose a problem in the wild – especially when water is scarce.” Interestingly, mammals without a GET2 receptor are unable to survive, whereas yeast cells can grow, since they have developed a backup mechanism that kicks in when the receptor is missing.

A remarkable observation for the researchers is the fact that the GET2 receptors of different organisms show great structural similarities despite differences in sequence. “This suggests that their function is evolutionarily conserved. That means that the GET pathway has been around for a very long time, and today’s organisms have inherited it from their last common ancestor during evolution,” elaborates Christopher Grefen. “The discovery of the protein sequence of GET2 from Arabidopsis provides an important piece of the puzzle for understanding the cross-kingdom evolution of the GET pathway and, at the same time, serves as basis for further studies in other plant and algal species.”

The research was funded by a PhD scholarship of the Carl Zeiss Foundation as well as by the German Research Foundation within the Collaborative Research Centres 1190 and 1101 and the Emmy Noether Programme, funding codes GR 4251/1-1 and 1-2.

Reference: Lisa Yasmin Asseck, Dietmar Gerald Mehlhorn, Jhon Rivera Monroy, Martiniano Maria Ricardi, Holger Breuninger, Niklas Wallmeroth, Kenneth Wayne Berendzen, Minou Nowrousian, Shuping Xing, Blanche Schwappach, Martin Bayer, Christopher Grefen: ER membrane receptors of the GET pathway are conserved throughout eukaryotes, in: PNAS, 2020, DOI: 10.1073/pnas.2017636118 https://www.pnas.org/content/118/1/e2017636118

Provided by RUHR- University Bocham

Study Reveals True Origin of Oldest Evidence of Animals (Earth Science)

Two teams of scientists have resolved a longstanding controversy surrounding the origins of complex life on Earth.

The joint studies found molecular fossils extracted from 635-million-year-old rocks aren’t the earliest evidence of animals, but instead common algae.

Submerged algae. © Image of courtesy of Ilya Bobrovskiy

The researchers from The Australian National University (ANU), Max Planck Institute and Caltech say the finding has big implications for our understanding of evolution.

“It brings the oldest evidence for animals nearly 100 million years closer to the present day,” Dr Lennart van Maldegem from ANU, co-author author of one study, said.

“We were able to demonstrate that certain molecules from common algae can be altered by geological processes – leading to molecules which are indistinguishable from those produced by sponge-like animals.

Professor Jochen Brocks, also based at ANU, said the mystery of when our very earliest animal ancestors emerged and became abundant in the oceans has puzzled palaeontologists for more than a century.

“Ten years ago, scientists discovered the molecular fossils of an animal steroid in rocks that were once at the bottom of an ancient sea in the Middle East,” Professor Brocks said.

Sponge © M. Neumann

“The big question was, how could these sponges have been so abundant, covering much of the seafloor across the world, but leave no body fossils?”

Dr Ilya Bobrovskiy, lead author of the other study, said the researchers have been able to “solve this mystery”.

“While it holds true sponges are the only living organism which can produce these steroids, chemical processes can mimic biology and transform common and abundant algae sterols into ‘animal’ sterols,” he said.

“These molecules can be generated in the lab when simulating geological time and temperatures, but we also showed such processes did happen in ancient rocks.”

The two complementary studies have been published in Nature Ecology and Evolution.

References: http://dx.doi.org/10.1038/s41559-020-01336-5

Provided by Australian National University

Cognitive Elements of Language Have Existed for 40 Million Years (Language)

Humans are not the only beings that can identify rules in complex language-like constructions – monkeys and great apes can do so, too, a study at the University of Zurich has shown. Researchers at the Department of Comparative Language Science of UZH used a series of experiments based on an ‘artificial grammar’ to conclude that this ability can be traced back to our ancient primate ancestors.

The chimpanzees learned that certain sounds were always followed by other specific sounds, even if they were sometimes separated by other acoustic signals. (Image: Istock.com/Juanmonino)

Language is one of the most powerful tools available to humankind, as it enables us to share information, culture, views and technology. “Research into language evolution is thus crucial if we want to understand what it means to be human,” says Stuart Watson, postdoctoral researcher at the Department of Comparative Language Science of the University of Zurich. Until now, however, little research has been conducted about how this unique communication system came to be.

Identifying connections between words
An international team led by Professor Simon Townsend at the Department of Comparative Language Science of the University of Zurich has now shed new light on the evolutionary origins of language. Their study examines one of the most important cognitive elements needed for language processing – that is, the ability to understand the relationship between the words in a phrase, even if they are separated by other parts of the phrase, known as a “non-adjacent dependency”. For example, we know that in the sentence “the dog that bit the cat ran away”, it is the dog who ran away, not the cat, even though there are several other words in between the two phrases. A comparison between apes, monkeys and and humans has now shown that the ability to identify such non-adjacent dependencies is likely to have developed as far back as 40 million years ago.

Acoustic signals instead of words

The researchers used a novel approach in their experiments: They invented an artificial grammar, where sequences are formed by combining different sounds rather than words. This enabled the researchers to compare the ability of three different species of primates to process non-adjacent dependencies, even though they do not share the same communication system. The experiments were carried out with common marmosets – a monkey native to Brazil – at the University of Zurich, chimpanzees (University of Texas) and humans (Osnabrück University).

Mistakes followed by telltale looks
First, the researchers taught their test subjects to understand the artificial grammar in several practice sessions. The subjects learned that certain sounds were always followed by other specific sounds (e.g. sound ‘B’ always follows sound ‘A’), even if they were sometimes separated by other acoustic signals (e.g. ‘A’ and ‘B’ are separated by ‘X’). This simulates a pattern in human language, where, for example, we expect a noun (e.g. “dog”) to be followed by a verb (e.g. “ran away”), regardless of any other phrasal parts in between (e.g. “that bit the cat”).

In the actual experiments that followed, the researchers played sound combinations that violated the previously learned rules. In these cases, the common marmosets and chimpanzees responded with an observable change of behavior; they looked at the loudspeaker emitting the sounds for about twice as long as they did towards familiar combinations of sounds. For the researchers, this was an indication of surprise in the animals caused by noticing a ‘grammatical error’. The human test subjects were asked directly whether they believed the sound sequences were correct or wrong.

Common origin of language

“The results show that all three species share the ability to process non-adjacent dependencies. It is therefore likely that this ability is widespread among primates,” says Townsend. “This suggests that this crucial element of language already existed in our most recent common ancestors with these species.” Since marmosets branched off from humanity’s ancestors around 40 million years ago, this crucial cognitive skill thus developed many million years before human language evolved.

References: Stuart K. Watson, Judith M. Burkart, Steven J. Schapiro, Susan P. Lambeth, Jutta L. Mueller and Simon W. Townsend. Non-adjacent dependency processing in monkeys, apes and humans. Science Advances, 21, vol. 6, no. 43. October 2020. DOI: 10.1126/sciadv.abb0725

Provided by University of Zurich