Extinct giant lemurs of Madagascar


This 25 September 2019 video says about itself:

Just a few thousand years ago, the island of Madagascar was inhabited by giant lemurs. How did such a diverse group of primates evolve in the first place, and how did they help shape the unique environments of Madagascar? And how did they get winnowed down, leaving only their smaller relatives behind?

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Australopithecus anamensis discovery in Ethiopia


This 28 August 2019 video says about itself:

MRD cranium – the face of Australopithecus anamensis

In the Woranso-Mille area, Afar, Ethiopia, a 3.8-million-year-old hominin fossil cranium was discovered. Researchers lead by Dr. Yohannes Haile-Selassie (Cleveland Museum of Natural History/Case Western Reserve University) conclude that the fossil cranium MRD-VP-1/1 belongs to the species Australopithecus anamensis.

From the Max Planck Institute for Evolutionary Anthropology in Germany:

A face for Lucy’s ancestor

August 28, 2019

Summary: Researchers have discovered a remarkably complete 3.8-million-year-old cranium of Australopithecus anamensis at Woranso-Mille in Ethiopia. The 3.8 million-year-old fossil cranium represents a time interval between 4.1 and 3.6 million years ago.

Australopithecus anamensis is the earliest-known species of Australopithecus and widely accepted as the progenitor of ‘Lucy‘s’ species, Australopithecus afarensis. Until now, A. anamensis was known mainly from jaws and teeth. Yohannes Haile-Selassie of the Cleveland Museum of Natural History, Stephanie Melillo of the Max Planck Institute for Evolutionary Anthropology and their colleagues have discovered the first cranium of A. anamensis at the paleontological site of Woranso-Mille, in the Afar Region of Ethiopia.

The 3.8 million-year-old fossil cranium represents a time interval between 4.1 and 3.6 million years ago, when A. anamensis gave rise to A. afarensis. Researchers used morphological features of the cranium to identify which species the fossil represents. “Features of the upper jaw and canine tooth were fundamental in determining that MRD was attributable to A. anamensis”, said Melillo. “It is good to finally be able to put a face to the name.” The MRD cranium, together with other fossils previously known from the Afar, show that A. anamensis and A. afarensis co-existed for approximately 100,000 years. This temporal overlap challenges the widely-accepted idea of a linear transition between these two early human ancestors. Haile-Selassie said: “This is a game-changer in our understanding of human evolution during the Pliocene.”

Working for the past 15 years at the site, the team discovered the cranium (MRD-VP-1/1, here referred to as “MRD”) in February 2016. In the years following their discovery, paleoanthropologists of the project conducted extensive analyses of MRD, while project geologists worked on determining the age and context of the specimen. The results of the team’s findings are published online in two papers in the international scientific journal Nature.

Discovery of the cranium

The Woranso-Mille project has been conducting field research in the central Afar region of Ethiopia since 2004. The project has collected more than 12,600 fossil specimens representing about 85 mammalian species. The fossil collection includes about 230 fossil hominin specimens dating to between more than 3.8 and about 3.0 million years ago. The first piece of MRD, the upper jaw, was found by Ali Bereino (a local Afar worker) on February 10, 2016 at a locality known as Miro Dora, Mille district of the Afar Regional State. The specimen was exposed on the surface and further investigation of the area resulted in the recovery of the rest of the cranium. “I couldn’t believe my eyes when I spotted the rest of the cranium. It was a eureka moment and a dream come true,” said Haile-Selassie.

Geology and age determination

In a companion paper published in the same issue of Nature, Beverly Saylor of Case Western Reserve University and her colleagues determined the age of the fossil as 3.8 million years by dating minerals in layers of volcanic rocks nearby. They mapped the dated levels to the fossil site using field observations and the chemistry and magnetic properties of rock layers. Saylor and her colleagues combined the field observations with analysis of microscopic biological remains to reconstruct the landscape, vegetation and hydrology where MRD died.

MRD was found in the sandy deposits of a delta where a river entered a lake. The river likely originated in the highlands of the Ethiopian plateau while the lake developed at lower elevations where rift activity caused the Earth surface to stretch and thin, creating the lowlands of the Afar region. Fossil pollen grains and chemical remains of fossil plant and algae that are preserved in the lake and delta sediments provide clues about the ancient environmental conditions. Specifically they indicate that the watershed of the lake was mostly dry but that there were also forested areas on the shores of the delta or along the side the river that fed the delta and lake system. “MRD lived near a large lake in a region that was dry. We’re eager to conduct more work in these deposits to understand the environment of the MRD specimen, the relationship to climate change and how it affected human evolution, if at all,” said Naomi Levin, a co-author on the study from University of Michigan.

A new face in the crowd

Australopithecus anamensis is the oldest known member of the genus Australopithecus. Due to the cranium’s rare near-complete state, the researchers identified never-before-seen facial features in the species. “MRD has a mix of primitive and derived facial and cranial features that I didn’t expect to see on a single individual,” Haile-Selassie said. Some characteristics were shared with later species, while others had more in common with those of even older and more primitive early human ancestor groups such as Ardipithecus and Sahelanthropus. “Until now, we had a big gap between the earliest-known human ancestors, which are about 6 million years old, and species like ‘Lucy’, which are two to three million years old. One of the most exciting aspects of this discovery is how it bridges the morphological space between these two groups,” said Melillo.

Branching out

Among the most important findings was the team’s conclusion that A. anamensis and its descendant species, the well-known A. afarensis, coexisted for a period of at least 100,000 years. This finding contradicts the long-held notion of an anagenetic relationship between these two taxa, instead supporting a branching pattern of evolution. Melillo explains: “We used to think that A. anamensis gradually turned into A. afarensis over time. We still think that these two species had an ancestor-descendent relationship, but this new discovery suggests that the two species were actually living together in the Afar for quite some time. It changes our understanding of the evolutionary process and brings up new questions — were these animals competing for food or space?”

This conclusion is based on the assignment of the 3.8-million-year-old MRD to A. anamensis and the 3.9-million-year-old hominin cranial fragment commonly known as the Belohdelie frontal, to A. afarensis. The Belohdelie frontal was discovered in the Middle Awash of Ethiopia by a team of paleontologists in 1981, but its taxonomic status has been questioned in the intervening years.

The new MRD cranium enabled the researchers to characterize frontal morphology in A. anamensis for the first time and to recognize that these features differed from the morphology common to the Belohdelie frontal and to other cranial specimens already known for Lucy’s species. As a result, the new study confirms that the Belohdelie frontal belonged to an individual of Lucy’s species. This identification extends the earliest record of A. afarensis back to 3.9 million years ago, while the discovery of MRD nudges the last appearance date of A. anamensis forward to 3.8 million years — indicating the overlap period of at least 100,000 years.

Paranthropus prehistoric hominins, video


This 24 August 2019 video says about itself:

Paranthropus Evolution

2 million years ago an upright walking group of hominins roamed Africa. Not our ancestors but Paranthropus. Who were they? How are we related? Did they give us herpes? Also, other questions!

Monkey, ape brain evolution, new research


This 21 August 2019 video says about itself:

See the digital reconstruction of an ancient monkey’s skull | Science News

The digital reconstruction of an extinct South American monkey’s fossilized skull, seen twirling in this video, offered a rare chance to study brain development in a 20-million-year-old animal. From high-resolution X-ray CT scans of the skull, researchers built a 3-D model of the brain of Chilecebus carrascoensis, seen in the second part of the video.

Read more here.

From the American Museum of Natural History in the USA:

20-million-year-old skull suggests complex brain evolution in monkeys, apes

New study reveals that brain enlargement and modern features evolved repeatedly in anthropoids

August 21, 2019

It has long been thought that the brain size of anthropoid primates — a diverse group of modern and extinct monkeys, humans, and their nearest kin — progressively increased over time. New research on one of the oldest and most complete fossil primate skulls from South America shows instead that the pattern of brain evolution in this group was far more checkered. The study, published today in the journal Science Advances and led by researchers from the American Museum of Natural History, the Chinese Academy of Sciences, and the University of California Santa Barbara, suggests that the brain enlarged repeatedly and independently over the course of anthropoid history, and was more complex in some early members of the group than previously recognized.

“Human beings have exceptionally enlarged brains, but we know very little about how far back this key trait started to develop,” said lead author Xijun Ni, a research associate at the Museum and a researcher at the Chinese Academy of Sciences. “This is in part because of the scarcity of well-preserved fossil skulls of much more ancient relatives.”

As part of a long-term collaboration with John Flynn, the Museum’s Frick Curator of Fossil Mammals, Ni spearheaded a detailed study of an exceptional 20-million-year-old anthropoid fossil discovered high in the Andes mountains of Chile, the skull and only known specimen of Chilecebus carrascoensis.

“Through more than three decades of partnership and close collaboration with the National Museum of Chile, we have recovered many remarkable new fossils from unexpected places in the rugged volcanic terrain of the Andes,” Flynn said. “Chilecebus is one of those rare and truly spectacular fossils, revealing new insights and surprising conclusions every time new analytical methods are applied to studying it.”

Previous research by Flynn, Ni, and their colleagues on Chilecebus provided a rough idea of the animal’s encephalization, or the brain size relative to body size. A high encephalization quotient (EQ) signifies a large brain for an animal of a given body size. Most primates have high EQs relative to other mammals, although some primates — especially humans and their closest relatives — have even higher EQs than others. The latest study takes this understanding one step further, illustrating the patterns across the broader anthropoid family tree. The resulting “PEQ” — or phylogenetic encephalization quotient, to correct for the effects of close evolutionary relationships — for Chilecebus is relatively small, at 0.79. Most living monkeys, by comparison, have PEQs ranging from 0.86 to 3.39, with humans coming in at an extraordinary 13.46 and having expanded brain sizes dramatically even compared to nearest relatives. With this new framework, the researchers confirmed that cerebral enlargement occurred repeatedly and independently in anthropoid evolution, in both New and Old World lineages, with occasional decreases in size.

High-resolution x-ray computed tomography (CT) scanning and 3D digital reconstruction of the inside of Chilecebus’ skull gave the research team new insights into the anatomy of its brain. In modern primates, the size of the visual and olfactory centers in the brain are negatively correlated, reflecting a potential evolutionary “trade-off”, meaning that visually acute primates typically have weaker senses of smell. Surprisingly, the researchers discovered that a small olfactory bulb in Chilecebus was not counterbalanced by an amplified visual system. This finding indicates that in primate evolution the visual and olfactory systems were far less tightly coupled than was widely assumed.

Other findings: The size of the opening for the optic nerve suggests that Chilecebus was diurnal. Also, the infolding (sulcus) pattern of the brain of Chilecebus, although far simpler than in most modern anthropoids, possesses at least seven pairs of sulcal grooves and is surprisingly complex for such an ancient primate.

“During his epic voyage on the Beagle, Charles Darwin explored the mouth of the canyon where Chilecebus was discovered 160 years later. Shut out of the higher cordillera by winter snow, Darwin was inspired by ‘scenes of the highest interest’ his vista presented. This exquisite fossil, found just a few kilometers east of where Darwin stood, would have thrilled him”, said co-author André Wyss from the University of California Santa Barbara.

‘Human-Neandertal split about 1 million years ago’


This March 2017 video says about itself:

National Geographic | THE NEANDERTHALS | FIRST PEOPLES OF EUROPE | HD Full Documentary

Neanderthals or Neandertals were a species or subspecies of archaic human, in the genus Homo, which became extinct around 40,000 years ago. They were closely related to modern humans, sharing 99.7% of DNA.

By Bruce Bower, 2:00pm, May 15, 2019:

Fossil teeth push the human-Neandertal split back to about 1 million years ago

A new study estimates the age of these hominids’ last common ancestor

People and Neandertals separated from a common ancestor more than 800,000 years ago — much earlier than many researchers had thought.

That conclusion, published online May 15 in Science Advances, stems from an analysis of early fossilized Neandertal teeth found at a Spanish site called Sima de los Huesos. During hominid evolution, tooth crowns changed in size and shape at a steady rate, says Aida Gómez-Robles, a paleoanthropologist at University College London. The Neandertal teeth, which date to around 430,000 years ago, could have evolved their distinctive shapes at a pace typical of other hominids only if Neandertals originated between 800,000 and 1.2 million years ago, she finds.

Gómez-Robles’ study indicates that, if a common ancestor of present-day humans and Neandertals existed after around 1 million years ago, “there wasn’t enough time for Neandertal teeth to change at the rate [teeth] do in other parts of the human family tree” in order to end up looking like the Spanish finds, says palaeoanthropologist Bernard Wood of George Washington University in Washington, D.C.

Many researchers have presumed that a species dubbed Homo heidelbergensis, thought to have inhabited Africa and Europe, originated around 700,000 years ago and gave rise to an ancestor of both Neandertals and Homo sapiens by roughly 400,000 years ago. Genetic evidence that Sima de los Huesos fossils came from Neandertals raised suspicions that a common ancestor with H. sapiens existed well before that (SN Online: 3/14/16). Recent Neandertal DNA studies place that common ancestor at between 550,000 and 765,000 years old. But those results rest on contested estimates of how fast and how consistently genetic changes accumulated over time.

With that molecular debate in mind, Gómez-Robles calculated the rate at which eight ancient hominid species evolved changes in tooth shape. That enabled her to gauge how long it must have taken for Sima de los Huesos teeth to evolve after Neandertals diverged from a common ancestor with H. sapiens.

Gómez-Robles used two possible evolutionary trees for the eight hominid species to estimate dental evolution rates. Aside from the Spanish Neandertals and Stone Age H. sapiens, teeth in her study came from African hominids dating to as early as 3.2 million years ago.

Moving back the date of an evolutionary split between Neandertals and H. sapiens appears reasonable based on the new data, says paleoanthropologist Aurélien Mounier of Musée de l’Homme in Paris. The timing of that split could still change, though, if further research modifies the Spanish fossils’ age, he says.

Other Spanish hominid teeth dating to nearly 800,000 years ago display some Neandertal features, supporting the new study’s conclusions, says New York University paleoanthropologist Shara Bailey. But it’s unclear if Gómez-Robles’ contention that hominid teeth evolved at a steady rate will hold true, Bailey says.

Declining fertility rates may explain Neanderthal extinction: here.

Denisovans, first hominins of Tibetan Plateau


This 2 May 2019 video is called Tibetan Monk Finds 160,000 Year-Old DENISOVAN Mandible,

From the Max Planck Institute for Evolutionary Anthropology in Germany:

First hominins on the Tibetan Plateau were Denisovans

Denisovan mandible likely represents the earliest hominin fossil on the Tibetan Plateau

May 1, 2019

Summary: So far Denisovans were only known from a small collection of fossil fragments from Denisova Cave in Siberia. A research team now describes a 160,000-year-old hominin mandible from Xiahe in China. Using ancient protein analysis the researchers found that the mandible’s owner belonged to a population that was closely related to the Denisovans from Siberia. This population occupied the Tibetan Plateau in the Middle Pleistocene and was adapted to this low-oxygen environment long before Homo sapiens arrived in the region.

Denisovans — an extinct sister group of Neandertals — were discovered in 2010, when a research team led by Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) sequenced the genome of a fossil finger bone found at Denisova Cave in Russia and showed that it belonged to a hominin group that was genetically distinct from Neandertals. “Traces of Denisovan DNA are found in present-day Asian, Australian and Melanesian populations, suggesting that these ancient hominins may have once been widespread,” says Jean-Jacques Hublin, director of the Department of Human Evolution at the MPI-EVA. “Yet so far the only fossils representing this ancient hominin group were identified at Denisova Cave.”

Mandible from Baishiya Karst Cave

In their new study, the researchers now describe a hominin lower mandible that was found on the Tibetan Plateau in Baishiya Karst Cave in Xiahe, China. The fossil was originally discovered in 1980 by a local monk who donated it to the 6th Gung-Thang Living Buddha who then passed it on to Lanzhou University. Since 2010, researchers Fahu Chen and Dongju Zhang from Lanzhou University have been studying the area of the discovery and the cave site from where the mandible originated. In 2016, they initiated a collaboration with the Department of Human Evolution at the MPI-EVA and have since been jointly analysing the fossil.

While the researchers could not find any traces of DNA preserved in this fossil, they managed to extract proteins from one of the molars, which they then analysed applying ancient protein analysis. “The ancient proteins in the mandible are highly degraded and clearly distinguishable from modern proteins that may contaminate a sample,” says Frido Welker of the MPI-EVA and the University of Copenhagen. “Our protein analysis shows that the Xiahe mandible belonged to a hominin population that was closely related to the Denisovans from Denisova Cave.”

Primitive shape and large molars

The researchers found the mandible to be well-preserved. Its robust primitive shape and the very large molars still attached to it suggest that this mandible once belonged to a Middle Pleistocene hominin sharing anatomical features with Neandertals and specimens from the Denisova Cave. Attached to the mandible was a heavy carbonate crust, and by applying U-series dating to the crust the researchers found that the Xiahe mandible is at least 160,000 years old. Chuan-Chou Shen from the Department of Geosciences at National Taiwan University, who conducted the dating, says: “This minimum age equals that of the oldest specimens from the Denisova Cave.”

“The Xiahe mandible likely represents the earliest hominin fossil on the Tibetan Plateau,” says Fahu Chen, director of the Institute of Tibetan Research, CAS. These people had already adapted to living in this high-altitude low-oxygen environment long before Homo sapiens even arrived in the region. Previous genetic studies found present-day Himalayan populations to carry the EPAS1 allele in their genome, passed on to them by Denisovans, which helps them to adapt to their specific environment.

“Archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene and successfully adapted to high-altitude low-oxygen environments long before the regional arrival of modern Homo sapiens,” says Dongju Zhang. According to Hublin, similarities with other Chinese specimens confirm the presence of Denisovans among the current Asian fossil record. “Our analyses pave the way towards a better understanding of the evolutionary history of Middle Pleistocene hominins in East Asia.”

An analysis of a 160,000-year-old archaic human [Denisovan] molar fossil discovered in China offers the first morphological evidence of interbreeding between archaic humans and Homo sapiens in Asia: here.

Genetic analysis has revealed that the ancestors of modern humans interbred with at least five different archaic human groups as they moved out of Africa and across Eurasia. While two of the archaic groups are currently known — the Neandertals and their sister group the Denisovans from Asia — the others remain unnamed and have only been detected as traces of DNA surviving in different modern populations. Island Southeast Asia appears to have been a particular hotbed of diversity: here.

This ancient Denisovan finger bone is surprisingly humanlike. Yet the extinct hominids had closer genetic ties to Neandertals than Homo sapiens: here.

Many people are familiar with the existence of Neanderthals, the humanoid species that was a precursor to modern humans, but far less is known Denisovans, a similar group that were contemporaries to the Neanderthals and who died out approximately 50,000 years ago. Researchers have now made a reconstruction of a Denisovan girl based on patterns of methylation (chemical changes) in their ancient DNA: here.

How tarsiers see, virtual reality


This May 2018 video is called Tarsier Goggles Demo.

From Dartmouth College in the USA:

New virtual reality tool allows you to see the world through the eyes of a tiny primate

‘Tarsier Goggles’ simulates vision of a tarsier

March 25, 2019

Imagine that you live in the rainforests of Southeast Asia, you’re a pint-sized primate with enormous eyes that are roughly the same size as your brain, and you look a little like Gizmo from the movie “Gremlins“, You’re a tarsier — a nocturnal animal whose giant eyes provide you with exceptional visual sensitivity, enabling a predatory advantage. A new virtual reality software, Tarsier Goggles, developed at Dartmouth College, simulates a tarsier‘s vision and illustrates the adaptive advantage of this animal’s oversized eyes. Both the virtual reality build and the team’s findings published recently in Evolution: Education and Outreach are available for free online.

Tarsier Goggles was developed by Samuel Gochman, while he was a student at Dartmouth and Nathaniel J. Dominy, the Charles Hansen Professor of Anthropology at Dartmouth, who studies the evolution of primate sensory systems, in collaboration with the Dartmouth Applied Learning and Innovation (DALI) Lab, where students design and build technology.

Gochman approached the DALI Lab with a problem: how could he change the human perception of our world by experiencing the tarsier‘s unique ocular adaptations. Through an iterative process, the DALI team explored different design solutions upon which Gochman and the team determined that a virtual reality experience would be best, as it is not only immersive but could also be used as a teaching tool in a classroom setting.

The open-access software, Tarsier Goggles, features three virtual learning environments — “Matrix”, “Labyrinth” and “Bornean Rainforest”, which simulate how a tarsier’s vision is different from a human’s in terms of acuity, color vision and brightness. Bornean tarsiers have protanopia, a form of red-green colorblindness. In the virtual Bornean Rainforest, users can move through the forest, leaping and clinging to trees in “a dark, maze-like space that is practically opaque under human visual conditions but navigable as a tarsier, demonstrating the advantages of tarsier visual sensitivity,” as described by the authors.

“Most ninth- and 10th-grade students in the U.S. learn about optics and natural selection, but the two topics are usually treated in isolation,” says Dominy, who served as one of the co-authors. “The tarsier is an effective means of unifying both concepts. You have to understand optical principles to understand why natural selection would favor such enormous eyes in such a tiny predator.”

At Dartmouth, Gochman focused in biological anthropology and human-centered design, and this project was one of the ways he applied these research interests. “I realized that most students’ learning of natural selection was limited to diagrams, slideshows and models,” says Gochman, who served as the lead author of the study. “Virtual reality offers an immersive experience for understanding some of the properties of the tarsier’s vision, as a result of its adaptations. Tarsier Goggles is a science education tool that engages students in hands-on scientific concepts in physics, perceptual science and biology”, he adds.

As part of the study, Gochman demonstrated Tarsier Goggles at two on-campus events at Dartmouth, an anthropological society meeting and to a class of sixth-graders visiting the Vermont Institute of Natural Science in Quechee, Vt. He also demonstrated the technology to high school students at Kimball Union Academy in Meriden, N.H., where students in science and anthropology classes watched a brief video on tarsiers’ foraging behavior followed by the opportunity to try out this virtual reality technology for five minutes each. The students then completed a brief post-survey with open-ended questions, which was part of Gochman’s formal assessment of the virtual reality tool.

“The Tarsier Goggles project engaged my students first-hand in a learning experience, which could not have been achieved through any other medium,” explains Marilyn Morano Lord ’95, MALS ’97, an anthropology and world history teacher at Kimball Union Academy, who also served as one of the co-authors of the paper.

Tarsier Goggles was built in Unity3D with SteamVR for the HTC VivePro, and was coded in C#. The Virtual Reality Toolkit was used to create functionalities such as teleportation. For many of the visual effects, Unity’s built-in post processing stack was utilized, and the assets were built in Maya. All the visual assets and experience was coded from scratch by the DALI team based on the lab’s collaborative, human-centered design approach.

Tarsier Goggles illustrates the possibilities for how virtual reality can be applied to science education by providing students with a fun, interactive way to explore complex concepts.