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.

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‘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.

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.

Animals’ emotions, new Frans de Waal boek


This 2016 video says about itself:

Jan van Hooff visits chimpanzee “Mama”, 59 yrs old and very sick. Emotional meeting

Mama, 59 years old and the oldest chimpanzee and the matriarch of the famous chimpanzee colony of the Royal Burgers Zoo in Arnhem, the Netherlands, was gravely ill.

Jan van Hooff (emeritus professor behavioural biology at Utrecht University and co-founder of the Burgers colony) who has known Mama since 1972, visited her in the week before she died of old age in April 2016. It took a while before she became aware of Jan’s presence. Her reaction was extremely emotional and heart-breaking. Mama played an important social role in the colony. This has been described in “Chimpanzee Politics” by Frans de Waal, who studied the colony since 1974.

By Erin Wayman, 6:00am, February 26, 2019:

‘Mama’s Last Hug’ showcases the emotional lives of animals

Primatologist Frans de Waal explores the roots of fear, laughter, empathy and more

Mama’s Last Hug
Frans de Waal
W.W. Norton & Co, $27.95

During the last few weeks of her life, Mama, an elderly chimpanzee at a zoo in the Netherlands, received a special visitor. As Mama lay curled up on a mound of straw, biologist Jan van Hooff entered her enclosure. Van Hooff, who had known Mama for more than 40 years, knelt down and stroked the arm of the listless chimp. When Mama looked up, her vacant face erupted into a smile. She reached out to van Hooff, calling out as she patted his face and neck.

For primatologist Frans de Waal, this touching scene isn’t difficult to interpret: Mama was happy to see her old friend. But such an interpretation has been taboo among many behavioral scientists, who have claimed nonhuman animals are like unthinking, emotionless machines that react to situations with preprogrammed instincts.

In the thought-provoking Mama’s Last Hug, de Waal dismantles that view. He presents piles of evidence that animals are emotional beings. The book is a companion to Are We Smart Enough to Know How Smart Animals Are?, in which he explored animal intelligence (SN: 12/24/16 & 1/7/17, p. 40).

Emotions, de Waal writes, “are bodily and mental states — from anger and fear to sexual desire and affection and seeking the upper hand — that drive behavior.” On page after page, he tells of depressed fish, empathetic rats, envious monkeys and other emotional creatures. More than a collection of fascinating anecdotes, Mama’s Last Hug weaves together formal observations of animals in the wild and in captivity, behavioral experiments and neuroscience research.

That animals have emotions makes sense from an evolutionary perspective, de Waal explains. The basic physiology and brain chemistry that give rise to emotions in humans are present in other members of the animal kingdom. And emotions offer a much more flexible way to evaluate and respond to events in an ever-changing environment than instincts do.

Of course, other animals’ emotions are not the same as human emotions, de Waal notes. There are differences “in the details, elaborations, applications and intensity.” And whether other animals are aware of their emotions, what de Waal defines as “feelings”, is still up for debate, he says.

De Waal’s conversational writing is at times moving, often funny and almost always eye-opening. Though some of his claims are more persuasive than others, it’s hard to walk away from Mama’s Last Hug without a deeper understanding of our fellow animals and our own emotions.

Ancestor species of humans, video


This 29 January 2019 video says about itself:

The Humans That Lived Before Us

As more and more fossil ancestors have been found, our genus has become more and more inclusive, incorporating more members that look less like us, Homo sapiens. By getting to know these other hominins–the ones who came before us–we can start to answer some big questions about what it essentially means to be human.

Chinese fossil human relative’s teeth, new research


This November 2015 video says about itself:

Late Pleistocene Hominins of Continental Asia

Hominin evolution just got alot more complicated! Maria Martinon-Torres discusses her work with Chinese palaeoanthropologists in China.

From Ohio State University in the USA:

An ancient relative of humans shows a surprisingly modern trait

Study finds an archaic hominin had modern dental growth

January 16, 2019

A relative of modern humans that lived at least 104,000 years ago in northern China showed evidence of dental growth and development very similar to that of people today, a new study found.

An international team of scientists performed the first systematic assessment of dental growth and development in an East Asian archaic hominin fossil that is known as the Xujiayao juvenile.

The fossil is of a 6 1/2-year-old who lived between 104,000 and 248,000 years ago found at the Xujiayao site in northern China.

The researchers were surprised to find that in most ways, this child’s dental development was very similar to what you would find in a child today, said Debbie Guatelli-Steinberg, co-author of the study and professor of anthropology at The Ohio State University.

“The Xujiayao juvenile is the oldest fossil found in east Asia that has dental development comparable to modern humans,” Guatelli-Steinberg said.

“It may suggest that these archaic humans had a slow life history like modern humans, with a prolonged period of childhood dependency.”

The study was published today (1-16-19) in the journal Science Advances.

Teeth provide some of the best data anthropologists have about the growth and development of our ancient ancestors, she said. That’s because growth lines in teeth retain a record of dental development.

Compared to our primate cousins, modern humans — including their teeth — take a long time to form and develop. Anthropologists believe this characteristic is associated with humans’ longer periods of child dependency — how long a juvenile relies on support from a caregiver.

Among other techniques, the researchers used synchrotron X-ray imaging to look inside the fossil to see the internal structure of the teeth, including growth lines that revealed the rate of tooth development.

The results were surprising in part because so many other features of this hominin are not modern, such as the shape and thickness of the skull and the large size of the teeth, according to the researchers.

“We don’t know exactly where this enigmatic East Asian hominin fits in human evolution,” said Song Xing, lead author of the study, who is at the Chinese Academy of Sciences in Beijing.

“It has some affinities to archaic human relatives like the Denisovans and Neanderthals with, as we found, some more modern features. It is a strange mosaic.”

Using the growth lines in the teeth, the researchers estimated the death of the Xujiayao juvenile at about 6 1/2 years of age, said study co-author Mackie O’Hara, a graduate student in anthropology at Ohio State.

The first molar of this juvenile — what we call the 6-year-molar today — had erupted a few months before death and had started to wear a bit. The root was about three-quarters complete, similar to humans today.

“We found that this juvenile was growing up — at least dentally — according to a schedule similar to that of modern people,” O’Hara said.

Another aspect that was similar to modern humans was the perikymata, which are the incremental growth lines that appear on the surface of the tooth.

“We found that the way these perikymata were distributed on the Xujiayao juvenile teeth was close to what we see in modern humans, and not to Neanderthals,” Guatelli-Steinberg said.

Another interesting finding related to the long-period growth line, which is laid down about every eight days in modern humans.

“This juvenile had a 10-day rhythm, which you don’t see very often in early hominins,” she said. “Most of the early hominins had a shorter rhythm, closer to seven days. This is another aspect that is much more modern.”

The one aspect of dental development in the Xujiayao juvenile that was not modern was the rate of growth in the roots of the teeth. Here, the juvenile showed relatively fast growth, compared to a slower growth in modern humans.

While the dental development of this juvenile suggested it had a slow life course similar to modern humans, Guatelli-Steinberg cautioned that we don’t know what happens in later childhood in hominins like this one.

“It would be interesting to see if dental development in later childhood, such as the growth and development of third molars, was also similar to modern humans,” she said.

An ancient child from East Asia grew teeth like a modern human. The youngster’s species is unknown for now. By Bruce Bower, 2:12pm, January 16, 2019.

Modern human DNA computational analysis suggests that the extinct species was a hybrid of Neanderthals and Denisovans and cross bred with Out of Africa modern humans in Asia. This finding would explain that the hybrid found this summer in the caves of Denisova — the offspring of a Neanderthal mother and a Denisovan father — was not an isolated case, but rather was part of a more general introgression process: here.

The first known fossil of a Denisovan skull has been found in a Siberian cave. DNA evidence hints that the hominids interbred with humans as recently as 15,000 years ago. By Bruce Bower, 11:01am, March 29, 2019.