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.

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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.

Primates’ origin in North America, not Asia?


This 29 November 2018 video from the USA says about itself:

Early primate ancestor may have come from North America

A mouse-sized primate known as Teilhardina eventually gave rise to today’s monkeys, apes and humans. But one of the persistent mysteries about this distant relative of ours is where it came from. New research by University of Florida doctoral graduate Paul Morse shows that Teilhardina brandti, a species found in Wyoming, is as old or older than its Asian and European relatives, upending the prevailing hypothesis that this early primate first appeared in China.

From the Florida Museum of Natural History in the USA:

Oldest-known ancestor of modern primates may have come from North America, not Asia

November 29, 2018

Summary: A new fossil analysis suggests the earliest-known ancestor of modern primates may have come from North America, not Asia, as previously thought.

About 56 million years ago, on an Earth so warm that palm trees graced the Arctic Circle, a mouse-sized primate known as Teilhardina first curled its fingers around a branch.

The earliest-known ancestor of modern primates, Teilhardina’s close relatives would eventually give rise to today’s monkeys, apes and humans. But one of the persistent mysteries about this distant cousin of ours is where it originated.

Teilhardina (ty-hahr-DEE’-nuh) species quickly spread across the forests of Asia, Europe and North America, a range unparalleled by all other primates except humans. But where did its journey begin?

New research shows that Teilhardina brandti, a species found in Wyoming, is as old or older than its Asian and European relatives, upending the prevailing hypothesis that Teilhardina first appeared in China.

Teilhardina’s origins, however, remain a riddle.

“The scientific conclusion is ‘We just don’t know,'” said Paul Morse, the study’s lead author and a recent University of Florida doctoral graduate. “While the fossils we’ve found potentially overturn past hypotheses of where Teilhardina came from and where it migrated, they definitely don’t offer a clearer scenario.”

What is clear, Morse said, is that T. brandti had a wide variety of features, some of which are as primitive as those found in Teilhardina asiatica, its Asian cousin, previously thought to be the oldest species in the genus.

To make this determination, Morse studied 163 teeth and jaws in the most comprehensive analysis of T. brandti to date.

Teeth contain a treasure-trove of information and often preserve better than bone, thanks to their tough enamel. They can reveal clues about an animal’s evolutionary past, its size, diet and age as an individual and in geological time.

Primate teeth have particularly distinct structures that are immediately recognizable to the trained eye, said Jonathan Bloch, study co-author and curator of vertebrate paleontology at the Florida Museum of Natural History.

“Identifying differences between primate teeth is not so different from a biker recognizing that a Harley is different from a scooter or an art critic evaluating whether an image was created by Picasso or Banksy,” he said. “In detail, they are very different from each other in specific, predictable ways.”

While Teilhardina bones are very rare in the fossil record, its teeth are more plentiful — if you know how to find them. Bloch’s team of paleontologists, Morse included, have spent years combing the surface of Wyoming’s Bighorn Basin on hands and knees and then packing out 50-pound bags of soil to a river to screen wash. The remaining bits of bones and teeth — which can be smaller than a flea — are examined under a microscope back at the museum.

This painstaking search has built up the dental record of T. brandti from a single molar — used to first describe the species in 1993 — to hundreds of teeth, providing a broad look at the primate’s population-level variation.

Still, Morse and Bloch were unprepared for the peculiar variation exhibited by specimen UF 333700, a jagged piece of jaw with T. brandti teeth.

“Jon and I started arguing about the alveoli” — empty tooth sockets — “and how they didn’t look right at all,” said Morse, now a postdoctoral researcher at Duke University. “By the end of the day, we realized that specimen completely overturned both the species definition of T. asiatica and part of the rationale for why it is the oldest Teilhardina species.”

Studies based on a small number of teeth simply missed the diversity in Teilhardina’s physical characteristics, Morse said.

“There’s likely a tremendous amount of variation in the fossil record, but it’s extremely difficult to capture and measure when you have a small sample size,” he said. “That’s one of the reasons collecting additional fossils is so important.”

The analysis also reshuffled the Teilhardina family tree, reducing the number of described species from nine to six and reclassifying two species as members of a new genus, Bownonomys, named for prominent vertebrate paleontologist Thomas Bown.

But the precise ages of Teilhardina species are still impossible to pinpoint and may remain that way.

Teilhardina appeared during the geological equivalent of a flash in the pan, a brief 200,000-year period known as the Paleocene-Eocene Thermal Maximum, or PETM. This era was characterized by a massive injection of carbon into the Earth’s atmosphere, which sent global temperatures soaring. Sea levels surged by 220 feet, ecosystems were overhauled and the waters at the North Pole warmed to 74 degrees.

Scientists can use the distinct carbon signature of the PETM to locate this period in the rock record, and carbon isotopes in teeth can also be used to identify fossil animals from the era.

But among Teilhardina fossil sites across the globe, only Wyoming has the uninterrupted, neatly demarcated layers of rock that allow paleontologists to hone in on more precise dates.

“The humblest statement would be to say that these species are essentially equivalent in age,” Bloch said. “Determining which came earlier in the PETM probably surpasses the level of resolution we have in the rock record. But what we can say is that the only place where you can really establish where Teilhardina appears in this climate event with confidence is in the Bighorn Basin.”

As the Earth warmed, plants and animals expanded their ranges northward, returning south as temperatures cooled at the end of the PETM.

“This dance of plants and animals with climate change happened over vast landscapes, with forests moving from the Gulf Coast to the Rocky Mountains in just a few thousand years,” Bloch said.

Teilhardina likely tracked the shifts in its forest habitats across the land bridges that then connected North America, Greenland and Eurasia, he said.

“Teilhardina is not throwing its bag over its shoulder and walking,” he said. “Its range is shifting from one generation to the next. Over 1,000 years, you get a lot of movement, and over 2,000-3,000 years, you could easily cover continental distances.”

While it was well-suited to Earth’s hothouse environment, Teilhardina disappeared with the PETM, replaced by new and physically distinct primates. It’s a sobering reminder of what can happen to species — including humans — during periods of swift climatic changes, Bloch said.

“A changing planet has dramatic effects on biology, ecosystems and evolution. It’s part of the process that has produced the diversity of life we see today and mass extinctions of life that have happened periodically in Earth’s history,” Bloch said. “One of the unexpected results of global warming 56 million years ago is that it marks the origin of the group that ultimately led to us. How we will fare under future warming scenarios is less certain.”

Primate evolution, video


This 16 October 2018 video says about itself:

Purgatorius, a kind of mammal called a plesiadapiform, might’ve been one of your earliest ancestors. But how did we get from a mouse-sized creature that looked more like a squirrel than a monkey — to you, a member of Homo sapiens?

Scientists look to fossils and evolutionary trees to help determine the rate of evolution — albeit with conflicting results. A new model has helped to resolve these contradictions: here.

MicroCT scans of the Australopithecus fossil known as Little Foot shows that the brain of this ancient human relative was small and shows features that are similar to our own brain and others that are closer to our ancestor shared with living chimpanzees: here.

Rare silky sifaka lemurs re-released in the wild


This 20 September 2018 video from Madagascar says about itself:

Incredibly Rare Silky Sifaka Lemurs Re-Released in the Wild | BBC Earth

After inspecting these rare white lemurs, the scientists free them again, and discover a pleasant surprise. Narrated by David Attenborough.

Lemur study suggests why some fruits smell so fruity. A new test with lemurs and birds suggests there’s more to fruit odors than simple ripening. By Susan Milius, 2:12pm, October 3, 2018.

Javan slow lorises freed from criminal traders


This video from Indonesia says about itself:

18 September 2018

International Animal Rescue recently released 20 Javan slow lorises in Bandung, West Java. Javan slow lorises (Nycticebus javanicus) are protected primates and yet are heavily trafficked in the wildlife trade.

Human origins, video


This 14 September 2018 video says about itself:

The story of human evolution began about 7 million years ago, when the lineages that lead to Homo sapiens and chimpanzees separated. Learn about the over 20 early human species that belong in our family tree and how the natural selection of certain physical and behavioral traits defined what it means to be human.