Ancestor of apes, humans weighed five kilograms


Apes, humans family tree, image courtesy of University of Tübingen

From the American Museum of Natural History in the USA:

Last common ancestor of humans and apes weighed about five kilograms

Ape ancestor was about the size of a gibbon

October 12, 2017

New research suggests that the last common ancestor of apes — including great apes and humans — was much smaller than previously thought, about the size of a gibbon. The findings, published today in the journal Nature Communications, are fundamental to understanding the evolution of the human family tree.

“Body size directly affects how an animal relates to its environment, and no trait has a wider range of biological implications,” said lead author Mark Grabowski, a visiting assistant professor at the Eberhard Karls University of Tübingen in Germany who conducted the work while he was a postdoctoral fellow in the American Museum of Natural History’s Division of Anthropology. “However, little is known about the size of the last common ancestor of humans and all living apes. This omission is startling because numerous paleobiological hypotheses depend on body size estimates at and prior to the root of our lineage.”

Among living primates, humans are most closely related to apes, which include the lesser apes (gibbons) and the great apes (chimpanzees, gorillas, and orangutans). These “hominoids” emerged and diversified during the Miocene, between about 23 million to 5 million years ago. Because fossils are so scarce, researchers do not know what the last common ancestors of living apes and humans looked like or where they originated.

To get a better idea of body mass evolution within this part of the primate family tree, Grabowski and coauthor William Jungers from Stony Brook University compared body size data from modern primates, including humans, to recently published estimates for fossil hominins and a wide sample of fossil primates including Miocene apes from Africa, Europe, and Asia. They found that the common ancestor of apes was likely small, probably weighing about 12 pounds, which goes against previous suggestions of a chimpanzee-sized, chimpanzee-like ancestor.

Among other things, the finding has implications for a behavior that’s essential for large, tree-dwelling primates: it implies that “suspensory locomotion,” overhand hanging and swinging, arose for other reasons than the animal simply getting too big to walk on top of branches. The researchers suggest that the ancestor was already somewhat suspensory, and larger body size evolved later, with both adaptations occurring at separate points. The development of suspensory locomotion could have been part of an “arms race” with a growing number of monkey species, the researchers said. Branch swinging allows an animal to get to a prized and otherwise inaccessible food — fruit on the edges of foliage — and larger body would let them engage in direct confrontation with monkeys when required.

The new research also reveals that australopiths, a group of early human relatives, were actually on average smaller than their ancestors, and that this smaller size continued until the arrival of Homo erectus.

“There appears to be a decrease in overall body size within our lineage, rather than size simply staying the same or getting bigger with time, which goes against how we generally think about evolution,” Grabowski said.

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Slow lorises saved from criminal pet trade


This video says about itself:

Slow Lorises Rescued From Illegal Pet Trade | National Geographic

3 October 2017

Officials in West Sumatra, Indonesia, rescued nine slow lorises from being sold on the illegal pet market.

Small primate species discovered in Angola


This 2011 video from Tanzania says about itself:

Andrew Perkin and Johan Karlsson conducting a galago [Galagoides] survey in Zanzibar.

From Sci-News.com:

Galagoides kumbirensis: New Species of Dwarf Galago Discovered in Angola

Apr 10, 2017 by Enrico de Lazaro

An international group of primatologists has discovered a new primate, Galagoides kumbirensis (Angolan dwarf galago), with features not been seen by science before.

Galagos, also known as bushbabies, are small, woolly, long-tailed primates that are widespread over sub-Saharan Africa, and make up the family Galagidae.

Over the last half century, their number of species recognized has slowly climbed from 6 to 19 species (including the new one).

The newly-discovered species, the Angolan dwarf galago, belongs to the genus Galagoides (dwarf galagos, or dwarf bushbabies).

“This new species is a very exciting discovery,” said Dr. Russell Mittermeier of Conservation International.

“It is only the fifth new primate described from the African mainland since 2000 and only the second species of galago. What is more, it is from Angola, where there has been very little primate research to date.”

The Angolan dwarf galago is a small gray-brown galago with a darker, long-haired tail.

It is the largest known dwarf galago: the typical head-and-body length for this species is from 6.7 to 7.9 inches (17-20 cm), and the tail varies from 6.7 to 9.5 inches (17-24 cm) long.

This new species is described in a paper published online recently in the American Journal of Physical Anthropology.

“Muzzle slightly up-turned, pink below and dark above, merging into dark eye-rings with a conspicuous white nose stripe between the eyes,” the authors wrote in the paper.

“The remainder of the face gray, suffused with brown, and set off from white cheeks, chin, and neck.”

“Inner ears white towards the base and yellowish towards margins. Ears gray above with two light spots where the ears join the crown. Crown, dorsum forelimbs, thighs, and flanks gray with a brown wash.”

“Ventrum, surface of forelimbs and hindlimbs creamy yellow. Yellow strongest where the light ventrum merges into the darker dorsum.”

“Tail darker towards the tip and slightly longer than the body. Tail held curled when at rest.”

The morphology and calls of the Angolan dwarf galago are so unique that there was no need to resort to genetic techniques to verify it further.

“When we first encountered the new species in Kumbira Forest in north-western Angola, we heard a distinctive ‘crescendo’ call similar to that of a tiny galago, but upon seeing one, we were struck by its remarkably large size,” said lead author Magdalena Svensson, a researcher with the Nocturnal Primate Research Group at Oxford Brookes University.

“Until now, call types have been the most reliable way to distinguish galago species, and to find one that did not match what we expected was very exciting.”

“The uncovering of this species is characteristic of the return of real biology,” said co-author Prof. Judith Masters, from Nelson Mandela Metropolitan University in South Africa.

“Although DNA has yielded new and sometimes highly contestable specimens, in the case of this new galago, the differences are obvious for all to see.”

Ancient primate fossil discovery in India


This 2014 video Lecture 16 Early Primate Evolution.

From the University of Southern California in the USA:

Newfound primate teeth take a big bite out of the evolutionary tree of life

The new species of primate from India is distantly related to the lemurs of Madagascar

February 28, 2017

Summary:

Fossil hunters have found part of an ancient primate jawbone related to lemurs — the primitive primate group distantly connected to monkeys, apes and humans, a researcher reports. Scientists named the new species Ramadapis sahnii and said that it existed 11 to 14 million years ago. It is a member of the ancient Sivaladapidae primate family, consumed leaves and was about the size of a house cat.

Fossil hunters have found part of an ancient primate jawbone related to lemurs — the primitive primate group distantly connected to monkeys, apes and humans, a USC researcher said.

Biren Patel, an associate professor of clinical cell and neurobiology at the Keck School of Medicine of USC, has been digging for fossils in a paleontologically rich area of Kashmir in northern India for six years. Although paleontologists have scoured this region for a century, relics of small extinct primates were rarely found or studied.

Scientists named the new species Ramadapis sahnii and said that it existed 11 to 14 million years ago. It is a member of the ancient Sivaladapidae primate family, consumed leaves and was about the size of a house cat, said Patel, co-author of the new study in the Journal of Human Evolution.

“Among the primates, the most common ones in the Kashmir region are from a genus called Sivapithecus, which were ancestral forms of orangutans,” Patel said. “The fossil we found is from a different group on the primate family tree — one that is poorly known in Asia. We are filling an ecological and biogeographical gap that wasn’t really well documented. Every little step adds to the understanding of our human family tree because we’re also primates.”

The last primate found in the area was 38 years ago. So, in addition to being a new species, this is the first primate fossil found in the area in decades.

“In the past, people were interested in searching for big things — things they could show off to other people,” Patel said. “A lot of the small fossils were not on their radar.”

The inch-and-a-quarter partial mandible belongs to a primate weighing less than 11 pounds that had outlived its other adapidae cousins found in North America, Europe and Africa by millions of years.

“New primates are always a hot topic, and this one is the first of its kind from its area in Asia, which has significant consequences for understanding primate evolution in the Old World,” said Michael Habib, an assistant professor of clinical cell and neurobiology at the Keck School of Medicine who was not involved in the study.

The question that remains is how the ecosystem in northern India supported this species when its relatives elsewhere were disappearing or had already gone extinct. Future fieldwork and recovering more fossil primates will help answer this question.

“People want to know about human origins, but to fully understand human origins, you need to understand all of primate origins, including the lemurs and these Sivaladapids,” Patel said. “Lemurs and sivaladapids are sister groups to what we are — the anthropoids — and we are all primates.”

Researchers from Hunter College of the City University of New York, New York Consortium in Evolutionary Primatology, Arizona State University, Stony Brook University and Panjab University also contributed to this study, which was supported by the Wenner-Gren Foundation, the American Association of Physical Anthropologists, the Institute of Human Origins and funding from some of the involved universities.

Primate ancestry, new research


This video says about itself:

24 April 2014

From opposable thumbs to bipedalism, follow the human evolution timeline in this gripping biology video that’s perfect for the classroom.

All primates, including humans, evolved from a common ancestor 50 million years ago. Our shared evolutionary history has resulted in many shared features, like hands that grasp and forward-facing eyes. Watch Neil Shubin find evidence of evolution in modern-day squirrel monkeys.

For more videos on human evolution, see our evolution playlist.

From Science News:

Picture of primate common ancestor coming into focus

New family tree analysis points to nocturnal, rodent-sized, tree-climbing critter

By Erin Wayman

7:00am, October 29, 2016

SALT LAKE CITY — The earliest primate was a tiny, solitary tree dweller that liked the night life. Those are just some conclusions from new reconstructions of the primate common ancestor, presented October 27 at the annual meeting of the Society of Vertebrate Paleontology.

Eva Hoffman, now a graduate student at the University of Texas at Austin, and colleagues at Yale University looked at behavioral and ecological data from 178 modern primate species. Examining patterns of traits across the primate family tree, the researchers inferred the most likely characteristics of ancestors at different branching points in the tree — all the way back to the common ancestor.

This ancient primate, which may have lived some 80 million to 70 million years ago, was probably no bigger than a guinea pig, lived alone and gave birth to one offspring at a time, the researchers suggest. Living in trees and active at night, the critter probably ventured out to the ends of tree branches to eat fruits, leaves and insects.

But this mix of traits probably didn’t arise in primates, Hoffman says. After adding tree shrews and colugosprimates’ closest living relatives — to the analysis, the researchers concluded these same attributes were also present in the three groups’ common ancestor. So explanations of early primate evolution that rely on these features need to be reconsidered, Hoffman says.

Stone age monkeys and humans


This video says about itself:

13 October 2016

Clip of capuchin stone on stone percussion and licking of passive hammer associated with capuchin grooming.

Credit: M. Haslam and the Primate Archaeology Group (University of Oxford)

From Science News:

Wild monkeys throw curve at stone-tool making‘s origins

Unlike early hominids, capuchins don’t use sharp-edged rocks to dig or cut

By Bruce Bower

1:00pm, October 19, 2016

A group of South American monkeys has rocked archaeologists’ assumptions about the origins of stone-tool making.

Wild bearded capuchin monkeys in Brazil use handheld stones to whack rocks poking out of cliffs and outcrops. The animals unintentionally break off sharp-edged stones that resemble stone tools made by ancient members of the human evolutionary family, say archaeologist Tomos Proffitt of the University of Oxford and his colleagues. It’s the first observation of this hominid-like rock-fracturing ability in a nonhuman primate.

The new finding indicates that early hominids needed no special mental ability, no fully opposable thumbs and not even any idea of what they were doing to get started as toolmakers, the researchers report October 19 in Nature. All it may have taken was a penchant for skillfully pounding rocks, as displayed by capuchins when cracking open nuts (SN Online: 4/30/15).

Archaeologists have traditionally thought that ancient stone tools appeared as hominid brains enlarged and hand grips became more humanlike.

“Without the intention of making a stone tool, and with the right rock types, capuchins produce objects that are shaped like stone tools,” says University of Oxford primatologist and archaeologist Susana Carvalho, who did not participate in the new study. She suspects the earliest known stone tools were made either by relatively small-brained hominids or, perhaps in some cases, nonhuman primates. “This is not a wild idea anymore.”

The oldest known hominid stone artifacts — a set of pounding rocks and sharp-edged stone flakes — date to 3.3 million years ago in East Africa (SN: 6/13/15, p. 6). Those tools display more elaborate modifications than observed on sharp-edged capuchin creations, Proffitt says. But researchers suspect simpler hominid tools go back 4 million years or more.  Those implements might have looked more like what the South American monkeys make, he speculates.

Three capuchins tracked during an episode of rock pounding did not use fractured pieces of sharp stone to cut, scrape or dig up anything. Observations of nearly 100 rounds of rock pounding show that the monkeys sometimes recycled stone flakes as rock-pounding tools. They also often licked or sniffed powdered stone produced as they pounded rocks. Perhaps capuchins want to ingest the trace nutrient silicon, which assists in bone growth, or find lichens for some medicinal purpose, Proffitt suggests.

His team studied 60 stone fragments left behind by capuchins after rock-pounding episodes and another 51 capuchin-modified stones found in two excavations where rock pounding occurred. These artifacts included complete and broken pounding stones, stone flakes and stones that had been struck by rock-wielding monkeys.

Capuchin stone flakes are smaller and contain fewer fractured areas than ancient hominid tools, such as the 3.3-million-year-old East African finds, says archaeologist David Braun of George Washington University in Washington, D.C. But sharp-edged stones produced by the monkeys display “remarkable similarity” to artifacts from a nearby Brazilian site that some researchers think were made by humans more than 20,000 years ago (SN: 10/18/14, p. 14), Braun says. Researchers now must determine whether stone artifacts found at several South American sites dating to more than 14,000 years ago were made by humans or monkeys, he suggests.

Capuchin rock smashers’ inadvertently sharpened debris also raises questions about how hominids started making tools in the first place. Techniques for using one stone to pound away pieces of another stone, creating a rock with smooth faces bordered by razor-sharp edges, “could have been invented independently in different hominid species through [stone-pounding] behaviors we have yet to identify,” Proffitt says.

Those initial tools may have resembled capuchins’ accidentally sharpened stones or even rocks used by chimpanzees to crack nuts, says archaeologist Sonia Harmand of Stony Brook University in New York. But only hominids, and especially humans, went on to make more sophisticated stone tools and, later, everything from smart phones to space stations, says Harmand, who led the team that discovered the 3.3-million-year-old hominid tools.

Human evolution, fire and smoke


This video says about itself:

Smoking Causes Cancer, Heart Disease, Emphysema

20 jul. 2012

This 3D medical animation created by Nucleus Medical Media shows the health risks of smoking tobacco.

ID#: ANH12071

Transcript:

Every time you smoke a cigarette, toxic gases pass into your lungs, then into your bloodstream, where they spread to every organ in your body. A cigarette is made using the tobacco leaf, which contains nicotine and a variety of other compounds. As the tobacco and compounds burn, they release thousands of dangerous chemicals, including over forty known to cause cancer. Cigarette smoke contains the poisonous gases carbon monoxide and nitrogen oxide, as well as trace amounts of cancer-causing radioactive particles. All forms of tobacco are dangerous, including cigars, pipes, and smokeless tobacco, such as chewing tobacco and snuff.

Nicotine is an addictive chemical in tobacco. Smoking causes death. People who smoke typically die at an earlier age than non-smokers. In fact, 1 of every 5 deaths in the United States is linked to cigarette smoking.

If you smoke, your risk for major health problems increases dramatically, including: heart disease, heart attack, stroke, lung cancer, and death from chronic obstructive pulmonary disease.

Smoking causes cardiovascular disease.

When nicotine flows through your adrenal glands, it stimulates the release of epinephrine, a hormone that raises your blood pressure. In addition, nicotine and carbon monoxide can damage the lining of the inner walls in your arteries. Fatty deposits, called plaque, can build up at these injury sites and become large enough to narrow the arteries and severely reduce blood flow, resulting in a condition called atherosclerosis. In coronary artery disease, atherosclerosis narrows the arteries that supply the heart, which reduces the supply of oxygen to your heart muscle, increasing your risk for a heart attack. Smoking also raises your risk for blood clots because it causes platelets in your blood to clump together. Smoking increases your risk for peripheral vascular disease, in which atherosclerotic plaques block the large arteries in your arms and legs. Smoking can also cause an abdominal aortic aneurysm, which is a swelling or weakening of your aorta where it runs through your abdomen.

Smoking damages two main parts of your lungs: your airways, also called bronchial tubes, and small air sacs called alveoli. Cigarette smoke irritates the lining of your bronchial tubes, causing them to swell and make mucus. Cigarette smoke also slows the movement of your cilia, causing some of the smoke and mucus to stay in your lungs. While you are sleeping, some of the cilia recover and start pushing more pollutants and mucus out of your lungs. When you wake up, your body attempts to expel this material by coughing repeatedly, a condition known as smoker’s cough. Over time, chronic bronchitis develops as your cilia stop working, your airways become clogged with scars and mucus, and breathing becomes difficult.

Your lungs are now more vulnerable to further disease. Cigarette smoke also damages your alveoli, making it harder for oxygen and carbon dioxide to exchange with your blood. Over time, so little oxygen can reach your blood that you may develop emphysema, a condition in which you must gasp for every breath and wear an oxygen tube under your nose in order to breathe.

Chronic bronchitis and emphysema are collectively called chronic obstructive pulmonary disease, or COPD. COPD is a gradual loss of the ability to breathe for which there is no cure.

Cigarette smoke contains at least 40 cancer-causing substances, called carcinogens, including cyanide, formaldehyde, benzene, and ammonia. In your body, healthy cells grow, make new cells, then die. Genetic material inside each cell, called DNA, directs this process. If you smoke, toxic chemicals can damage the DNA in your healthy cells. As a result, your damaged cells create new unhealthy cells, which grow out of control and may spread to other parts of your body. Cigarettes can cause cancer in other parts of your body, such as: in the blood and bone marrow, mouth, larynx, throat, esophagus, stomach, pancreas, kidney, bladder, uterus, and cervix.

Smoking can cause infertility in both men and women. If a woman is pregnant and smokes during pregnancy, she exposes her baby to the cigarette’s poisonous chemicals, causing a greater risk of: low birth weight, miscarriage, preterm delivery, stillbirth, infant death, and sudden infant death syndrome. Smoking is also dangerous if a mother is breastfeeding. Nicotine passes to the baby through breast milk, and can cause restlessness, rapid heartbeat, vomiting, interrupted sleep, or diarrhea.

Other health effects of smoking include: low bone density and increased risk for hip fracture among women; gum disease, often leading to tooth loss and surgery; immune system dysfunction and delayed wound healing; and sexual impotence in men.

From Leiden University in the Netherlands:

Are modern humans simply bad at smoking?

Published on 21 September 2016

Scientists looked for the genetic footprint of fire use in our genes, but found that our prehistoric cousins – the Neanderthals – and even the great apes seem better at dealing with the toxins in smoke than modern humans.

Mixed blessing

The art of making and using fire was one of the greatest discoveries ‘ever made by man’, wrote Charles Darwin. Besides providing protection against cold temperatures, the use of fire in food preparation and the introduction of energy-rich cooked foods in our prehistoric diet had a major impact in the development of humankind. However, fire use comes at a cost. Exposure to the toxic compounds in smoke carries major risks for developing pneumonia, adverse pregnancy outcomes in women and reduced sperm quality in males, as well as cataracts, tuberculosis, heart disease, and chronic lung disease. In short, the use of fire is a mixed blessing.

Debate

This mixed blessing, however, put researchers at Leiden University and Wageningen University on the trail of finding genetic markers for the use of fire in prehistoric and recent humans. The use of fire is notoriously difficult to ‘see’ for archaeologists, and this has led to strong disagreement over the history of its usage. A very early start is advocated by Harvard primatologist Richard Wrangham, who argues that our Homo erectus ancestors were already using fire around two million years ago. However, numerous excavations and intensive research carried out by archaeologists in Europe and the Near East suggest that control of fire occurred much later, around 350,000 years ago.

Genetic markers for fire use

In order to bring fresh data into this ‘hot’ debate, the Leiden/Wageningen team studied the biological adaptations of prehistoric and recent humans to the toxic compounds of smoke: fire usage implies frequent exposure to hazardous compounds from smoke and heated food, which is expected to result in the selection of gene variants conferring an improved defence against these toxic compounds. To study whether such genetic selection indeed occurred, the team investigated the gene variants occurring in Neanderthals, in Denisovans (contemporaries of the Neanderthals, more related to them than to modern humans), and in prehistoric modern humans.

Tobacco

Single nucleotide variants in 19 genes were tested that are known from modern tobacco-smoking studies to increase the risk of fertility and reproduction problems when exposed to smoke and hazardous compounds formed in heated food.

These genes were compared with variants observed in Neanderthals and their Denisovan cousins, and were also studied in chimpanzees and gorillas, two closely related species that are obviously not using fire, and are therefore not exposed to smoke on a regular basis.

Neanderthal more efficient in handling smoke?

In a study now published in PLOS ONE, the team shows that Neanderthals and the Denisovan predominantly possessed gene variants that were more efficient in handling the toxic compounds in smoke than modern humans. Surprisingly, these efficient variants were also observed in chimpanzees and gorillas, and therefore appeared to be evolutionary very old (ancestral) variants.

Plant toxins

The less efficient variants are observable from the first modern human hunter-gatherers for which we have genetic information onward, i.e. from about 40,000 years ago. The efficient defence against toxic compounds in chimpanzees and gorillas may be related to the toxins in their plant food. Smoke defence capacities in humans apparently hitchhike on those adaptations, developed deep in our primate past. Our prehistoric ancestors were probably already good at dealing with the toxic compounds of smoke, long before they started producing it through their campfires. What allowed for the emergence of less efficient hazardous chemical defence genes in modern humans is a question for future research.

Traces of long-lost human cousins may be hiding in modern people’s DNA, a new computer analysis suggests. People from Melanesia, a region in the South Pacific encompassing Papua New Guinea and surrounding islands, may carry genetic evidence of a previously unknown extinct hominid species, Ryan Bohlender reported October 20 at the annual meeting of the American Society of Human Genetics. That species is probably not Neandertal or Denisovan, but a different, related hominid group, said Bohlender, a statistical geneticist at the University of Texas MD Anderson Cancer Center in Houston. “We’re missing a population or we’re misunderstanding something about the relationships,” he said: here.