Madagascar sifaka lemurs’ problems getting food


This 30 December 2019 video says about itself:

Sifaka Lemurs Make A Treacherous Journey For Food | BBC Earth

Sifaka lemurs in Madagascar have to make a perilous journey with babies on board to reach their next feeding area.

Chimpanzee origin of human dancing?


This 2014 video shows an orangutan dancing after drinking orange juice.

From the University of Warwick in England:

How humans learned to dance: From the chimpanzee conga line

December 12, 2019

Psychologists observing two chimpanzees in a zoo have discovered that they performed a behaviour hitherto never seen, they coordinated together in a rhythmic social ritual.

Two chimpanzees housed in a zoo in the US have sparked the question about how human dance evolved after being observed performing a duo dance-like behaviour, similar to a human conga-line.

In the paper ‘Coupled whole-body rhythmic entrainment between two chimpanzees’ published today, the 12th of December in the journal Scientific Reports, researchers led by the University of Warwick found the levels of motoric co-ordination, synchrony and rhythm between the two female chimpanzees matched the levels shown by orchestra players performing the same musical piece.

Other species have been shown to be able to entertain by moving to the pace of a rhythmic tempo by an external stimulus and solo individuals, however this is the first time it hasn’t been triggered by nonhuman partners or signals.

Although the newly described behaviour probably represents a new form a stereotypy in captivity in this great ape species, the behaviour forces scientists interested in the evolution of human dance to consider new conditions that may have catalysed the emergence of one of human’s most exuberant and richest forms of expression.

Dr Adriano Lameira, from the Department of Psychology at the University of Warwick comments:

“Dance is an icon of human expression. Despite astounding diversity around the world’s cultures and dazzling abundance of reminiscent animal systems, the evolution of dance in the human clade remains obscure.

“Dance requires individuals to interactively synchronize their whole-body tempo to their partner’s, with near-perfect precision, this explains why no dance forms were present amongst nonhuman primates. Critically, this is evidence for conjoined full-body rhythmic entrainment in great apes that could help reconstruct possible proto-stages of human dance is still lacking.”

The researchers report an endogenously-effected case of ritualized dance-like behaviour between two captive chimpanzees — synchronized bipedalism. By studying videos they revealed that synchronisation between individuals was non-random, predictable, phase concordant, maintained with instantaneous centi-second precision and jointly regulated, with individuals also taking turns as “pace-makers.”

Apes and monkeys evolution, new research


This 2008 video is called Aegyptopithecus Mandible Fragments.

From the American Museum of Natural History in the USA:

Fossil suggests apes, old world monkeys moved in opposite directions from shared ancestor

Hip joint study could help explain why apes, humans, and Old World monkeys move so differently

In terms of their body plan, Old World monkeys — a group that includes primates like baboons and macaques — are generally considered more similar to ancestral species than apes are. But a new study that analyzes the first well-preserved femur of Aegyptopithecus zeuxis, a common ancestor of Old World monkeys and apes, suggests that as far as locomotion goes, apes and Old World monkeys each evolved a way of moving that was different from the ancestral species as they adapted to different niches in their environments.

“Our study shows that Aegyptopithecus preserves an ancient hip morphology not present in living anthropoid primates,” said Sergio Almécija, a paleoanthropologist and evolutionary biologist in the Division of Anthropology at the American Museum of Natural History who is first author on the study, which was published in Nature Communications this week. “As far as the hip is concerned, it seems that apes, humans, and Old World monkeys have all parted ways long ago — which would explain why they move around so differently today.”

The fossil analyzed in the study was discovered in 2009 and is the most complete femur of Aegyptopithecus, a 15-lb (7-kg) likely tree-dwelling species that lived in Egypt about 30 million years ago, close to the time when hominoids (the group that includes apes and humans) split from the larger group that includes Old World monkeys. A well-preserved femur allowed researchers to glean details about the hip joint, a major anatomical region for inferring locomotion, using a combination of 3D morphometric analysis and evolutionary modeling.

For the analysis, the authors compared the fossil bone to other extinct and modern species, including humans, chimpanzees, and Victoriapithecus and Homunculus (extinct Old World and New World monkeys, respectively). The evolutionary modeling analysis used in the study included a method that was developed to identify convergent evolution in anole lizards in the Caribbean, which have independently developed comparable niche-specific adaptations across various islands.

The results indicate that the ancestral hip joint is, from an evolutionary perspective, as far from the hip joint of modern Old World monkeys as from those of the great apes — suggesting that each group evolved a distinct way of moving as they specialized for success in different environmental niches.

In addition, evolutionary modeling suggests that living great apes — including orangutans, chimpanzees, and gorillas — may have independently developed similar hip joint anatomy that allows wide-ranging, flexible movement through their arboreal habitats.

“What I find really exciting about the modeling approach is that we can develop better hypotheses about what drove the divergence of apes and monkeys, and the emerging picture is that navigating the environment is one of the key factors,” said Ashley Hammond, assistant curator in the Division of Anthropology and an author on the study.

Southern lesser galago video


This 28 October 2019 video from Botswana says about itself:

The Southern Lesser Galago, also known as a Bushbaby, is perfectly adapted to hunt insects at night. Their tiny bodies are offset by their large, saucer-like eyes, and they will wash their feet and hands in their own urine to make them stickier and help in climbing trees.

Madagascar aye-aye lemurs have six fingers


This June 2015 video says about itself:

Brian Cox Meets An Aye-Aye | Wonders of Life | BBC

Professor Brian Cox gets a rare and up-close look at a sedated aye-aye, known for it’s unusual way of hunting for food.

By Sofie Bates in Science News, October 22, 2019 at 4:25 pm:

Aye-ayes just got weirder with the discovery of a tiny, sixth ‘finger’

An extra digit, a pseudothumb, may help the primates grip objects

Aye-ayes just got even more unusual. The tiny lemurs of Madagascar, known for their large cartoonish ears and continuously growing incisor teeth, also have a sixth “finger” on each hand.

The extra digit — a nubby little “pseudothumb” made of bone and cartilage — can move in three directions and carries its own distinctive fingerprint, researchers report October 21 in the American Journal of Physical Anthropology.

“It’s more than just a nub. It actually has a lot of function to it,” says study coauthor Adam Hartstone-Rose, a comparative anatomist at North Carolina State University in Raleigh. The pseudothumb, which is manipulated by three muscles, may help aye-ayes (Daubentonia madagascariensis) grip objects or branches.

It’s the first time that a pseudothumb has been discovered on any primate, although some people are born with extra fingers (SN: 6/12/19). Other species also have pseudothumbs, including giant pandas, which use their sixth digits to grasp bamboo stalks (SN: 1/31/19). Giant pandas may have acquired that extra digit after the rest of their fingers became less specialized so that the bears could better walk. That’s not the case with aye-ayes, though, the scientists think.

Instead, the little lemurs’ hands may have become too specialized, with thin, elongated fingers, including an especially long third digit that has a ball-and-socket joint. That finger, in particular, is used in a hunting technique called tap foraging, where the animals tap the finger on dead and rotting wood and use echolocation to find bugs hiding inside. Then the primates bite the wood, puncturing a hole, and again use their long third finger for fishing out bugs and grubs found inside.

“Their fingers became so long and spindly that they were no longer good at finger stuff, like grasping,” Hartstone-Rose suggests. The pseudothumb may compensate for the aye-ayes’ other, overspecialized fingers, he and colleagues say.

This interpretation is plausible, says John Hutchinson, an evolutionary biologist at the Royal Veterinary College at the University of London, who was not involved in the work. But he notes that, in general, scientists “don’t know much about what false digits do in most species.”

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?