Capuchin monkeys’ stone-tool use evolution


This June 2018 video says about itself:

White-faced capuchin (Cebus capucinus imitator) stone tool use in Coiba National Park, Panama

Higher Quality Supplemental Video from the paper “Habitual stone-tool aided extractive foraging in white-faced capuchins, Cebus capucinus.” Currently up on BioRxiV as a preprint and in peer review.

Preprint available here.

By Bruce Bower, 11:00am, June 24, 2019:

Capuchin monkeys’ stone-tool use has evolved over 3,000 years

A Brazilian site shows the animals’ long history of selecting various types of pounding devices

Excavations in Brazil have pounded out new insights into the handiness of ancient monkeys.

South American capuchin monkeys have not only hammered and dug with carefully chosen stones for the last 3,000 years, but also have selected pounding tools of varying sizes and weights along the way.

Capuchin stone implements recovered at a site in northeastern Brazil display signs of shifts during the last three millennia between a focus on dealing with either relatively small, soft foods or larger, hard-shelled edibles, researchers report. These discoveries, described online June 24 in Nature Ecology & Evolution, are the first evidence of changing patterns of stone-tool use in a nonhuman primate.

“It’s likely that local vegetation changes after 3,000 years ago led to changes in capuchin stone tools”, says archaeologist Tomos Proffitt of University College London. The new findings raise the possibility that chimpanzees and macaque monkeys, which also use stones to pound and dig, have shifted their tool-use styles over the long haul, perhaps in response to climate and habitat changes, Proffitt says.

Archaeological sites linked to apes and monkeys are rare, though. Previous excavations in West Africa unearthed nut-cracking stones wielded by chimps around 4,300 years ago (SN: 11/21/09, p. 24). Present-day chimps inhabiting the same part of Africa crack nuts with similar-looking rocks.

Evidence of long-term changes in tools used by wild capuchins (Sapajus libidinosus) comes from a site in Brazil’s Serra da Capivara National Park. Excavations there have also yielded ancient human stone tools (SN: 10/18/14, p. 14). But the newly unearthed artifacts more closely resemble stone tools used by modern capuchins at the same site (SN: 11/26/16, p. 16), rather than Stone Age human implements, the researchers say.

Primatologist Tiago Falótico of the University of São Paulo, Proffitt and their colleagues recovered 122 capuchin stone artifacts from four sediment layers. Radiocarbon dating of charred wood bits in each layer provided age estimates for the finds. Excavated tools consisted of partial and complete pounding stones, rocks used as platforms on which to pound objects, and pieces of rock that detached from pounding stones and platforms during use.

Relatively small, heavily damaged pounding implements from between around 3,000 and 2,500 years ago were likely used to smash open tiny foods such as seeds or fruits with soft rinds, the researchers say. Similar tools uncovered at the site date to around 600 years ago. Larger pounding stones from overlying sediment appeared about 300 years ago. The appearance of bigger capuchin tools by around that time denoted a shift to eating hard-shelled fruits and nuts that required high-impact pounding to open, the team says.

Then starting roughly 100 years ago, capuchins downsized pounding stones slightly to crack cashews efficiently, the researchers suspect. Capuchins living near the site today like to eat cashews that the animals crack with similar pounding stones.

Either of two scenarios accounted for the variety of stone artifacts found at the Brazilian monkey site, Proffitt says. Different capuchin populations may have visited the location at various times, each using particular types of stones to crack or open preferred seeds, nuts or fruits. Or, a single capuchin population may have regularly returned to the site and changed its tool use over time in order to exploit different types of foods.

Stone tool modifications that occurred over the last 3,000 years among Brazilian capuchins are comparable to those observed among West African chimp communities today, says University of Oxford primatologist and archaeologist Susana Carvalho. These chimps use large, heavy stones to crack hard Panda nuts as well as small stones to break open softer palm oil nuts. “What’s novel is that a stone tool pattern we had already seen in chimps today is now recognizable from the archaeological evidence for capuchins.”

Still, differences between large and small capuchin and chimp tools are modest relative to contrasts among ancient hominid tools, such as simple chopping implements and oval hand axes, Carvalho says. Hominids began making and using stone tools at least 2.6 million years ago.

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Prehistoric crocodiles, video


This 23 June 2019 video says about itself:

5 of the Strangest Prehistoric Crocs

Over the years, scientists have found evidence for a lot of weird prehistoric animals, but some of the strangest have been the crocodyliformes!

Swiming sea cucumbers, video


This 14 June 2019 video says about itself:

Weird and Wonderful: Swimming sea cucumbers

It can be hard to move from place to place for many animals that live on the seafloor and move slowly. Most sea cucumbers (Holothurians) live a sedentary life on the bottom of the ocean, eating sediment or detritus that rains down from above. But some sea cucumbers leave the life of eating and pooping on the seafloor temporarily by swimming. They may do this as a defense behavior, or to find a mate. Sea cucumbers have made remarkable adaptations to master the challenges of living in the deep sea.

For more information on the importance of holothurians in deep ecosystems see here.

Clownfish and sea anemones, new research


This 2014 video is called Clownfish and Anemones.

From the American Museum of Natural History in the USA:

Finding ‘Nemo’s’ family tree of anemones

New study details evolutionary relationships of clownfish-hosting

June 19, 2019

Summary: A recent study presents a new tree of life for clownfish-hosting sea anemones along with some surprises about their taxonomy and origins.

Thanks in part to the popular film Finding Nemo, clownfishes are well known to the public and well represented in scientific literature. But the same can’t be said for the equally colorful sea anemones — venomous, tentacled animals — that protect clownfishes and that the fish nourish and protect in return. A new study published online this month in the journal Molecular Phylogenetics and Evolution takes a step to change that, presenting a new tree of life for clownfish-hosting sea anemones along with some surprises about their taxonomy and origins.

“It’s astounding that when we look at the relationship between clownfishes and sea anemones, which is perhaps one of the most popular examples of symbiosis out there, we have essentially no clue what is going on with one of the two major players,” said Estefanía Rodríguez, one of the co-authors on the new study and an associate curator in the American Museum of Natural History’s Division of Invertebrate Zoology.

The relationship between the anemone and the clownfish is a mutually beneficial one. The fish have the ability to produce a mucus coating that allows them to shelter within the anemone’s venom-filled tentacles without being stung. This protects clownfishes from bigger fishes, like moray eels, which can be stung by the anemone if they get too close. In return, the highly territorial clownfishes will ward away animals that might try to eat the anemone. In addition, their feces serve as an important source of nitrogen for the anemone, and some research suggests that as the fish wiggle through the anemone’s swaying tentacles, they help oxygenate the host, possibly helping it grow.

There are about 30 clownfishes that have this symbiotic relationship with anemones, and they originated in the “coral triangle” of southeast Asia. There are 10 described species of clownfish-hosting anemones, but scientists suspect that the total number may be much higher. And the information on the origin of these species, as well as the number of times the symbiosis evolved in anemones, is sparse and dated. To fill in these gaps, the research team, led by Museum Gerstner Scholar and Lerner Gray Postdoctoral Fellow Benjamin Titus, built a phylogenetic tree based on DNA from newly collected anemone specimens.

They found that as a group, anemones independently evolved the ability to host clownfish three times throughout history. That finding in itself was not unexpected, but the groupings of the species were very different than what previous work had predicted.

Two of the three independent groups originated in the Tethys Sea, an ancient ocean that separated the supercontinent of Laurasia from Gondwana during much of the Mesozoic, and in today’s geography, is located near the Arabian Peninsula. The data are unclear about the origin of the third group.

“For a symbiosis that’s supposedly highly co-evolved, the groups originated in very different parts of the world and probably also at very different times,” Titus said.

The findings suggest that these anemones, at least the ones that originated in the Tethys, are quite old, living at least 12 to 20 million years ago and possibly earlier.

Research on this group is especially relevant as clownfishes — and their anemones — face threats from the aquarium and pet trade.

“These are very heavily collected animals, but we don’t even know how many species exist in this group,” Rodríguez said. “We have a lot of work to do so we can determine what’s there now, what kind of threats they face, and how we can protect them.”

Other authors include Charlotte Benedict, Auburn University; Robert Laroche, University of Houston; Luciana C. Gusmão, Vanessa Van Deusen, and Tommaso Chiodo, American Museum of Natural History; Christopher P. Meyer, National Museum of Natural History; Michael L. Berumen, King Abdullah University of Science and Technology; Aaron Bartholomew, American University of Sharjah; Kensuke Yanagi, Costal Branch of Natural History Museum and Institute, Japan; James D. Reimer, University of the Ryukyus, Japan; Takuma Fujii, Kagoshima University; and Marymegan Daly, The Ohio State University.

This work was supported in part by the Gerstner Scholars Postdoctoral Fellowship and the Gerstner Family Foundation, the Lerner-Gray Fund for Marine Research, and the Richard Gilder Graduate School at the American Museum of Natural History; the National Science Foundation’s (NSF) Research Experience for Undergraduates program (grant # DBI 1358465); NSF 1457581 and DEB 1257630; the Japan Science and Technology Agency and the Japan International Cooperation Agency in cooperation with Palau International Coral Reef Center and Palau Community College (SATREPS P-CoRIE); Japan Society for the Promotion of Science Kakenhi Grants (JP255440221, JP17K15198, JP17H01913); Kagoshima University; King Abdullah University of Science and Technology Office of Competitive Research Funds (CRG-1-2012-BER-002).

Entelodonts, prehistoric ‘hell pigs’


This 5 June 2019 video says about itself:

Despite the name, we don’t know where the so-called “hell pigs” belong in the mammalian family tree. They walked on hooves, like pigs do, but had longer legs, almost like deer. They had hunched backs, a bit like rhinos or bison. But as is often, if not always, the case, there is some evolutionary method to this anatomical madness.

Thanks to Ceri Thomas for the excellent Entelodont illustrations!

Narwhals, belugas can interbreed, new research


This September 2018 video says about itself:

Belugas adopt wayward narwhal in Canadian waters

A lonely narwhal finds majestic company in Canadian waters. Having strayed far from its Arctic habitat, the juvenile managed to join a pod of belugas.

From the University of Copenhagen in Denmark:

Narwhals and belugas can interbreed

June 20, 2019

A team of University of Copenhagen researchers has compiled the first and only evidence that narwhals and beluga whales can breed successfully. DNA and stable isotope analysis of an anomalous skull from the Natural History Museum of Denmark has allowed researchers to confirm the existence of a narwhal-beluga hybrid.

For nearly thirty years, a strange-looking whale skull has gathered dust in the collections of the Natural History Museum of Denmark. Now, a team of researchers has determined the reason for the skull’s unique characteristics: it belongs to a narwhal-beluga hybrid.

A Greenlandic hunter shot the whale in the 1980’s and was puzzled by its odd appearance. He therefore kept the skull and placed it on the roof of his toolshed. Several years later, Professor Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources visited the settlement and also immediately recognized the skull’s strange characteristics. He interviewed the hunter about the anomalous whale he had shot, and sent the skull to Copenhagen. Since then, it has been stored at the Zoological Museum, a part of the Natural History Museum of Denmark.

“As far as we know, this is the first and only evidence in the world that these two Arctic whale species can interbreed. Based on the intermediate shape of the skull and teeth, it was suggested that the specimen might be a narwhal-beluga hybrid, but this could not be confirmed. Now we provide the data that confirm that yes — it is indeed a hybrid,” says Eline Lorenzen, evolutionary biologist and curator at the University of Copenhagen’s Natural History Museum of Denmark. Lorenzen led the study, which was published today in Scientific Reports.

Using DNA and stable isotope analysis, the scientists determined that the skull belonged to a male, first-generation hybrid between a female narwhal and male beluga.

Bizarre set of chops

The hybrid’s skull was considerably larger than that of a typical narwhal or beluga. But the teeth were markedly different. Whereas narwhals have only one or rarely two long spiraling tusks, belugas have a set of uniform conical teeth that are aligned in straight rows. The hybrid skull has a set of long, spiraling and pointed teeth, that are angled horizontally.

“This whale has a bizarre set of teeth. The isotope analysis allowed us to determine that the animal’s diet was entirely different than that of a narwhal or beluga — and it is possible that its teeth influenced its foraging strategy. Whereas the other two species fed in the water column, the hybrid was a bottom dweller”, according to Mikkel Skovrind, a PhD student at the Natural History Museum and first author of the paper.

The researchers do not know what prompted the two species to mate, but it suggests a new phenomenon:

“We have analyzed the nuclear genomes of a narwhal and a beluga, but see no evidence of interbreeding for at least the past 1.25 million years of their evolutionary histories. So, interbreeding between the species appears to be either a very rare or a new occurrence. To my knowledge, it has not been observed or recorded before,” says Eline Lorenzen.

Gems among the museum collections

Lorenzen points out that she and her colleagues used novel analytical methods that have only recently been developed.

“There are some true gems in the world’s natural history collections that can provide us with key insights into the evolution and diversity of life on Earth. It is incredible when material — such as this skull, which has been stored in our collection for decades — can be revisited with new methodologies to gain novel biological insights” says Eline Lorenzen.

Mikkel Skovrind adds: “It would be interesting to find out if similar hybrid whales have been spotted elsewhere.”

FACTS:

  • By extracting DNA from the anomalous whale skull and comparing it to a genetic reference panel of narwhal and beluga, researchers established the whale’s genomic affiliation.
  • Researchers analyzed reference stocks of narwhal and beluga for stable isotopes and compared these with isotope values from the hybrid skull. By measuring bone carbon and nitrogen concentrations, researchers were able to discern whether the whale’s diet consisted of food from the water column or from the sea floor. The isotopes demonstrated that the hybrid whale’s dietary choices were very different than those of either narwhal or beluga.
  • Narwhals and belugas are the only toothed whales endemic to the Arctic region. While they are each other’s closest relatives and roughly equal in size, the two species differ in their morphology and behaviour. The narwhal is characterized by its long, spiraled tusk and has a greyish-brown, mottled pigmentation, whereas belugas have two rows of uniform teeth, and adults are completely white. Narwhals are specialists when it comes to dietary choice, and belugas are generalists.
  • The research is a collaboration between the Natural History Museum of Denmark at the University of Copenhagen, the Greenland Institute of Natural Resources and the Department of Anthropology, Trent University (CA).
  • The research is supported by the Carlsberg Foundation, the Villum Fonden Young Investigator programme and the Canada Research Chair programme.