Hyena saves impalas from hunting leopard


This 30 November 2019 video from Africa says about itself:

A Leopard’s Carefully Planned Ambush is Ruined by a Hyena

A female leopard uses her superior night vision to get closer to a herd of grazing impala. Just as she’s about to pounce, a hyena shows up revealing her position and taking away her element of surprise.

Ancient African ostrich eggshell beads, new research


This April 2018 video says about itself:

Oldest Known Jewellery Ever Discovered

1. The Neanderthal Jewelry from Croatia

2. Nassarius Snail Beads

3. Ostrich Shell Beads of Kenya

4. Denisovan Stone Bracelet

5. The Gold Riches of Varna

6. Glasswork of Egypt

7. Mesopotamian jewelry

From the Max Planck Institute for the Science of Human History in Germany:

Ostrich eggshell beads reveal 10,000 years of cultural interaction across Africa

November 27, 2019

Summary: Researchers present an expanded analysis of African ostrich eggshell beads, testing the hypothesis that larger beads signal the arrival of herders. The data reveals a more nuanced interpretation that provides greater insight into the history of economic change and cultural contact.

Ostrich eggshell beads are some of the oldest ornaments made by humankind, and they can be found dating back at least 50,000 years in Africa. Previous research in southern Africa has shown that the beads increase in size about 2,000 years ago, when herding populations first enter the region. In the current study, researchers Jennifer Miller and Elizabeth Sawchuk investigate this idea using increased data and evaluate the hypothesis in a new region where it has never before been tested.

Review of old ideas, analysis of old collections

To conduct their study, the researchers recorded the diameters of 1,200 ostrich eggshell beads unearthed from 30 sites in Africa dating to the last 10,000 years. Many of these bead measurements were taken from decades-old unstudied collections, and so are being reported here for the first time. This new data increases the published bead diameter measurements from less than 100 to over 1,000, and reveals new trends that oppose longstanding beliefs.

The ostrich eggshell beads reflect different responses to the introduction of herding between eastern and southern Africa. In southern Africa, new bead styles appear alongside signs of herding, but do not replace the existing forager bead traditions. On the other hand, beads from the eastern Africa sites showed no change in style with the introduction of herding. Although eastern African bead sizes are consistently larger than those from southern Africa, the larger southern African herder beads fall within the eastern African forager size range, hinting at contact between these regions as herding spread. “These beads are symbols that were made by hunter-gatherers from both regions for more than 40,000 years,” says lead author Jennifer Miller, “so changes — or lack thereof — in these symbols tells us how these communities responded to cultural contact and economic change.”

Ostrich eggshell beads tell the story of ancient interaction

The story told by ostrich eggshell beads is more nuanced than previously believed. Contact with outside groups of herders likely introduced new bead styles along with domesticated animals, but the archaeological record suggests the incoming influence did not overwhelm existing local traditions. The existing customs were not replaced with new ones; rather they continued and incorporated some of the new elements.

In eastern Africa, studied here for the first time, there was no apparent change in bead style with the arrival of herding groups from the north. This may be because local foragers adopted herding while retaining their bead-making traditions, because migrant herders possessed similar traditions prior to contact, and/or because incoming herders adopted local styles. “In the modern world, migration, cultural contact, and economic change often create tension,” says Sawchuk, “ancient peoples experienced these situations too, and the patterns in cultural objects like ostrich eggshell beads give us a chance to study how they navigated these experiences.”

The researchers hope that this work inspires a renewed interest into ostrich eggshell beads, and recommend that future studies present individual bead diameters rather than a single average of many. Future research should also investigate questions related to manufacture, chemical identification, and the effects of taphonomic processes and wear on bead diameter. “This study shows that examining old collections can generate important findings without new excavation,” says Miller, “and we hope that future studies will take advantage of the wealth of artifacts that have been excavated but not yet studied.”

Prehistoric African carnivorous mammals


This 19 November 2019 video says about itself:

When Giant Hypercarnivores Prowled Africa

These hyaenodonts gave the world some of its largest terrestrial, carnivorous mammals ever known. And while these behemoths were the apex predators of their time, they were no match for a changing world.

Thanks to Dr. Matthew Borths and Dr. Nancy Stevens for allowing us to use images from their recent paper on Simbakubwa, including the wonderful paleoart of Mauricio Antón.

And big thanks to these paleoartists for allowing us to use their wonderful illustrations:

Julio Lacerda (Simbakubwa kutokaafrika and Hyainailouros sulzeri).

Ceri Thomas (Megistotherium osteothlastes and Hyainailouros napakensis)

Prehistoric humans and climate change


This May 2018 video is called A short video describing the main debated theories around Homo sapiens dispersal across the globe.

From the Garvan Institute of Medical Research in Australia:

The homeland of modern humans

October 28, 2019

Summary: A landmark study pinpoints the birthplace of modern humans in southern Africa and suggests how past climate shifts drove their first migration.

A study has concluded that the earliest ancestors of anatomically modern humans (Homo sapiens sapiens) emerged in a southern African ‘homeland’ and thrived there for 70 thousand years.

The breakthrough findings are published in the prestigious journal Nature today.

The authors propose that changes in Africa’s climate triggered the first human explorations, which initiated the development of humans’ genetic, ethnic and cultural diversity.

This study provides a window into the first 100 thousand years of modern humans’ history.

DNA as a time capsule

“It has been clear for some time that anatomically modern humans appeared in Africa roughly 200 thousand years ago. What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors,” says study lead Professor Vanessa Hayes from the Garvan Institute of Medical Research and University of Sydney, and Extraordinary Professor at the University of Pretoria.

“Mitochondrial DNA acts like a time capsule of our ancestral mothers, accumulating changes slowly over generations. Comparing the complete DNA code, or mitogenome, from different individuals provides information on how closely they are related.”

In their study, Professor Hayes and her colleagues collected blood samples to establish a comprehensive catalogue of modern human’s earliest mitogenomes from the so-called ‘L0’ lineage. “Our work would not have been possible without the generous contributions of local communities and study participants in Namibia and South Africa, which allowed us to uncover rare and new L0 sub-branches,” says study author and public health Professor Riana Bornman from the University of Pretoria.

“We merged 198 new, rare mitogenomes to the current database of modern human’s earliest known population, the L0 lineage. This allowed us to refine the evolutionary tree of our earliest ancestral branches better than ever before,” says first author Dr Eva Chan from the Garvan Institute of Medical Research, who led the phylogenetic analyses.

By combining the L0 lineage timeline with the linguistic, cultural and geographic distributions of different sub-lineages, the study authors revealed that 200 thousand years ago, the first Homo sapiens sapiens maternal lineage emerged in a ‘homeland’ south of the Greater Zambezi River Basin region, which includes the entire expanse of northern Botswana into Namibia to the west and Zimbabwe to the east.

A homeland perfect for life to thrive

Investigating existing geological, archeological and fossil evidence, geologist Dr Andy Moore, from Rhodes University, revealed that the homeland region once held Africa’s largest ever lake system, Lake Makgadikgadi.

“Prior to modern human emergence, the lake had begun to drain due to shifts in underlying tectonic plates. This would have created, a vast wetland, which is known to be one of the most productive ecosystems for sustaining life,” says Dr Moore.

Modern humans’ first migrations

The authors’ new evolutionary timelines suggest that the ancient wetland ecosystem provided a stable ecological environment for modern humans’ first ancestors to thrive for 70 thousand years.

“We observed significant genetic divergence in the modern humans’ earliest maternal sub-lineages, that indicates our ancestors migrated out of the homeland between 130 and 110 thousand years ago,” explains Professor Hayes. “The first migrants ventured northeast, followed by a second wave of migrants who travelled southwest. A third population remained in the homeland until today.”

“In contrast to the northeasterly migrants, the southwesterly explorers appear to flourish, experiencing steady population growth,” says Professor Hayes. The authors speculate that the success of this migration was most likely a result of adaptation to marine foraging, which is further supported by extensive archaeological evidence along the southern tip of Africa.

Climate effects

To investigate what may have driven these early human migrations, co-corresponding author Professor Axel Timmermann, Director of the IBS Center for Climate Physics at Pusan National University, analysed climate computer model simulations and geological data, which capture Southern Africa’s climate history of the past 250 thousand years.

“Our simulations suggest that the slow wobble of Earth’s axis changes summer solar radiation in the Southern Hemisphere, leading to periodic shifts in rainfall across southern Africa,” says Professor Timmermann. “These shifts in climate would have opened green, vegetated corridors, first 130 thousand years ago to the northeast, and then around 110 thousand years ago to the southwest, allowing our earliest ancestors to migrate away from the homeland for the first time.”

“These first migrants left behind a homeland population,” remarks Professor Hayes. “Eventually adapting to the drying lands, maternal descendants of the homeland population can be found in the greater Kalahari region today.”

This study uniquely combined the disciplines of genetics, geology and climatic physics to rewrite our earliest human history.

The research was supported by an Australian Research Council Discovery Project grant (DP170103071) and the Institute for Basic Science (IBS-R028-D1). Professor Vanessa Hayes holds the Sydney University Petre Chair of Prostate Cancer Research.

African toad pretends to be a snake


This 21 October 2019 video says about itself:

It is well known that some harmless animals mimic dangerous animals to ward off predators.

Eg, the Brazilian galliwasp lizard poses like a toxic millipede. And the zebra shark can mimic a highly poisonous banded sea snake.

Such posing is called Batesian mimicry. But the Congolese giant toad takes Batesian mimicry to a new level. According to a paper in the Journal of Natural History, the toad not only transform into a very good copy of a Gaboon Viper. It also tries to mimic the hiss the deadly snake make before an attack. The toad also postures so that its front limbs aren’t visible — making it look more snake-like. The Congolese giant toad are found in locations inhabited by the Gaboon viper. The Gaboon viper has the longest fangs and carries the most venom.

From ScienceDaily:

Toad disguises itself as deadly viper to avoid attack

Decades of fieldwork uncover hissing and strike-warning impersonations by toad

October 21, 2019

The first study of a toad mimicking a venomous snake reveals that it likely imitates one of Africa’s largest vipers in both appearance and behaviour, according to results published in the Journal of Natural History.

The Congolese giant toad, a triple cheeseburger-sized prize for any predator, may use its ability to mimic the highly venomous Gaboon viper to escape being eaten. The viper has the longest snake fangs in the world and produces more venom than any other snake.

“Our study is based on ten years of fieldwork and on direct observation by researchers lucky enough to see the toad’s behaviour first-hand. We’re convinced that this is an example of Batesian mimicry, where a harmless species avoids predators by pretending to be a dangerous or toxic one,” says Dr Eli Greenbaum from the University of Texas at El Paso. “To fully test our hypothesis, we’d have to demonstrate that predators are successfully duped, but this would be very difficult in the wild, where the toads are only encountered rarely. However, based on multiple sources of evidence provided in our study, we are confident that our mimicry hypothesis is well-supported.”

The researchers made comparisons between the appearance of the toad, found in central African rainforests, and the viper, which is more widespread in central, eastern and southern Africa. Using live wild-caught and captive specimens, as well as preserved museum ones, they found that the colour pattern and shape of the toad’s body is similar to that of the viper’s head. Most striking are two dark brown spots and a dark brown stripe that extends down the toad’s back, the triangular shape of the body, a sharp demarcation between the tan back and dark brown flanks, and the species’ extraordinarily smooth skin for a toad. Because the Gaboon viper is capable of causing deadly bites, would-be predators likely avoid the similar-looking toads to ensure they don’t make a lethal mistake.

Some mimics are exclusively visual, but for the Congolese giant toad, getting the look right is only part of the impersonation. If a Gaboon viper feels threatened, it will often incline its head and emit a long, loud warning hiss before it actually makes a strike. Similarly, Congolese herpetologist Chifundera Kusamba observed the toad emitting a hissing noise resembling the sound of air being slowly released from a balloon. Over a century ago, American biologist James Chapin observed a bow display by the toad, where the front limbs no longer prop up the viperine-shaped body, which looks similar to the cocked head of a snake threatening to strike.

The final part of the impersonation is getting the location right. Even the best impression will only work if predators of the harmless species are familiar with the venomous one. The researchers compared the geographical range of the toad and viper in the Democratic Republic of Congo (DRC) and found that the Congolese giant toad does not seem to occur in areas where the Gaboon viper is absent. The researchers identified 11 locations in the eastern rainforests where the range of both species overlaps.

Based on speciation dating estimates from genetic data, the Congolese giant toad and Gaboon viper first evolved at about the same time in the early Pliocene about 4-5 million years ago. Considered with their similar appearance, behaviour, and overlapping geographic distribution, the toads and vipers likely coevolved together, further supporting the mimicry hypothesis.

“Given the relatively large size and therefore calorific value of this toad compared to other species, it would make tempting prey to a large variety of generalist predators, including primates and other mammals, lizards, snakes and birds,” says Kusamba, from the Centre de Recherche en Sciences Naturelles, DRC. “Many of these predators use vision to find their prey, and because the viper is deadly venomous, they probably recognise the distinctive, contrasting markings from a considerable distance and avoid the toad because of them, receiving a threatening hiss if the appearance doesn’t put them off.”

Perhaps the best-known examples of Batesian mimicry are in butterflies, where around a quarter of over 200 Papilio swallowtail butterfly species are non-toxic impersonators of toxic ones. Other examples from the animal kingdom include comet fish that fool predators into thinking their tail is a moray eel‘s head, the Brazilian galliwasp lizard that mimics a toxic millipede, and zebra sharks that take on the coloration and undulating movements of venomous sea snakes. Many harmless snakes mimic venomous ones, and some caterpillars, legless lizards, and even birds are able to do so. However, the current study is the first to identify an amphibian mimicking a venomous snake.