The monkey hunters: Humans colonized South Asian rainforest by hunting primates

A multidisciplinary study has found evidence for humans hunting small mammals in the forests of Sri Lanka at least 45,000 years ago. The researchers discovered the remains of small mammals, including primates, with evidence of cut-marks and burning at the oldest archaeological site occupied by humans in Sri Lanka, alongside sophisticated bone and stone tools. The hunting of such animals is an example of the uniquely human adaptability that allowed H. sapiens to rapidly colonize a series of extreme environments apparently untouched by its hominin relatives.

The monkey hunters: Humans colonized South Asian rainforest by hunting primates
This is an example of tools manufactured from monkey bones and teeth recovered from the Late Pleistocene layers
of Fa Hien Cave, Sri Lanka [Credit: N. Amano]

In a new paper published in Nature Communications, an international team of scientists has revealed novel evidence for the unique adaptability of Homo sapiens. The study, led by scientists from the Max Planck Institute for the Science of Human History, alongside colleagues from Sri Lankan and other international institutions, shows that human populations were able to specialize in the hunting of small arboreal animals for tens of thousands of years. This is the oldest and longest record of sophisticated, active primate hunting by foragers. This work also highlights the distinctive ecological capacities of H. sapiens relative to its hominin ancestors and relatives.
Tropical rainforests: a unique challenge

Recent research has demonstrated that our species adapted to a diversity of extreme environments as they spread around the world, including deserts, high altitude settings, palaeoarctic conditions, and tropical forests. Previously, however, discussion of the migration of our species into Europe, the Middle East, and Asia has often focused on our increased efficiency in hunting, butchering, and consuming medium to large game in open ‘savanna’ settings. Alternatively, coastal settings have been seen as important sources of protein, stimulating human evolution and migration.

The monkey hunters: Humans colonized South Asian rainforest by hunting primates
This is an exterior view of the entrance of Fa-Hien Lena cave in Sri Lanka
[Credit: O. Wedage]

Tropical rainforests have been somewhat neglected in discussions of human migrations and dispersal. In public and academic perception, these environments are often seen as isolated barriers to human movement, with disease, dangerous animals, and limited resources all posing challenges. In particular, when compared to the large animals of open savannas, small, fast forest monkeys and squirrels are difficult to capture and provide smaller amounts of protein.
Small mammals and hunting complexity

The procurement of small mammals has long been considered a feature of technological and behavioural ‘complexity’ or ‘modernity’ unique to our species. Previous research in Europe and West Asia has linked increased capture and consumption of agile small mammals both to human population growth and to climatically-driven crises. Traditionally, these have been considered to be particularly extreme ~20,000 years ago.

The monkey hunters: Humans colonized South Asian rainforest by hunting primates
This is a gray tufted langur (S. priam), one of the monkey species targeted by early humans that settled
in Fa Hien Cave, Sri Lanka [Credit: O. Wedage]

However, the onset and behavioural context of small mammal hunting in other parts of the world, particularly Asia, has remained poorly studied. This is particularly the case outside of temperate environments. «Over the last two decades, research has highlighted human occupation of tropical rainforests in South Asia, Southeast Asia, and Melanesia at least as early as 45,000 years ago, so the potential for human reliance on small mammals in these settings prior to 20,000 years ago seems likely,» says co-senior author Dr. Patrick Roberts of the Max Planck Institute for the Science of Human History.

A Sri Lankan specialty

Sri Lanka has been a prominent part of discussions of early human adaptations to tropical rainforests, though there has been a general lack of systematic, detailed analysis of animal remains associated with archaeological sites on the island. For the current study, the researchers produced new chronological information, analysis of animal remains, and studies of lithic and bone tool assemblages from Fa-Hien Lena Cave, the site of the earliest fossil and archaeological evidence of H. sapiens in Sri Lanka.

The monkey hunters: Humans colonized South Asian rainforest by hunting primates
Map of Sri Lanka, showing the location of Fa-Hien Lena and the country’s
vegetation zones [Credit: N. Amano. Wedage et al. 2019]

«The results demonstrate specialized, sophisticated hunting of semi-arboreal and arboreal monkey and squirrel populations from 45,000 years ago in a tropical rainforest environment,» says Oshan Wedage, lead author of the study, of the Max Planck Institute for the Science of Human History. Co-author Dr. Noel Amano, also of the Max Planck Institute for the Science of Human History, adds, «This was complemented by sophisticated bone tool technologies which were, in turn, created from the bones of hunted monkeys.»
Fine-tuned adaptations, not ‘monkey business’

Together, the results of this new work demonstrate a highly tuned focus on monkey and other small mammal hunting over 45,000 years. A sustained focus on adult monkeys throughout this time period suggests that this strategy continued to be sustainable during this lengthy period and that the tropical rainforests were not over-taxed by human presence and practices.

«This ‘monkey menu’ was not a one-off, and the use of these difficult-to-catch resources is one more example of the behavioural and technological flexibility of H. sapiens,» says Prof. Michael Petraglia of the Max Planck Institute for the Science of Human History, a senior author of the study. Further detailed analysis of the tools and animal remains left behind by early members of our species promises to yield more insights into the variety of strategies that enabled H. sapiens to colonize the world’s continents and left us the last hominin standing.

Source: The Max Planck Institute for the Science of Human History [February 19, 2019]



Sluggish Movements With its large neurons and relatively…

Sluggish Movements

With its large neurons and relatively simple circuits, the sea slug Aplysia californica (pictured) is a valuable model system in neurobiology, famous for Nobel prize-winning work on learning and memory. Most recently, researchers used Aplysia neurons to investigate how cells control the movement of mitochondria. These vital organelles, producing energy in the form of ATP, are transported within cells to areas where this energy is most needed. When two neurons form a connection, or synapse, mitochondria fuel the signal transmission between them. Scientists found that, in Aplysia, synapse formation boosts mitochondrial movement, and triggers changes in the activity of around 4000 genes, causing a long-term shift in the pre-synaptic neuron’s makeup. These new insights could help find ways to address problems with mitochondrial transport, thought to be involved in neurodegenerative diseases like Alzheimer’s.

Written by Emmanuelle Briolat

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Captioned Image Spotlight (19 Feb 2019): A Recent Impact Site in…

Captioned Image Spotlight (19 Feb 2019): A Recent Impact Site in Noachis Terra

This image shows a recent impact in Noachis Terra in the southern mid-latitudes of Mars. The impact occurred in dark-toned ejecta material from a degraded, 60-kilometer crater to the south.

Rather than a single impact crater, we see multiple impacts like a shotgun blast. This suggests that the impactor broke up in the atmosphere on entry. Although the atmosphere of Mars is thinner than Earth’s, it still has the capacity to break up small impactors, especially ones comprised of weaker materials, like a stony meteoroid versus a iron-nickel one.

Our image depicts 21 distinctive craters ranging in size from 1 to 7 meters in diameter. They are distributed over an area that spans about 305 meters. Most observed recent impacts expose darker-toned materials underlying bright dusty surfaces. However, this impact does the opposite, showing us lighter-toned materials that lie beneath a darker colored surface.

The impact was initially discovered in a 2016 Context Camera image, and was not seen in a 2009 picture. This implies that the impact may be only two years old, but certainly no more than nine years.

NASA/JPL/University of Arizona