Category: Environment

{During the last Ice Age, Australia, Tasmania and New Guinea formed a single landmass, called Sahul. It was a strange and often hostile place populated by a bizarre cast of giant animals.}

There were 500-pound kangaroos, marsupial tapirs the size of horses and wombat-like creatures the size of hippos. There were flightless birds that weighed twice as much as modern emu, 33-foot snakes, 20-foot crocodiles, 8-foot turtles with horned heads and spiked tails, and giant monitor lizards that measured greater than 6 feet from tip to tail and were likely venomous.

By about 30,000 years ago, however, most of these ‘megafauna’ had disappeared from the Sahul as part of a global mass extinction that saw the end of nearly all of the super-sized animals that had evolved to survive in extreme Ice Age climates. The factors that forced the Australian megafauna into extinction remain a matter of considerable controversy. Many experts argue that the ancestors of the Australian aborigines, who made an appearance approximately 50,000 years ago, either hunted them into extinction or gradually destroyed the habitat they required by practices such as fire-stick burning. Others argue that the gradual drying out of Australia and weakening of the Australian monsoon played a major role in their demise.

A new study has compared the diet of a variety of Australian megafaunal herbivores from the period when they were widespread (350,000 to 570,000 years ago) to a period when they were in decline (30,000 to 40,000 years ago) by studying their fossil teeth. The analysis suggests that climate change had a significant impact on their diets and may well have been a primary factor in their extinction.

“We have found evidence that, as the climate was changing and getting drier, animal diets were shifting dramatically,” said Larisa DeSantis, assistant professor of earth and environmental studies at Vanderbilt University, who directed the study. “If climate change was a primary or contributing factor in their demise, as it appears, we need to pay more attention to how current levels of climate change are affecting animals today.”

The results of the study are described in a paper titled “Dietary responses of Sahul (Pleistocene Australia-New Guinea) megafauna to climate and environmental change” published on Jan. 25 by the journal Paleobiology. Co-authors on the paper are Judith Field and John Dodson from the University of New South Wales and Stephen Wroe from the University of New England.

Michael Archer, a leading Australian paleontologist at the University of New South Wales who was not involved in the study, commented, “This new study, based on hard evidence, makes it clear that changes in late Pleistocene climate had a major impact on the late Pleistocene megafauna of Australia, adding even more evidence to challenge the imaginative a priori assumption that ‘blitzkrieg’ by early humans caused the extinction of this continent’s lost megafauna.Climate change clearly has been in the past and will continue to be a major cause of extinction into the future.”

The teeth that were analyzed came from the Cuddie Springs site in southeastern Australia. It is located on a prehistoric ephemeral lake and it is the only site on mainland Australia that has produced fossil evidence of the co-existence of humans and megafauna. “Unfortunately, many of the advocates of the human predation hypothesis have discounted Cuddie Springs because it does not support the popular ‘blitzkrieg’ theory that maintains the megafauna went extinct in the 1,000-year period after humans arrived on the scene,” said DeSantis.

It’s amazing how much information about the prehistoric environment paleontologists can extract from fossil teeth using a dental drill, dental impression material and some sophisticated instruments. The ratios of oxygen and carbon isotopes locked in the enamel provide clues about the animals’ diet and the average temperature and humidity of the environment at the time the teeth formed. Differences within individual teeth mirror climate variability. Analysis of the microscopic scratches on the surface of the teeth provides evidence of what the animal was eating in the last few weeks of its life. Differences in wear-patterns can differentiate between animals that were grazing on grass and browsing on bushes.

“For example, we know from the analysis of modern day kangaroos that oxygen isotope ratios in their teeth are highly correlated with the relative humidity and amount of precipitation in their environment,” DeSantis said. “This makes them ideally suited for tracking changes in aridity over time.”

During the megafaunal heyday around 500,000 years ago, the dental analysis revealed that the climate was semi-arid. In addition, the animals’ diets were highly variable, implying that there were a number of ecological niches available to them.

That contrasts markedly with the period from 30,000 to 40,000 years ago. Here, the analysis indicates that the climate was substantially drier and the diet of the giant herbivores was considerably more restricted.

“It appears that long-term aridification may have reduced the ability of megafauna to consume certain types of plants, including salt-bush. Eating salt-rich plants requires drinking additional water that was less available and likely increased competition for similar plant resources,” said DeSantis. “These data clarify the impacts of climatic change on marsupial megafauna and suggest that the long-term drying out of Australia, identified here and in other records, likely played a key role in the decline and disappearance of this unique suite of animals.”

The work was supported by National Science Foundation grants EAR1053839 and FAIN1455198,Australian Research Foundation grants ARC LP211430 and DPO5579230, University of New South Wales, the University of Sydney, Oak Ridge Associated Universities and Vanderbilt University.

{Scientists discover key mechanism that controls when fruit flies sexually mature.}

Like humans, insects go through puberty. The process is known as metamorphosis. Examples include caterpillars turning into butterflies and maggots turning into flies.

But, it has been a long-standing mystery as to what internal mechanisms control how insects go through metamorphosis and why it is irreversible.

Now, a team of scientists, led by an assistant professor at the University of California, Riverside, has solved the mystery. They also believe the findings, which were just published in an early version in the journal PLOS Genetics, could be applied to mammals, including humans. The final version of the paper will be published Feb. 8.

Using the model organism fruit flies, the researchers found that the amount of DNA in the fruit fly controls the initial production of steroid hormones, which signal the start of metamorphosis.

More specifically, the cells that produce steroid hormones keep duplicating their DNA without cell division, making their nuclei huge. The team found that this amount of DNA in steroid hormone-producing cells is a critical indicator of their juvenile development, and it even determines when the insects get into metamorphosis.

Naoki Yamanaka, an assistant professor of entomology at UC Riverside, likened the accumulation of DNA to rings found inside trees that are used to date trees.

“The amount of DNA is like an internal timer for insect development,” Yamanaka said. “It tells the insect, ‘OK, I will grow up now.’”

Their finding explains, for the first time, why insect metamorphosis, just like human puberty, is an irreversible process. It is irreversible since DNA duplication cannot be reversed in cells. Once the cells increase the amount of DNA and start producing steroid hormones, that is the point of no return; they cannot go back to their childhood.

The findings could have multiple applications. In the short term, they could be used to help control agricultural pests by manipulating their steroid signaling pathways. They could also be used to aid beneficial insects, such as bees.

In the long term, the findings could also be used to develop better ways to treat diseases in humans related to sexual maturation, since human puberty is also controlled by steroid hormones, just like insects. The results may also aide future studies on steroid-related diseases such as breast cancer, prostate cancer, and menopause-related symptoms.

Yamanaka will continue this research by focusing on other insects, such as bumblebees and mosquitos, to see if they have a similar internal timer.

{Analyses of energy cycle offer a new explanation of climate change.}

Researchers know that more, and more dangerous, storms have begun to occur as the climate warms. A team of scientists has reported an underlying explanation, using meteorological satellite data gathered over a 35-year period.

The examination of the movement and interaction of mechanical energies across the atmosphere, published Jan. 24 in the journal Nature Communications, is the first to explore long-term variations of the Lorenz energy cycle — a complex formula used to describe the interaction between potential and kinetic energy in the atmosphere — and offers a new perspective on what is happening with global warming.

“It is a new way to look at and explain what people have observed,” said Liming Li, assistant professor of physics at the University of Houston and corresponding author of the paper. “We found that the efficiency of Earth’s global atmosphere as a heat engine is increasing during the past four decades in response to climate change.”

In this case, increased efficiency isn’t a good thing. It suggests more potential energy is being converted to kinetic energy — energy that is driving atmospheric movement — resulting in a greater potential for destructive storms in regions where the conversion takes place.

“Our analyses suggest that most energy components in the Lorenz energy cycle have positive trends,” the researchers wrote. “As a result, the efficiency of Earth’s global atmosphere as a heat engine increased during the past 35 years.”

In addition to Li, researchers involved in the work include Yefeng Pan, first author and a former doctoral student at UH; Xun Jiang, associate professor of earth and atmospheric sciences at UH; Gan Li, Wentao Zhang and Xinyue Wang, all of Guilin University of Electronic Technology; and Andrew P. Ingersoll of the California Institute of Technology.

The researchers used three independent meteorological datasets to track variables including three-dimensional wind field, geopotential-height field and temperature field at points across the globe from 1979 to 2013. They then used the data to compute the Lorenz energy cycle of the global atmosphere. Such an energy cycle in the atmosphere significantly influences weather and climate.

Previous studies have covered only five-year and 10-year periods before 1973, Li said. “Now we can investigate the Lorenz energy cycle of the global atmosphere during the past 35 years, using satellite-based observations,” he said.

While the researchers reported that the total mechanical energy of the global atmosphere remains constant over time, there has been a significant increase in what they describe as “eddy energies,” or the energies associated with storms, eddies and turbulence.

Li said the positive trends for eddy energies were especially pronounced in the southern hemisphere and over parts of Asia, and the researchers point out that intensifying storm activity over the southern oceans and increasing drought in Central Asia contribute to the positive trends.

“This is a new perspective to explain global warming from an energy standpoint,” he said.

{Where do insects go in winter? A new study published in the journal Science found that flying insects migrate on a seasonal basis. This movement constitutes the largest migration found in today’s world, creating a mass that is almost eight times that of birds that migrate from Britain to Africa. “The migration of 3.5 trillion insects, with a biomass over seven times that of the birds that migrate from Britain to Africa, has significant ecological ramifications. Insects are highly sensitive to climate change, and this may lead to dramatic changes in the population of migrating insects, causing important environmental changes,” explains Dr. Nir Sapir of the Department of Evolutionary and Environmental Biology at the University of Haifa, who is one of the authors of the article.}

Although flying insects constitute one of the largest populations on the planet, no comprehensive quantitative study has been undertaken until now examining the phenomenon of insect migration. Researchers assumed that many insect populations migrate, but did not know which insects do so, when, what the scope of migration is, and so forth. A broad-based international study undertaken by researchers from the University of Haifa, Nanjing Agricultural University, the University of Exeter, the Hebrew University of Jerusalem, the University of Greenwich, and Rothamsted Research has now changed this picture. In order to collect data, radars were installed some 15 years ago in southern England. Data from these radars was used to estimate insect bio-flow over an area of 70,000 square kilometers. The radars measured the weight of the insects, their flight speed and their direction and height. For very small insects that weigh less than 10 mg and are not picked up by the radar, special nets were used to catch samples in the air. Between 2000 and 2009, data were collected for insects flying at height of over 150 meters above.

The findings clearly showed a southward movement of these insect populations in fall and a northward movement in spring. The researchers were surprised by the scale of this phenomenon: some 3.5 trillion insects, creating a biomass of 3,200 tons, migrated in each season. The study did not examine the starting points and destinations of each insect population, but the researchers believe that this migration takes place over distances of at least several hundred kilometers, and possibly much more. “Since there is evidence that this migration also takes place over sea, and since Great Britain is an island, these insects must have come to Britain in the spring, and at least some of them must reach continental Europe in the fall,” Dr. Sapir explains.

Also surprisingly, the data also showed that insects use the wind in order to reach their destination, choosing to “hitch a ride” on specific wind flows. The insects exploited the southerly winds in spring and the northerly winds in the fall. “They actually chose the direction they wanted to go in. We were surprised to find that insects make conscious use of navigation capabilities in order to reach their destinations using these winds,” said Dr. Sapir. The larger insects even combined their natural flight speed with the wind in order to reach a speed of up to 58 kilometers per hour during the migration seasons. These findings have ramifications for many ecosystems, and even for our own everyday lives. In most cases, insects’ bodies include 10 percent nitrogen and one percent phosphorus. This makes them excellent fertilizer for plants and crops and nutritious food for insect eaters, such as birds, bats, and other animals. In addition, insects also pollinate, constitute crop pests as well as killing some other pest insects, transfer diseases and parasites, and play other functions. “Such a large biomass has tremendous importance for the functioning of diverse ecosystems across large parts of the globe, and for other aspects of our daily lives,” Dr. Sapir explains. “Cycles of nitrogen and phosphorus in nature are extremely significant, particularly since these chemicals form a limited component in the food chain. This massive movement of insects transports these vital materials across enormous distances.”

The important ramifications of insect migration highlight a further finding by the researchers: The total biomass of insects varies from one year to another, with the difference sometimes being as great as 200 tons. They explain that more insects are born in warmer summers, and accordingly the quantity of migration is greater. Conversely, in cooler summers fewer insects are born, and accordingly the biomass is smaller. Global climactic changes mean that the climate around the world is getting warmer, and accordingly it can be assumed with a large degree of certainty that the number of insects will increase significantly. “We do not know yet whether all types of insects are reproducing more, or whether only certain types are doing so. An increase in the number of some insects could be harmful, while in other cases it could actually be beneficial. Accordingly, it is too soon to tell whether this change should be welcomed. But what is certain is that this is the largest and most influential continental migration in the world, as far as we know to date. We need to start monitoring it carefully,” Dr. Sapir concludes.

{In cooperation with an international team of experts, scientists from the German Primate Center (DPZ) demand immediate measures to protect primates.}

Worldwide, around 60 per cent of the 500 known primate species are threatened with extinction. primates live in tropical and subtropical areas and are mainly found in regions of Africa, South America, Madagascar and Asia. However, the extinction of a species must be considered a global problem. An international research team that includes two scientists from the German Primate Center — Leibniz Institute for Primate Research, evaluated the economic, social, cultural, ecological and scientific importance of primates and the global consequences of species extinctions. They call for a strengthening of awareness and a rethinking of the impending extinction events. In order to protect primates, immediate action must be focused on conservation and sustainability.

Golden snub-nosed monkey, ring-tailed lemur, Javan slow loris, Azara’s night monkey — we still have a large diversity of primates. They are an essential part of tropical biodiversity, contribute to natural regeneration and thus to the functioning of tropical habitats and are an integral part of many cultures and religions. Worldwide, more than half of all primate species are threatened with extinction. In order to evaluate the role of human-induced threats to primate survival, the researchers combined data from the International Red List of the world nature conservation organization International Union for the Conservation of Nature (IUCN) with data from the United Nations (UN) database. This enabled the scientists to establish forecasts and development trends for the next 50 years. For the next 50 years the scientists predict extinction events for many primate species. “Humans increasingly encroach primate habitats and exploit natural resources,” explains Christian Roos, a scientist at the German Primate Center (DPZ) and a co-author of the study.

The natural habitat of primates is mostly found in regions with high levels of poverty and a lack of education. These conditions lead to the exploitation of natural resources. Deforestation for agricultural land-use has become widespread. Road networks are built for the transportation and the export of goods. Around 76 per cent of the species have lost large parts of their habitat because of agricultural expansion. Another major threat is illegal hunting and the primate trade. In some regions, up to 90 per cent of species are affected. Immediate action in these regions should be aimed at improving health and providing access to education for the local populations. In order to preserve the traditional livelihoods that will contribute to food security and environmental protection, sustainable land-use initiatives must be developed. “The lifestyle and the economy in the industrialized countries contribute to the threat for primates. Many of the resources and products such as mineral resources, beef, palm oil and soya that are destroying the habitats of primates are ultimately consumed in industrialized countries,” says Eckhard W. Heymann, a scientist at the DPZ and a co-author of the study.

The team of experts calls on government officials, academics, international organizations, non-governmental organizations, the business community and citizens to strengthen the awareness of the extinction events and the immediate consequences for humans. “Conservation is an ecological, cultural and social necessity. When our closest relatives, the non-human primates, become extinct, this will send a warning signal that the living conditions for humans will soon deteriorate dramatically,” says Heymann.

{Researchers have pinpointed a brain region monkeys use to evaluate their ability to recall memories. To date, this metamemory process, which requires a higher level of self-reflection about our own cognition, was thought by some to be unique to humans, though this research suggests otherwise.}

Evaluating one’s own memory requires access to information about the strength of memory traces, though the brain structures and neural mechanisms involved in this effort — and whether they are distinct from normal memory recall — remain unknown.

Here, to shed light in this space, Kentaro Miyamoto and colleagues devised a metamemory test in which macaques judged their own confidence in remembering past experiences; the animals opted for higher bets on the outcome of a memory recall test when they were surer their memory judgments were correct.

Using this setup, as well as whole-brain searches by functional neuroimaging, the researchers identified a specific region in the prefrontal brain essential for metamemory decision making. Its inactivation caused selective impairment of metamemory, but not of memory itself.

The results pave the way to further study of the neuronal underpinnings of metacognition using an animal model, where metamemory has previously been difficult to evaluate.

{Settling a persistent scientific controversy, a long-awaited report shows that restricting calories does indeed help rhesus monkeys live longer, healthier lives.
}

A remarkable collaboration between two competing research teams — one from the University of Wisconsin-Madison and one from the National Institute on Aging — is the first time the groups worked together to resolve one of the most controversial stories in aging research.

The findings by the collaboration — including Senior Scientist Ricki Colman of the Wisconsin National Primate Research Center and UW-Madison Associate Professor of Medicine Rozalyn Anderson; and NIA Staff Scientist and Nonhuman Primate Core Facility Head Julie Mattison and Senior Investigator and Chief of the Translational Gerontology Branch Rafael de Cabo — were published in the journal Nature Communications.

In 2009, the UW-Madison study team reported significant benefits in survival and reductions in cancer, cardiovascular disease, and insulin resistance for monkeys that ate less than their peers. In 2012, however, the NIA study team reported no significant improvement in survival, but did find a trend toward improved health.

“These conflicting outcomes had cast a shadow of doubt on the translatability of the caloric-restriction paradigm as a means to understand aging and what creates age-related disease vulnerability,” says Anderson, one of the report’s corresponding authors. Working together, the competing laboratories analyzed data gathered over many years and including data from almost 200 monkeys from both studies. Now, scientists think they know why the studies showed different results.

First, the animals in the two studies had their diets restricted at different ages. Comparative analysis reveals that eating less is beneficial in adult and older primates but is not beneficial for younger animals. This is a major departure from prior studies in rodents, where starting at an earlier age is better in achieving the benefits of a low-calorie diet.

Second, in the old-onset group of monkeys at NIA, the control monkeys ate less than the Wisconsin control group. This lower food intake was associated with improved survival compared to the Wisconsin controls. The previously reported lack of difference in survival between control and restricted groups for older-onset monkeys within NIA emerges as beneficial differences when compared to the UW-Madison data. In this way, it seems that small differences in food intake in primates could meaningfully affect aging and health.

Third, diet composition was substantially different between studies. The NIA monkeys ate naturally sourced foods and the UW-Madison monkeys, part of the colony at the Wisconsin National Primate Research Center, ate processed food with higher sugar content. The UW-Madison control animals were fatter than the control monkeys at NIA, indicating that at nonrestricted levels of food intake, what is eaten can make a big difference for fat mass and body composition.

Finally, the team identified key sex differences in the relationship between diet, adiposity (fat), and insulin sensitivity, where females seem to be less vulnerable to adverse effects of adiposity than males. This new insight appears to be particularly important in primates and likely is translatable to humans.

The upshot of the report is that caloric restriction does indeed seem to be a means to affect aging. However, for primates, age, diet and sex must all be factored in to realize the full benefits of lower caloric intake.

{The ghosts of Ice Age mammals can teach valuable, real-world lessons about what happens to an ecosystem when its most distinct species go extinct, according to a Yale University study.}

Researcher Matt Davis tracked the history of some of the world’s largest mammals and the roles they played within their respective environments. The findings appear in the Jan. 11 online edition of the journal Proceedings of the Royal Society B.

On the plus side, Davis said, the Ice Age wasn’t as hard on functional diversity — the role that an animal plays within an ecosystem — as previously thought. Animals that survived the Ice Age, such as the beaver, proved to be just as distinct as those that did not survive. On the minus side, Davis found, our planet has reached a point where losing even a handful of key mammals will leave as much of a gap as all of the Ice Age mammal extinctions put together.

The planet lost about 38% of its large-mammal, functional diversity during the Ice Age. Those species included woolly mammoths, giant ground sloths, stout-legged llamas, and giant beavers.

“You can think of it like a big tent where every animal is holding a pole to keep the tent up,” said Davis, a graduate student in Yale’s Department of Geology and Geophysics. “We lost a lot of species when humans first arrived in North America, so part of our tent fell down — but not as big of a part as we previously thought. However, now we only have a few animals left holding up those poles. If they die, the whole tent could collapse.”

The study looked at 94 large mammal species in North America over the last 50,000 years. These included Columbian mammoths, Canadian lynx, long-horned bison, and sabertooths, as well as cougars, moose, coyotes, elk, raccoons, dogs, and cows.

One aim of the study was to examine the relationship between functional diversity and extinction risk: Were the most distinct species the ones most at risk? Davis found that for large Ice Age mammals in North America, distinct species with unique traits were not more likely to go extinct. That is why the Ice Age extinctions were not as harsh on the surrounding ecosystems, Davis said.

In the case of mammoths, nothing was able to replace their lost function — essentially, being really, really big — once they were gone. However, Davis found that European domestic animals, introduced later, did restore some functional diversity. Another example of this is burros, which came along after the extinction of Shasta ground sloths. Both the burro and the Shasta ground sloth share similar diets and body masses.

For today’s species, such redundancies in functionality are much less frequent, Davis explained. Vulnerable species like polar bears, jaguars, and giant anteaters have no functional equivalent.

“Examining the past through the fossil record actually allows us to better predict future extinctions,” Davis said. “We can’t understand how valuable or vulnerable species are today without considering the ‘ghosts’ of those species that died before them.”

Partial funding for the study came from the Yale Institute for Biospheric Studies, the Geological Society of America, the American Society of Mammalogists, and a Smithsonian Institution Predoctoral Fellowship.

{Sixty six million years ago, the sudden extinction of the dinosaurs started the ascent of the mammals, ultimately resulting in humankind’s reign on Earth. Climate scientists now reconstructed how tiny droplets of sulfuric acid formed high up in the air after the well-known impact of a large asteroid and blocking the sunlight for several years, had a profound influence on life on Earth. Plants died, and death spread through the food web. Previous theories focused on the shorter-lived dust ejected by the impact. The new computer simulations show that the droplets resulted in long-lasting cooling, a likely contributor to the death of land-living dinosaurs. An additional kill mechanism might have been a vigorous mixing of the oceans, caused by the surface cooling, severely disturbing marine ecosystems.}

“The big chill following the impact of the asteroid that formed the Chicxulub crater in Mexico is a turning point in Earth history,” says Julia Brugger from the Potsdam Institute for Climate Impact Research (PIK), lead author of the study to be published in the Geophysical Research Letters. “We can now contribute new insights for understanding the much debated ultimate cause for the demise of the dinosaurs at the end of the Cretaceous era.” To investigate the phenomenon, the scientists for the first time used a specific kind of computer simulation normally applied in different contexts, a climate model coupling atmosphere, ocean and sea ice. They build on research showing that sulfur- bearing gases that evaporated from the violent asteroid impact on our planet’s surface were the main factor for blocking the sunlight and cooling down Earth.

In the tropics, annual mean temperature fell from 27 to 5 degrees Celsius

“It became cold, I mean, really cold,” says Brugger. Global annual mean surface air temperature dropped by at least 26 degrees Celsius. The dinosaurs were used to living in a lush climate. After the asteroid’s impact, the annual average temperature was below freezing point for about 3 years. Evidently, the ice caps expanded. Even in the tropics, annual mean temperatures went from 27 degrees to mere 5 degrees. “The long-term cooling caused by the sulfate aerosols was much more important for the mass extinction than the dust that stays in the atmosphere for only a relatively short time. It was also more important than local events like the extreme heat close to the impact, wildfires or tsunamis,” says co-author Georg Feulner who leads the research team at PIK. It took the climate about 30 years to recover, the scientists found.

In addition to this, ocean circulation became disturbed. Surface waters cooled down, thereby becoming denser and hence heavier. While these cooler water masses sank into the depths, warmer water from deeper ocean layers rose to the surface, carrying nutrients that likely led to massive blooms of algae, the scientists argue. It is conceivable that these algal blooms produced toxic substances, further affecting life at the coasts. Yet in any case, marine ecosystems were severely shaken up, and this likely contributed to the extinction of species in the oceans, like the ammonites.

“It illustrates how important the climate is for all lifeforms on our planet”

The dinosaurs, until then the masters of Earth, made space for the rise of the mammals, and eventually humankind. The study of Earth’s past also shows that efforts to study future threats by asteroids have more than just academic interest. “It is fascinating to see how evolution is partly driven by an accident like an asteroid’s impact — mass extinctions show that life on Earth is vulnerable,” says Feulner. “It also illustrates how important the climate is for all lifeforms on our planet. Ironically today, the most immediate threat is not from natural cooling but from human-made global warming.”

{Baboons produce vocalizations comparable to vowels. This is what has been demonstrated by an international team coordinated by researchers from the Gipsa-Lab (CNRS/Grenoble INP/Grenoble Alpes University), the Laboratory of Cognitive Psychology (CNRS/AMU), and the Laboratory of Anatomy at the University of Montpellier, using acoustic analyses of vocalizations coupled with an anatomical study of the tongue muscles and the modeling of the acoustic potential of the vocal tract in monkeys. Published in PLOS ONE on January 11, 2017, the data confirm that baboons are capable of producing at least five vocalizations with the properties of vowels, in spite of their high larynx, and that they are capable of combining them when they communicate with their partners. The vocalizations of baboons thus point to a system of speech among non-human primates.}

Language is a distinctive characteristic of the human species. The question of its origins and how it evolved is one of the most intractable in all science. One of the dominant theories in this field associates the possibility of producing differentiated sounds, the basis of spoken communication, with the “descent of the larynx” observed over the course of the evolution of Homo sapiens. This theory argues that human speech requires a low larynx (in relation to the cervical vertebrae) and that a high larynx, as found in baboons (Papio papio), prevents the production of a system of vocalizations analogous to the vowel system that exists in all languages.

According to this theory, only humans over the age of one can produce differentiated sounds, whereas babies, Neanderthal man and all species of monkey are incapable of doing so because their larynx is positioned too high. Researchers from the Gipsa-Lab (CNRS/Grenoble INP/Grenoble Alpes University) had already shown that the high position of the larynx in babies and Neanderthals is not a handicap in terms of producing different vowels. However, it remained to be proved that monkeys, in particular baboons, were indeed capable of producing these types of vocalizations.

The researchers acoustically analyzed the vocalizations of baboons, performed an anatomical study of their tongue muscles, and modeled the acoustic potential of their vocal tract. They thereby discovered that these baboons produce sounds comparable to five human vowels [ɨ æ ɑ o u]. Researchers describe these sounds as “vowel-like” because they share some of the acoustic characteristics of vowels, without having all of their properties.

In addition, they show that the vowel-like sounds [ɑ] and [u] are each used in two distinct vocalizations, produced depending on the situation, and that baboons can also produce a sequence of these two vowel-like sounds with the vocalization “wahoo.” This protosystem combines with vibration frequencies of the vocal folds in a frequency range that is markedly wider than that of speech.

This demonstration of a vocalic protosystem in non-human primates confirms that they can produce different vocalizations, in spite of their high larynx1. Although monkeys do not produce speech sounds, the data suggest evolutionary links between the vocalizations of baboons and human phonological systems. More generally, spoken languages may have evolved from ancient articulatory skills already possessed by our last common ancestor Cercopithecoidae, around 25 million years ago.

This research was conducted thanks to close collaboration between many specialists from the Gipsa-Lab (CNRS/Grenoble INP/Grenoble Alpes University), the Laboratory of Cognitive Psychology (CNRS/AMU), the Laboratory of Anatomy at the University of Montpellier, the Speech and Language Laboratory (CNRS/AMU), and New College, University of Alabama. It received support from the Labex Brain & Language Research Institute (BRLI).

1 Other research, published by an American team in Science Advances in December 2016, corroborates these results thanks to articulatory measurements of the vocal tract of monkeys.