Studying Mouse Lemur Genetics Reveals Ancient Forest Mosaic Environment

Today, Madagascar is home to a mosaic of different habitats--a lush rainforest in the east and a dry deciduous forest in the west, separated by largely open highlands. But the island off the southeast coast of Africa hasn't always been like that--a new study published in the Proceedings of the National Academy of Sciences announces that these two ecologically different portions of the island were once linked by a patchwork of forested areas. And to figure it out, the scientists analyzed the DNA of some of the cutest animals on earth--mouse lemurs.

"For a long time, scientists weren't sure how or why Madagascar's biogeography changed in very recent geological time, specifically at the key period around when humans arrived on the island a few thousand years ago. It has been proposed they heavily impacted the Central Highland forests," says Steve Goodman, MacArthur Field Biologist at The Field Museum in Chicago, who co-authored the study and has been studying Malagasy animals for thirty years. "This study shows the landscape was changing thousands of years before humans arrived."

So scientists wanted to learn about the history of Madagascar's landscape--why study mouse lemurs? The tiny primates are the perfect combination of fast-breeding, hardy, and unique to the island. "They reach reproductive maturity within a year, and that means that a lot of generations are produced very quickly," explains Goodman. "That enables us to see evolution at work faster than we would in an animal that took, say, five years to first reproduce." The lemurs, which are found only on Madagascar, live across much of the island, even forested areas that have been damaged by humans. That means that for scientists studying how the island changed over time, mouse lemurs are a jackpot. "The mouse lemurs are forest dependent--as the forest changes, they change. By studying how mouse lemurs evolved in different areas of the island, we're able to glimpse how the island itself changed and learn whether those changes were caused by humans," says Goodman.

By analyzing DNA from five different mouse lemur species, the scientists were able to tell when the different kinds of lemurs branched out from each other. "We were able to characterize tens of thousands of changes in the genomes of mouse lemurs that are now isolated and form separate species. By analyzing these DNA changes, we were able to understand when the species diverged from each other, and by inference, identify the ecological forces that might have driven them apart," says Anne Yoder, Director of the Duke University Lemur Center and lead author on the paper.

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Dental development in living and fossil orangutans

Dental development in living and fossil orangutans

Author:

Smith

Abstract:

Numerous studies have investigated molar development in extant and fossil hominoids, yet relatively little is known about orangutans, the only great ape with an extensive fossil record. This study characterizes aspects of dental development, including cuspal enamel daily secretion rate, long-period line periodicities, cusp-specific molar crown formation times and extension rates, and initiation and completion ages in living and fossil orangutan postcanine teeth. Daily secretion rate and periodicities in living orangutans are similar to previous reports, while crown formation times often exceed published values, although direct comparisons are limited. One wild Bornean individual died at 4.5 years of age with fully erupted first molars (M1s), while a captive individual and a wild Sumatran individual likely erupted their M1s around five or six years of age. These data underscore the need for additional samples of orangutans of known sex, species, and developmental environment to explore potential sources of variation in molar emergence and their relationship to life history variables. Fossil orangutans possess larger crowns than living orangutans, show similarities in periodicities, and have faster daily secretion rate, longer crown formation times, and slower extension rates. Molar crown formation times exceed reported values for other fossil apes, including Gigantopithecus blacki. When compared to African apes, both living and fossil orangutans show greater cuspal enamel thickness values and periodicities, resulting in longer crown formation times and slower extension rates. Several of these variables are similar to modern humans, representing examples of convergent evolution. Molar crown formation does not appear to be equivalent among extant great apes or consistent within living and fossil members of Pongo or Homo.

Does Climate Change Threaten the Primates?

This is the battle that nobody wins. According to a new study, climate change will adversely affect every single primate species on Earth. That’s every ape, monkey, gibbon, lemur and loris, no matter how super or strong they might be.

The study, published in the International Journal of Primatology, reveals that primate habitats will, on average, feel the pinch of a warming world 10 percent more severely than non-primate habitats. Not only will temperatures change, so will rainfall, with some species experiencing 7.5 percent more or less precipitation per degree C of global warming.

This is troubling news for the world’s primates, as many species rely on narrow habitats or have extremely specialized diets. Some primates only eat one or two things, so their food and habitats are particularly sensitive to disruption. Many primates are already endangered by habitat loss, hunting, or the illegal pet trade, so this additional threat could push several species over the brink.

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Do West African Chimpanzees Have a Culture With Rituals?

Chimp stone throwing compilation from laura kehoe on Vimeo.

Chimpanzee accumulative stone throwing

Authors:

Kühl et al

Abstract:

The study of the archaeological remains of fossil hominins must rely on reconstructions to elucidate the behaviour that may have resulted in particular stone tools and their accumulation. Comparatively, stone tool use among living primates has illuminated behaviours that are also amenable to archaeological examination, permitting direct observations of the behaviour leading to artefacts and their assemblages to be incorporated. Here, we describe newly discovered stone tool-use behaviour and stone accumulation sites in wild chimpanzees reminiscent of human cairns. In addition to data from 17 mid- to long-term chimpanzee research sites, we sampled a further 34 Pan troglodytes communities. We found four populations in West Africa where chimpanzees habitually bang and throw rocks against trees, or toss them into tree cavities, resulting in conspicuous stone accumulations at these sites. This represents the first record of repeated observations of individual chimpanzees exhibiting stone tool use for a purpose other than extractive foraging at what appear to be targeted trees. The ritualized behavioural display and collection of artefacts at particular locations observed in chimpanzee accumulative stone throwing may have implications for the inferences that can be drawn from archaeological stone assemblages and the origins of ritual sites.

Pop sci write up at Scientific American by one of the researchers.

New World Monkeys Percieve Pitch Like Humans

Complex pitch perception mechanisms are shared by humans and a New World monkey

Authors:

Song et al

Abstract:

The perception of the pitch of harmonic complex sounds is a crucial function of human audition, especially in music and speech processing. Whether the underlying mechanisms of pitch perception are unique to humans, however, is unknown. Based on estimates of frequency resolution at the level of the auditory periphery, psychoacoustic studies in humans have revealed several primary features of central pitch mechanisms. It has been shown that (i) pitch strength of a harmonic tone is dominated by resolved harmonics; (ii) pitch of resolved harmonics is sensitive to the quality of spectral harmonicity; and (iii) pitch of unresolved harmonics is sensitive to the salience of temporal envelope cues. Here we show, for a standard musical tuning fundamental frequency of 440 Hz, that the common marmoset (Callithrix jacchus), a New World monkey with a hearing range similar to that of humans, exhibits all of the primary features of central pitch mechanisms demonstrated in humans. Thus, marmosets and humans may share similar pitch perception mechanisms, suggesting that these mechanisms may have emerged early in primate evolution.

Human Evolved More Efficient Sleep, Require Less Than Other Primates

Insomniacs take heart: Humans get by on significantly less sleep than our closest animal relatives. The secret, according to a new study, is that our sleep is more efficient.

Researchers from Duke University scoured the scientific literature and compiled a database of slumber patterns across hundreds of mammals including 21 species of primates -- from baboons and lemurs to orangutans, chimpanzees and people. They then used statistical techniques to account for each species' position in the primate family tree.

They found that humans are exceptionally short sleepers -- getting by on an average of seven hours of sleep a night, whereas other primate species, such as southern pig-tailed macaques and gray mouse lemurs, need as many as 14 to 17 hours.

What's more, our sleep tends to be more efficient, meaning we spend a smaller proportion of time in light stages of sleep, and more of our sleep time in deeper stages of sleep. A dream state called rapid eye movement sleep, or REM, for example, makes up nearly 25 percent of our overall sleep. But in primates such as mouse lemurs, mongoose lemurs and African green monkeys, REM sleep barely climbs above five percent.

"Humans are unique in having shorter, higher quality sleep," said anthropologist and study co-author David Samson of Duke, who logged nearly 2,000 hours watching orangutans in REM and non-REM sleep as part of his dissertation research prior to coming to Duke.

link.

The Chimpanzee Stone Age has Begun

In the rainforests of west Africa, the woodlands of Brazil and the beaches of Thailand, archaeologists have unearthed some truly remarkable stone tools.

It's not the workmanship that makes them special. If anything, a casual observer might struggle to even identify them as ancient tools. It's not their antiquity that's exceptional either: they're only about the same age as the Egyptian pyramids.

What makes these tools noteworthy is that the hands that held them weren't human.

These stone tools were wielded by chimpanzees, capuchins and macaques. The sites where they have been unearthed are the basis of a brand new field of science: primate archaeology.

The tools are crude. A chimpanzee or monkey stone hammer is hardly a work of art to rival the beauty of an ancient human hand axe. But that's not the point. These primates have developed a culture that makes routine use of a stone-based technology. That means they have entered the Stone Age.

link.

The question is whether or not the stone tools have been worked or if they just stones picked up to be used.

There Were Distinct Major Papionin Primate Clades in the Pliocene/Pleistocene South Africa

Cercopithecoid humeri from Taung support the distinction of major papionin clades in the South African fossil record

Authors:

Gilbert et al

Abstract:

Associated cercopithecoid postcrania are rare in the Plio-Pleistocene fossil record, particularly in the case of South African karst cave sites. However, as clear postcranial differences between major papionin clades have been documented, it should be possible to assign isolated papionin postcrania to the Cercocebus/Mandrillus and Papio/Lophocebus/Theropithecus groups wherever sufficient anatomy is preserved. Here, we demonstrate that two partial humeri preserved at Taung, UCMP 56693 and UCMP 125898, are most likely attributable to the Cercocebus/Mandrillus and Papio/Lophocebus/Theropithecus clades, respectively. Univariate analyses (ANOVAs and t-tests) and multivariate analyses (discriminant function analyses) of humeral features, combined with a phylogenetic analysis of 24 humeral characters, all support our assessment. Given that the overwhelming number of craniodental specimens at Taung are attributable to two papionin taxa, Procercocebus antiquus (a member of the Cercocebus/Mandrillus clade) and Papio izodi (a purported fossil species of the modern genus Papio), we assign UCMP 56693 to Pr. antiquus and UCMP 125868 to P. izodi with a high degree of confidence. Implications for cercopithecoid evolution and biogeography are discussed, with a particular emphasis on these two fossil taxa.

Chimps are REALLY Tongue Tied, Unable to Learn Other Groups' Languages

Research published earlier this year claiming chimpanzees can learn each others' language is not supported, a team of scientists concludes after reviewing the study.

The scholarship in question, published in the journal Current Biology in February, centered on the examination of two sets of chimpanzees in the Edinburgh Zoo: one that had been captive for several years in the facility and one that had recently arrived from the Beekse Bergen Safari Park in the Netherlands. Over a three-year period, the researchers claimed that the latter set had altered their sounds to those of the former set when communicating about a common object, apples, resulting in what they saw as a newly shared vocalization.

The original study team, which included faculty from the University of York, the University of Zurich, and the University of St. Andrews, posited that the findings "provide the first evidence for vocal learning in a referential call in non-humans." This was offered as evidence that chimpanzees can learn different calls for the same object, which was widely interpreted as an important finding for the study of language evolution.

But a review of the Current Biology study by researchers at the German Primate Center in Göttingen, the University of Kent, and New York University, suggests these conclusions are off-base.

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Distinct Functional Roles of Primate Grasping Hands and Feet During Arboreal Quadrupedal Locomotion

Distinct functional roles of primate grasping hands and feet during arboreal quadrupedal locomotion

Authors:

Patel et al

Abstract:

It has long been thought that quadrupedal primates successfully occupy arboreal environments, in part, by relying on their grasping feet to control balance and propulsion, which frees their hands to test unstable branches and forage. If this interlimb decoupling of function is real, there should be discernible differences in forelimb versus hind limb musculoskeletal control, specifically in how manual and pedal digital flexor muscles are recruited to grasp during arboreal locomotion. New electromyography data from extrinsic flexor muscles in red ruffed lemurs (Varecia rubra) walking on a simulated arboreal substrate reveal that toe flexors are activated at relatively higher levels and for longer durations than finger flexors during stance phase. This demonstrates that the extremities of primates indeed have different functional roles during arboreal locomotion, with the feet emphasizing maintenance of secure grips. When this dichotomous muscle activity pattern between the forelimbs and hind limbs is coupled with other features of primate quadrupedal locomotion, including greater hind limb weight support and the use of diagonal-sequence footfall patterns, a complex suite of biomechanical characters emerges in primates that allow for the co-option of hands toward non-locomotor roles. Early selection for limb functional differentiation in primates probably aided the evolution of fine manipulation capabilities in the hands of bipedal humans.

Pliobates cataloniae: new Gibbon-like Hominoid From Miocene Neogene Spain

Miocene small-bodied ape from Eurasia sheds light on hominoid evolution

Authors:

Alba et al

Abstract:

INTRODUCTION

Reconstructing the ancestral morphotype from which extant hominoids (apes and humans) evolved is complicated by the mosaic nature of ape evolution, the confounding effects of independently evolved features (homoplasy), and the virtual lack of hylobatids (gibbons and siamangs) in the Miocene fossil record. For several decades, small-bodied anthropoid primates from Africa and Eurasia have not played an important role in this debate, because they generally lack the shared derived features of extant catarrhines (hominoids and Old World monkeys) and are thus considered to precede their divergence. Even some small-bodied catarrhines from Africa (dendropithecids), considered to be stem hominoids by some authors, are viewed as more primitive than the larger-bodied stem ape Proconsul. This has led to the assumption that hylobatids are a dwarfed lineage that evolved from a larger-bodied and more great ape–like common ancestor with hominids (great apes and humans).

RATIONALE

Here we describe a new genus of small-bodied (4 to 5 kg) ape from the Miocene (11.6 Ma), discovered in the Abocador de Can Mata stratigraphic series (Vallès-Penedès Basin, northeast Iberian Peninsula), that challenges current views on the last common ancestor of extant hominoids. This genus is based on a partial skeleton that enables a reliable reconstruction of cranial morphology and a detailed assessment of elbow and wrist anatomy. It exhibits a mosaic of primitive (stem catarrhine–like) and derived (extant hominoid–like) features that forces us to reevaluate the role played by small-bodied catarrhines in ape evolution.

RESULTS

The new genus retains some features that are suggestive of generalized above-branch quadrupedalism, but it possesses more extensive hominoid-like postcranial features (mostly related to enhanced forearm rotation and ulnar deviation capabilities) than those convergently displayed by atelids. Its overall body plan is more compatible with an emphasis on cautious and eclectic climbing, combined with some degree of below-branch forelimb-dominated suspension (although less acrobatic than in extant gibbons). Its relative brain size implies a monkey-like degree of encephalization (similar to that of hylobatids but below that of great apes), and dental microwear indicates a frugivorous diet. From a phylogenetic viewpoint, the new genus combines craniodental and postcranial primitive features (similar to those of dendropithecids) with multiple derived cranial and postcranial features shared with extant hominoids. Some cranial similarities with gibbons would support a closer phylogenetic link between the new genus and hylobatids. However, this possibility is not supported by the total evidence. A cladistic analysis based on more than 300 craniodental and postcranial features reveals that the new genus is a stem hominoid (preceding the divergence between hylobatids and hominids), although more derived than previously known small catarrhines and Proconsul.

CONCLUSION

As the first known Miocene small-bodied catarrhine to share abundant derived features with extant hominoids, the new genus indicates a greater morphological diversity than previously recognized among this heterogeneous group, and it provides key insight into the last common ancestor of hylobatids and hominids. Our cladistic results, coupled with the chronology and location of the new genus, suggest that it represents a late-surviving offshoot of a small African stem hominoid that is more closely related to crown hominoids than Proconsul is. These results suggest that, at least in size and cranial morphology, the last common ancestor of extant hominoids might have been more gibbon-like (less great ape–like) than generally assumed.

Nacholapithecus kerioi: a Miocene Neogene Hominoid From Kenya That Moved Like Orangutans in the Trees

Morphology of the thoracolumbar spine of the middle Miocene hominoid Nacholapithecus kerioi from northern Kenya

Authors:

Kikuchi et al

Abstract:

A new caudal thoracic and a new lumbar vertebra of Nacholapithecus kerioi, a middle Miocene hominoid from northern Kenya, are reported. The caudal thoracic vertebral body of N. kerioi has a rounded median ventral keel and its lateral sides are moderately concave. The lumbar vertebral body has an obvious median ventral keel. Based on a comparison of vertebral body cranial articular surface size between the caudal thoracic vertebrae in the present study and one discussed in a previous study (KNM-BG 35250BO, a diaphragmatic vertebra), N. kerioi has at least two post-diaphragmatic vertebrae (rib-bearing lumbar-type thoracic vertebrae), unlike extant hominoids. It also has thick, rounded, and moderately long metapophyses on the lumbar vertebra that project dorsolaterally. The spinous process bases of its caudal thoracic and lumbar vertebrae originate caudally between the postzygapophyses, as described previously in the KNM-BG 35250 holotype specimen. In other words, the postzygapophyses of N. kerioi do not project below the caudal border of the spinous processes, similar to those of extant great apes, and unlike small apes and monkeys, which have more caudally projecting postzygapophyses. Nacholapithecus kerioi has a craniocaudally expanded spinous process in relation to vertebral body length, also similar to extant great apes. Both these spinous process features of N. kerioi differ from those of Proconsul nyanzae. The caudal thoracic vertebra of N. kerioi has a caudally-directed spinous process, whose tip is tear-drop shaped. These features resemble those of extant apes. The morphology of the spinous process tips presumably helps vertebral stability by closely stacking adjacent spinous process tips as seen in extant hominoids. The morphology of the spinous process and postzygapophyses limits the intervertebral space and contributes to the stability of the functional lumbar region as seen in extant great apes, suggesting that antipronograde activity was included in the positional behavior of N. kerioi.

A new Small Pliopithecoid Hominoid Primate From Miocene Neogene Thailand

A new small pliopithecoid primate from the Middle Miocene of Thailand

Authors:

Chaimanee et al

Abstract:

Pliopithecoids represent a monophyletic group of putative stem catarrhines whose evolutionary history is incompletely known. They have been recorded from Europe and Asia, between the late Early Miocene and the Late Miocene. Asian pliopithecoids are less well documented than their European counterparts, often being represented by a fragmentary fossil record. New discoveries are therefore critical to reconstruct the evolutionary history of the whole group. Here, we describe two isolated molars from Ban San Klang, a late Middle Miocene locality in northern Thailand, which confirms the presence of pliopithecoids in Southeast Asia. The lower molar had originally been described as being that of a dendropithecoid, but it was later recognized as pertaining to a pliopithecoid. The discovery, in the same locality, of an additional upper molar attributed to the same species confirms the pliopithecoid status of this taxon and highlights its distinctiveness with respect to other known Asian pliopithecoids. However, the mosaic of primitive and autapomorphic features characterizing this Thai fossil, as well as its limited anatomical representation, preclude us from assigning it to either of the known pliopithecid subfamilies. Nevertheless, it represents the only pliopithecoid in Southeast Asia and displays a mosaic of unique characters which emphasizes the peculiarity of that province, as suggested previously with respect to its hominoid primate.

What Environment did Miocene Neogene ape Lufengpithecus lufengensis Live in?

Pollen evidence of the palaeoenvironments of Lufengpithecus lufengensis in the Zhaotong Basin, southeastern margin of the Tibetan Plateau

Authors:

Chang et al

Abstract:

Evolutionary processes in hominoid primates were closely related to global and/or regional environmental changes, and therefore palaeoenvironmental reconstruction is fundamental for understanding how environmental changes shaped their evolution. Here, we present pollen data from the 16-m-thick Shuitangba (STB) section, Yunnan Province, southwestern China, bearing remains of the hominoid Lufengpithecus lufengensis of the terminal Miocene; and use principal component analysis to reconstruct the palaeovegetation and palaeoclimate during the key period when the hominoid lived. Our results show that before the STB hominoid appeared (Zone A), the vegetation was dominated by subtropical evergreen broad-leaved taxa with a few temperate deciduous taxa (e.g., Quercus, Castanea/Castanopsis, Alnus). The development of aquatic plants commencing at the ~ 12 m depth is a prominent feature, indicating a warm and humid climate. During the time when the hominoid lived (Zone B), evergreen broad-leaved forests with evergreen Quercus were predominant, while grasses including Poaceae began to expand, and simultaneously conifers decreased, indicating a warm climate. The significant presence of aquatic pollen taxa in subzone A-2 and Zone B suggests the occurrence of lacustrine or swampy environments. In contrast, in Zone C, the vegetation changed to coniferous forest, indicating cooler and drier conditions. These results provide substantive evidence of the vegetation conditions when the hominoid lived, suggesting that the greater diversity of vegetation and the warm humid climate, compared to the present day, would have favoured its survival.

Does a Bigger Brain Help With Greater Geographic Primate Distrbution?

Hominin geographical range dynamics and relative brain size: Do non-human primates provide a good analogy?

Authors:

MacDonald et al

Abstract:

We use climatic and satellite remote sensing data to characterize environmental seasonality in the geographical ranges of extant non-human primates in order to assess the effect of relative brain size on tolerance of more seasonal habitats. Demonstration of such an effect in living non-human primates could provide a comparative framework for modeling hominin dispersals and geographical range dynamics in the Pliocene and Pleistocene. Our analyses found no such effect: there are neither positive nor negative correlations between relative brain size and either geographical range size or the average and range of values for environmental seasonality, whether analysed at the level of all primates, or within parvorders (strepsirrhine, catarrhine, platyrrhine). Independent analyses by other researchers comparing feeding behaviour and ecology at individual primate study sites demonstrate that in seasonal environments, the year-round metabolic costs of maintaining a relatively large brain are met by adaptive behavioural/dietary strategies. However, consistent with our own results, those comparative studies found that there was no overall association, whether positive or negative, between ‘raw’ environmental seasonality and primate relative brain size. We must therefore look elsewhere for a comparative model of hominin geographical range dynamics in the Pleistocene.

Two new Eocene Paleogene South American Platyrrhines Which Verify African Origin for New World Monkeys

Eocene primates of South America and the African origins of New World monkeys

Authors:

Bond et al

Abstract:

The platyrrhine primates, or New World monkeys, are immigrant mammals whose fossil record comes from Tertiary and Quaternary sediments of South America and the Caribbean Greater Antilles. The time and place of platyrrhine origins are some of the most controversial issues in primate palaeontology, although an African Palaeogene ancestry has been presumed by most primatologists. Until now, the oldest fossil records of New World monkeys have come from Salla, Bolivia, and date to approximately 26 million years ago, or the Late Oligocene epoch. Here we report the discovery of new primates from the ?Late Eocene epoch of Amazonian Peru, which extends the fossil record of primates in South America back approximately 10 million years. The new specimens are important for understanding the origin and early evolution of modern platyrrhine primates because they bear little resemblance to any extinct or living South American primate, but they do bear striking resemblances to Eocene African anthropoids, and our phylogenetic analysis suggests a relationship with African taxa. The discovery of these new primates brings the first appearance datum of caviomorph rodents and primates in South America back into close correspondence, but raises new questions about the timing and means of arrival of these two mammalian groups.

That Settles it: Gorillas are the Inbred Hill Billies of the Hominid Family

Mountain gorilla genomes reveal the impact of long-term population decline and inbreeding

Authors:

Xue et al

Abstract:

Mountain gorillas are an endangered great ape subspecies and a prominent focus for conservation, yet we know little about their genomic diversity and evolutionary past. We sequenced whole genomes from multiple wild individuals and compared the genomes of all four Gorilla subspecies. We found that the two eastern subspecies have experienced a prolonged population decline over the past 100,000 years, resulting in very low genetic diversity and an increased overall burden of deleterious variation. A further recent decline in the mountain gorilla population has led to extensive inbreeding, such that individuals are typically homozygous at 34% of their sequence, leading to the purging of severely deleterious recessive mutations from the population. We discuss the causes of their decline and the consequences for their future survival.

If you hear bango music in the African Mountains,you run.  Fast.

pop sci link one and two.  Closely related, of course.

Monkeys Have a Human-like Thirst for Knowledge?

Monkeys are notoriously curious, and new research has quantified just how eager they are to gain new information, even if there are not immediate benefits. The findings offer insights into how a certain part of the brain shared by monkeys and humans plays a role in decision making, and perhaps even in some disorders and addictions in humans.

The study, by researchers at the University of Rochester and Columbia University, shows that rhesus macaques have such robust curiosity that they are willing to give up a surprisingly large portion of a potential prize in order to quickly find out if they selected the winning option at a game of chance.

link.

Lemur Subfossils Found in Flooded Cave in Madagascar

Deep below the surface of a water-filled cave in Madagascar, divers and paleontologists have uncovered a boneyard full of extinct giant lemurs.

Hundreds of bones dot the silty bottom of Aven Cave in Tsimanampetsotse National Park. The remains include exotic species such as the extinct elephant bird, a flightless giant similar to an ostrich, but the most numerous bones are from long-lost giant lemurs.

The largest of the extinct lemurs were as big as gorillas, and paleontologists sometimes refer to the different types as sloth lemurs, koala lemurs, and monkey lemurs to describe their different lifestyles and the living animals they most closely resemble. Sometime between 2,000 and 500 years ago, all these giants disappeared, possibly at the hands of humans.

The underwater caves offer an unprecedented look at these lost species. "The preservation is really incredible," says Brooklyn College anthropologist Alfred Rosenberger, a National Geographic grantee who is leading the project.

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Spin Matters for Influencing Apes Just Like Humans

Humans aren't the only species to be influenced by spin. Our closest primate relatives are susceptible, too.

For example, people are known to rate a burger as more tasty when it is described as "75 percent lean" than when it is described as "25 percent fat," even though that's the same thing. And they're more willing to recommend a medical procedure when they are told it has a 50 percent success rate than when they are told it has a 50 percent chance of failure -- again, exactly the same thing.

A Duke University study has found that positive and negative framing make a big difference for chimpanzees and bonobos too.

In experiments conducted at Tchimpounga Chimpanzee Sanctuary in the Republic of Congo and Lola ya Bonobo Sanctuary in the Democratic Republic of Congo, researchers presented 23 chimpanzees and 17 bonobos with a choice between two snacks -- a handful of nuts and some fruit.

In one series of trials, the researchers framed the fruit option positively -- by offering one piece of fruit, with a 50 percent chance of a surprise bonus piece.

In another series of trials, the researchers framed the fruit option negatively. This time they offered two pieces of fruit rather than one, but if the apes chose the fruit, half the time they were shortchanged and received only one piece instead.

Chimps and bonobos were more likely to choose the fruit over the nuts when they were offered a smaller amount of fruit but sometimes got more, versus when they were initially offered more but sometimes got less -- despite receiving equal average payoffs in both scenarios.

The preference for the option framed as a prize rather than a penalty was especially strong in males, the researchers found.

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