Bonobos and Chimpanzees had a Human/Neandertal Like Fling

A new whole-genome analysis of chimpanzees and bonobos reveals that these two great ape species likely interbred several hundred thousand years ago. A better understanding of the genetic flow between humans' closest living relatives could shed light on processes that might have played a recurring role in great ape evolution. While chimpanzees and bonobos are known to interbreed in captivity, the historic genetic flow between the two species in the wild is less clear. To gain better insights into possible historical gene flow between them, Marc de Manuel et al. analyzed the complete genomes of 10 bonobos and 65 chimpanzees. Significantly, more chimpanzees were included in their analysis, and from various regions in Africa, because previous genetic studies have suggested that four distinct species of chimpanzee exist. Following their analysis, the researchers observed clear evidence for gene flow between the two species, occurring between 200 and 550 thousand years ago, they estimate. Central, eastern, and Nigeria-Cameroon chimpanzees share significantly more genetic information with bonobos than do western chimpanzees, they report. What's more, similar to Neanderthal genetic patterns in humans, some background bonobo genetic information has been deleted in the chimpanzee genome, suggesting that some bonobo genes may have been disadvantageous for chimpanzees.

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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.

Last Common Ancestor of Gorillas and People was ~9 Million Years Ago

New geological and palaeontological age constraint for the gorilla–human lineage split

Authors:

Kotah et al

Abstract:

The palaeobiological record of 12 million to 7 million years ago (Ma) is crucial to the elucidation of African ape and human origins, but few fossil assemblages of this period have been reported from sub-Saharan Africa. Since the 1970s, the Chorora Formation, Ethiopia, has been widely considered to contain ~10.5 million year (Myr) old mammalian fossils. More recently, Chororapithecus abyssinicus, a probable primitive member of the gorilla clade, was discovered from the formation. Here we report new field observations and geochemical, magnetostratigraphic and radioisotopic results that securely place the Chorora Formation sediments to between ~9 and ~7 Ma. The C. abyssinicus fossils are ~8.0 Myr old, forming a revised age constraint of the human–gorilla split. Other Chorora fossils range in age from ~8.5 to 7 Ma and comprise the first sub-Saharan mammalian assemblage that spans this period. These fossils suggest indigenous African evolution of multiple mammalian lineages/groups between 10 and 7 Ma, including a possible ancestral-descendent relationship between the ~9.8 Myr old Nakalipithecus nakayamai and C. abyssinicus. The new chronology and fossils suggest that faunal provinciality between eastern Africa and Eurasia had intensified by ~9 Ma, with decreased faunal interchange thereafter. The Chorora evidence supports the hypothesis of in situ African evolution of the Gorilla–Pan–human clade, and is concordant with the deeper divergence estimates of humans and great apes based on lower mutation rates of ~0.5 × 10−9 per site per year.

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.

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

Human Unique Genes may Protect From Dementia

Many human gene variants have evolved specifically to protect older adults against neurodegenerative and cardiovascular diseases, thus preserving their contributions to society, report University of California, San Diego School of Medicine researchers in the November 30 issue of Proceedings of the National Academy of Sciences.

"We unexpectedly discovered that humans have evolved gene variants that can help protect the elderly from dementia," said Ajit Varki, MD, Distinguished Professor of Medicine and Cellular and Molecular Medicine at UC San Diego School of Medicine, adjunct professor at the Salk Institute for Biological Studies and co-director of the UC San Diego/Salk Center for Academic Research and Training in Anthropogeny (CARTA). "Such genes likely evolved to preserve valuable and wise grandmothers and other elders, as well as to delay or prevent the emergence of dependent individuals who could divert resources and effort away from the care of the young." Varki led the study, along with Pascal Gagneux, PhD, associate professor of pathology and associate director of CARTA.

The standard model of natural selection predicts that once the age of reproduction ends, individuals die. That's because selection early in life strongly favors variants that benefit reproductive success, even at the cost of negative consequences late in life -- one major reason we age. This is indeed the case in almost all vertebrates. Humans (and certain whales) are an exception to this rule, living decades beyond reproductive age. Such elders contribute to the fitness of younger individuals by caring for grandchildren and also by passing down important cultural knowledge. Age-related cognitive decline compromises these benefits, and eventually burdens the group with the need to care for dependent older members.

In this first-of-its kind discovery, Varki, Gagneux and their teams initially focused on the gene that encodes the CD33 protein. CD33 is a receptor that projects from the surface of immune cells, where it keeps immune reactions in check, preventing "self" attack and curtailing unwanted inflammation. Previous studies suggested that a certain form of CD33 suppresses amyloid beta peptide accumulation in the brain. Amyloid beta accumulation is thought to contribute to late-onset Alzheimer's disease, a post-reproductive condition that uniquely affects humans and is aggravated by inflammation and cerebral vascular disease.

The researchers compared CD33 regulation in humans and our closest living relatives, chimpanzees. They found that levels of the CD33 variant that protects against Alzheimer's are four-fold higher in humans than chimpanzees.

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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.

link.

Slow, Progressive Transition From the Trees, Embrace of Tools Conjectured for Hominin Evolution

Fossil hominin shoulders support an African ape-like last common ancestor of humans and chimpanzees

Authors:

Young et al

Abstract:

Reconstructing the behavioral shifts that drove hominin evolution requires knowledge of the timing, magnitude, and direction of anatomical changes over the past ∼6–7 million years. These reconstructions depend on assumptions regarding the morphotype of the Homo–Pan last common ancestor (LCA). However, there is little consensus for the LCA, with proposed models ranging from African ape to orangutan or generalized Miocene ape-like. The ancestral state of the shoulder is of particular interest because it is functionally associated with important behavioral shifts in hominins, such as reduced arboreality, high-speed throwing, and tool use. However, previous morphometric analyses of both living and fossil taxa have yielded contradictory results. Here, we generated a 3D morphospace of ape and human scapular shape to plot evolutionary trajectories, predict ancestral morphologies, and directly test alternative evolutionary hypotheses using the hominin fossil evidence. We show that the most parsimonious model for the evolution of hominin shoulder shape starts with an African ape-like ancestral state. We propose that the shoulder evolved gradually along a single morphocline, achieving modern human-like configuration and function within the genus Homo. These data are consistent with a slow, progressive loss of arboreality and increased tool use throughout human evolution.

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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Chimpanzees can Learn 'Food Calls'

Chimpanzees living in captivity are capable of learning calls that refer to specific food items. This was shown by an evolutionary biologist from the University of Zurich together with English researchers. They now published a behavioral study suggesting, that great apes are capable of referring to objects and socially learn meaningful calls.

A special feature of human language is that objects and events are named with socially learned symbols or words. Non-human primates like chimpanzees are arguably capable of producing alarm and food calls,that refer to objects in their environment. However so far researchers assumed, that the acoustic structures of these calls are an expression of their excitement and cannot be controlled by the chimpanzees. Now Simon Townsend, Evolutionary biologist from the University of Zurich has shown together with his English colleagues, that also chimpanzees can learn calls that refer to specific objects.

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Trust in Chimpanzees

Chimpanzees trust conspecifics to engage in low-cost reciprocity

Authors:

Engelmann et al

Abstract:

Many of humans' most important social interactions rely on trust, including most notably among strangers. But little is known about the evolutionary roots of human trust. We presented chimpanzees (Pan troglodytes) with a modified version of the human trust game—trust in reciprocity—in which subjects could opt either to obtain a small but safe reward on their own or else to send a larger reward to a partner and trust her to reciprocate a part of the reward that she could not access herself. In a series of three studies, we found strong evidence that in interacting with a conspecific, chimpanzees show spontaneous trust in a novel context; flexibly adjust their level of trust to the trustworthiness of their partner and develop patterns of trusting reciprocity over time. At least in some contexts then, trust in reciprocity is not unique to humans, but rather has its evolutionary roots in the social interactions of humans' closest primate relatives.

How Gorillas and Chimpanzees Partitioned Ecological Niches in Historical Overlapping Territories

Niche Partitioning in Sympatric Gorilla and Pan from Cameroon: Implications for Life History Strategies and for Reconstructing the Evolution of Hominin Life History

Authors:

Macho et al

Abstract:

Factors influencing the hominoid life histories are poorly understood, and little is known about how ecological conditions modulate the pace of their development. Yet our limited understanding of these interactions underpins life history interpretations in extinct hominins. Here we determined the synchronisation of dental mineralization/eruption with brain size in a 20th century museum collection of sympatric Gorilla gorilla and Pan troglodytes from Central Cameroon. Using δ13C and δ15N of individuals’ hair, we assessed whether and how differences in diet and habitat use may have impacted on ape development. The results show that, overall, gorilla hair δ13C and δ15N values are more variable than those of chimpanzees, and that gorillas are consistently lower in δ13C and δ15N compared to chimpanzees. Within a restricted, isotopically-constrained area, gorilla brain development appears delayed relative to dental mineralization/eruption [or dental development is accelerated relative to brains]: only about 87.8% of adult brain size is attained by the time first permanent molars come into occlusion, whereas it is 92.3% in chimpanzees. Even when M1s are already in full functional occlusion, gorilla brains lag behind those of chimpanzee (91% versus 96.4%), relative to tooth development. Both bootstrap analyses and stable isotope results confirm that these results are unlikely due to sampling error. Rather, δ15N values imply that gorillas are not fully weaned (physiologically mature) until well after M1 are in full functional occlusion. In chimpanzees the transition from infant to adult feeding appears (a) more gradual and (b) earlier relative to somatic development. Taken together, the findings are consistent with life history theory that predicts delayed development when non-density dependent mortality is low, i.e. in closed habitats, and with the “risk aversion” hypothesis for frugivorous species as a means to avert starvation. Furthermore, the results highlight the complexity and plasticity of hominoid/hominin development.

Wild Chimpanzees Show Foreplanning

Wild chimpanzees plan their breakfast time, type, and location

Authors:

Janmaat et al

Abstract:

Not all tropical fruits are equally desired by rainforest foragers and some fruit trees get depleted more quickly and carry fruit for shorter periods than others. We investigated whether a ripe-fruit specialist, the chimpanzee (Pan troglodytes verus), arrived earlier at breakfast sites with very ephemeral and highly sought-after fruit, like figs, than sites with less ephemeral fruit that can be more predictably obtained throughout the entire day. We recorded when and where five adult female chimpanzees spent the night and acquired food for a total of 275 full days during three fruit-scarce periods in a West African tropical rainforest. We found that chimpanzees left their sleeping nests earlier (often before sunrise when the forest is still dark) when breakfasting on very ephemeral fruits, especially when they were farther away. Moreover, the females positioned their sleeping nests more in the direction of the next day’s breakfast sites with ephemeral fruit compared with breakfast sites with other fruit. By analyzing departure times and nest positioning as a function of fruit type and location, while controlling for more parsimonious explanations, such as temperature, we found evidence that wild chimpanzees flexibly plan their breakfast time, type, and location after weighing multiple disparate pieces of information. Our study reveals a cognitive mechanism by which large-brained primates can buffer the effects of seasonal declines in food availability and increased interspecific competition to facilitate first access to nutritious food. We discuss the implications for theories on hominoid brain-size evolution.

Chimps Teach Other Chimps

Social Network Analysis Shows Direct Evidence for Social Transmission of Tool Use in Wild Chimpanzees

Authors:

Hobalter et al

Abstract:

Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition—that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, “moss-sponging” and “leaf-sponge re-use,” in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most “cultural” of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans.

Chimpanzees are Just Inherently Violent

Of all of the world's species, humans and chimpanzees are some of the only to engage in coordinated attacks on other members of their same species. Jane Goodall was among the first to introduce the occurrence of lethal inter-community killings and since then primatologists and anthropologists have long debated the concept of warfare in this genus. Research theories have pointed to increased gains and benefits of killing off competitors and opening up increased access to key resources such as food or mates. In contrast, others have argued that warfare is a result of human impact on chimpanzees, such as habitat destruction or food provisioning, rather than adaptive strategies.

New research from an international coalition of ape researchers, published September 18 in the journal Nature, has shed new light on the subject, suggesting that human encroachment and interference is not, as previous researchers have claimed, an influential predictor of chimp-on-chimp aggression.

The study began as a response to a growing number of commentators claiming that chimpanzee violence was caused by human impacts. "This is an important question to get right. If we are using chimpanzees as a model for understanding human violence, we need to know what really causes chimpanzees to be violent," said University of Minnesota researcher Michael L. Wilson, lead author on the study.

"Humans have long impacted African tropical forests and chimpanzees, and one of the long-standing questions is if human disturbance is an underlying factor causing the lethal aggression observed," explained co-author David Morgan, PhD, research fellow with the Lester E Fisher Center for the Study and Conservation of Apes at Lincoln Park Zoo in Chicago. Morgan has studied chimpanzees deep in the forests of Republic of Congo for 14 years. "A key take-away from this research is that human influence does not spur increased aggression within or between chimpanzee communities."

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Is Intelligence Genetic?

A chimpanzee's intelligence is largely determined by its genes, while environmental factors may be less important than scientists previously thought, according to a Georgia State University research study.

The study found that some, but not all, cognitive, or mental, abilities, in chimpanzees depend significantly on the genes they inherit. The findings are reported in the latest issue of Current Biology.

"Intelligence runs in families," said Dr. William Hopkins, professor in the Center for Behavioral Neuroscience at Georgia State and research scientist in the Yerkes National Primate Research Center at Emory University. "The suggestion here is that genes play a really important role in their performance on tasks while non-genetic factors didn't seem to explain a lot. So that's new."

The role of genes in human intelligence or IQ has been studied for years, but Hopkins' study is among the first to address heritability in cognitive abilities in nonhuman primates. Studies have shown that human intelligence is inherited through genes, but social and environmental factors, such as formal education and socioeconomic status, also play a role and are somewhat confounded with genetic factors. Chimpanzees, which are highly intelligent and genetically similar to humans, do not have these additional socio-cultural influences.

"Chimps offer a really simple way of thinking about how genes might influence intelligence without, in essence, the baggage of these other mechanisms that are confounded with genes in research on human intelligence," Hopkins said.

The study involved 99 chimpanzees, ranging in age from 9 to 54, who completed 13 cognitive tasks designed to test a variety of abilities. Hopkins used quantitative genetics analysis to link the degree of relatedness between the chimpanzees to their similarities or differences in performance on the various cognitive measures to determine whether cognitive performance is inherited in chimpanzees.

Genes were found to play a role in overall cognitive abilities, as well as the performance on tasks in several categories.

Traditionally, researchers studying animal intelligence or animal learning have shared the view that environment and how previous behavior is reinforced affect how animals perform on a particular task.

"In our case, at least, it suggests that purely environmental explanations don't really seem to tell the whole story," Hopkins said. "Genes matter as well."

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Gift Which Keeps in Giving: Chimps Gave Homo erectus HERPES 1.6 Million Years ago

Researchers at the University of California, San Diego School of Medicine have identified the evolutionary origins of human herpes simplex virus (HSV) -1 and -2, reporting that the former infected hominids before their evolutionary split from chimpanzees 6 million years ago while the latter jumped from ancient chimpanzees to ancestors of modern humans – Homo erectus – approximately 1.6 million years ago.

The findings are published in the June 10 online issue of Molecular Biology and Evolution.

"The results help us to better understand how these viruses evolved and found their way into humans," said Joel O. Wertheim, PhD, assistant research scientist at the UC San Diego AntiViral Research Center and lead author of the study. "Animal disease reservoirs are extremely important for global public health. Understanding where our viruses come from will help guide us in preventing future viruses from making the jump into humans."

Approximately two-thirds of the human population is infected with at least one herpes simplex virus. The viruses are most commonly presented as cold sores on the mouth or lips or blisters on the genitals.

"Humans are the only primates we know of that have two herpes simplex viruses," said Wertheim. "We wanted to determine why."

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HIV, herpes (HSV-2)...guys, just DON'T do Chimps!  geez!

Its Not Just What You Have, But How You use It: Epigenetics Very Different Between Humans, Chimps & Rhesus Monkeys

Humans share over 90% of their DNA with their primate cousins. The expression or activity patterns of genes differ across species in ways that help explain each species' distinct biology and behavior.

DNA factors that contribute to the differences were described on Nov. 6 at the American Society of Human Genetics 2012 meeting in a presentation by Yoav Gilad, Ph.D., associate professor of human genetics at the University of Chicago.

Dr. Gilad reported that up to 40% of the differences in the expression or activity patterns of genes between humans, chimpanzees and rhesus monkeys can be explained by regulatory mechanisms that determine whether and how a gene's recipe for a protein is transcribed to the RNA molecule that carries the recipe instructions to the sites in cells where proteins are manufactured.

In addition to improving scientific understanding of the uniqueness of humans, studies such as the investigation conducted by Dr. Gilad and colleagues could have relevance to human health and disease.

"Through inter-species' comparisons at the DNA sequence and expression levels, we hope to identify the genetic basis of human specific traits and in particular the genetic variations underlying the higher susceptibility to certain diseases such as malaria and cancer in humans than in non-human primates," said Dr. Gilad.

Dr. Gilad and his colleagues studied gene expression in lymphoblastoid cell lines, laboratory cultures of immortalized white blood cells, from eight humans, eight chimpanzees and eight rhesus monkeys.

They found that the distinct gene expression patterns of the three species can be explained by corresponding changes in genetic and epigenetic regulatory mechanisms that determine when and how a gene's DNA code is transcribed to a messenger RNA (mRNA) molecule.

Dr. Gilad also determined that the epigenetics process known as histone modification also differs in the three species. The presence of histone marks during gene transcription indicates that the process is being prevented or modified.

"These data allowed us to identify both conserved and species-specific enhancer and repressor regulatory elements, as well as characterize similarities and differences across species in transcription factor binding to these regulatory elements," Dr. Gilad said.

Among the similarities among the three species were the promoter regions of DNA that initiated transcription of a particular gene.

In all three species, Dr. Gilad's lab found that transcription factor binding and histone modifications were identical in over 67% of regulatory elements in DNA segments that are regarded as promoter regions.

Chimps Working Hard for Their Honey

Via Nat Geo.