Paleolithic Papers #33

Genus Homo:

Were the other hominins the first victims of the Sixth Mass Extinction?

45,000 year old projectiles have been found in Europe.

45,000 year old microlith tools have been found in Sri Lanka.

How long range endurance evolutionary pressure shaped the modern human heart.

Teeth from modern humans and possibly Neandertals have been found in the Manot Cave in Israel.

Foot bones from the Manot Cave appear to be both Neandertal and modern human.

What was the environment of the Manot Cave in?

Analysis of premolar teeth roots suggest a very complex demographic situation in China during the Pleistocene.

Modern Melanesians have introgressed genes associated from Denisovans and Neandertals.

There are genetic traces of paleolithic populations in North Africa.

There are potential adaptations to bipedalism in H. sapiens in the thoracic and lumbar vertebrae.

John Hawks questions whether or not the 3 root teeth found in east asians is really an introgression from Denisovans.

H sapiens:

What would a truly modern human look like?

The coastal paleoecology of modern humans in Easter Africa from the Pleistocene to Holocene.

Humans have been harvesting clams along the coast of British Columbia since at least the Terminal Pleistocene.

Was modern humanity's original home the wetlands of Botswana?

Modern humans may have followed the monsoons out of Africa.

These Yana Culture (modern humans) lived above the arctic circle 30,000 years ago.

H. neanderthalensis:

A spat over Upper Paleothic tech has begun.

Some dispute Neandertals were the source of cave art in Spain.

However, an eagle talon necklace was found in for the first time in Spain and has been ascribed to the Neandertals.

The Neandertal teeth of Marillac get examined.

H. erectus:

Hamadryas baboons are used as a proxy to understand H erectus behavioral evolution.

H. erectus could have been a persistence hunter based on estimated water loss.

Genus Australopithecus:

How Australopithecus changed how we thought humanity evolved.

Cerebral blood flow rates in Australopithecines was lower than in modern great apes for similar brain sizes.

Studying the origination and extinction of hominin species using A. anamesis, A afarensis, and Aridopithecus ramidus.

Genus Orrorin:

The environment of the site where Orrorin died was swampy.

Genus Danuvius:

A new bipedal brachiator ape from the Miocene recently found from Germany may usurp the Dryopithecus from the ancestral position for hominins.

META:

The hominiod to hominid difference in third molar enamel.

How human brains develop differently than great ape.

How scientists know human ancestors ate bugs.

Differences between human and other primate saliva might be because of diet.

The brain was considerably reorganized during hominin evolution.

When did hominins become behaviorally and psychologically modern?

Studying stone flakes can tell a lot about hunter gatherer behavior.

Paleolithic Papers #28

Genus Homo:

How did ancient Homo choose places to do its cave paintings?

H. sapiens (modern humans):

Apparently, Late Pleistocene hunter gatherers survived in Iberian ancestry.

Modern humans originated in South Africa and spread through Africa just before migrating out of the continent.

Researchers have found a narrative piece of art from Paleolithic Europe.

A very bold paper claims Australian Aboriginals arrived in Australia 120,000 years ago.

Neandertals:

A commentary is made on the dating of La Quina Amont.

Neandertals might have had adaptations to the cold like wooly mammoths.

Denisovans:

The first pieces of Denisovan skulls have been verified.

Tongzi Hominin:

The Tongzi hominin's teeth are not like H. erectus teeth like had been previously thought.

H. floresiensis (Hobbits):

The environment of Flores at the time of the Hobbit was explored: it was a grassland!  Or so sayeth the rats.

H. erectus:

How big were the groups in Paleolithic India?

H. erectus purposefully started fires on grasslands.  Time to rethink the anthropocene start, folks.

H. naledi:

The root and pulp morphology of a molar for H. naledi gets examined.

Genus Australopithecus:

The brain sizes of A. afarensis and A. africanus are examined.  Did they grow large from eating bone marrow?

Genus Paranthropus:

Dental caries were found in a molar from a P. robustus.

Comparing the metatarsal of Paranthropus to extent hominoids.

META:

The ability to miniaturize stone tools sets hominins apart from other primates.

Did the slowing of the Antarctic current regulate the glaciation cycle?

Green corridors in the Sahara might have facilitated hominin dispersal.

The grandmother hypothesis might explain why women live longer than men.

Why do humans have wisdom teeth that need to be removed?

Unravelling ancient signals of DNA introgression in modern humans.

Paleolithic Papers #16

Genus Homo:

H. sapiens (modern humanity):

Humans are still evolving.

Did modern humans leave Africa to attempt to escape a drying climate?

Facial phenotypes support a multiple dispersal for modern humans.

Modern human spit contains some surprises about our hominin ancestry.

It appears settling down and abandoning, or at least reducing the nomadic life style, allowed technology to start developing faster 64,000 years ago.

Some of the mutations associated with white skin have an African origin.

Did Paleolithic humans realize the dangers of inbreeding and have breeding networks?

A child from 2,000 years ago in south africa gives hints that modern humans originated 300k years ago.

Rock art in Australia appears to show the extinct giant bird Genyornis.

H. neanderthalensis (Neandertals):

DNA analysis of different Neandertal populations advances our understanding of hominin evolution.  (psst, the Altai Neandertals were the hillbillies of their world).

DNA analysis also suggests a higher percentage of Neandertal DNA survives in modern populations.

Neandertals appeared to grow at a similar rate as modern humans.

How thick was the enamel of the Neandertal canine teeth?

Were Neandertals distilling and using tar?

Neandertal City aka Gibraltar, gets profiled.

Rethinking the Upper Paleolithic Transition in Grotte Mandrin.

What was the mechanism that caused the Neandertals to go extinct and be replaced by modern humans?

What traits are tied to the introgression of Neandertal genes into the modern Human line?

H. georgicus:

The Georgian hominins from Dzudzuana and Satsurblia caves are described.

H. erectus:

A trackway from H. erectus in Kenya is studied.

Genus Paranthropus:

P. bosei:

The probable source of herpes has been claimed: Paranthropus bosei.  Yes, friends, one human ancestor couldn't keep it zipped.  I'm looking at you, H. erectus.  Like we REALLY believe the watering hole story, Upright Man.

Genus Australopithecus:

A. anamensis:

Where did A. anamensis live?  What sort of environment was it?

META:

The fossils trackways from the Greek hominin from 5.7 million years ago are in danger.

How facial features have evolved in hominins through time.

Chimps can learn to use tools without being taught.

Savannah living chimps don't seem to eat more meat than their forest cousins.

The rest of their dietary comparison is here.

Tool using macaques are wiping out shellfish populations.

Was bipedality in hominins a by-product of developmental processes?

The differences in loading on the 3rd metacarpal heads in humans and chimpanzees.

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.

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.

Did Gigantopithecus go Extinct due to its Large Size?

Sometimes, in evolution, the bigger they are, the harder they fall.

And Gigantopithecus was pretty darn big. Fossils indicate it stood as high as 10 feet (3 meters) and weighed up to 1,100 pounds (500 kilograms)

If you’re an animal, there are advantages to being gigantic. You’re less vulnerable to predators, and you’re able to cover a lot of territory when looking for food. Gigantopithecus thrived in the tropical forests of what is now southern China for six to nine million years.

But around 100,000 years ago, at the beginning of the last of the Pleistocene ice ages, it went extinct—because in the changed climate its size had become a fatal handicap, a new study suggests.

link.

The Predicted Ancestor of Modern Humans and Neandertals

Virtual ancestor reconstruction: Revealing the ancestor of modern humans and Neandertals

Authors:

Mounier et al

Abstract:

The timing and geographic origin of the common ancestor of modern humans and Neandertals remain controversial. A poor Pleistocene hominin fossil record and the evolutionary complexities introduced by dispersals and regionalisation of lineages have fuelled taxonomic uncertainty, while new ancient genomic data have raised completely new questions. Here, we use maximum likelihood and 3D geometric morphometric methods to predict possible morphologies of the last common ancestor of modern humans and Neandertals from a simplified, fully resolved phylogeny. We describe the fully rendered 3D shapes of the predicted ancestors of humans and Neandertals, and assess their similarity to individual fossils or populations of fossils of Pleistocene age. Our results support models of an Afro-European ancestral population in the Middle Pleistocene (Homo heidelbergensis sensu lato) and further predict an African origin for this ancestral population.

Hominins From Lower Paleolithic Schöningen Spear Site ate a lot of Horse

The larger mammal fauna from the Lower Paleolithic Schöningen Spear site and its contribution to hominin subsistence

Authors:

van Kolfschoten et al

Abstract:

The locality Schöningen (Germany) is an important source of knowledge about Lower Paleolithic hominin subsistence. The locality includes a series of sites dated to the late Middle Pleistocene with a Holsteinian (MIS 11) and Reinsdorf Interglacial (MIS 9) age. One of the youngest sites is Schöningen 13 II-4, the Spear Horizon site also known as the Horse Butchery site. The organic remains excavated here are exceptionally well-preserved as they were embedded in anaerobic, waterlogged sediments in an area where the groundwater is rich in calcium carbonate. The fossil assemblage is ideal for the study of patterns in hominin interference with the mammalian species encountered at the site.

The vertebrate record is extensive and very diverse. The fossil larger carnivore guild of the Spear Horizon faunal assemblage includes saber-toothed cat, fox, and wolf. Herbivores are represented by an elephant species, two equid species, two rhinoceros species, two cervid species, and two large bovid species.

Evidence of hominin interference presents itself as either marks on skeletal remains related to the use of bones as knapping tools or hammers, or as marks that indicate butchering activities such as skinning, dismembering, defleshing, filleting, and marrow extraction. The humerus of the saber-toothed cat clearly shows that the bone has been used as a knapping tool. The fossil remains of the other larger carnivores do not show any signs of hominin interference or exploitation. This also applies to the limited number of elephant and rhinoceros remains found at the site. The large horse Equus mosbachensis dominates the larger mammal record and played a major role in hominin subsistence. Marks on the horse bones indicate that a large number of carcasses have been butchered. Traces on the fossil remains of both red deer (Cervus elaphus) and the large bovids also indicate exploitation by Lower Paleolithic hominins.

Comparing the Radii From 89 Specimens of the Sierra de Atapuerca Hominins

Fossil hominin radii from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain)

Authors:

Rodriguez et al

Abstract:

Complete radii in the fossil record preceding recent humans and Neandertals are very scarce. Here we introduce the radial remains recovered from the Sima de los Huesos (SH) site in the Sierra de Atapuerca between 1976 and 2011 and which have been dated in excess of 430 ky (thousands of years) ago. The sample comprises 89 specimens, 49 of which are attributed to adults representing a minimum of seven individuals. All elements are described anatomically and metrically, and compared with other fossil hominins and recent humans in order to examine the phylogenetic polarity of certain radial features. Radial remains from SH have some traits that differentiate them from those of recent humans and make them more similar to Neandertals, including strongly curved shafts, anteroposterior expanded radial heads and both absolutely and relatively long necks. In contrast, the SH sample differs from Neandertals in showing a high overall gracility as well as a high frequency (80%) of an anteriorly oriented radial tuberosity. Thus, like the cranial and dental remains from the SH site, characteristic Neandertal radial morphology is not present fully in the SH radii. We also analyzed the cross-sectional properties of the SH radial sample at two different levels: mid-shaft and at the midpoint of the neck length. When standardized by shaft length, no difference in the mid-shaft cross-sectional properties were found between the SH hominins, Neandertals and recent humans. Nevertheless, due to their long neck length, the SH hominins show a higher lever efficiency than either Neandertals or recent humans. Functionally, the SH radial morphology is consistent with more efficient pronation-supination and flexion-extension movements. The particular trait composition in the SH sample and Neandertals resembles more closely morphology evident in recent human males.

Spinal Cord Evolution in Early Homo

Spinal cord evolution in early Homo

Authors:

Meyer et al

Abstract:

The discovery at Nariokotome of the Homo erectus skeleton KNM-WT 15000, with a narrow spinal canal, seemed to show that this relatively large-brained hominin retained the primitive spinal cord size of African apes and that brain size expansion preceded postcranial neurological evolution. Here we compare the size and shape of the KNM-WT 15000 spinal canal with modern and fossil taxa including H. erectus from Dmanisi, Homo antecessor, the European middle Pleistocene hominins from Sima de los Huesos, and Pan troglodytes. In terms of shape and absolute and relative size of the spinal canal, we find all of the Dmanisi and most of the vertebrae of KNM-WT 15000 are within the human range of variation except for the C7, T2, and T3 of KNM-WT 15000, which are constricted, suggesting spinal stenosis. While additional fossils might definitively indicate whether H. erectus had evolved a human-like enlarged spinal canal, the evidence from the Dmanisi spinal canal and the unaffected levels of KNM-WT 15000 show that unlike Australopithecus, H. erectus had a spinal canal size and shape equivalent to that of modern humans. Subadult status is unlikely to affect our results, as spinal canal growth is complete in both individuals. We contest the notion that vertebrae yield information about respiratory control or language evolution, but suggest that, like H. antecessor and European middle Pleistocene hominins from Sima de los Huesos, early Homo possessed a postcranial neurological endowment roughly commensurate to modern humans, with implications for neurological, structural, and vascular improvements over Pan and Australopithecus.

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.

Climate Driven Ecological Instability Greatly Impacted Hominin Evolution

Alternating high and low climate variability: The context of natural selection and speciation in Plio-Pleistocene hominin evolution

Authors:

Potts et al

Abstract:

Interaction of orbital insolation cycles defines a predictive model of alternating phases of high- and low-climate variability for tropical East Africa over the past 5 million years. This model, which is described in terms of climate variability stages, implies repeated increases in landscape/resource instability and intervening periods of stability in East Africa. It predicts eight prolonged (>192 kyr) eras of intensified habitat instability (high variability stages) in which hominin evolutionary innovations are likely to have occurred, potentially by variability selection. The prediction that repeated shifts toward high climate variability affected paleoenvironments and evolution is tested in three ways. In the first test, deep-sea records of northeast African terrigenous dust flux (Sites 721/722) and eastern Mediterranean sapropels (Site 967A) show increased and decreased variability in concert with predicted shifts in climate variability. These regional measurements of climate dynamics are complemented by stratigraphic observations in five basins with lengthy stratigraphic and paleoenvironmental records: the mid-Pleistocene Olorgesailie Basin, the Plio-Pleistocene Turkana and Olduvai Basins, and the Pliocene Tugen Hills sequence and Hadar Basin—all of which show that highly variable landscapes inhabited by hominin populations were indeed concentrated in predicted stages of prolonged high climate variability. Second, stringent null-model tests demonstrate a significant association of currently known first and last appearance datums (FADs and LADs) of the major hominin lineages, suites of technological behaviors, and dispersal events with the predicted intervals of prolonged high climate variability. Palynological study in the Nihewan Basin, China, provides a third test, which shows the occupation of highly diverse habitats in eastern Asia, consistent with the predicted increase in adaptability in dispersing Oldowan hominins. Integration of fossil, archeological, sedimentary, and paleolandscape evidence illustrates the potential influence of prolonged high variability on the origin and spread of critical adaptations and lineages in the evolution of Homo. The growing body of data concerning environmental dynamics supports the idea that the evolution of adaptability in response to climate and overall ecological instability represents a unifying theme in hominin evolutionary history.

The Planet of the Apes is NIgh: Koko the Gorilla Appears to be Learning to Talk

Koko, a 44-year-old gorilla famous for her ability to communicate with keepers using sign language, is now showing signs of early speech. “Koko has developed vocal and breathing behaviors associated with the ability to talk, which were previously thought to be impossible in her species,” The Daily Mail reports. The new development could further blur the line between what distinguishes humans from some of our more hirsute cousins.

link.

Hat tip to Randy.

yes, I made the joke the original author referenced.

Is Australopithecus bahrelghazali a Relict Population?

Pliocene hominin biogeography and ecology

Author:

Macho

Abstract:

Australopithecus bahrelghazali, its origin and palaeobiology are not well understood. Reported from only one location some several thousand kilometres away from East African Pliocene hominin sites, it appears to have predominantly fed on C4 sources. Yet, it lacks the morphological adaptations of other primate C4 consumers like Paranthropus boisei and Theropithecus oswaldi. Furthermore, although considered to belong to Australopithecus afarensis by most researchers, A. bahrelghazali appears to differ from the former in a key aspect of its morphology: enamel thickness. To assess the phylogeny and palaeobiology of A. bahrelghazali, I first evaluate the dietary adaptations and energetics of A. bahrelghazali using empirical data of the feeding ecology of extant baboons, Papio cynocephalus. Information published on A. bahrelghazali morphology and habitat preference is used to select C4 foods with the appropriate mechanical properties and availability within the environment to create the models. By altering the feeding time on various food categories, I then test whether A. bahrelghazali could have subsisted on a C4 diet, thus accounting for the δ13C composition of its dental tissue. The effects of body mass on the volume of food consumed are taken into account. The outcomes of these simulations indicate that A. bahrelghazali could have subsisted on a diet of predominantly sedges, albeit with limitations. At higher energy requirements, i.e., above 3.5 times the BMR, it would be difficult for a medium-sized primate to obtain sufficient energy from a sedge-based diet. This is apparently due to constraints on foraging/feeding time, not because of the nutritional value of sedges per se. These results are discussed against the backdrop of A. bahrelghazali biogeography, palaeoenvironment, and phylogeny. The combined evidence makes it plausible to suggest that Northern Chad may have been a refugium for migrating mammals, including hominins, and throws new light on the deep history of A. bahrelghazali.

Selection Detected on X Chromosomes of Great Apes

Extreme selective sweeps independently targeted the X chromosomes of the great apes

Authors:

Nam et al

Abstract:

The unique inheritance pattern of the X chromosome exposes it to natural selection in a way that is different from that of the autosomes, potentially resulting in accelerated evolution. We perform a comparative analysis of X chromosome polymorphism in 10 great ape species, including humans. In most species, we identify striking megabase-wide regions, where nucleotide diversity is less than 20% of the chromosomal average. Such regions are found exclusively on the X chromosome. The regions overlap partially among species, suggesting that the underlying targets are partly shared among species. The regions have higher proportions of singleton SNPs, higher levels of population differentiation, and a higher nonsynonymous-to-synonymous substitution ratio than the rest of the X chromosome. We show that the extent to which diversity is reduced is incompatible with direct selection or the action of background selection and soft selective sweeps alone, and therefore, we suggest that very strong selective sweeps have independently targeted these specific regions in several species. The only genomic feature that we can identify as strongly associated with loss of diversity is the location of testis-expressed ampliconic genes, which also have reduced diversity around them. We hypothesize that these genes may be responsible for selective sweeps in the form of meiotic drive caused by an intragenomic conflict in male meiosis.

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.

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.

link.

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.

link.

Gorilla Genetics and Their Implications for Their Demographics

Inference of Gorilla demographic and selective history from whole genome sequence data

Authors:

McMannus et al

Abstract:

While population-level genomic sequence data have been gathered extensively for humans, similar data from our closest living relatives are just beginning to emerge. Examination of genomic variation within great apes offers many opportunities to increase our understanding of the forces that have differentially shaped the evolutionary history of hominid taxa. Here, we expand upon the work of the Great Ape Genome Project by analyzing medium to high coverage whole genome sequences from 14 western lowland gorillas (Gorilla gorilla gorilla), 2 eastern lowland gorillas (Gorilla beringei graueri), and a single Cross River individual (Gorilla gorilla diehli). We infer that the ancestors of western and eastern lowland gorillas diverged from a common ancestor ~261 thousand years ago (kya), and that the ancestors of the Cross River population diverged from the western lowland gorilla lineage ~68 kya. Using a diffusion approximation approach to model the genome-wide site frequency spectrum, we infer a history of western lowland gorillas that includes an ancestral population expansion of ~1.4-fold around ~970 kya and a recent ~5.6-fold contraction in population size ~23 kya. The latter may correspond to a major reduction in African equatorial forests around the Last Glacial Maximum. We also analyze patterns of variation among western lowland gorillas to identify several genomic regions with strong signatures of recent selective sweeps. We find that processes related to taste, pancreatic and saliva secretion, sodium ion transmembrane transport, and cardiac muscle function are overrepresented in genomic regions predicted to have experienced recent positive selection.