Why words make language

By: Thomas Schmitt Attorney on November 12, 2019 / comment : 0 Anthropology, Human Evolution, Linguistics

From hieroglyphics to emojis, and grunts to gestures, humans have always used multiple modes to communicate, including language.

Modes of communication [Credit: Wits University]

If you've ever sent a text using emojis, which the recipient received and understood, then you've communicated in a new language code. Communication codes have been with us since the grunts of our ancestors developed in to the first languages—Aramaic, Sanskrit, Tamil—the latter having made an appearance in 300 BC and considered the world's oldest language.

Dr. Gilles Baro, a sociolinguist at Wits, says that what we consider languages today are "organised, systematised guides to communication". "People have always communicated using multiple modes, such as gestures, sounds, words, scripts and images. Languages are one of those modes and they are not 'invented'. Rather, people—usually the elite—decide on a norm for communication, and that is what we consider 'language' today."

Linguistic migration

Over time, this code evolves, says Maxwell Kadenge, Associate Professor and Head of the Department of Linguistics in the School of Literature, Language and Media at Wits. And where this code will be in future is anyone's guess.

"Languages evolve naturally as a result of the migration of people, which in turn results in languages getting into contact with each other. Think of Afrikaans, which was originally spoken by the Dutch, but began to develop distinct characteristics as a result of its contact and borrowing from South African languages, especially Khoe and San languages."

Similarly, says Kadenge, South African spoken languages that evolved because of contact between existing languages include Fanagalo and Tsotsitaal. "Both of them have borrowings from Bantu languages like Zulu, Xhosa, English and Afrikaans. Chilapalapa developed in Zimbabwe [then Rhodesia] from the contact between English, Shona varieties and Zambia languages," he says.

Brave new word

Baro says that along with migration, new environments and technology also influence how language evolves. Emojis and text language are an example of how spoken language has merged with digital communication.

"Today, considering the internet, language is more open and in a way more vulnerable to be changed or influenced. We are exposed to a lot more variations than in the past. For example, a study done at the University of Cape Town showed the increasing use of the word 'like' as a quotative, hedge, or discourse particle by young South Africans was influenced by their exposure to North American popular culture, via movies and songs. Often the accent and vocabulary of a nearby community will influence a language too, through the borrowing of words."

A quotative is a grammatical device to mark quoted speech—essentially "spoken quotation marks"—while hedge and discourse particles make speech less direct and manage the flow of dialogue.

Degrees of understanding

"The word 'language' is broad and fluid, as it has both linguistic and political connotations. In simple terms, a language is a communally owned means of communication, which is passed on from one generation to the other through the process of socialisation," says Kadenge.

The reason we have differences in languages and dialects is essentially to understand each other in a particular space and time. "One of the criterion that are used to consider varieties such as dialects of the same language, or as distinct languages, is mutual intelligibility. This simply refers to the degree to which speakers of different languages understand each other in the same conversation," he says.

Kadenge explains: "Normally, varieties that are mutually intelligible are considered dialects of the same language. For example, the Zimbabwean language—Shona—is made up of four main dialects, namely Karanga, Zezuru, Korekore and Manyika, whose degree of mutual intelligibility varies. These varieties are considered dialects of the Shona language. However, Scandinavian languages—Danish, Norwegian and Swedish—are mutually intelligible, just like the Shona dialects, but are considered different languages, probably because they are spoken in different countries. Against this background, the question on what makes a language a language is not easy to define."

EmpoWORDment

Some would argue that language is steeped in our identity, and can separate communities. Baro says variations in language are also clues to particular traits of identity. "So when hearing someone use language, we can guess their gender or sex, race, class, etc."

Language, being a social aspect of life, has the power to divide as much as it brings people together. In South Africa particularly, it is contentious when public discussions are held in a language that only some can understand. People who cannot speak the language would undoubtedly feel excluded from the group.

"Languages signify identity and belonging. This is primarily because people who speak the same language understand each other, the languages contain words that all the members of a community understand," Kadenge says.

"In South Africa, due to internal colonialism, some big and politically powerful groups tend to suppress smaller groups. This is evident in language policies and practices. Why is it that the national anthem has English, Afrikaans, Nguni and Sotho languages but does not include Venda and Tsonga languages? The national anthem is one of the main national symbols; sacrosanct heritage and rallying point of the country. This tells you who is in power and who is not. Language symbolises power, and when you exclude some languages in the linguistic landscape, such as a national anthem, you are disempowering the speakers."

Culture carrier

But language also allows us to pass our cultural values and sensibilities from one generation to another, says Kadenge. "Hence, we usually say language is a carrier of culture. It is the means through which we share our values and socialise our children."

Simultaneously, language also allows us access into other cultures. "Many people around the world now have access to the Chinese culture because the Chinese language is spreading around the world through the establishment of Confucius Institutes and the teaching of the language all over the world. This is how English culture has spread around the world. English is now considered a global language. Right now, South Africa is strengthening its links with East Africa by introducing the teaching of Swahili in its education system. It is why Swahili has been taught at the University of Zimbabwe for a while."

Thinking aloud

While the number of spoken languages is said to be reducing globally, language code is developing in other ways. English is being manipulated, moulded and restructured using psycholinguistics, or psychology of language, which considers the way that it is shared and understood.

Baro adds, "Agency is important, meaning that people purposefully make use of different variations of language in order to perform aspects of identity. Formality versus informality, humour, or wanting to sound serious, for example."

"Because of our agency to use language as one form of communication, we get to express ourselves using language based on how the language and its different forms or variations are perceived in society. One will use different forms of language if they want to appear friendly or unfriendly, for example. This is why language is considered a system, because each word, sound, accent, variant, indexes a particular meaning," says Baro.

Author: Shanthini Naidoo | Source: Wits University [November 12, 2019]

Largest-ever ancient-DNA study illuminates millennia of South and Central Asian prehistory

By: Thomas Schmitt Attorney on September 05, 2019 / comment : 0 Archaeology, Asia, Genetics, India, Linguistics, South Asia

The largest-ever study of ancient human DNA, along with the first genome of an individual from the ancient Indus Valley Civilization, reveal in unprecedented detail the shifting ancestry of Central and South Asian populations over time.

The first sequenced genome from an archaeological site associated with the ancient Indus Valley Civilization came from this woman buried at the city of Rakhigarhi [Credit: Shinde and Narasimhan et al. 2019]

The research, published in a pair of papers in Science and Cell, also answers longstanding questions about the origins of farming and the source of Indo-European languages in South and Central Asia.

Geneticists, archaeologists and anthropologists from North America, Europe, Central Asia and South Asia analyzed the genomes of 524 never before-studied ancient individuals. The work increased the worldwide total of published ancient genomes by about 25 percent.

By comparing these genomes to one another and to previously sequenced genomes, and by putting the information into context alongside archaeological, linguistic and other records, the researchers filled in many of the key details about who lived in various parts of this region from the Mesolithic Era (about 12,000 years ago) to the Iron Age (until around 2,000 years ago) and how they relate to the people who live there today.

"With this many samples, we can detect subtle interactions between populations as well as outliers within populations, something that has only become possible in the last couple of years through technological advances," said David Reich, co-senior author of both papers and professor of genetics in the Blavatnik Institute at Harvard Medical School.

This map depicts the geographical span of the Indus Valley Civilization (IVC), showing the location of Rakhigarhi (blue), other significant IVC sites (red), and sites to the north and west from other archaeological cultures (other colors). The yellow labels indicate two sites where a minority  of buried individuals yielded ancient DNA matched that of the Rakhigarhi individuals [Credit: Vasant Shinde/Deccan College Post Graduate and Research Institute]

"These studies speak to two of the most profound cultural transformations in ancient Eurasia--the transition from hunting and gathering to farming and the spread of Indo-European languages, which are spoken today from the British Isles to South Asia--along with the movement of people," said Vagheesh Narasimhan, co-first author of both papers and a postdoctoral fellow in the Reich lab. "The studies are particularly significant because Central and South Asia are such understudied parts of the world."

"One of the most exciting aspects of this study is the way it integrates genetics with archaeology and linguistics," said Ron Pinhasi of the University of Vienna, co-senior author of the Science paper. "The new results emerged after combining data, methods and perspectives from diverse academic disciplines, an integrative approach that provides much more information about the past than any one of these disciplines could alone."

"In addition, the introduction of new sampling methodologies allowed us to minimize damage to skeletons while maximizing the chance of obtaining genetic data from regions where DNA preservation is often poor," Pinhasi added.

Language key

Indo-European languages--including Hindi/Urdu, Bengali, Punjabi, Persian, Russian, English, Spanish, Gaelic and more than 400 others--make up the largest language family on Earth.

The largest-ever ancient DNA study illuminates millennia of Central and South Asian population history [Credit: Oliver Uberti, Vagheesh M. Narasimhan et al. 2019]

For decades, specialists have debated how Indo-European languages made their way to distant parts of the world. Did they spread via herders from the Eurasian Steppe? Or did they travel with farmers moving west and east from Anatolia (present-day Turkey)?

A 2015 paper by Reich and colleagues indicated that Indo-European languages arrived in Europe via the steppe. The Science study now makes a similar case for South Asia by showing that present-day South Asians have little if any ancestry from farmers with Anatolian roots.

"We can rule out a large-scale spread of farmers with Anatolian roots into South Asia, the centerpiece of the 'Anatolian hypothesis' that such movement brought farming and Indo-European languages into the region," said Reich, who is also an investigator of the Howard Hughes Medical Institute and the Broad Institute. "Since no substantial movements of people occurred, this is checkmate for the Anatolian hypothesis."

One new line of evidence in favor of a steppe origin for Indo-European languages is the detection of genetic patterns that connect speakers of the Indo-Iranian and Balto-Slavic branches of Indo-European. The researchers found that present-day speakers of both branches descend from a subgroup of steppe pastoralists who moved west toward Europe almost 5,000 years ago and then spread back eastward into Central and South Asia in the following 1,500 years.

A photograph of a red slipped ware globular pot placed near the head of the skeleton  that yielded ancient DNA. There are lines as well as indentations on the upper right side, just below the rim. The indentations on the body of the pot could be examples of ancient graffiti and/or "Indus script" [Credit: Vasant Shinde/ Deccan College Post Graduate and Research Institute]

"This provides a simple explanation in terms of ancient movements of people for the otherwise puzzling shared linguistic features of these two branches of Indo-European, which today are separated by vast geographic distances," said Reich.

A second line of evidence in favor of a steppe origin is the researchers' discovery that of the 140 present-day South Asian populations analyzed in the study, a handful show a remarkable spike in ancestry from the steppe. All but one of these steppe-enriched populations are historically priestly groups, including Brahmins--traditional custodians of texts written in the ancient Indo-European language Sanskrit.

"The finding that Brahmins often have more steppe ancestry than other groups in South Asia, controlling for other factors, provides a fascinating new argument in favor of a steppe origin for Indo-European languages in South Asia," said Reich.

"This study has filled in a large piece of the puzzle of the spread of Indo-European," said co-author Nick Patterson, research fellow in genetics at HMS and a staff scientist at the Broad Institute of MIT and Harvard. "I believe the high-level picture is now understood."

"This problem has been in the air for 200 years or more and it's now rapidly being sorted out," he added. "I'm very excited by that."

Agriculture origins

The studies inform another longstanding debate, this one about whether the change from a hunting and gathering economy to one based on farming was driven more by movements of people, the copying of ideas or local invention.

Detail of excavated human remains from a middle Bronze Age tomb at the site of Dali, Kazakhstan. Samples from  this burial show a significant change in the ancestry of inhabitants after 2000 BC, shifting from a mixture of West Siberian Hunter gatherers and Iranian farmers, to mixed ancestry with central steppe groups and southern central Asian populations [Credit: Michael Frachetti]

In Europe, ancient-DNA studies have shown that agriculture arrived along with an influx of people with ancestry from Anatolia.

The new study reveals a similar dynamic in Iran and Turan (southern Central Asia), where the researchers found that Anatolian-related ancestry and farming arrived around the same time.

"This confirms that the spread of agriculture entailed not only a westward route from Anatolia to Europe but also an eastward route from Anatolia into regions of Asia previously only inhabited by hunter-gatherer groups," said Pinhasi.

Then, as farming spread northward through the mountains of Inner Asia thousands of years after taking hold in Iran and Turan, "the links between ancestry and economy get more complex," said archaeologist Michael Frachetti of Washington University in St. Louis, co-senior author who led much of the skeletal sampling for the Science paper.

By around 5,000 years ago, the researchers found, southwestern Asian ancestry flowed north along with farming technology, while Siberian or steppe ancestry flowed south onto the Iranian plateau. The two-way pattern of movement took place along the mountains, a corridor that Frachetti previously showed was a "Bronze Age Silk Road" along which people exchanged crops and ideas between East and West.

In South Asia, however, the story appears quite different. Not only did the researchers find no trace of the Anatolian-related ancestry that is a hallmark of the spread of farming to the west, but the Iranian-related ancestry they detected in South Asians comes from a lineage that separated from ancient Iranian farmers and hunter-gatherers before those groups split from each other.

The researchers concluded that farming in South Asia was not due to the movement of people from the earlier farming cultures of the west; instead, local foragers adopted it.

"Prior to the arrival of steppe pastoralists bringing their Indo-European languages about 4,000 years ago, we find no evidence of large-scale movements of people into South Asia," said Reich.

First glimpse of the ancestry of the Indus Valley Civilization

Running from the Himalayas to the Arabian Sea, the Indus River Valley was the site of one of the first civilizations of the ancient world, flourishing between 4,000 and 5,000 years ago. People built towns with populations in the tens of thousands. They used standardized weights and measures and exchanged goods with places as far-flung as East Africa. But who were they?

This middle Bronze Age burial tomb at Dali, Kazakshtan (ca. 1700 BCE) was robbed in antiquity and the human remains were piled haphazardly outside the burial cist. DNA extracted from these remains helped trace the spread of steppe ancestry east and south toward India, from 2000-1500 BCE [Credit: Michael Frachetti]

Before now, geneticists were unable to extract viable data from skeletons buried at Indus Valley Civilization archaeological sites because the heat and volatile climate of lowland South Asia have degraded most DNA beyond scientists' ability to analyze it. The Cell paper changes this.

After screening more than 60 skeletal samples from the largest known town of the Indus Valley Civilization, called Rakhigarhi, the authors found one with a hint of ancient DNA. After more than 100 sequencing attempts, they generated enough data to reach meaningful conclusions.

The ancient woman's genome matched those of 11 other ancient people reported in the Science paper who lived in what is now Iran and Turkmenistan at sites known to have exchanged objects with the Indus Valley Civilization. All 12 had a distinctive mix of ancestry, including a lineage related to Southeast Asian hunter-gatherers and an Iranian-related lineage specific to South Asia. Because this mix was different from the majority of people living in Iran and Turkmenistan at that time, the authors propose that the 11 individuals reported in the Science paper were migrants, likely from the Indus Valley Civilization.

None of the 12 had evidence of ancestry from steppe pastoralists, consistent with the model that that group hadn't arrived yet in South Asia.

The Science paper further showed that after the decline of the Indus Valley Civilization between 4,000 and 3,500 years ago, a portion of the group to which these 12 individuals belonged mixed with people coming from the north who had steppe pastoralist ancestry, forming the Ancestral North Indians, one of the two primary ancestral populations of present-day people in India. A portion of the original group also mixed with people from peninsular India to form the other primary source population, the Ancestral South Indians.

"Mixtures of the Ancestral North Indians and Ancestral South Indians--both of whom owe their primary ancestry to people like that of the Indus Valley Civilization individual we sequenced--form the primary ancestry of South Asians today," said Patterson.

"The study directly ties present-day South Asians to the ancient peoples of South Asia's first civilization," added Narasimhan.

The authors caution that analyzing the genome of only one individual limits the conclusions that can be drawn about the entire population of the Indus Valley Civilization.

"My best guess is that the Indus Valley Civilization itself was genetically extremely diverse," said Patterson. "Additional genomes will surely enrich the picture."

Source: Harvard Medical School [September 05, 2019]

Hand gestures point towards the origins of language

By: Thomas Schmitt Attorney on August 20, 2019 / comment : 0 Anthropology, Human Evolution, Linguistics

Communication gestures used by humans and our primate relatives are providing clues about how our species' ability to use spoken language evolved.

Comparing brain scans from different primates could help us understand the origins of language in humans [Credit: Susanne Jutzeler/Pixabay/Pixabay]

There are few one-offs in life on Earth—rarely can a single species boast a trait or ability that no other possesses. But human language is one such oddity. Our ability to use subtle combinations of sounds produced by our vocal cords to create words and sentences, which when combined with grammatical rules, convey complex ideas.

There were attempts in the 1950s to teach chimpanzees to 'speak' some words, but these completely failed. And with no other living relatives able to communicate as we do, it has made understanding the origins of language a knotty problem.

But Dr. Adrien Meguerditchian, a primatologist at the French National Centre for Scientific Research and Aix-Marseille University, believes that gestures could be a key landmark in the evolution of language—and these are something we do have in common with other primates.

Many primate species use gestures to communicate with others in their groups. Wild chimpanzees, for example, have been seen to use at least 66 different hand signals and movements to communicate with each other. Lifting a foot towards another chimp, for example, means 'climb on me," while stroking their mouth can mean 'give me the object." In the past, researchers have also successfully taught apes more than 100 words in sign language. A chimp named Nim was taught around 125 signs in a project at Columbia University, while the gorilla Koko in a Californian reserve learnt around 100 signs.

"The idea is to look at language, not just as speech, but seeing it as a constellation of many cognitive properties," said Dr. Meguerditchian. Most language properties involve asymmetric organisation of the human brain between the two hemispheres. Given that gestures in primates seems to involve several key properties that underpin spoken language, Dr. Meguerditchian wants to see if primates undergo similar brain asymmetry when they gesture to each other.

"If you want to understand the origins of language, you need to understand not only animal cognition and communication but also its brain specialisation in comparison with humans and that is what we do in primate species," said Dr. Meguerditchian, who is leading the research under the GESTIMAGE project.

Baby brains

As both primates and humans can communicate through gestures, it provides a way of comparing how gestures are related to brain asymmetry for language and to unravel whether there are differences in how each species communicate.

Dr. Meguerditchian is studying both adult and baby baboons (Papio anubis) to see which gestures they learn and the parts of their brains that might be involved.

"When baboons invite someone to play, they will use their hands," he said. "Baboons are also able to point to food they want and use gaze, like children can."

In human babies, which learn to gesture at objects before they can speak, the left side of their brain seems to be engaged when they do so. Certain regions on the left side of our brain, such as Broca's area, are especially important when we speak. Named after French physician Paul Broca, who studied patients who had lost ability to speak, Broca's area is found in the frontal area of the brain of the dominant hemisphere (usually left).

Dr. Meguerditchian is using magnetic resonance imaging (MRI) to study baboon baby brains to see if they use a similar part of their brain when they learn to gesture.

"The questions is, if language is mostly in the left hemisphere in humans, what about gesture in non-human primates?" he said. "If it is the same system, which was used by a common ancestor between us, gesture in baboons might also be related to this left hemisphere specialisation of the brain (in baboons)."

So far, early results from 27 brain scans of baby baboons suggest that his hypothesis is correct, and apes use similar asymmetric brain areas when they gesture as humans do when they gesture and speak.

By comparing these results in baboons with other primates, including humans, gorillas, chimps and monkeys, Dr. Meguerditchian hopes to unravel whether they too share a similar asymmetric system in the brain for communication. This might help discern where on our evolutionary tree gesture communication, and the brain structures needed for it, first arose and perhaps sowed the seeds for our spoken language.

But he is not alone in thinking that some of the earliest forms of language in our species may well have been gestural rather than vocal.

"But for some reason, speech won out evolutionarily," said Professor Wendy Sandler, a linguist at the University of Haifa, Israel. "We have not discovered any community of hearing people who happen to use sign language as their main mode of communication."

Prof. Sandler is exploring the relationship between physical communication and the composition of human language. She believes sign languages can provide some clues to the structure of human language and how language may have emerged in our ancestors.

Unlike all spoken languages, which are thousands of years old and descended from other ancient languages, sign language can be born whenever a group of deaf people have an opportunity to meet and communicate.

"The visual aspect of language is much more important than linguists used to believe," added Prof. Sandler, who is leading a project called the Grammar of the Body (GRAMBY). Part of the work has involved studying the complexity of newly emerging sign languages and sign language in a number of different cultures.

Signing

"Different parts of the body convey different linguistic functions," she said. "The hands convey words, but the intonation, so the rise and fall of voice, is conveyed in sign language by facial expressions and different tilts of the head."

She and her colleagues also studied video footage of chimp displays at a Zambian wildlife orphanage to see if they use combinations of facial and gestural signals to convey complex meanings. Humans can knit together smaller elements of meaning according to known rules to form composites, which gives us the ability to communicate an infinite number of messages.

Prof. Sandler gives an example of this in the words 'train station," which we know is a station for trains because of the words and rules we know apply in English. We also easily understand that 'train station ticket office' is a kind of office, and so forth. She has also studied the expression of extreme emotion in athletes who have won and lost a competition.

Taking all her studies together, she has concluded that humans are 'compositional communicators."

"This means we can express complex messages by reorganising the same units according to their meanings and the rules of our language," Prof. Sandler said. This compositional complexity is critical in human communication.

Can chimps stack meaning like this to create a higher meaning? So far the answer is certainly negative in our nearest relatives. However, Prof. Sandler discovered that chimps can separate and recombine some gesture and facial expressions, which 'is a stepping stone to the compositionality of human language."

Scientists still do not know how or when language arose in our ancestors, a crucial mystery in unravelling our uniqueness. But a better understanding of how humans use gestures and our closest primate relatives communicate may reveal more about how and when we learned to speak.

Author: Anthony King | Source: Horizon Magazine [August 20, 2019]

Variation in the shape of speech organs influences language evolution

By: Thomas Schmitt Attorney on August 19, 2019 / comment : 0 Anthropology, Human Evolution, Linguistics

Why do languages sound so different when people across the world have roughly the same speech organs (mouth, lips, tongue and jaw)? Does the shape of our vocal tract explain some of the variation in speech sounds? In extreme individual cases, it clearly does: When children are born with a cleft palate, the roof of the mouth is not formed properly, which affects their speech. However, it is unclear whether subtle anatomical differences between normal speakers play a role.

Credit: Malecula/Shutterstock

Language and speech are also shaped by repeated use and transmission from parents to children. As language is passed on to new generations, small differences may sometimes be amplified. This observation led a team based at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, to ask what happens when tiny differences in vocal tract anatomy meet cultural transmission.

The team decided to focus on whether the shape of the hard palate might influence the way vowels are learned, articulated and passed on across generations of artificial agents. Because changing the shape of the hard palate in human participants is ethically and practically problematic, the scientists opted for a computational study, adapting an existing computer model of the vocal tract.

The team imported actual hard palate shapes from more than 100 MRI scans of human participants into the computer model. Via machine learning, they trained agents to articulate five common vowels, such as the 'ee' sound in "beet" and the 'oo' sound in "boot." Next, a second generation tried to learn these particular vowels, which were then passed on to the next generation, and so on for 50 generations.

"This simulates a simple model of language change and evolution in a computer," explains co-author Rick Janssen, currently machine learning specialist at ALTEN and Philips Research in the Netherlands. Would subtle anatomical differences in palate shape lead to differences in pronunciation? And crucially, would these differences become more pronounced through repeated transmission?

The anatomy of the vocal tract shows continuous and overlapping but identifiable variation between broad ethno-linguistic groups. We show the results of the Canonical Variate Analysis (CVA) of 57 classical anthropological measurements of the oral vocal tract derived from the 3D intra-oral optical scans of n=94 participants from the ArtiVarK sample [ref16], distributed in four broad self-declared ethno-linguistic groups. These groups are: "Ca" = European or North American  of European Descent, speaking Indo-European (mostly Germanic and Romance) languages; "NI" = North Indian, speaking Indo-Aryan languages; "SI" = South Indian, speaking Dravidian languages; and "C" = Chinese, speaking Sino-Tibetan languages. Panels (a) and (b) show the distribution of the participants (represented by their group) in the space of the first three Canonical Axes (CVs; explaining, sequentially, 49.3%, 37.6% and 13.1% of variance);  the solid polygons are the convex hulls and the colored ellipses are the 95% confidence ellipses. Panel (c) plots the posterior probabilities of each participant belonging to the four groups (vertical bars), while the top symbols  show the actual group (the squares) and the assigned group (the circles; gray circles represent "outlier" participants which cannot be assigned to any group because they are below the horizontal solid line of the 5% threshold); the dotted horizontal line shows the probability of 1.0. In this case, CVA is very successful at recovering the groups despite a few misclassifications and "outliers" (84% overall classification accuracy) and it can be seen that, while overlapping, the four groups are separated by the first three CVs [Credit: Dan Dediu / Scott Moisik]

The subtle differences in the shape of the hard palate did influence how accurately the five vowels were articulated. Importantly, the cultural transmission of speech sounds across generations amplified these small differences, even though the agents actively tried to compensate for their hard palate shape by using other articulators (such as the tongue). "Even small variations in the shape of our vocal tract may affect the way we speak, and this may even be amplified—across generations—to the level of differences between dialects and languages. Thus, biology matters," explains the lead author, Dan Dediu, currently at the Laboratoire Dynamique Du Langage, Universite Lumiere Lyon 2 in France.

According to the authors, this result may also help researchers to better understand the effects of anatomical variation on speech and how to correct it when desired, for instance, in case of speech pathology, forensic linguistics, dentistry and post-surgery recovery. But most importantly, the study highlights the importance of individual variation in speech and language in the context of our universal similarities: Co-author Scott Moisik, currently at the School of Humanities, Nanyang Technological University in Singapore, concludes: "While we are all humans and fundamentally the same, we are also unique individuals, and one can really hear it."

The study is published in Nature Human Behaviour.

Source: Max Planck Society [August 19, 2019]

Community size matters when people create a new language

By: Thomas Schmitt Attorney on July 17, 2019 / comment : 0 Anthropology, Human Evolution, Linguistics, Society

Why are languages so different from each other? After comparing more than two thousand languages, scientists noticed that languages with more speakers are usually simpler than smaller languages. For instance, most English nouns can be turned into plurals by simply adding -s, whereas the German system is notoriously irregular. Linguists have proposed that languages adapt to fit different social structures.

Credit: iStockphoto, Kronick

"But we actually don't know whether it is the size of the community that drives the difference in complexity," says lead author Limor Raviv from the Max Planck Institute for Psycholinguistics. Perhaps the bigger languages have simpler grammars because they cover larger geographical space and speakers are far from each other, or because large communities have more contact with outsiders. Together with her colleagues, Antje Meyer from the Max Planck Institute for Psycholinguistics and Radboud University and Shiri Lev-Ari from the Royal Holloway University of London, Raviv set out to test whether community size alone plays a role in shaping grammar.

'Wowo-ik' and 'wowo-ii'

To test the role of group size experimentally, the psycholinguists used a communication game. In this game, participants had to communicate without using any language they know, leading them to create a new language. The goal of the game was to communicate successfully about different novel scenes, using only invented nonsense words.

A 'speaker' would see one of four shapes moving in some direction on a screen and type in nonsense words to describe the scene (its shape and direction). The 'listener' would then guess which scene the other person was referring to, by selecting one of eight scenes on their own screen. Participants received points for every successful interaction (correct guesses). Participants paired up with a different person from their group at every new round, taking turns producing and guessing words.

At the start of the game, people would randomly guess meanings and make up new names. Over the course of several hours, participants started to combine words or part-words systematically, creating an actual mini-language.

For instance, in one group, 'wowo-ik' meant that a specific shape was going up and right, whereas 'wowo-ii' meant that the same shape was going straight up. With such a 'regular' system, it becomes easier to predict the meaning of new labels ('mop-ik' meant a different shape going up and right). Participants played in either 'small' groups of four participants or 'large' groups of eight participants. Would the large groups invent 'simpler' (more systematic) languages than the small groups?

Variability promotes structure

By the end of the experiment, the large groups had indeed created languages with more systematic grammars. "The pressure to create systematic languages is much higher in larger groups," explains Raviv. This is because there are more word versions in the larger groups. In order to understand each other, members of a large group must overcome this variability and develop systematic structure. So the more variability, the more it pushed people to make their language even simpler.

The researchers also found that the size of the group predicted how similar that group was to the other groups. All large groups reached similar levels of structure and communicative success. However, the small groups differed a lot from each other: some never developed systematic grammars, while others were very successful." This might mean that in the real world, larger languages are potentially more similar to each other than smaller languages," Raviv says.

"Our study shows that the social environment in which languages evolve, and specifically the number of people in the community, can affect the grammar of languages," concludes Raviv. "This could possibly explain why some languages have more complex grammar than others. The results also support the idea that an increase in human population size was one of the main drivers for the evolution of natural languages."

The study is published in the Proceedings of the Royal Society B: Biological Sciences.

Source: Max Planck Institute for Psycholinguistics [July 17, 2019]

How language developed: Comprehension learning precedes vocal production

By: Thomas Schmitt Attorney on May 27, 2019 / comment : 0 Africa, Anthropology, Human Evolution, Linguistics, Wildlife

Human language and communication skills are unique in the animal kingdom. How they developed in the course of evolution is being researched, among other things, using the alarm call system of vervet monkeys. East African vervet monkeys warn their conspecifics against predators with special alarm calls that mean "leopard", "eagle" or "snake". In a recently published study, scientists from the German Primate Center (DPZ) - Leibniz Institute for Primate Research have investigated how the closely related West African green monkeys react to unknown sounds.

West African green monkey (Chlorocebus sabaeus) in Senegal [Credit: Julia Fischer]

To do this, they flew a drone over a group of West African green monkeys and later played them a sound recording of the drone noise. From the reactions of the animals, the researchers were able to conclude that the animals learn very quickly what the drone noise means. However, the monkeys did not create a new alarm call, but used a call that the East African vervet monkey uses to warn against aerial predators like eagles. This suggests that the call structure is conserved and was determined long ago in the course of evolution.

There are three main predators that pose a threat to East African vervet monkeys: leopards, eagles and snakes. For each of these predators, the monkeys have developed special alarm calls to which the animals respond with appropriate strategies: When the call for "leopard" is uttered, they climb a tree, when they hear the call for "eagle", they search the sky and hide and when the call for "snake" is uttered, they stand on two legs and remain motionless.

The closely related West African green monkeys also emit alarm calls for leopards and snakes, however none for aerial predators. With these animals, the team around behavioral scientist Julia Fischer from the German Primate Center has now carried out a playback experiment in order to investigate the evolution of the alarm call system and ultimately to draw conclusions about the development of language.

The drone experiment

West African green monkeys occur near the DPZ research station Simenti in Senegal. Julia Fischer and her team have confronted these animals with a new potential threat from the air: a drone, which they flew over the animals at a height of 60 meters. The sounds of the drone were recorded and later played to the animals.

The researchers wanted to find out how quickly the animals learned the meaning of the sounds. In the playback experiment, the animals reacted to the drone sound with alarm calls, some searched the sky and hid. These alarm calls were very different from the sounds the animals made in the presence of snakes and leopards. However, the calls resembled the alarm calls that East African vervet monkeys utter when an eagle approaches from the air.

Fast auditory learning

"The animals quickly learned what the previously unknown sounds mean and remembered this information," says Julia Fischer, head of the Cognitive Ethology Laboratory at the German Primate Center and lead author of the study. "This shows their ability for auditory learning."

Vocal production conserved during evolution

The West African green monkeys have warned their conspecifics of the new threat from the air with a call that sounds very similar to the calls that the closely related East African vervet monkeys utter when threatened by an eagle. "The structure of the alarm calls seems to be deeply rooted in the evolution of vervet monkeys," Julia Fischer adds.

The study is published in Nature Ecology & Evolution.

Source: Deutsches Primatenzentrum (DPZ)/German Primate Center [May 27, 2019]

Climate a driver of language diversity

By: Thomas Schmitt Attorney on May 17, 2019 / comment : 0 Anthropology, Climate Change, Linguistics

A region's climate has a greater impact than landscape on how many languages are spoken there, new research from The Australian National University (ANU) shows.

Credit: Sherrie Thai/Flickr

The research team mapped language diversity around the world and found areas with more productive climates tend to have more languages.

"We were able to show that despite popular belief, climatic factors have a stronger effect than landscape factors - like how mountainous it is, or how many rivers there are - when it comes to language diversity," ANU biologist Professor Lindell Bromham said.

The researchers think this could have a lot to do with food production - another driver of language diversity.

"If an area can reliably support food production for more of the year it may allow human groups to persist in smaller areas, so you can pack more different cultures into one region, and therefore more languages," Professor Bromham explained.

"If you're up in a region with a shorter growing season, or less reliable food productivity, you might need to make sure you've got links with other groups so you can support each other. It might be harder to form a small, isolated, self-sufficient band."

Professor Bromham said the study showed language diversity and biodiversity might both be affected by similar factors.

"Our results look a lot like a map of biodiversity," Professor Bromham said. "You could overlay a map of language diversity and a map of biodiversity and they'd show some very similar patterns.

"For example, there's more diversity around the equator, and less as you go towards the poles.

"If you've got an area where it's hard for animals to live, it's generally also hard for people to live there. So unsurprisingly, in those areas, there are less languages."

As part of the study, the researchers pin-pointed areas where language diversity could not be easily explained by factors like climate and landscape alone. A few areas stood out.

The eastern Himalayas, west Africa and Papua New Guinea had far more unexplained language diversity than other parts of the world.

"Papua New Guinea is home to 10 per cent of the world's languages, despite taking up just 0.5 per cent of the world's land area. Incredibly, it not only has many languages, but languages that are fundamentally different from each other," said study lead Dr Xia Hua.

"If we can understand what's driving this, I think we'd understand a lot more about the drivers of cultural diversity in general."

This could have extra significance in places like Australia that have experienced a high rate of language loss.

"Every language we lose is a rich source of information on the way languages have evolved. The more we lose, the harder it will be for us to understand language origins," Professor Bromham said.

"Biologists face the same problem - when we lose species to extinction we lose information about the evolutionary process that created those species."

The research has been published in Nature Communications.

Source: Australian National University [May 17, 2019]

Academic cracks Voynich code, solving century-old mystery of medieval text

By: Thomas Schmitt Attorney on May 15, 2019 / comment : 0 Archaeology, Europe, Italy, Linguistics, Southern Europe, UK

A University of Bristol academic has succeeded where countless cryptographers, linguistics scholars and computer programs have failed - by cracking the code of the 'world's most mysterious text', the Voynich manuscript.

Vignette A illustrates the erupting volcano that prompted the rescue mission and the drawing of the map. It rose from the seabed to create a new island given the name Vulcanello, which later became joined to the island of Vulcano following another eruption in 1550. Vignette B depicts the volcano of Ischia, vignette C shows the islet of Castello Aragonese, and vignette D represents the island of Lipari. Each vignette includes a combination of naïvely drawn and somewhat  stylized images along with annotations to explain and add detail. The other five vignettes describe further  details of the story [Credit: Voynich manuscript]

Although the purpose and meaning of the manuscript had eluded scholars for over a century, it took Research Associate Dr. Gerard Cheshire two weeks, using a combination of lateral thinking and ingenuity, to identify the language and writing system of the famously inscrutable document.

In his peer-reviewed paper published in the journal Romance Studies, Cheshire describes how he successfully deciphered the manuscript's codex and, at the same time, revealed the only known example of proto-Romance language.

"I experienced a series of 'eureka' moments whilst deciphering the code, followed by a sense of disbelief and excitement when I realised the magnitude of the achievement, both in terms of its linguistic importance and the revelations about the origin and content of the manuscript.

This shows the word 'palina' which is a rod for measuring the depth of water, sometimes called a stadia rod or ruler. The letter 'p' has been extended [Credit: Voynich manuscript]

"What it reveals is even more amazing than the myths and fantasies it has generated. For example, the manuscript was compiled by Dominican nuns as a source of reference for Maria of Castile, Queen of Aragon, who happens to have been great aunt to Catherine of Aragon.

"It is also no exaggeration to say this work represents one of the most important developments to date in Romance linguistics. The manuscript is written in proto-Romance - ancestral to today's Romance languages including Portuguese, Spanish, French, Italian, Romanian, Catalan and Galician. The language used was ubiquitous in the Mediterranean during the Medieval period, but it was seldom written in official or important documents because Latin was the language of royalty, church and government. As a result, proto-Romance was lost from the record, until now."

Cheshire explains in linguistic terms what makes the manuscript so unusual: "It uses an extinct language. Its alphabet is a combination of unfamiliar and more familiar symbols. It includes no dedicated punctuation marks, although some letters have symbol variants to indicate punctuation or phonetic accents. All of the letters are in lower case and there are no double consonants. It includes diphthong, triphthongs, quadriphthongs and even quintiphthongs for the abbreviation of phonetic components. It also includes some words and abbreviations in Latin."

		This shows two women dealing with five children in a bath. The words describe different temperaments: tozosr (buzzing: too noisy), orla la (on the edge: losing patience), tolora (silly/foolish), noror (cloudy: dull/sad), or aus (golden bird: well behaved), oleios (oiled: slippery). These words survive in Catalan [tozos], Portuguese [orla], Portuguese [tolos],  Romanian [noros], Catalan [or aus] and Portuguese [oleio]. The words orla la describe the mood of the woman on the left and may well be the root of the French phrase 'oh là là', which has a very similar sentiment [Credit: Voynich manuscript]

The next step is to use this knowledge to translate the entire manuscript and compile a lexicon, which Cheshire acknowledges will take some time and funding, as it comprises more than 200 pages.

"Now the language and writing system have been explained, the pages of the manuscript have been laid open for scholars to explore and reveal, for the first time, its true linguistic and informative content."

Source: University of Bristol [May 15, 2019]

Ancient DNA suggests that some Northern Europeans got their languages from Siberia

By: Thomas Schmitt Attorney on May 09, 2019 / comment : 0 Anthropology, Estonia, Europe, Genetics, Linguistics, Northern Europe, Siberia

Most Europeans descend from a combination of European hunter-gatherers, Anatolian early farmers, and Steppe herders. But only European speakers of Uralic languages like Estonian and Finnish also have DNA from ancient Siberians. Now, with the help of ancient DNA samples, researchers reporting in Current Biology suggest that these languages may have arrived from Siberia by the beginning of the Iron Age, about 2,500 years ago, rather than evolving in Northern Europe.

Bronze Age stone cist graves in Northern Estonia  [Credit: WikiCommons]

The findings highlight the way in which a combination of genetic, archaeological, and linguistic data can converge to tell the same story about what happened in particular areas in the distant past.

"Since the transition from Bronze to Iron Age coincides with the diversification and arrival time of Finnic languages in the Eastern Baltic proposed by linguists, it is plausible that the people who brought Siberian ancestry to the region also brought Uralic languages with them," says Lehti Saag of University of Tartu, Estonia.

Although researchers knew that the Uralic-speaking people share common Siberian ancestry, its arrival time in the Eastern Baltic had remained uncertain. To characterize the genetic ancestry of people from the as-yet-unstudied cultural layers, Saag along with Kristiina Tambets and colleagues extracted DNA from the tooth roots of 56 individuals, 33 of which yielded enough DNA to include in the analysis.

Corded Ware culture pottery and stone axes from Estonia  [Credit: WikiCommons]

"Studying ancient DNA makes it possible to pinpoint the moment in time when the genetic components that we see in modern populations reached the area since, instead of predicting past events based on modern genomes, we are analyzing the DNA of individuals who actually lived in a particular time in the past," Saag explains.

Their data suggest that the Siberian ancestry reached the coasts of the Baltic Sea no later than the mid-first millennium BC--around the time of the diversification of west Uralic/Finnic languages. It also indicates an influx of people from regions with strong Western hunter-gatherer characteristics in the Bronze Age, including many traits we now associate with modern Northern Europeans, like pale skins, blue eyes, and lactose tolerance.

"The Bronze Age individuals from the Eastern Baltic show an increase in hunter-gatherer ancestry compared to Late Neolithic people and also in the frequency of light eyes, hair, and skin and lactose tolerance," Tambets says, noting that those characteristics continue amongst present-day Northern Europeans.

The researchers are now expanding their study to better understand the Iron Age migration processes in Europe. They say they will also "move forward in time and focus on the genetic structure of the medieval time period."

Source: Cell Press [May 09, 2019]

Origin of Sino-Tibetan language family revealed by new research

By: Thomas Schmitt Attorney on May 06, 2019 / comment : 0 Anthropology, Asia, China, Linguistics, Tibet

The Sino-Tibetan language family includes early literary languages, such as Chinese, Tibetan, and Burmese, and is represented by more than 400 modern languages spoken in China, India, Burma, and Nepal. It is one of the most diverse language families in the world, spoken by 1.4 billion speakers. Although the language family has been studied since the beginning of the 19th century, scholars' knowledge of the origin of these languages is still severely limited.

Harvesting foxtail millet (Setaria italica) in Taiwan [Credit: © Chih-hung Yang]

An interdisciplinary study published in Proceedings of the National Academy of Sciences, led by scientists of the Centre des Recherches Linguistiques sur l'Asie Orientale (Paris), the Max Planck Institute for the Science of Human History (Jena), and the Centre de Recherches en Mathématiques de la Décision (Paris), now sheds new light on the place and date of the origin of these languages. Based on a phylogenetic study of 50 ancient and modern Sino-Tibetan languages, the scholars conclude that the Sino-Tibetan languages originated among millet farmers, located in North China, around 7,200 years ago.

During the past 10,000 years, two of the world's largest language families emerged, one in the west and one in the east of Eurasia. Together, these families account for nearly 60% of the world's population: Indo-European (3.2 billion speakers), and Sino-Tibetan (1.4 billion).

Presumed pathways of the expansion of non-Sinitic Sino-Tibetan languages, contrasted with findings of early domesticates and early Neolithic cultures in China [Credit: J.-M. List and H. Sell]

The Sino-Tibetan family comprises about 500 languages spoken across a wide geographic range, from the west coast of the Pacific to Nepal, India, and Pakistan. Speakers of these languages have played a major role in human prehistory, giving rise to early high cultures China, Tibet, Burma, and Nepal. However, while archaeogeneticists, phylogeneticists, and linguists have energetically discussed the origins of the Indo-European language family, the formation of Sino-Tibetan languages has previously received little attention.

One of the world's most diverse language families

"The Sino-Tibetan language family is one of the most diverse families in the world. It includes all of the different types of morphological systems, ranging from isolating languages, such as Chinese, Burmese, and Tujia, to polysynthetic languages, such as Gyalrongic and Kiranti languages," explains Guillaume Jacques of the Centre des Recherches Linguistiques sur l'Asie Orientale, co-first author of the study. "While our knowledge of how to compare these languages linguistically is improving, important aspects of the development of their sound systems and their grammar remain poorly understood."

A database of core words from 50 Sino-Tibetan languages

In order to shed light on the complex history of these languages, the scholars assembled a lexical database containing core vocabulary from 50 Sino-Tibetan languages. This database, published here for the first time, includes ancient languages spoken 1000 and more years ago, such as Old Chinese, Old Burmese, and Old Tibetan, as well as modern languages documented by field work.

Linguistic comparison of words meaning “cloud” across different Sino-Tibetan languages in the lexical database [Credit: © Johann-Mattis List]

"In order to compare these languages in a transparent way, we developed a specific annotation framework that allows us not only to mark which words we identify as sharing a common origin, but also which sounds in the words we think are related," says Johann-Mattis List of the Max Planck Institute for the Science of Human History, who led the study.

"A particular problem in identifying the truly related words were the numerous cases where languages borrowed words from each other," mentions Jacques. "Luckily, we know the history of particular languages rather well and could rely on techniques that we developed before to reveal the true history concealed by these borrowings."

Evolutionary trees suggest that the language family originated about 7200 years ago

Using powerful computational phylogenetic methods, the team inferred the most probable relationships between these languages and then estimated when these languages might have originated in the past.

A basketful of harvested ears of foxtail millet (Setaria italica) [Credit: © Chih-hung Yang]

"We find clear evidence for seven major subgroups with a complex pattern of overlapping signals beyond that level," says Simon J. Greenhill of the Max Planck Institute for the Science of Human History. "Our estimates suggest that the ancestral language has arisen around 7,200 years ago."

An agricultural analysis reveals the most likely origin and expansion scenario of the language family

To further resolve the complex pathways of the evolution of the Sino-Tibetan languages, the authors looked at related words describing domesticates, because they may reveal how agricultural knowledge spread through the region. This agricultural analysis suggests an origin of the Sino-Tibetan family in Northern Chinese communities of millet farmers of the Neolithic cultures of late Cishan and early Yangshao.


"The most likely expansion scenario of the languages involves an initial separation between an Eastern group, from which the Chinese dialects evolved, and a Western group, which is ancestral to the rest of the Sino-Tibetan languages," summarizes Laurent Sagart of the Centre des Recherches Linguistiques sur l'Asie Orientale, co-first author of the study, who carried out the agricultural analysis.

"We are very excited about our findings," says List. "Our approach combines robust, traditional scholarship with cutting-edge computational methods within a computer-assisted framework that allows us to use our knowledge of today's languages as a key to their past."

Source: Max Planck Institute for the Science of Human History [May 06, 2019]

A shared past for East Africa's hunter-gatherers

By: Thomas Schmitt Attorney on February 18, 2019 / comment : 0 Africa, Anthropology, Genetics, Indigenous Cultures, Linguistics

Languages that involve "clicks" are relatively rare worldwide but are spoken by several groups in Africa. The Khoisan language family includes a handful of these click languages, spoken by hunter-gatherer groups in southern and eastern Africa. But the grouping of these populations into a single language family has been controversial, with some linguists convinced that a few of the languages are too different to be classified together.

The Penn-led study examined genetic data from 50 distinct African populations, including many who practice hunter-gatherer lifestyles, such as the (clockwise from upper left) Sabue, San, Hadza, and Sandawe. The team found that some of these hunting and gathering groups share a common ancestry, and also underscored the important role of diet and disease as drivers of local adaptation around the continent [Credit: Tishkoff lab]

A genomic study of 50 African populations led by researchers at the University of Pennsylvania adds some clarity to the relationships between these click-speaking groups and many others. The results point to a relatively recent shared ancestry for a few of the click-speaking hunter-gatherer populations, indicating they are more closely related to one another than to their neighbors that practice other subsistence lifestyles, such as farming or animal herding.

The analysis, one of the most extensive of its kind of ethnically diverse populations in Africa, also demonstrates the importance of infectious disease, immunity, and diet in shaping the diversity of popluations across Africa. The work is published in the journal Proceedings of the National Academy of Sciences.

"It's very rare to have a study of this many groups that are genetically different in terms of ancestry, in their susbsistence patterns, and are geographicaly dispersed as well," says Sarah Tishkoff, a geneticist and Penn Integrates Knowledge Professor who was the senior author on the paper. "This allows us to characterize population structure and demographic history as well as to look at signatures of natural selection acting on these populations."

The analysis builds upon decades of work by the Tishkoff lab and African collaborators to explore African genetic diversity. The research, says Tishkoff, facilitates genomics research overall by examining populations that have been otherwise understudied, and it can play a role in identifying genetic variants that influence health and disease in Africa and around the world.

This study probes deeply into the genomic landscape of 840 Africans, identifying 621,000 separate nucleotides in the DNA of each participant.

The 50 groups surveyed are spread across sub-Saharan Africa and include almost all groups that practice a hunting-and-gathering lifestyle, or have until recently.

Tishkoff, Scheinfeldt, and colleagues were particularly interested in what these study participants' genomes would reveal about ancient relationships among hunter-gatherer populations, particularly those speaking languages that had been classified as Khoisan. East Africa's Hadza and Sandawe hunter-gatherers had been labeled Khoisan by some linguistic analyses, grouped with southern Africa's San hunter-gatherers.

"Some linguists say it's not correct to place all of these into the Khoisan family, arguing that the Hadza and Sandawe languages are so different from each other and from the San that they really should be in separate language classifications," says Tishkoff.

The researchers also included study participants from the Dahalo of Ethiopia, who have never been studied genetically but speak a language with remnant clicks. "It's an ongoing question in linguistics and genetics," Tishkoff says, "and we wanted to ask the question, 'Do these groups with click phonemes have a common genetic ancestry?'"

They were also curious to know whether a shared subsistence lifestyle practice--that of hunting and gathering--indicated a shared ancestry. Among the 16 hunter-gatherer populations they studied was a group called the Sabue who live in southwestern Ethiopia, surrounded by pastoralist groups. The Sabue had never before participated in genomic research and speak a language that is thus far unclassified.

Using the genetic information they obtained to map out the populations' likely relationships to one another, the researchers unexpectedly found that four hunter-gatherer populations--the Hadza, Sandawe, Dahalo, and Sabue, each of whom dwell in distinct areas of eastern Africa--clustered together.

"Typically what we see is that populations cluster by geography, but here we're seeing an exception to that," Tishkoff says. "Here you have three groups that either speak a click language, have remnant clicks, or have an unclassified language, and they're showing a common ancestry even though they're spread across different countries."

Although the researchers could not identify a uniquely shared ancestry between these four groups of eastern African Khoisan hunter-gatherers and the southern African San people, who also speak a language with clicks, they did observe shared ancestry between the San and rainforest hunter-gatherers from Central Africa, despite being geographically far apart.

In contrast, other hunter-gatherer groups, such as the Wata, El Molo, and Yaaku, appeared more genetically similar to neighboring agriculturalist and pastorlist groups.

The common ancestry for the four East Africa hunter-gatherer groups dates back more than 20,000 years ago, according to the team's analysis, around the beginning of the last glacial maximum, when ice covered extensive portions of Earth and the climate was much different than it is today.

"The idea is that this may have changed environmental conditions and introduced a barrier between populations," says Laura Scheinfeldt, the lead author who was a research associate in Tishkoff's lab, and is now with the Coriell Institute for Medical Research.

The researchers' techniques also allowed for a better understanding of the forces that have acted to differentiate the groups they studied.

"What we found was the strongest signatures of adaptation tended to be population-specific," says Scheinfeldt. In other words, targets of natural selection were different in the different groups and may well have contributed to the uniqueness of each.

Despite these individual differences, the categories of the genes that were selected were shared among populations, the researchers discovered.

"Genes involved in immune responses, diet, and metabolism were the broad categories that we saw coming up over and over again," Scheinfeldt notes. "We know infectious disease in general is a very strong pressure, and, when you look solely at how prevalent malaria is, that also explains some of the patterns we see in adaptive signatures. Just that one disease is a very strong selective pressure."

In future studies, Tishkoff and colleagues will be zooming in to see how particular genetic variants may affect physical traits in the people who possess them, studies that could shed light on genetic causes of disease susceptibility. They'll also be using powerful whole-genome sequencing techniques to further illuminate the relationships among Africa's diverse populations.

Source: University of Pennsylvania [February 18, 2019]