Thursday, October 30, 2014

Babies learn words differently as they age, researcher finds

Study findings can help speech therapists, parents broaden toddlers' vocabularies

Research has shown that most 18-month-olds learn an average of two to five new words a day; however, little is known about how children process information to learn new words as they move through the preschool years. In a new study, a University of Missouri researcher has found that toddlers learn words differently as they age, and a limit exists as to how many words they can learn each day. These findings could help parents enhance their children's vocabularies and assist speech-language professionals in developing and refining interventions to help children with language delays.

"We found that babies' abilities to accurately guess the meaning of new words increases between 18 and 30 months of age, and by 24 to 36 months, toddlers are able to accurately guess the meanings of new words at a significantly higher level," said Judith Goodman, an associate professor in the MU School of Health Professions and chair of the Department of Communication Science and Disorders. "Interestingly, we observed that even from the time children mature from 18 to 30 months of age, the cues toddlers use to learn new words change."

In the study, researchers taught six new words to children, who ranged in age from 18 to 36 months, using three types of cues. The cues were presented alone or in pairs, and the researchers recorded the children's ability to accurately guess what the words meant.

"When children were presented with a new word and asked to choose between an item for which they already had a name and an unfamiliar object, they appropriately assigned the new word to the unfamiliar object, and this ability improved as children aged," Goodman said. "The toddlers' ability to infer a word's meaning from linguistic context, such as figuring out that a 'kiwi' must be a food item when they hear, 'Sammy eats the kiwi,' also improved as the children aged. However, using social cues, such as eye gaze, became less effective as the children matured. By 36 months of age, children were less likely to assume a word referred to the particular object a speaker was looking at – looking at a kiwi when teaching the child the word 'kiwi' – than younger children were."

Goodman also found that a limit exists as to how many words toddlers can retain. A day after the children learned the six words, the researchers tested whether the children remembered the words. The children better remembered the first three words they had learned the first day, Goodman said.

Children who are struggling with learning language may benefit from being presented with specific cues, Goodman said. Additionally, the research reinforces the importance of providing children with rich word-learning environments, in which toddlers are exposed to many words and are provided with a variety of cues to help them learn and remember those words and what they represent, Goodman said.

"When you're working with young children who are learning language, it's important to talk to them all the time and label everything in their environments," Goodman said. "At home, parents can name household items or foods the children are eating. If out on an excursion, such as a trip to the zoo, parents can label the animals they see."
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EurekAlert. 2014. “Babies learn words differently as they age, researcher finds”. EurekAlert. Posted: September 17, 2014. Available online: http://www.eurekalert.org/pub_releases/2014-09/uom-blw091714.php

Wednesday, October 29, 2014

NOAA team reveals forgotten ghost ships off Golden Gate

San Francisco area divers provided valuable assistance to help identify wrecks

A team of NOAA researchers today confirmed the discovery just outside San Francisco's Golden Gate strait of the 1910 shipwreck SS Selja and an unidentified early steam tugboat wreck tagged the "mystery wreck." The researchers also located the 1863 wreck of the clipper ship Noonday, currently obscured by mud and silt on the ocean floor.

These and other shipwreck investigations mark the first mission of a two-year project to locate, identify and better understand some of the estimated 300 wrecks in Gulf of the Farallones National Marine Sanctuary, and the adjacent Golden Gate National Recreation Area.

"The waters of the sanctuary and the park are one of the great undersea museums in the nation," said James Delgado, director of Maritime Heritage for the Office of National Marine Sanctuaries. "These wrecks tell the powerful story of the people who helped build California and opened America to the Pacific for nearly two centuries. Finding the remains of these ships links the past to the present."

NOAA's Office of National Marine Sanctuaries and the U.S. National Park Service, which began researching the wrecks in the 1980s, published the first detailed inventory and history of the submerged heritage of the region in 1990. Since then, Robert Schwemmer, project co-leader and NOAA maritime archaeologist, has conducted new research in archives around the world, and interviewed fishermen and pioneering wreck divers like Bruce and Robert Lanham of San Francisco.

The Lanham brothers have discovered a number of historic Bay-area wrecks. Bruce Lanham joined the recent NOAA expedition, and with his brother led the NOAA team to a widely scattered wreck site they believed was the Selja. In 1910 the steamer Selja sank in a fatal collision, which featured prominently in a legal case that ultimately was argued before the U.S. Supreme Court over a key aspect of maritime law, the "rule of the road."

"Bruce and Bob were crucial to the success of the mission as was volunteer Gary Fabian, who re-analyzed hours of NOAA sonar data to pinpoint wreck sites," said Schwemmer.

One of the targets Fabian pointed out was the right size and in the right location to be the clipper ship Noonday, lost in 1863 and part of the fleet of fast-sailing vessels that brought men and supplies to California during and after the Gold Rush. "Noonday Rock," north of the Farallones, was named for the wreck.

In addition to the newly identified ships, Vitad Pradith, a researcher with NOAA's Office of Coast Survey Navigation Response Team 6, completed the first-ever sonar survey of the submerged portions of the wrecks of the tankers Frank H. Buck and Lyman Stewart. The engines of both vessels are visible at low tide off San Francisco's Lands End, inside the waters of Golden Gate National Recreation Area.

"Buck and Stewart are probably the best known wrecks in the park," said Stephen Haller, park historian, who joined the project team on the just-completed mission. "We now have a better understanding of how the two wrecks lie next to each other, and what has survived beneath the surface."

The NOAA team used remote controlled cameras and sensing equipment and will continue to analyze data from the recent dives, conduct additional research, and plan for the next phase. Brian Johnson, Gulf of the Farallones sanctuary deputy superintendent, said findings from current and future research expeditions will be shared with the public.

"The shipwrecks off the Golden Gate are places to explore, discover and appreciate our country's maritime cultural heritage," Johnson said. "Through the study, protection and promotion of this diverse legacy, Americans can learn more about our shared past."
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EurekAlert. 2014. “NOAA team reveals forgotten ghost ships off Golden Gate”. EurekAlert. Posted: September 16, 2014. Available online: http://www.eurekalert.org/pub_releases/2014-09/nh-ntr091514.php

Tuesday, October 28, 2014

How learning to talk is in the genes

Researchers have found evidence that genetic factors may contribute to the development of language during infancy.

Scientists from the Medical Research Council (MRC) Integrative Epidemiology Unit at the University of Bristol worked with colleagues around the world to discover a significant link between genetic changes near the ROBO2 gene and the number of words spoken by children in the early stages of language development.

Children produce words at about 10 to 15 months of age and our range of vocabulary expands as we grow -- from around 50 words at 15 to 18 months, 200 words at 18 to 30 months, 14,000 words at six-years-old and then over 50,000 words by the time we leave secondary school.

The researchers found the genetic link during the ages of 15 to 18 months when toddlers typically communicate with single words only before their linguistic skills advance to two-word combinations and more complex grammatical structures.

The results, published in Nature Communications today [16 Sept], shed further light on a specific genetic region on chromosome 3, which has been previously implicated in dyslexia and speech-related disorders.

The ROBO2 gene contains the instructions for making the ROBO2 protein. This protein directs chemicals in brain cells and other neuronal cell formations that may help infants to develop language but also to produce sounds.

The ROBO2 protein also closely interacts with other ROBO proteins that have previously been linked to problems with reading and the storage of speech sounds. Dr Beate St Pourcain, who jointly led the research with Professor Davey Smith at the MRC Integrative Epidemiology Unit, said: "This research helps us to better understand the genetic factors which may be involved in the early language development in healthy children, particularly at a time when children speak with single words only, and strengthens the link between ROBO proteins and a variety of linguistic skills in humans."

Dr Claire Haworth, one of the lead authors, based at the University of Warwick, commented: "In this study we found that results using DNA confirm those we get from twin studies about the importance of genetic influences for language development. This is good news as it means that current DNA-based investigations can be used to detect most of the genetic factors that contribute to these early language skills." The study was carried out by an international team of scientists from the EArly Genetics and Lifecourse Epidemiology Consortium (EAGLE) and involved data from over 10,000 children.
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Science Daily. 2014. “How learning to talk is in the genes”. Science Daily. Posted: September 16, 2014. Available online: http://www.sciencedaily.com/releases/2014/09/140916112242.htm

Monday, October 27, 2014

How the British treated ‘hardcore’ Mau Mau women

New research on the treatment of ‘hardcore’ female Mau Mau prisoners by the British in the late 1950s sheds new light on how ideas about gender, deviancy and mental health shaped colonial practices of punishment.

The research, published in the Journal of Eastern African Studies, was conducted by Gates Cambridge Scholar Katherine Bruce-Lockhart and is the first study to make use of new material on a camp in Gitamayu used to hold “hardcore” female detainees. The treatment of the Mau Mau by the British has led to compensation claims in the courts. Last year the British government agreed to pay out £19.9m in costs and compensation to more than 5,000 elderly Kenyans who suffered torture and abuse during the Mau Mau uprising in the 50s. Two of those involved in the recent case were women and further female compensation cases are pending.

Bruce-Lockhart is interested in the treatment of “hardcore” Mau Mau women in the final years of the Emergency Period, one that was marked by uncertainty, violence and an increasing reliance on ethno-psychiatry.

From 1954 to 1960, the British detained approximately 8,000 women under the Emergency Powers imposed to combat the Mau Mau Rebellion in Kenya. The majority of female detainees were held in Kamiti Detention Camp and its importance has been widely acknowledged by historians. However, new documentary evidence released from the Hanslope Park Archive since 2011 has revealed the existence of a second camp established for women at Gitamayu, created in 1958 in order to deal with the remaining “hardcore” female detainees.

The Archive contains over 1,500 files and was uncovered in 2011 by historians working on the London High Court case between the British Foreign and Commonwealth Office and Kenyan plaintiffs who were held in detention camps during the Emergency Period. The files were considered too sensitive to fall into the hands of the Kenyan government, and were taken out of Kenya by the British prior to independence. The files have been pivotal in the London High Court Case, as their contents show how senior British officials sanctioned the use of systematic force against Mau Mau detainees in the camps, stretching the legal limits of legitimate violence. The documents relating to Kamiti and Gitamayu reveal how this systematic use of violence was extended to hardcore women and the multiple ways colonial officials tried to hide it.

The intensity of this struggle with hardcore detainees, and the trajectory it took, has been overlooked by previous scholarly works on Mau Mau women, which have provided a general overview of female involvement in the movement, as well as their detention at Kamiti. Much more is known about hardcore men, who have authored over a dozen Mau Mau memoirs and are the subject of extensive scholarly analysis. The stories and identities of these men, from Jomo Kenyatta to J.M. Kariuki, are well known. The hardcore male camps, such as Manyani, Athi River, and Hola, are remembered as the sites of intense struggles between detainees and warders. Recent work from historian David Anderson has detailed the British policy toward hardcore males, which became more brutal and systematic from 1957 onwards.

Bruce-Lockhart says: “In contrast, the history of women’s detention has not been investigated in detail, especially in the latter years of the Emergency Period. Women’s punishment broadly followed a pattern similar to that of their male counterparts, with increasing severity of treatment characterising the final phase of incarceration as the British endeavored to compel inmates to confess their crimes. But the story of the female detainees at Gitamayu and Kamiti also reveals unique elements that were determined by colonial ideas about female deviancy, these ultimately becoming the defining feature of incarceration for Mau Mau’s hardcore women.

“The Hanslope archives reveal the strategies that the colonial administration employed to deal with hardcore women in the late 1950s. Whereas previously there was an assumption that women were malleable and could be easily persuaded away from the Mau Mau cause this expectation greatly diminished during this time, and was replaced with a discourse of madness, as certain elements of the colonial administration pressed for hardcore women to be classified as insane. This move was instrumental rather than genuine, meant to explain away women’s physical ailments in order to cover up mistreatment in the camp.”

She adds: “Debates about how to deal with this group of women engaged and perplexed the highest levels of the colonial administration, generating tensions between legal, political, and medical officials. At the centre of these debates was the question of the female detainees’ sanity, with some officials pressing for these women to be classified as insane. Examining the British approach to these detainees illuminates how ideas about gender, deviancy, and mental health shaped colonial practices of punishment.”
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2014. “How the British treated ‘hardcore’ Mau Mau women”. Heritage Daily. Posted: September 16, 2014. Available online: http://www.heritagedaily.com/2014/09/british-treated-hardcore-mau-mau-women/104842

Sunday, October 26, 2014

The creation of the Vuoksi River preceded a significant cultural shift

The creation of the Vuoksi River and the subsequent rapid decrease in the water level of Lake Saimaa approximately 6,000 years ago revealed thousands of square kilometers of new, fertile land in eastern Finland.

The creation of the Vuoksi River and the subsequent rapid decrease in the water level of Lake Saimaa approximately 6,000 years ago revealed thousands of square kilometres of new, fertile land in eastern Finland. A multidisciplinary research project organised by University of Helsinki researchers has studied the role that the decrease in water levels has played in the interaction between nature and humans. After dramatic shifts in the waterways, human life in the area underwent significant changes and gave rise to a new, innovative culture. This stemmed from an increase in the elk population, which flourished on the pioneer flora growing on the newly emerged land. Later, the culture regressed as the ecosystem in the area shifted towards old-growth spruce-dominated forests which could not maintain the large elk population.

After the end of the last ice age, post-glacial rebound caused the Earth's crust in eastern Fenno-Scandinavia to tilt, increasing the amount of water and size of the body of water that would later become Lake Saimaa. Approximately 6,000 years ago, the Salpausselkä ridge could no longer hold back the waters, which burst through and penetrated the glacial till and bedrock with incredible force. This created the Vuoksi River, and resulted in an approximately four-metre decrease in the water level of Lake Saimaa, revealing thousands of square kilometres of new land in Eastern Finland.

Run by University of Helsinki biologists, scientists and archaeologists together with the National Board of Antiquities, the Finnish Game and Fisheries Research Institute and the University of Bristol, the multidisciplinary research project has studied the role which the creation of the Vuoksi River played in the simultaneous spread of the most significant culture in our prehistory.

One of the basic principles of science is that the cause must come before the effect, emphasises Docent Markku Oinonen, who is the director of the Natural Sciences Unit of the Finnish Museum of Natural History, a University of Helsinki independent institute.

The research is based on probable sequences of events indicated by radiocarbon and Bayesian dating, which suggest that Vuoksi was created a few decades before the culture in the area changed. After the emergence of the river, the culture which used asbestos in its pottery disappeared and was replaced by an innovative culture which employed timber housing, flint and amber – as is typical of the Pit-Comb Ware culture.

Electron microscope analyses of the pottery together with stylistic differences of the pieces themselves and the eradication of the solidifying asbestos in the pottery indicate that distinct changes in pottery-making occurred.

The archaeological study of bones in the area reveals that the significance of elk as game was much greater in the emerging culture compared with the cultures that came before or after it. Another factor in the changes may have been the near-simultaneous spread of eastern spruce trees, which continue to be the dominant tree in the area.

We are beginning to understand how pioneer growth on the emerging land increased the elk population, which attracted people who had new ways of working and enabled the increase in the human population," Oinonen explains.

The spread of typical Pit-Comb Ware culture to the Saimaa region is related to the wider phenomenon of the Stone Age population maximum, i.e., the stage when the population in Finland was at its largest. The new culture was at its peak for a few centuries and regressed as the ecosystem became dominated by old-growth spruce forests which provided a less ideal elk habitat than the recently-emerged land.
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EurekAlert. 2014. “The creation of the Vuoksi River preceded a significant cultural shift”. EurekAlert. Posted: September 15, 2014. Available online: http://www.eurekalert.org/pub_releases/2014-09/uoh-tco091514.php

Saturday, October 25, 2014

Language evolution: Quicker on the uptake

The ability to acquire and creatively manipulate spoken language is unique to humans. "The genetic changes that occurred over the past 6 million years of human evolution to make this possible are largely unknown, but Foxp2 is the best candidate gene we now have," says Wolfgang Enard, Professor of Anthropology and Human Biology at LMU. In his efforts to understand the molecular biological basis of language Enard has now taken an important step forward. The results of his latest study, undertaken in collaboration with scientists at several universities, including the Massachusetts Institute of Technology in Cambridge and the Max Planck Institute for Evolutionary Anthropology, have recently appeared in the journal Proceedings of the National Academy of Sciences (PNAS).

The human homolog of Foxp2 codes for a protein – a so-called transcription factor – that regulates the activity of hundreds of genes expressed in various mammalian cell types. Individuals who carry only one functional copy of the gene instead of the usual two experience specific difficulties in learning to speak and in language comprehension. "Genetic mutations that occurred during the 6 million years since our lineage diverged from that of chimpanzees have resulted in localized alterations in two regions of the Foxp2 protein. That is quite striking when one considers that the normal mouse version differs from that found in chimps by only a single mutation, although these two species are separated by over 100 million years of evolution. The question is how the human variant of this transcription factor contributes to the process of language acquisition," says Enard.

Enard and his coworkers had previously shown that the alterations in the human gene for Foxp2 specifically affect certain regions of the brain. When the two human-specific substitutions were introduced into the mouse version of the gene, he and his team observed anatomical changes exclusively in two neuronal circuits in the basal ganglia of the mouse cortex, which are involved in the control of motor function. "These circuits play a crucial role in the acquisition of habitual behaviors and other cognitive and motor capabilities," Enard explains.

Conscious and unconscious learning processes

In their latest work with the same mouse model, Enard and his collaborators found that, under certain conditions, the human version of Foxp2 actually enhances learning. "We have shown for the first time that the evolved alterations in the human gene have an effect on learning ability. The human version modifies the balance between declarative and motor neuron circuits in the brain. As a result, the mice take less time to associate a given stimulus with the appropriate response, and hence learn more rapidly," says Enard.

Learning to speak clearly requires interactions between conscious "declarative" knowledge and the unconscious effects of repetitive stimulation of particular patterns of neural activity. "As we learn, the underlying neuronal processes become automated, they are converted into routine procedures, enabling us to learn faster," Enard explains. Using various tests, the researchers demonstrated that the human-specific mutations enhance cooperative interactions between the two affected circuits in the basal ganglia of the mouse brain. "The human variant of the Foxp2 gene modulates the associative and sensorimotor nerve connections formed, as well as levels of the neurotransmitter dopamine in the basal ganglia, during the learning process. The increased ability to switch between conscious and unconscious forms of learning may play a role in the acquisition of language," Enard concludes.

Foxp2 is the only gene so far that has been shown to be directly associated with the evolution of language, and studies of Foxp2 function promise to throw new light on the evolution of the human brain. The mutation that first revealed the link with language was discovered in a kindred, many of whose members displayed severe speech difficulties, primarily as a consequence of defective control of the muscles of the larynx, the lips and the face.
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EurekAlert. 2014. “Language evolution: Quicker on the uptake”. EurekAlert. Posted: September 18, 2014. Available online: http://www.eurekalert.org/pub_releases/2014-09/lm-leq091814.php

Friday, October 24, 2014

How Ancient DNA Is Rewriting Human History

There are no written records of the most important developments in our history: the transition from hunting and gathering to farming, the initial colonization of regions outside Africa, and, most crucially, the appearance of modern humans and the vanishing of archaic ones.

Our primary information sources about these “pre-historic” events are ancient tools, weapons, bones, and, more recently, DNA. Like an ancient text that has picked up interpolations over the millennia, our genetic history can be difficult to recover from the DNA of people alive today. But with the invention of methods to read DNA taken from ancient bones, we now have access to much older copies of our genetic history, and it’s radically changing how we understand our deep past. What seemed like an episode of Lost turns out to be much more like Game of Thrones: instead of a story of small, isolated groups that colonized distant new territory, human history is a story of ancient populations that migrated and mixed all over the world.

There is no question that most human evolutionary history took place in Africa. But by one million years ago—long before modern humans evolved—archaic human species were already living throughout Asia and Europe. By 30,000 years ago, the archaic humans had vanished, and modern humans had taken their place. How did that happen?

From the results of early DNA studies in the late 1980s and early ’90s, scientists argued that anatomically modern humans evolved in Africa, and then expanded into Asia, Oceania, and Europe, beginning about 60,000 years ago. The idea was that modern humans colonized the rest of the world in a succession of small founding groups—each one a tiny sampling of the total modern human gene pool. These small, isolated groups settled new territory and replaced the archaic humans that lived there. As a result, humans in different parts of the world today have their own distinctive DNA signature, consisting of the genetic quirks of their ancestors who first settled the area, as well as the genetic adaptations to the local environment that evolved later.

This view of human history, called the “serial founder effect model,” has big implications for our understanding of how we came to be who we are. Most importantly, under this model, genetic differences between geographically separated human populations reflect deep branchings in the human family tree, branches that go back tens of thousands of years. It also declares that people have evolutionary adaptations that are matched to their geographical area, such as lighter skin in Asians and Europeans or high altitude tolerance among Andeans and Tibetans. With a few exceptions, such as the genetic mixing after Europeans colonized the Americas, our geography reflects our deep ancestry.

Well, it’s time to scrap this picture of human history. Looking over the stunning new data generated in just the last five years, geneticists Joseph Pickrell at the New York Genome Center and David Reich at Harvard University argue that the genetic record of the first modern humans leaving Africa has long been “overwritten” by later developments. “It is now clear that the data contradict any model in which the genetic structure of the world today is approximately the same as it was immediately following the out-of-Africa expansion,” they write. Present-day geography of human genes is not a good guide to our ancestry.

Pickrell and Reich lay out the case for “a systematic reevaluation of human history” in light of the new genetic data collected with new technologies. Much of this new data comes from recent large-scale collections of human genomes, which provide a much more comprehensive picture of geographical patterns in the DNA of living human populations. But the truly revolutionary findings come from studies that look directly at ancient DNA. Instead of trying to reconstruct our ancient genetic record with only modern sources, scientists can now, in some cases, examine the original source itself. The Neanderthal genome, published in 2010, is the most famous case, but researchers have published many more ancient DNA studies since then. The results are clear: There are very few isolated branches of the human family tree. People in nearly every part of the world are a product of many different ancient populations, and sometimes surprisingly close relationships span a wide geographical distance.

One surprising finding, published in January, is that the traces of European DNA in contemporary Native Americans can’t all be chalked up to the arrival of Christopher Columbus. A team of scientists led by Eske Willerslev at the University of Copenhagen sequenced DNA taken from the bones of a boy who died 24,000 years ago in south-central Siberia. Their results show that this boy was from an ancient population that contributed to the ancestry of both Europeans and Native Americans. Other ancient DNA studies published within the past year include analyses of Stone Age hunter-gatherers and farmers from Scandinavia and Spain, a Bronze-age population from the Ukrainian steppes, and a 12,000-year-old Native American that lived in what is now Western Montana. The story coming out of these genetic studies is still developing, but one feature is clear. As Pickrell and Reich put it, “Human history is not one of stasis.” We can easily see this in written history, which tells why most African Americans and Latinos have a mixed ancestry. The genetic record shows that for the past tens of thousands of years, mixed human ancestry is the rule and not the exception. This finding has implications for the role of evolution in shaping who we are. Genetic adaptations that first evolved in one environment were sometimes brought to other parts of the world with very different environments. This means that we need to be wary about accepting overly simple stories about how present-day people in a particular region carry genes that have evolved to fit their particular niche—those evolved genes may be recent arrivals from somewhere else.

Reading deep human history from the record of our DNA is a tricky business, but it’s also a powerful way to answer some compelling questions about our past—a past that is more surprising and complex than we originally thought.
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White, Michael. 2014. “How Ancient DNA Is Rewriting Human History”. Pacific Standard Magazine. Posted: September 12, 2014. Available online: http://www.psmag.com/navigation/nature-and-technology/ancient-dna-rewriting-human-history-90578/