Ancient ancestor of humans with tiny brain discovered

Date:September 10, 2015

Source:University of Colorado Anschutz Medical Campus

Summary:Scientists have discovered a new species of hominin, a small creature with a tiny brain that opens the door to a new way of thinking about our ancient ancestors.

An international team of scientists, including one from the University of Colorado Denver and another from the University of Colorado Anschutz Medical Campus in Aurora, announced the discovery Thursday of a new species of hominin, a small creature with a tiny brain that opens the door to a new way of thinking about our ancient ancestors.

The discovery of 15 individuals, consisting of 1,550 bones, represents the largest fossil hominin find on the African continent.

“We found adults and children in the cave who are members of genus Homo but very different from modern humans,” said CU Denver Associate Professor of Anthropology Charles Musiba, PhD, who took part in a press conference Thursday near the discovery inside the Rising Star Cave in the Cradle of Humankind World Heritage Site outside Johannesburg, South Africa. “They are very petite and have the brain size of chimpanzees. The only thing similar we know of are the so-called `hobbits’ of Flores Island in Indonesia.”

Homofloresiensis or Flores Man was discovered in 2003. Like this latest finding, it stood 3.5 five feet high and seems to have existed relatively recently though the exact age is unknown.

Caley Orr, PhD, an assistant professor of cell and developmental biology at the University of Colorado School of Medicine, analyzed the fossil hands.

“The hand has human-like features for manipulation of objects and curved fingers that are well adapted for climbing,” Orr said. “But its exact position on our family tree is still unknown.”

The new species has been dubbed Homo naledi after the cave where it was found — naledi means `star’ in the local South African language Sesotho.

One of the most intriguing aspects of the discovery is that the bodies appear to have been deposited in the cave intentionally. Scientists have long believed this sort of ritualized or repeated behavior was limited to humans.

The team of 35 to 40 scientists was led by Lee Berger, research professor in the Evolutionary Studies Institute at the University of Witwatersrand in South Africa. It was supported by the National Geographic Society and the National Research Foundation. The October issue of National Geographic magazine will feature the discovery as its cover story. It will also be the subject of a NOVA/National Geographic Special airing Sept. 16.

Getting inside the Dinaledi chamber of the remote cave system was difficult, requiring the help of six `underground astronauts,’ who squeezed through a 7-inch wide gap to reach the remains.

“The chamber has not given up all of its secrets,” said Berger, a National Geographic Explorer-in-Residence. “There are potentially hundreds if not thousands of remains of H. naledi still down there.”

The announcement coincides with the publication of two studies about the new species in the journal eLife, co-authored by Musiba and Orr.

In it, the researchers try to place Homonaledi in context with other species. Generally speaking, they say, there is an assumption that any new group of fossils must belong to an existing species.

But it’s not that simple here.

“Assigning these remains to any known species of Homo is problematic,” the study said. “While Homo(naledi) shares aspects of cranial and mandibular morphology with Homohabilis, Homorudolfensis, Homoerectus, MP Homo and Homosapiens, it differs from all of these taxa in its unique combination of derived cranial vault, maxillary, and mandibular morphology.”

The study suggests that Homonaledi most closely resembles Homoerectus with its small brain and body size. Yet it also resembles Australopithecus which highlights its own uniqueness.

Complicating matters is the fact that researchers still don’t know the exact age of the fossil site.

“If these fossils are late Pliocene or early Pleistocene, it is possible that this new species of small-brained, early Homorepresents an intermediate between Australopithecus and Homoerectus,” the study said.

That would also make the new species very old.

But if the fossils are more recent, they theorize, it raises the possibility that a small-brained Homolived in southern Africa at the same time as larger brained Homospecies were evolving.

“This raises many questions,” Musiba said. “How many species of human were there? Were their lines that simply extended outward and then disappeared? Did they co-exist with modern humans? Did they interbreed?”

Homonaledi has a chest similar to a chimpanzee and hands and feet proportionate with modern humans, though with curved fingers.

“They would have had great climbing ability,” said Musiba. “The oldest adults were about 45 and the youngest were infants.”

He described poring over the bones late at night as akin to `hitting the jackpot.’

“You just didn’t want to go home because it was so exciting,” he said. “I felt like a kid in a candy store.” The find represents another milestone in Musiba’s efforts to advance the understanding of our earliest human relatives.

As director of CU Denver’s Tanzania Field School, he takes groups of students each year to gain hands-on experience working in and around the famed Laetoli hominin footprints site and Olduvai Gorge where some of the oldest hominin remains have been found.

Not long ago, they discovered ancient footprints of lions, rhinos and antelopes near those of the early hominins.

And last year, Musiba was appointed to an international team of advisors dedicated to building a museum complex in Tanzania to showcase a collection of 70 hominin footprints, estimated at 3.6 million years old. They are considered the earliest example of bipedalism among hominins.

Musiba said the Rising Star expedition was notable for getting so many anthropologists to work together.

“Anthropology can be a cut-throat profession with all these scientists scrambling for limited resources,” he said. “To me one of the most exciting aspects of this research was the collaborative nature of it.”


Story Source:

The above post is reprinted from materials provided by University of Colorado Anschutz Medical Campus. The original item was written by David Kelly. Note: Materials may be edited for content and length.


Journal Reference:

  1. Paul HGM Dirks, Lee R Berger, Eric M Roberts, Jan D Kramers, John Hawks, Patrick S Randolph-Quinney, Marina Elliott, Charles M Musiba, Steven E Churchill, Darryl J de Ruiter, Peter Schmid, Lucinda R Backwell, Georgy A Belyanin, Pedro Boshoff, K Lindsay Hunter, Elen M Feuerriegel, Alia Gurtov, James du G Harrison, Rick Hunter, Ashley Kruger, Hannah Morris, Tebogo V Makhubela, Becca Peixotto, Steven Tucker. Geological and taphonomic context for the new hominin speciesHomo naledifrom the Dinaledi Chamber, South Africa. eLife, 2015; 4 DOI: 10.7554/eLife.09561
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How childhood stress can affect female fertility

Date:September 10, 2015

Source:Taylor & Francis

Summary:Can events you endured as a child really impact your ability to have children yourself? New research examines the mechanism by which adverse experiences in childhood impact female fertility. Researchers explore the hypothesis that negative experiences in childhood can result in menstrual cycle irregularities, which consequently impact fertility. They relate their hypothesis to life-history theory, which talks of balancing the preservation of one’s health and the production of offspring that will survive to reproduce themselves.

Can events you endured as a child really impact your ability to have children yourself? New research in the Journal of Psychosomatic Obstetrics & Gynecology examines the mechanism by which adverse experiences in childhood impact female fertility. In their paper ‘Adverse childhood event experiences, fertility difficulties and menstrual cycle characteristics’, Marni B. Jacobs et al. explore the hypothesis that negative experiences in childhood can result in menstrual cycle irregularities, which consequently impact fertility. They relate their hypothesis to life-history theory, which talks of balancing the preservation of one’s health and the production of offspring that will survive to reproduce themselves, and theorize that “early life stressors may predispose an individual to adaptively suppress fertility when situations are less than optimal, leading to periods of fertility difficulties even following previous births.”

The study examined data from 774 women of reproductive age, 195 of whom were pregnant. It analysed fertility difficulties, menstrual cycle irregularities and adverse childhood experiences, through a mixture of in-person interviews and take-home questionnaires.

Following their research, the team came to the conclusion that those women who had experienced negative events at a young age — such as “abuse, neglect, household dysfunction or parental substance abuse” — were more likely to have faced fertility difficulties and abnormal absences of menstruation lasting three months or more, and also took a longer time to get pregnant. Their research also suggests that certain harmful events in childhood can potentially have a greater impact on fertility than others.


Story Source:

The above post is reprinted from materials provided by Taylor & Francis. Note: Materials may be edited for content and length.


Journal Reference:

  1. Marni B. Jacobs, Renee D. Boynton-Jarrett, Emily W. Harville. Adverse childhood event experiences, fertility difficulties and menstrual cycle characteristics. Journal of Psychosomatic Obstetrics & Gynecology, 2015; 36 (2): 46 DOI: 10.3109/0167482X.2015.1026892

When it comes to touch, to give is to receive

Date:September 10, 2015

Source:Cell Press

Summary:Have you ever touched someone else and wondered why his or her skin felt so incredibly soft? Well, now researchers present evidence that this experience may often be an illusion.

Have you ever touched someone else and wondered why his or her skin felt so incredibly soft? Well, now researchers reporting in the Cell Press journal Current Biology on September 10 present evidence that this experience may often be an illusion.

In a series of studies led by Aikaterini Fotopoulou of the University College London, participants consistently rated the skin of another person as being softer than their own, whether or not it really was softer. The researchers suggest that this phenomenon may exist to ensure that humans are motivated to build social bonds through touch.

“What is intriguing about the illusion is its specificity,” says Antje Gentsch, also of the University College London. “We found the illusion to be strongest when the stroking was applied intentionally and according to the optimal properties of the specialized system in the skin for receiving affective touch.”

This system typically responds to slow, gentle stroking found in intimate relationships and encodes the pleasure of touch, Gentsch explains. In other words, this “social softness illusion” in the mind of the touch-giver is selective to the body parts and the stroking speeds that are most likely to elicit pleasure in the receiver.

“The illusion reveals a largely automatic and unconscious mechanism by which ‘giving pleasure is receiving pleasure’ in the touch domain,” Fotopoulou says.

In fact, social touch plays a powerful role in human life, from infancy to old age, with beneficial effects on physical and mental health. Many studies have focused on the benefits of touch for the person receiving it. For instance, premature infants benefit greatly from time spent in direct physical contact with their mothers. Yet, Fotopoulou and her colleagues say, remarkably little is known about the psychological benefits of actively touching others.

Earlier studies showed that softness and smoothness stimulate parts of the brain associated with emotion and reward. Therefore, this “illusion” that other people are softer ensures that reaching out and touching another person comes as its own reward.

This rewarding illusion acts as a kind of “social glue,” bonding people to each other. For example, touching a baby in a gentle manner seems to give the mother tactile pleasure, the researchers say, over and above any other thoughts or feelings the mother may have in the moment.

Fotopoulou says the next step is to examine the neurophysiological mechanisms involved in giving affective touch. They are also curious to examine any differences that may exist in the experience of this softness illusion among partners, friends, and strangers.


Story Source:

The above post is reprinted from materials provided by Cell Press. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gentsch et al. Active Interpersonal Touch Gives Rise to the Social Softness Illusion. Current Biology, September 2015 DOI: 10.1016/j.cub.2015.07.049

Scientists home in on origin of human, chimpanzee facial differences

Date: September 10, 2015

Source: Stanford University Medical Center

Summary: A study of species-specific regulation of gene expression in chimps and humans has identified regions important in human facial development and variation.

The face of a chimpanzee is decidedly different from that of a human, despite the fact that the apes are our nearest relative in the primate tree. Now researchers at the Stanford University School of Medicine have begun to pinpoint how those structural differences could arise in two species with nearly identical genetic backgrounds.

The key lies in how genes involved in facial development and human facial diversity are regulated — how much, when and where the genes are expressed– rather than dissimilarities among the genes themselves. In particular, the researchers found that chimps and humans express different levels of proteins known to control facial development, including some involved in jaw and nose length and skin pigmentation.

“We are trying to understand the regulatory changes in our DNA that occurred during recent evolution and make us different from the great apes,” said Joanna Wysocka, PhD, associate professor of developmental biology and of chemical and systems biology. “In particular, we are interested in craniofacial structures, which have undergone a number of adaptations in head shape, eye placement and facial structure that allow us to house larger brains, walk upright and even use our larynx for complex speech.”

The researchers coined the term “cellular anthropology” to explain how some steps of early primate development can be mimicked in a dish, and thus used to study gene-expression changes that can shed light on our recent evolutionary past.

A study describing the research will be published online Sept. 10 in Cell. Graduate student Sara Prescott is the lead author. Wysocka and senior research scientist Tomasz Swigut, PhD, share senior authorship of the study.

The role of enhancer regions

For their comparison, the researchers focused on areas of DNA known as enhancer regions in human and chimpanzee genomes. These regions contain chemical tags and proteins bound to the DNA that control when, where and how nearby genes are expressed. Prescott and her colleagues wondered whether differences in the way proteins bind to these enhancer regions during development could explain morphological differences between humans and chimpanzees.

“We wanted to look at how the activity of these enhancer regions may have changed during recent evolution,” said Wysocka. “Many recent studies have shown that changes in the DNA sequences of enhancers may mediate morphological differences among species.”

To conduct the study, however, Prescott and her colleagues had to obtain a specialized type of cell present only in very early primate development. The cells, called cranial neural crest cells, originate in humans within about five to six weeks after conception. Although they first appear along what eventually becomes the spinal cord, the neural crest cells then migrate over time to affect facial morphology and differentiate into bone, cartilage and connective tissue of the head, and face.

“These cells are unique,” said Prescott. “If we want to understand what makes human and chimp faces different, we have to look to the source — to the cell types responsible for making these early patterning decisions. If we were to look later in development or in adult tissues, we would see differences between the species but they will tell us little about how those differences were created during embryogenesis. But accessing early cell types like neural crest cells can be quite difficult, especially when studying primates.”

To obtain this elusive cell type, the researchers used induced pluripotent stem cells, or iPS cells, made from chimpanzees. IPS cells, which are made from easy-to-obtain skin or blood samples, can be coaxed to become other tissues. Although iPS cells from humans have been well-studied, they’ve only recently been made from chimpanzees in the laboratory of Fred Gage, PhD, a professor of genetics at the Salk Institute for Biological Studies and a co-author of the study.

Prescott and her colleagues coaxed human and chimpanzee iPS cells to become cranial neural crest cells by growing them in the laboratory under a specific set of conditions. They then examined enhancer regions throughout the genome, looking for those that were not just active and therefore likely to be involved in craniofacial development, but also those whose patterns or degrees of activity seemed to vary between human and chimpanzee cells.

“Of course, humans and chimps are very closely related,” said Wysocka. “Most of the regulatory elements are the same between the two species. But we did find some differences. In particular, we found about 1,000 enhancer regions that are what we termed species-biased, meaning they are more active in one species or the other. Interestingly, many of the genes with species-biased enhancers and expression have been previously shown to be important in craniofacial development or associated with normal intrahuman facial variation.”

Snout length, shape and pigmentation

In particular, the researchers found that two genes, PAX3 and PAX7, known to affect snout length and shape in laboratory mice, as well as skin pigmentation, were expressed at higher levels in chimpanzees than in humans. Humans with less than the normal amount of PAX3 have a condition called Waardenburg syndrome, which includes craniofacial, auditory and pigmentation defects. Genomewide association studies in humans have identified PAX3 as a region involved in normal facial variation.

In contrast, another gene known to be involved in determining the shape of the beaks of finches and the jaw of a fish called a cichlid was expressed at higher levels in humans than in chimpanzees. In mice, overexpression of this gene, BMP4, in cranial neural crest cells causes a marked change in face shape, including a rounding of the skull and eyes that are more near the front of the face.

“We are now following up on some of these more interesting species-biased enhancers to better understand how they impact morphological differences,” said Wysocka. “It’s becoming clear that these cellular pathways can be used in many ways to affect facial shape.”

Another Stanford-affiliated author of the study is research assistant Rajini Srinivasan.

The research was supported by the National Institutes of Health (grants R01GMO095555 and U01DE024430), the California Institute for Regenerative Medicine, the W.M. Keck Foundation and the Innovation Fund.


Story Source:

The above post is reprinted from materials provided by Stanford University Medical Center. The original item was written by Krista Conger. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sara L. Prescott, Rajini Srinivasan, Maria Carolina Marchetto, Irina Grishina, Iñigo Narvaiza, Licia Selleri, Fred H. Gage, Tomek Swigut, Joanna Wysocka. Enhancer Divergence and cis-Regulatory Evolution in the Human and Chimp Neural Crest. Cell, 2015 DOI: 10.1016/j.cell.2015.08.036

People worldwide — even nomads in Tanzania — think of colors the same way

Assigning names to colors combines nature, nurture

Date:
September 10, 2015
Source:
Ohio State University
Summary:
Would a color by any other name be thought of in the same way, regardless of the language used to describe it? According to new research, the answer is yes.

A new study examines how a culture of nomadic hunter-gatherers names colors, and shows that they group colors into categories that align with patterns of color grouping evident in 110 other world languages.

This study population — the Hadza people of Tanzania — has relatively few commonly shared color words in its language. During the study, the most common response by Hadza participants to a request to name a color was “Don’t know.”

However, the way the participants grouped the colors they did name — regardless of what name they used — tended to match color-naming conventions of Somali-speaking immigrants and native English speakers, and of many other cultures around the world.

“Looking at the Hadza data, we see a relatively modern color vocabulary emerging, but the color terms are distributed across the entire population,” said Delwin Lindsey, professor of psychology at The Ohio State University Mansfield Campus and lead author of the study. “We captured a point in time culturally where the stuff for creating a complex color naming exists, but it’s not in the head of any one individual. It’s distributed in bits and pieces across the culture.”

Scientists know a lot about how the human brain responds to seeing color — and that universality of perception makes color naming a good model for studying patterns in language change.

“This study provides a very useful framework for thinking about how the terms that are used to describe things in our environment actually emerge and evolve,” Lindsey said. “You can think of the words as species that are evolving — they are competing for space in our heads. So this is an example of cultural evolution that closely mirrors biological evolution.”

The research is published in the journal Current Biology.

Lindsey said the finding suggests that color naming is not a matter of nature versus nurture, but a combination of the two. The result also suggests that both prevailing theories about color naming apply around the world: Cultures create color names, but individuals from vastly different societies (Hadza, Somali and American) share the same perceptions of colors in their mind.

“Clearly, there are certain constraints within the mind that guide how colors are going to be grouped together,” said Lindsey, also a professor of optometry on Ohio State’s Columbus campus. “But this illustrates an interesting trade-off between culture and biology as determinants of human thought. There are cultural universals, but within each culture there is dramatic diversity. If the culture were playing the preeminent role, members of a society would establish conventions that they all agree on. But they’re clearly not all agreeing on anything.”

How does it play out in English? One person’s lilac shirt is called lavender by her neighbor.

Lindsey and collaborator Angela Brown, professor of optometry at Ohio State, reported in 2006 on their analysis of data of the World Color Survey, a collection of color names obtained by University of California, Berkeley researcher Paul Kay and associates from 2,616 people of 110 languages spoken by mostly preindustrial societies.

That analysis confirmed that, across cultures, people tend to classify hundreds of different chromatic colors into only eight distinct categories: red, green, yellow-or-orange, blue, purple, brown, pink and grue (green or blue).

In 2009, Lindsey and Brown published a second paper describing further analysis of the World Color Survey, in which they showed that four common, distinct groupings of color categories, which they called “motifs,” occur worldwide: black, white and red; black, white, red and gray; black, white, red and a single cool green or blue category; and black, white, red, green, blue and yellow. A surprising result was that the motifs observed within a society are nearly as diverse as those observed across cultures.

“We found that these motifs occurred with minor variations across 110 languages,” Brown said. “A person from Cameroon, Africa, can name colors more similarly to somebody from Northwestern Australia than to his Cameroon neighbor. And that Cameroon neighbor might be more similar to a different person in Northwestern Australia.”

Larger color vocabularies are generally associated in more technologically advanced societies.

“To try to get at how these motifs might emerge, we wanted to go as far back technologically as we could. That’s where the hunter-gatherers fit in,” Lindsey said.

He and Brown collaborated with co-corresponding author Coren Apicella and her colleague David Brainard, both on the psychology faculty at the University of Pennsylvania, to survey the Hadza people. Apicella has been working with the Hadza people for more than a decade.


Story Source:

The above post is reprinted from materials provided by Ohio State University. The original item was written by Emily Caldwell. Note: Materials may be edited for content and length.


Journal Reference:

  1. Delwin T. Lindsey et al. Hunter-Gatherer Color Naming Provides New Insight into the Evolution of Color Terms. Current Biology, September 2015 DOI: 10.1016/j.cub.2015.08.006