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Human - Homo sapiens
#16
Scientists discover oldest known modern human fossil outside of Africa
Analysis of fossil suggests Homo sapiens left Africa at least 50,000 years earlier than previously thought


Date: January 25, 2018
Source: Binghamton University

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This is the left hemi-maxilla with teeth.
Credit: Rolf Quam

A large international research team, led by Israel Hershkovitz from Tel Aviv University and including Rolf Quam from Binghamton University, State University of New York, has discovered the earliest modern human fossil ever found outside of Africa. The finding suggests that modern humans left the continent at least 50,000 years earlier than previously thought.

"Misliya is an exciting discovery," says Rolf Quam, Binghamton University anthropology professor and a coauthor of the study. "It provides the clearest evidence yet that our ancestors first migrated out of Africa much earlier than we previously believed. It also means that modern humans were potentially meeting and interacting during a longer period of time with other archaic human groups, providing more opportunity for cultural and biological exchanges."

The fossil, an upper jawbone with several teeth, was found at a site called Misliya Cave in Israel, one of several prehistoric cave sites located on Mount Carmel. Several dating techniques applied to archaeological materials and the fossil itself suggest the jawbone is between 175,000-200,000 years old, pushing back the modern human migration out of Africa by at least 50,000 years.

Researchers analyzed the fossil remains relying on microCT scans and 3D virtual models and compared it with other hominin fossils from Africa, Europe and Asia.

"While all of the anatomical details in the Misliya fossil are fully consistent with modern humans, some features are also found in Neandertals and other human groups," said Quam, associate professor of anthropology at Binghamton. "One of the challenges in this study was identifying features in Misliya that are found only in modern humans. These are the features that provide the clearest signal of what species the Misliya fossil represents."

The archaeological evidence reveals that the inhabitants of Misliya Cave were capable hunters of large game species, controlled the production of fire and were associated with an Early Middle Paleolithic stone tool kit, similar to that found with the earliest modern humans in Africa.

While older fossils of modern humans have been found in Africa, the timing and routes of modern human migration out of Africa are key issues for understanding the evolution of our own species, said the researchers. The region of the Middle East represents a major corridor for hominin migrations during the Pleistocene and has been occupied at different times by both modern humans and Neandertals.

This new discovery opens the door to demographic replacement or genetic admixture with local populations earlier than previously thought, said Quam. Indeed, the evidence from Misliya is consistent with recent suggestions based on ancient DNA for an earlier migration, prior to 220,000 years ago, of modern humans out of Africa. Several recent archaeological and fossil discoveries in Asia are also pushing back the first appearance of modern humans in the region and, by implication, the migration out of Africa.

Story Source: Binghamton University. "Scientists discover oldest known modern human fossil outside of Africa: Analysis of fossil suggests Homo sapiens left Africa at least 50,000 years earlier than previously thought." ScienceDaily. www.sciencedaily.com/releases/2018/01/180125140923.htm (accessed January 26, 2018).




Journal Reference:
Israel Hershkovitz, Gerhard W. Weber, Rolf Quam, Mathieu Duval, Rainer Grün, Leslie Kinsley, Avner Ayalon, Miryam Bar-Matthews, Helene Valladas, Norbert Mercier, Juan Luis Arsuaga, María Martinón-Torres, José María Bermúdez de Castro, Cinzia Fornai, Laura Martín-Francés, Rachel Sarig, Hila May, Viktoria A. Krenn, Viviane Slon, Laura Rodríguez, Rebeca García, Carlos Lorenzo, Jose Miguel Carretero, Amos Frumkin, Ruth Shahack-Gross, Daniella E. Bar-Yosef Mayer, Yaming Cui, Xinzhi Wu, Natan Peled, Iris Groman-Yaroslavski, Lior Weissbrod, Reuven Yeshurun, Alexander Tsatskin, Yossi Zaidner, Mina Weinstein-Evron. The earliest modern humans outside Africa. Science, 26 Jan 2018 456-459 DOI: 10.1126/science.aap8369

Abstract
To date, the earliest modern human fossils found outside of Africa are dated to around 90,000 to 120,000 years ago at the Levantine sites of Skhul and Qafzeh. A maxilla and associated dentition recently discovered at Misliya Cave, Israel, was dated to 177,000 to 194,000 years ago, suggesting that members of the Homo sapiens clade left Africa earlier than previously thought. This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of Homo sapiens around 220,000 years ago. The Misliya maxilla is associated with full-fledged Levallois technology in the Levant, suggesting that the emergence of this technology is linked to the appearance of Homo sapiens in the region, as has been documented in Africa.

http://science.sciencemag.org/content/359/6374/456
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#17
Homo sapiens developed a new ecological niche that separated it from other hominins


July 30, 2018, Max Planck Society

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Map of the potential distribution of archaic hominins, including H. erectus, H. floresiensis, H. neanderthalenesis, Denisovans and archaic African hominins, in the Old World at the time of the evolution and dispersal of H. sapiens between approximately 300 and 60 thousand years ago. Credit: Roberts and Stewart. 2018. Defining the 'generalist specialist' niche for Pleistocene Homo sapiens. Nature Human Behaviour. 10.1038/s41562-018-0394-4

Critical review of growing archaeological and palaeoenvironmental datasets relating to the Middle and Late Pleistocene (300-12 thousand years ago) hominin dispersals within and beyond Africa, published today in Nature Human Behaviour, demonstrates unique environmental settings and adaptations for Homo sapiens relative to previous and coexisting hominins such as Homo neanderthalensis and Homo erectus. Our species' ability to occupy diverse and 'extreme' settings around the world stands in stark contrast to the ecological adaptations of other hominin taxa, and may explain how our species became the last surviving hominin on the planet.

The paper, by scientists from the Max Planck Institute for the Science of Human History and the University of Michigan suggests investigations into what it means to be human should shift from attempts to uncover the earliest material traces of 'art', 'language', or technological 'complexity' towards understanding what makes our species ecologically unique. In contrast to our ancestors and contemporary relatives, our species not only colonized a diversity of challenging environments, including deserts, tropical rainforests, high altitude settings, and the palaeoarctic, but also specialized in its adaptation to some of these extremes.

Ancestral ecologies—the ecology of Early and Middle Pleistocene Homo

Although all hominins that make up the genus Homo are often termed 'human' in academic and public circles, this evolutionary group, which emerged in Africa around 3 million years ago, is highly diverse. Some members of the genus Homo (namely Homo erectus) had made it to Spain, Georgia, China, and Indonesia by 1 million years ago. Yet, existing information from fossil animals, ancient plants, and chemical methods all suggest that these groups followed and exploited environmental mosaics of forest and grassland. It has been argued that Homo erectus and the 'Hobbit', or Homo floresiensis, used humid, resource-scarce tropical rainforest habitats in Southeast Asia from 1 million years ago to 100,000 and 50,000 years ago, respectively. However, the authors found no reliable evidence for this.

It has also been argued that our closest hominin relatives, Homo neanderthalensis - or the Neanderthals—were specialized to the occupation of high latitude Eurasia between 250,000 and 40,000 years ago. The base for this includes a face shape potentially adapted to cold temperatures and a hunting focus on large animals such as woolly mammoths. Nevertheless, a review of the evidence led the authors to again conclude that Neanderthals primarily exploited a diversity of forest and grassland habitats, and hunted a diversity of animas, from temperature northern Eurasia to the Mediterranean.

Deserts, rainforests, mountains, and the arctic

In contrast to these other members of the genus Homo, our species - Homo sapiens - had expanded to higher-elevation niches than its hominin predecessors and contemporaries by 80-50,000 years ago, and by at least 45,000 years ago was rapidly colonizing a range of palaeoarctic settings and tropical rainforest conditions across Asia, Melanesia, and the Americas. Furthermore, the authors argue that the continued accumulation of better-dated, higher resolution environmental datasets associated with our species' crossing the deserts of northern Africa, the Arabian Peninsula, and northwest India, as well as the high elevations of Tibet and the Andes, will further help to determine the degree to which our species demonstrated novel colonizing capacities in entering these regions.

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Map showing the youngest suggested dates of persistent occupation of the different environmental extremes discussed by our species based on current evidence. Credit: Maps from NASA Worldview. In Roberts and Stewart. 2018. Defining the 'generalist specialist' niche for Pleistocene Homo sapiens. Nature Human Behaviour. 10.1038/s41562-018-0394-4

Finding the origins of this ecological 'plasticity', or the ability to occupy a number of very different environments, currently remains difficult in Africa, particularly back towards the evolutionary origins of Homo sapiens 300-200,000 years ago. However, the authors argue that there are tantalizing hints for novel environmental contexts of human habitation and associated technological shifts across Africa just after this timeframe. They hypothesize that the drivers of these changes will become more apparent with future work, especially that which tightly integrates archaeological evidence with highly resolved local palaeoecological data. For example, lead author of the paper, Dr. Patrick Roberts, suggests, "although a focus on finding new fossils or genetic characterization of our species and its ancestors has helped rough out the broad timing and location of hominin specifications, such efforts are largely silent on the various environmental contexts of biocultural selection".

The 'generalist specialist' - a very sapiens niche

One of the main new claims of the authors is that the evidence for human occupation of a huge diversity of environmental settings across the majority of the Earth's continents by the Late Pleistocene hints at a new ecological niche, that of the 'generalist specialist'. As Roberts states "A traditional ecological dichotomy exists between 'generalists', who can make use of a variety of different resources and inhabit a variety of environmental conditions, and 'specialists', who have a limited diet and narrow environmental tolerance. However, Homo sapiens furnish evidence for 'specialist' populations, such as mountain rainforest foragers or palaeoarctic mammoth hunters, existing within what is traditionally defined as a 'generalist' species".

This ecological ability may have been aided by extensive cooperation between non-kin individuals among Pleistocene Homo sapiens, argues Dr. Brian Stewart, co-author of the study. "Non-kin food sharing, long-distance exchange, and ritual relationships would have allowed populations to 'reflexively' adapt to local climatic and environmental fluctuations, and outcompete and replace other hominin species." In essence, accumulating, drawing from, and passing down a large pool of cumulative cultural knowledge, in material or idea form, may have been crucial in the creation and maintenance of the generalist-specialist niche by our species in the Pleistocene.

Implications for our pursuit of ancient humanity

The authors are clear that this proposition remains hypothetical and could be disproven by evidence for the use of 'extreme' environments by other members of the genus Homo. However, testing the 'generalist specialist' niche in our species encourages research in more extreme environments that have previously been neglected as unpromising for palaeoanthropological and archaeological work, including the Gobi Desert and Amazon rainforest. The expansion of such research is particularly important in Africa, the evolutionary cradle of Homo sapiens, where more detailed archaeological and environmental records dating back to 300-200,000 years ago are becoming increasingly crucial if we are to track the ecological abilities of the earliest humans.

It is also clear that growing evidence for hominin interbreeding and a complex anatomical and behavioural origin of our species in Africa highlights that archaeologists and palaeoanthropologists should focus on looking at the environmental associations of fossils. "While we often get excited by the discovery of new fossils or genomes, perhaps we need to think about the behavioural implications of these discoveries in more detail, and pay more attention to what these new finds tell us about new the passing of ecological thresholds" says Stewart. Work focusing on how the genetics of different hominins may have led to ecological and physical benefits such as high-altitude capacities or UV tolerance remain highly fruitful ways forward in this regard.

"As with other definitions of human origins, problems of preservation also make it difficult to pinpoint the origins of humans as an ecological pioneer. However, an ecological perspective on the origins and nature of our species potentially illuminates the unique path of Homo sapiens as it rapidly came to dominate the Earth's diverse continents and environments", concludes Roberts. The testing of this hypothesis should open up new avenues for research and, if correct, new perspectives as to whether the 'generalist specialist' will continue to be an adaptive success in the face of growing issues of sustainability and environmental conflict.

https://phys.org/news/2018-07-homo-sapiens-ecological-niche-hominins.html




Journal References:
Patrick Roberts et al, Defining the 'generalist specialist' niche for Pleistocene Homo sapiens, Nature Human Behaviour (2018). DOI: 10.1038/s41562-018-0394-4

Abstract
Definitions of our species as unique within the hominin clade have tended to focus on differences in capacities for symbolism, language, social networking, technological competence and cognitive development. More recently, however, attention has been turned towards humans’ unique ecological plasticity. Here, we critically review the growing archaeological and palaeoenvironmental datasets relating to the Middle–Late Pleistocene (300–12 thousand years ago) dispersal of our species within and beyond Africa. We argue, based on comparison with the available information for other members of the genus Homo, that our species developed a new ecological niche, that of the ‘generalist specialist’. Not only did it occupy and utilize a diversity of environments, but it also specialized in its adaptation to some of these environmental extremes. Understanding this ecological niche provides a framework for discussing what it means to be human and how our species became the last surviving hominin on the planet.

https://www.nature.com/articles/s41562-018-0394-4 
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#18
Gender differences in strength and muscle fiber characteristics.

Abstract
Strength and muscle characteristics were examined in biceps brachii and vastus lateralis of eight men and eight women. Measurements included motor unit number, size and activation and voluntary strength of the elbow flexors and knee extensors. Fiber areas and type were determined from needle biopsies and muscle areas by computerized tomographical scanning. The women were approximately 52% and 66% as strong as the men in the upper and lower body respectively. The men were also stronger relative to lean body mass. A significant correlation was found between strength and muscle cross-sectional area (CSA; P < or = 0.05). The women had 45, 41, 30 and 25% smaller muscle CSAs for the biceps brachii, total elbow flexors, vastus lateralis and total knee extensors respectively. The men had significantly larger type I fiber areas (4597 vs 3483 microns2) and mean fiber areas (6632 vs 3963 microns2) than the women in biceps brachii and significantly larger type II fiber areas (7700 vs 4040 microns2) and mean fiber areas (7070 vs 4290 microns2) in vastus lateralis. No significant gender difference was found in the strength to CSA ratio for elbow flexion or knee extension, in biceps fiber number (180,620 in men vs 156,872 in women), muscle area to fiber area ratio in the vastus lateralis 451,468 vs 465,007) or any motor unit characteristics. Data suggest that the greater strength of the men was due primarily to larger fibers. The greater gender difference in upper body strength can probably be attributed to the fact that women tend to have a lower proportion of their lean tissue distributed in the upper body.(ABSTRACT TRUNCATED AT 250 WORDS).

https://www.ncbi.nlm.nih.gov/pubmed/8477683
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#19
Direct estimation of mutations in great apes reconciles phylogenetic dating

Abstract

The human mutation rate per generation estimated from trio sequencing has revealed an almost linear relationship with the age of the father and the age of the mother, with fathers contributing about three times as many mutations per year as mothers. The yearly trio-based mutation rate estimate of around 0.43 × 10−9 is markedly lower than previous indirect estimates of about 1 × 10−9 per year from phylogenetic comparisons of the great apes calibrated by fossil evidence. This suggests either a slowdown in the accumulation of mutations per year in the human lineage over the past 10 million years or an inaccurate interpretation of the fossil record. Here we inferred de novo mutations in chimpanzee, gorilla, and orangutan parent-offspring trios. Extrapolating the relationship between the mutation rate and the age of parents from humans to these other great apes, we estimated that each species has higher mutation rates per year by factors of 1.50 ± 0.10, 1.51 ± 0.23, and 1.42 ± 0.22 for chimpanzee, gorilla, and orangutan, respectively, and by a factor of 1.48 ± 0.08 for the three species combined. These estimates suggest an appreciable slowdown in the yearly mutation rate in the human lineage that is likely to be recent as genome comparisons almost adhere to a molecular clock. If the nonhuman rates rather than the human rate are extrapolated over the phylogeny of the great apes, we estimate divergence and speciation times that are much more in line with the fossil record and the biogeography.

https://www.nature.com/articles/s41559-018-0778-x

Something Strange Is Happening To Human Evolution, And We're Not Sure Why

According to research recently published in Nature Ecology and Evolution, humans today are mutating at a slower pace than our ancestors – and other species of primates. Not only does this mean we're unlikely to develop any X-men-style superpowers anytime soon, it straightens out a few inconsistencies in the evolutionary timeline.

Science has a fairly good understanding of human mutation rates but research into mutation rates in other primates has been lacking. And so experts at Aarhus University, Denmark, and Copenhagen Zoo have attempted to rectify the situation by whole-genome sequencing ape families – seven chimp families, two gorilla families, and one orangutan family.

"Over the past six years, several large studies have done this for humans, so we have extensive knowledge about the number of new mutations that occur in humans every year," Søren Besenbacher from Aarhus University said in a statement.

"Until now, however, there have not been any good estimates of mutation rates in our closest primate relatives."

The result – the human annual mutation rate is about one-third lower than the mutation rates of other apes. The researchers are not entirely sure what caused this slowdown but suspect it could have something to do with changes in our environment or that it may relate to our later puberty and longer generational timespans.

Whatever the reason, it has important implications when it comes to our evolutionary timeline, specifically when we split away from the other great apes.

In the past, estimates based on mutation rates have been inconsistent with the fossil record. For example, based on human mutation rates alone, scientists put the point of divergence between humans and orangutans at 35 million years ago. The physical evidence, however, suggests this split occurred 20 million years ago at the very earliest.

But apply these new mutation rates and the team at Aarhus estimate the divergence between humans and orangutans materialized approximately 15.9 million years ago, while the divergence between humans and gorillas happened some 9.1 million years ago. They also estimate the separation between humans and chimpanzees took place roughly 6.6 million years ago, rather than the 10 million years you end up with if you apply human mutation rates only.

The more ape genomes are sequenced, the surer we can be of the predictions. Still, in summary, the research pushes all speciation rates closer to the present. And that doesn't only apply to living primates but to our extinct hominid relatives, like the Neanderthals, too.

"The times of speciation we can now calculate on the basis of the new rate fit in much better with the speciation times we would expect from the dated fossils of human ancestors that we know of," Mikkel Heide Schierup from Aarhus University added.

There are also practical implications. Experts at Copenhagen Zoo say it could help conservation efforts directed at the great apes.

"All species of great apes are endangered in the wild," said Christina Hvilsom, who works in research and conservation at Copenhagen Zoo.

"With more accurate dating of how populations have changed in relation to climate over time, we can get a picture of how species could cope with future climate change."

https://www.iflscience.com/plants-and-an...line-/all/
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#20
Quote:Human 'super predator' more terrifying than bears, wolves and dogs
Bears, wolves and other large carnivores are frightening beasts but the fear they inspire in their prey pales in comparison to that caused by the human 'super predator.' A new study demonstrates that smaller carnivores, like European badgers, that may be prey to large carnivores, actually perceive humans as far more frightening.

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A new study by Western University demonstrates that smaller carnivores, like European badgers, that may be prey to large carnivores, actually perceive humans as far more frightening. Globally, humans now kill smaller carnivores at much higher rates than large carnivores do, and these results indicate that smaller carnivores have learned to fear the human 'super predator' far more than they fear their traditional enemies.

These findings by Liana Zanette and Michael Clinchy from Western's Faculty of Science, in collaboration with celebrated British biologist David Macdonald from University of Oxford's Wildlife Conservation Research Unit (WildCRU) and others, were published this week in Behavioral Ecology.

Zanette, a professor in Western's Department of Biology, and her colleagues experimentally demonstrated that smaller carnivores, like badgers, foxes and raccoons, that may appear to be habituated to humans because they live among us, are actually experiencing elevated levels of fear -- living in fear of the human 'super predator' in human-dominated landscapes.

"Our previous research has shown that the fear large carnivores inspire can itself shape ecosystems. These new results indicate that the fear of humans, being greater, likely has even greater impacts on the environment, meaning humans may be distorting ecosystem processes even more than previously imagined," explains Zanette, a wildlife ecologist. "These results have important implications for conservation, wildlife management and public policy."

By frightening their prey, large carnivores help maintain healthy ecosystems by preventing smaller carnivores from eating everything in sight, and the loss of this 'landscape of fear' adds to conservation concerns regarding the worldwide loss of large carnivores. Fear of humans has been proposed to act as a substitute, but these new results demonstrate that the fear of humans is qualitatively different and cannot be expected to fulfill the same ecosystem function.

The team conducted the study on Europeans badgers in Wytham Woods, just outside of Oxford (UK). To experimentally compare their relative fearfulness, the team played badgers the sounds of bears, wolves, dogs and humans in their natural habitat and filmed their responses, using hidden automated speakers and cameras. Whereas hearing bears and dogs had some effect, simply hearing the sound of people speaking, in conversation, or reading passages from books, prevented most badgers from feeding entirely, and dramatically reduced the time spent feeding by those few badgers that were brave enough to venture forth -- while hearing the sound of the human 'super predator.'
Source: https://www.sciencedaily.com/releases/20...135357.htm
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#21
Any other members had a DNA analysis done?

I rated 2% Neanderthal, what % archaic human do you carry?
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#22
Uhhhhh....this may be interesting...

6-Fingered Family's Impressive Dexterity Suggests We All Need an Extra Digit
"It may be of value to augment normal five-fingered hands with an artificial supernumerary finger."
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By Emma Betuel on June 15, 2019


While having an extra digit was once revered by ancient canyon dwellers, extra fingers are usually removed today. A recent case study of two unique individuals published in Nature Communications, however, suggests they’re worth keeping, outlining the impressive advantages that extra digits can bring and how the brain can drive this superior dexterity.

The case study, published in early June, describes a 52-year-old mother and her 17-year-old child who were both born with an extra finger between their pointer finger and thumb. It’s been reported that roughly 0.2 percent of people are born with extra digits (in various positions on the hands and feet), but others estimate that one person out of every 700 to 1,000 live births has an extra appendage.

Not all those people can move their extra digits. But those investigated in the case study were capable of some extraordinary dexterity, says study author Carsten Mehring, Ph.D., at the University of Freiburg in Germany. He and his colleagues were so impressed that they wrote: “it may be of value to augment normal five-fingered hands with an artificial supernumerary finger.”

The Six-Fingered Hand

“Our subjects can use their extra fingers independently, similar to an additional thumb, either alone or together with the other five fingers, which makes manipulation extraordinary versatile and skilful,” said Mehring. “For instance, in our experiments subjects can carry out a task with one hand, for which we normally need two hands.”

These extra fingers were controlled by their own networks of muscles and tendons, and, crucially, had their own pathways in the brain. The team is hoping their discovery may inform how we design robotic appendages to fit both our bodies and our brains.

Mehring, working with Etienne Burdet, Ph.D., a professor of human robotics at Imperial College London and a team of others, had each subject perform a series of physical tasks to test the capacity of their extra digits. The team observed that the extra digits were able to operate independently in spherical space, moving similarly to a thumb, affording their subjects an “extra degree of freedom.”

This ability greatly increased the amount of movements their individual hands could do, which included tying shoes with one hand, flipping book pages, folding napkins, and rolling towels.

The Six-Fingered Brain

The authors were curious about the roots of that extra dexterity in the brain. Using brain imaging from one of the participants, (the other had a metal dental implant, so no brain scans there), the team showed how the brain adapted to manage it. That extra finger, it seems, was commanded by its own neural resources in the sensorimotor cortex. In other words, these individuals had developed an additional neural pathway that was dedicated solely to that extra digit:

“The results show that the representation of the supplemental finger in the primary sensorimotor cortices was distinct from the representations of all other fingers, including the thumb,” the team writes. “This demonstrates that separate neural resources are used to control movements of the supplemental finger in this six-fingered subject.”

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Brain scans on one of the study subjects showed that the extra digit recruited extra neural resources to help control its movements.

Crucially, the dedication of these additional resources in the brain didn’t come at the expense of other digits. “In a nutshell, it is amazing that the brain has enough capacity to do it without sacrificing elsewhere,” added Burdet. He and Mehring, who have both studied brain computer interfaces and robotics, offer up their findings as a blueprint for the development of additional artificial appendages, at least from a biomechanical standpoint.

One snag they’ll have to get over, however, is the fact that the people in the case study had their extra digits from birth, whereas people who get artificial appendages have never had an extra limb. It isn’t clear how or if their brains will adapt.

“The additional extremities have been trained in the subjects since birth,” the authors write. “This does not necessarily mean that similar functionality can be achieved when artificial limbs are supplemented later in life.”

Those of us who have never known any digits beyond five may find that even with our new flashy robotic appendages, our brains come up short. As advanced as artificial limbs and digits may become, the key to making them useful will be ensuring there are pathways in the brain that allow us to control them as if they were there since birth.

Augmented manipulation ability in humans with six-fingered hands

Abstract

Neurotechnology attempts to develop supernumerary limbs, but can the human brain deal with the complexity to control an extra limb and yield advantages from it? Here, we analyzed the neuromechanics and manipulation abilities of two polydactyly subjects who each possess six fingers on their hands. Anatomical MRI of the supernumerary finger (SF) revealed that it is actuated by extra muscles and nerves, and fMRI identified a distinct cortical representation of the SF. In both subjects, the SF was able to move independently from the other fingers. Polydactyly subjects were able to coordinate the SF with their other fingers for more complex movements than five fingered subjects, and so carry out with only one hand tasks normally requiring two hands. These results demonstrate that a body with significantly more degrees-of-freedom can be controlled by the human nervous system without causing motor deficits or impairments and can instead provide superior manipulation abilities.
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