Human Evolution

[Darwinsbulldog]

ScienceDaily (Apr. 20, 2012) — Carnivory is behind the evolutionary success of humankind. When early humans started to eat meat and eventually hunt, their new, higher-quality diet meant that women could wean their children earlier. Women could then give birth to more children during their reproductive life, which is a possible contribution to the population gradually spreading over the world. The connection between eating meat and a faster weaning process is shown by a research group from Lund University in Sweden, which compared close to 70 mammalian species and found clear patterns.
Learning to hunt was a decisive step in human evolution. Hunting necessitated communication, planning and the use of tools, all of which demanded a larger brain. At the same time, adding meat to the diet made it possible to develop this larger brain.
"This has been known for a long time. However, no one has previously shown the strong connection between meat eating and the duration of breast-feeding, which is a crucial piece of the puzzle in this context. Eating meat enabled the breast-feeding periods and thereby the time between births, to be shortened. This must have had a crucial impact on human evolution," says Elia Psouni of Lund University.
She is a developmental psychologist and has, together with neurophysiologist Martin Garwicz (also in Lund) and evolutionary geneticist Axel Janke (currently in Frankfurt but previously in Lund) published her findings in the journal PLoS ONE.
Among natural fertility societies, the average duration of breast-feeding is 2 years and 4 months. This is not much in relation to the maximum lifespan of our species, around 120 years. It is even less if compared to our closest relatives: female chimpanzees suckle their young for 4-5 years, whereas the maximum lifespan for chimpanzees is only 60 years.
Many researchers have tried to explain the relatively shorter breast-feeding period of humans based on social and behavioral theories of parenting and family size. But the Lund group has now shown that humans are in fact no different than other mammals with respect to the timing of weaning. If you enter brain development and diet composition into the equation, the time when our young stop suckling fits precisely with the pattern in other mammals.
This is the type of mathematical model that Elia Psouni and her colleagues have built. They entered data on close to 70 mammalian species of various types into the model -- data on brain size and diet. Species for which at least 20 per cent of the energy content of their diet comes from meat were categorised as carnivores. The model shows that the young of all species cease to suckle when their brains have reached a particular stage of development on the path from conception to full brain-size. Carnivores, due to their high quality diet, can wean earlier than herbivores and omnivores.
The model also shows that humans do not differ from other carnivores with respect to timing of weaning. All carnivorous species, from small animals such as ferrets and raccoons to large ones like panthers, killer whales and humans, have a relatively short breast-feeding period. The difference between us and the great apes, which has puzzled previous researchers, seems to depend merely on the fact that as a species we are carnivores, whereas gorillas, orangutans and chimpanzees are herbivores or omnivores.
A few years ago, the Lund group published an acclaimed study on the point at which the young of various animals start to walk. Here too, similar patterns were discovered between mammalian species that diverged in evolution millions of years ago. A particular stage in brain development seems quite simply to be the time to start to walk, independently of whether you are a hedgehog, a ferret or a human being.
"That humans seem to be so similar to other animals can of course be taken as provocative. We like to think that culture makes us different as a species. But when it comes to breast-feeding and weaning, no social or cultural explanations are needed; for our species as a whole it is a question of simple biology. Social and cultural factors surely influence the variation between humans," says Elia Psouni.
She is careful to emphasize that their results concern human evolution. The research is about how carnivory can have contributed to the human species' spreading on earth and says nothing about what we should or should not eat today in order to have a good diet.

http://www.sciencedaily.com/releases...0420105539.htm

Psouni, E., A. Janke, et al. (2012). "Impact of Carnivory on Human Development and Evolution Revealed by a New Unifying Model of Weaning in Mammals." PLoS ONE 7(4): e32452.

Our large brain, long life span and high fertility are key elements of human evolutionary success and are often thought to have evolved in interplay with tool use, carnivory and hunting. However, the specific impact of carnivory on human evolution, life history and development remains controversial. Here we show in quantitative terms that dietary profile is a key factor influencing time to weaning across a wide taxonomic range of mammals, including humans. In a model encompassing a total of 67 species and genera from 12 mammalian orders, adult brain mass and two dichotomous variables reflecting species differences regarding limb biomechanics and dietary profile, accounted for 75.5%, 10.3% and 3.4% of variance in time to weaning, respectively, together capturing 89.2% of total variance. Crucially, carnivory predicted the time point of early weaning in humans with remarkable precision, yielding a prediction error of less than 5% with a sample of forty-six human natural fertility societies as reference. Hence, carnivory appears to provide both a necessary and sufficient explanation as to why humans wean so much earlier than the great apes. While early weaning is regarded as essentially differentiating the genus Homo from the great apes, its timing seems to be determined by the same limited set of factors in humans as in mammals in general, despite some 90 million years of evolution. Our analysis emphasizes the high degree of similarity of relative time scales in mammalian development and life history across 67 genera from 12 mammalian orders and shows that the impact of carnivory on time to weaning in humans is quantifiable, and critical. Since early weaning yields shorter interbirth intervals and higher rates of reproduction, with profound effects on population dynamics, our findings highlight the emergence of carnivory as a process fundamentally determining human evolution.

FULL PAPER DOWNLOAD:-

http://www.plosone.org/article/info%...l.pone.0032452

[Darwinsbulldog]

http://www.sciencedaily.com/releases...0507154025.htm

Anthropologist Finds Explanation for Hominin Brain Evolution in Famous Fossils

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Taung surrounded by a juvenile chimp skull and human skull, the latter having a fontanelle and metopic suture. The metopic suture is visible on the frontal lobe of Taung's endocast. (Credit: CT-based images by M. Ponce de León and Ch. Zollikofer, University of Zurich)

ScienceDaily (May 7, 2012) — One of the world's most important fossils has a story to tell about the brain evolution of modern humans and their ancestors, according to Florida State University evolutionary anthropologist Dean Falk.
The Taung fossil -- the first australopithecine ever discovered -- has two significant features that were analyzed by Falk and a group of anthropological researchers. Their findings, which suggest brain evolution was a result of a complex set of interrelated dynamics in childbirth among new bipeds, were published May 7 in the Proceedings of the National Academy of Sciences.
"These findings are significant because they provide a highly plausible explanation as to why the hominin brain might grow larger and more complex," Falk said.
The first feature is a "persistent metopic suture," or unfused seam, in the frontal bone, which allows a baby's skull to be pliable during childbirth as it squeezes through the birth canal. In great apes -- gorillas, orangutans and chimpanzees -- the metopic suture closes shortly after birth. In humans, it does not fuse until around 2 years of age to accommodate rapid brain growth.
The second feature is the fossil's endocast, or imprint of the outside surface of the brain transferred to the inside of the skull. The endocast allows researchers to examine the brain's form and structure.
After examining the Taung fossil, as well as huge numbers of skulls belonging to apes and humans, as well as corresponding 3-D CT (three-dimensional computed tomographic) scans, and taking into account the fossil record for the past 3 million years, Falk and her colleagues noted three important findings: The persistent metopic suture is an adaptation for giving birth to babies with larger brains; is related to the shift to a rapidly growing brain after birth; and may be related to expansion in the frontal lobes.
"The persistent metopic suture, an advanced trait, probably occurred in conjunction with refining the ability to walk on two legs," Falk said. "The ability to walk upright caused an obstretric dilemma. Childbirth became more difficult because the shape of the birth canal became constricted while the size of the brain increased. The persistent metopic suture contributes to an evolutionary solution to this dilemma."
The later fusion of the metopic suture is most likely an adaptation of hominins who walked upright to be able to more easily give birth to babies with relatively large brains. The unfused seam is also related to the shift to rapidly growing brains after birth, an advanced human-like feature as compared to apes.
"The later fusion was also associated with evolutionary expansion of the frontal lobes, which is evident from the endocasts of australopithecines such as Taung," Falk said.
The Taung fossil, which is estimated to be around 2½ million years old, was discovered in 1924 in Taung, South Africa. It became the "type specimen," or main model, of the genus Australopithecus africanus when it was announced in 1925.
An australopithecine is any species of the extinct genera Australopithecus or Paranthropus that lived in Africa, walked on two legs and had relatively small brains.
Falk conducted the research with Marcia S. Ponce de Leon, Christoph P.E. Zollikofer and Naoki Morimoto of the Anthropological Institute and Museum at the University of Zurich in Switzerland.

[Darwinsbulldog]

Luncz, Lydia V., R. Mundry, et al. "Evidence for Cultural Differences between Neighboring Chimpanzee Communities." Current Biology(0).

Summary The majority of evidence for cultural behavior in animals has come from comparisons between populations separated by large geographical distances that often inhabit different environments [1–6]. The difficulty of excluding ecological and genetic variation as potential explanations for observed behaviors has led some researchers to challenge the idea of animal culture [7–9]. Chimpanzees (Pan troglodytes verus) in the Taï National Park, Côte d'Ivoire, crack Coula edulis nuts using stone and wooden hammers and tree root anvils [10–12]. In this study, we compare for the first time hammer selection for nut cracking across three neighboring chimpanzee communities that live in the same forest habitat, which reduces the likelihood of ecological variation. Furthermore, the study communities experience frequent dispersal of females at maturity, which eliminates significant genetic variation [13, 14]. We compared key ecological factors, such as hammer availability and nut hardness, between the three neighboring communities and found striking differences in group-specific hammer selection among communities despite similar ecological conditions. Differences were found in the selection of hammer material and hammer size in response to changes in nut resistance over time. Our findings highlight the subtleties of cultural differences in wild chimpanzees and illustrate how cultural knowledge is able to shape behavior, creating differences among neighboring social groups.

http://www.sciencedirect.com/science...60982212003181

SD write-up:-

Chimpanzee Cultures Differ Between Neighbors: Neighboring Chimpanzee Groups Use Different Hammers to Crack Nuts
Chimpanzee using a wooden hammer to break nuts. (Credit: © MPI f.Evolutionary Anthropology/Sonja Metzger)

ScienceDaily (May 10, 2012) — Culture has long been proposed to be a distinguishing feature of the human species. However, an increasing amount of evidence from the field has shown that in several animals, differences in behaviors between populations actually reflect the presence of culture in these species. These studies have mainly come from populations that live far apart from each other which make it difficult to exclude ecological or genetic differences as being the underlying reasons for the observed behavioral differences.
Now for the first time, cultural differences between directly neighboring chimpanzee groups have been found in the wild and are reported by Lydia Luncz, Roger Mundry and Christophe Boesch of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
The Taï chimpanzee project field site in Côte d'Ivoire presents the unique opportunity to study three neighboring chimpanzee communities at the same time, making it possible to directly compare the behaviors present in each community. Chimpanzees in Côte d'Ivoire use stone and wooden tools to crack nuts. Lydia Luncz was therefore able to observe how the chimpanzees were selecting hammers to crack Coula nuts in the three adjacent communities. After placing gathered Coula nuts on root anvils, the chimpanzees of all three neighboring communities primarily select stones to use as hammers.
However, as the nut season advances and nuts get drier and easier to crack, the chimpanzees of two of the communities select a greater proportion of wooden hammers which are easier to find in the forest, while the members of the third community continue to favor stone hammers. Furthermore, the two communities that select wooden hammers choose distinctly different sized hammers. All of the chimpanzees live in a contiguous stretch of the large Taï National Park and therefore ecological differences are unlikely to explain the differences in tool selection.
"In humans, cultural differences are an essential part of what distinguishes neighboring groups that live in very similar environments," said Lydia Luncz of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, the lead author of the paper. "For the first time, a very similar situation has been found in wild chimpanzees living in the Taï National Park, Côte d'Ivoire, and this demonstrates that they share with us the ability for fine-scale cultural differentiation."
"In many ways, chimpanzees are very similar to us humans," Christophe Boesch said, the director of the Taï chimpanzee project, and co-author of the paper. "By studying the similarities to our closest living relatives in their natural habitat in Africa, we have the opportunity to learn more about the evolutionary roots of culture, which is for us humans one of the key elements of our identity."
Certainly more can be learned about the cultural abilities of chimpanzees in the wild by studying this specific population. Therefore, Lydia Luncz will be returning to Côte d'Ivoire early next year to study different aspects of the cultural life of the Taï chimpanzees. Time is of the essence, however, as chimpanzees are threatened across their natural range. Further, a great deal of chimpanzee cultural variation must have vanished over the last few decades, as 90% of the chimpanzee populations in Cote d'Ivoire have disappeared over the last 20 years. The Wild Chimpanzee Foundation was created by Christophe Boesch to enhance the survival of the remaining wild chimpanzee populations and their habitat, the tropical rain forest, throughout tropical Africa.

http://www.sciencedaily.com/releases...0510131438.htm

[Darwinsbulldog]

Chimpanzee Uses Innovative Foresighted Methods to Fool Humans

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The series shows the chimpanzee when he slowly moved towards the group of visitors before releasing his projectiles. Note the two projectiles in his left hand. The picture on the left was taken 31 seconds before the throw; the central picture, where he picks up an apple from the water moat, was taken 15 seconds before; the right picture was taken 1 second before the throw. (Credit: Photo by Tomas Persson; Osvath et al, doi/10.1371/journal.pone.0036782.g001)

ScienceDaily (May 10, 2012) — Chimpanzee Santino achieved international fame in 2009 for his habit of gathering stones and manufacturing concrete projectiles to throw at zoo visitors. A new study shows that Santino's innovativeness when he plans his stone-throwing is greater than researchers have previously observed. He not only gathers stones and manufactures projectiles in advance; he also finds innovative ways of fooling the visitors.
The study, which was carried out at Lund University, has been published in PLoS ONE.
The new study looked at the chimpanzee's ability to carry out complex planning. The case study shows how humans' closest relatives in the animal kingdom appear to be able to plan to deceive others, and that they can also plan their deception inventively. The behaviour of the chimpanzee Santino is of particular interest because it is done while the humans to be deceived are out of sight. That means that the chimpanzee can plan without having immediate perceptual feedback of his goal -- the visitors to the zoo -- to aid in his planning.
The subject of the study is Santino the chimpanzee, who achieved international fame in 2009 for his habit of gathering stones and manufacturing concrete projectiles to throw at visitors from the safety of his enclosure at Furuvik Zoo north of Stockholm. His behaviour was reported as an example of spontaneous planning for a future event, in which his psychological state was visibly quite different from that of his subsequent aggressive displays. Previously, such cognitive abilities had been widely believed to be restricted to humans.
The new study sought to collect more detailed data on Santino's projectile-throwing behaviour over the course of the 2010 zoo season.
In the new study, the chimpanzee continued and extended his previous behaviour of caching projectiles for later use in aggressive throwing displays. The new behaviour involved innovative use of concealments: both naturally occurring ones and ones he manufactured from hay. All were placed near the visitors' area. This allowed Santino to throw his missiles before the crowd had time to back away.
The first hay concealment was made after the zoo guide had repeatedly backed visitors away when the chimpanzee made throwing attempts. All concealments were made when the visitors were out of sight, and the hidden projectiles were used when they returned. In order to make the hay concealments the chimpanzee had bring the hay from the inside enclosure. Over the course of the season, the researchers observed that the use of concealments became the chimpanzees preferred strategy. Moreover, Santino combined two deception strategies consistently: hiding projectiles and inhibiting the displays of dominance that otherwise preceded his throws.
The new findings suggest that chimpanzees may be able to represent the future behaviour of others while those others are not present. It is also critical that the chimpanzee's initial behaviour produced a future event, rather than merely preparing for one that had reliably occurred before. This in turn, suggest a flexible planning ability which, in humans, relies on creative re-combining of memories, mentally acted out in a 'what if' future scenario.
The authors of the study are Mathias Osvath, from the Department of Cognitive Science at Lund University, and Elin Karvonen, from the University's Primate Research Station. The article is entitled 'Spontaneous innovation for future deception in a male chimpanzee' and has appeared in the journal PLoS One, published by the Public Library of Science.

http://www.sciencedaily.com/releases...0510100225.htm

FULL PAPER:-

Osvath, M. and E. Karvonen (2012). "Spontaneous Innovation for Future Deception in a Male Chimpanzee." PLoS ONE 7(5): e36782.

The ability to invent means to deceive others, where the deception lies in the perceptually or contextually detached future, appears to require the coordination of sophisticated cognitive skills toward a single goal. Meanwhile innovation for a current situation has been observed in a wide range of species. Planning, on the one hand, and the social cognition required for deception on the other, have been linked to one another, both from a co-evolutionary and a neuroanatomical perspective. Innovation and deception have also been suggested to be connected in their nature of relying on novelty.
We report on systematic observations suggesting innovation for future deception by a captive male chimpanzee (Pan troglodytes). As an extension of previously described behaviour – caching projectiles for later throwing at zoo visitors – the chimpanzee, again in advance, manufactured concealments from hay, as well as used naturally occurring concealments. All were placed near the visitors' observation area, allowing the chimpanzee to make throws before the crowd could back off. We observed what was likely the first instance of this innovation. Further observations showed that the creation of future-oriented concealments became the significantly preferred strategy. What is more, the chimpanzee appeared consistently to combine two deceptive strategies: hiding projectiles and inhibiting dominance display behaviour.
The findings suggest that chimpanzees can represent the future behaviours of others while those others are not present, as well as take actions in the current situation towards such potential future behaviours. Importantly, the behaviour of the chimpanzee produced a future event, rather than merely prepared for an event that had been reliably re-occurring in the past. These findings might indicate that the chimpanzee recombined episodic memories in perceptual simulations.

http://www.plosone.org/article/info%...l.pone.0036782

[Darwinsbulldog]

http://www.sciencedaily.com/releases...0510095936.htm

Testosterone-Fueled Infantile Males Might Be a Product of Mom's Behavior

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Angry boy. Testosterone levels in infancy are not inherited genetically but rather determined by environmental factors, new research suggests. (Credit: © crestajohnson / Fotolia)

ScienceDaily (May 10, 2012) — By comparing the testosterone levels of five-month old pairs of twins, both identical and non-identical, University of Montreal researchers were able to establish that testosterone levels in infancy are not inherited genetically but rather determined by environmental factors.
"Testosterone is a key hormone for the development of male reproductive organs, and it is also associated with behavioural traits, such as sexual behaviour and aggression," said lead author Dr. Richard E. Tremblay of the university's Research Unit on Children's Psychosocial Maladjustment. "Our study is the largest to be undertaken with newborns, and our results contrast with the findings gained by scientists working with adolescents and adults, indicating that testosterone levels are inherited."
The findings were presented in an article published in Psychoneuroendocrinology on May 7, 2012.
The researchers took saliva samples from 314 pairs of twins and measured the levels of testosterone. They then compared the similarity in testosterone levels between identical and fraternal twins to determine the contribution of genetic and environmental factors. Results indicated that differences in levels of testosterone were due mainly to environmental factors. "The study was not designed to specifically identify these environmental factors which could include a variety of environmental conditions, such as maternal diet, maternal smoking, breastfeeding and parent-child interactions."
"Because our study suggests that testosterone levels in infants are determined by the circumstances in which the child develops before and after birth, further studies will be needed to find out exactly what these influencing factors are and to what extent they change from birth to puberty," Tremblay said.

http://www.sciencedaily.com/releases...0510095936.htm

NB:-<Source-linky broken at time of posting>

[Mjt]

This is really interesting, thanks puppy. I would love to know the why. is he having fun, or is he pissed off at being looked at all the time? Or is he just being territorial? It would be most interesting, but I don't know how one would study that

[Darwinsbulldog]

Chimps are complex beings, just like us. It could be a variety of reasons. Until recently, most animal's intelligence and degree of self-awareness were somewhat underestimated. Perhaps he is bored, perhaps he is defending turf, perhaps its revenge against some visiter that abused him. Perhaps all of the above.

[Mjt]

Yeah Puppy, if people were standing staring at me all day, I'd throw rocks at them too

[Darwinsbulldog]

Originally Posted by Mjt

Yeah Puppy, if people were standing staring at me all day, I'd throw rocks at them too

The other thing is that humans stand upright, and in the ape world that is a threat gesture. We were taught at the zoo, that the best way to make friends is to squat, and not give them too much eyeball. Staring is also a threat.

[Mjt]

Did you get to work at the zoo?
luckiest Puppy ever!!!!
Tomorrow I will drag out my early childhood development books to see at what age the little bald chimps are able to plan for future events. Cant remember off the top of my head. I seem to recall that the ability to modify behavior to decieve, is quite advanced, as in the chimps ability to hide its usual aggression traits before the missile launch. Sorry I cant help but laugh, good on him.