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Early Human Ancestors Had More Variable Diet
Scientists conducted an analysis of the fossil teeth, indicating that Australopithecus, a predecessor of early Homo, had a more varied diet than early Homo. Its diet was also more variable than the diet of another distant human relative known as Paranthropus.
An international team of researchers, including Professor Francis Thackeray, Director of the Institute for Human Evolution at Wits University, will be publishing their latest research on what our early ancestors ate, online in the journal, Nature, on August 8, 2012. The paper titled 'Evidence for diet but not landscape use in South African early hominins' was authored by Vincent Balter from the Ecole Normale Supérieure in Lyon, France; Jose´ Braga from the Université de Toulouse Paul Sabatier in Toulouse in France; Philippe Te´louk from the Ecole Normale Supérieure in Lyon in France; and Thackeray from the University of the Witwatersrand in Johannesburg in South Africa.
According to Thackeray, the results of the study show that Paranthropus had a primarily herbivorous-like diet, while Homo included a greater consumption of meat.
Signatures of essential chemical elements have been found in trace amounts in the tooth enamel of the three fossils genera, and the results are indicators of what South African hominins ate and what their habitat preferences were.
Strontium and barium levels in organic tissues, including teeth, decrease in animals higher in the food chain. The scientists used a laser ablation device, which allowed them to sample very small quantities of fossil material for analysis. Since the laser beam was pointed along the growth prisms of dental enamel, it was possible to reconstruct the dietary changes for each hominin individual.
Thackeray states that the greater consumption of meat in the diet of early forms of Homo could have contributed to the increase in brain size in this genus.
Australopithecus probably ate both meat and the leaves and fruits of woody plants. The composition of this diet may have varied seasonally.
Apart from the dietary differences, the new results indicate that the home-range area was of similar size for species of the three hominin genera.
The scientists have also measured the strontium isotope composition of dental enamel. Strontium isotope compositions are free of dietary effects but are characteristic of the geological substrate on which the animals lived.
According to the results all the hominids lived in the same general area, not far from the caves where their bones and teeth are found today.
Professor Vincent Balter of the Geological Laboratory of Lyon in France, suggests that up until two millions years ago in South Africa, the Australopithecines were generalists, but gave up their broad niche to Paranthropus and Homo, both being more specialised than their common ancestor.
Link:http://www.sciencedaily.com/releases/2012/08/120808132711.htm
Giant Moa Had Climate Change Figured out
Moa feet
The population size of the giant moa remained stable over the past
40,000 years until the arrival of humans in New Zealand around 1280 AD.
The study was undertaken by researchers from the University of
Adelaide's Australian Centre for Ancient DNA, the University of
Colorado, and the University of Waikato and Landcare Research in New
Zealand. The results are published online in the journal Quaternary Science Reviews.
The giant birds -- measuring up to 2.5 metres high and weighing 250
kilograms -- were the largest herbivores in New Zealand's pre-human
environment but were quickly exterminated after the arrival of
Polynesian settlers.
"Until now it has been difficult to determine how megafauna responded
to environmental change over the past 50,000 years, because human
arrival and climate change occurred simultaneously in many parts of the
world," says Dr Nic Rawlence, lead author of the study and a
postdoctoral research fellow from the Australian Centre for Ancient DNA
and the University of Waikato.
"Using ancient DNA, radiocarbon dating and stable dietary isotope
analysis, we have been able to show that before humans arrived, moa
mitigated the effects of climate change by tracking their preferred
habitat as it expanded, contracted and shifted during warming and
cooling events," Dr Rawlence says.
"Moa were not in serious decline before humans arrived, as has been
previously suggested, but had relatively stable population sizes. The
overwhelming evidence suggests that the extinction of moa occurred due
to overhunting and habitat destruction, at a time of relative climatic
stability."
Co-author of the study, Dr Jamie Wood from Landcare Research, says
the results "show that range shifts and minor population fluctuations
observable in the fossil and genetic record are a natural response to
environmental change and do not necessarily lead to extinction."
"Climate change has been blamed for megafaunal extinctions in other
parts of the world, but this is not the case for moa," says co-author Dr
Jessica Metcalf from the University of Colorado.
ACAD Director and project leader Professor Alan Cooper says: "The
very recent extinctions in New Zealand provide a unique opportunity to
examine the extinction of Ice Age megafauna and the relative roles of
human hunting and climate change."
The study was funded by an Australian Research Council (ARC) Discovery Grant.
Later Stone Age Got Earlier Start in South Africa Than Thought
The study shows the onset of the Later Stone Age in South Africa likely began some 44,000 to 42,000 years ago, said Paola Villa, a curator at the University of Colorado Museum of Natural History and lead study author. The new dates are based on the use of precisely calibrated radiocarbon dates linked to organic artifacts found at Border Cave in the Lebombo Mountains on the border of South Africa and Swaziland containing evidence of hominid occupation going back 200,000 years.
The Later Stone Age is synonymous to many archaeologists with the Upper Paleolithic Period, when modern humans moved from Africa into Europe roughly 45,000 years ago and spread rapidly, displacing and eventually driving Neanderthals to extinction. The timing of the technological innovations and changes in the Later Stone Age in South Africa are comparable to that of the Upper Paleolithic, said Villa.
"Our research proves that the Later Stone Age emerged in South Africa far earlier than has been believed and occurred at about the same time as the arrival of modern humans in Europe," said Villa. "But differences in technology and culture between the two areas are very strong, showing the people of the two regions chose very different paths to the evolution of technology and society."
A paper on the subject was published July 30 in the Proceedings of the National Academy of Sciences. Co-authors included Sylvain Soriano of the Center National de la Recherche Scientifique, or CNRS, at the University of Paris; Tsenka Tsanova of the Max Planck Institute of Evolutionary Biology in Leipzig, Germany; Ilaria Degano, Jeannette Lucejko and Maria Perla Colombini of the University of Pisa in Italy; Thomas Highham of the University of Oxford in England; Francesco d'Errico of the CNRS at the University of Bordeaux in France; Lucinda Blackwell of the University of Witwatersrand in South Africa; and Peter Beaumont of the McGregor Museum in South Africa.
A companion paper published in PNAS and led by d'Errico reports on organic materials found at Border Cave dating to the Later Stone Age, an indication that the San hunter-gatherer culture first thought to have begun about 20,000 years ago in the region probably emerged as early as 44,000 years ago, said Villa.
Organic artifact assemblages at Border Cave dating to the Later Stone Age included ostrich eggshell beads, thin bone arrowhead points, wooden digging sticks, a gummy substance called pitch that was used to haft, or attach, bone and stone blades to shafts and a lump of beeswax likely used for hafting. The assemblage also included worked tusks of members of the pig family, which likely were used to plane wood, and notched bones that may have been used for counting.
A wooden digging stick from Border Cave dated to about 40,000 years ago was found in association with bored but broken stones likely used to weight such sticks. The sticks and stone weights are similar to digging implements used by women of the prehistoric San hunter-gatherer culture in the region to unearth bulbs and termite larvae, a practice that continued into historic times, said Villa. "These digging sticks from Border Cave are the oldest artifacts of this kind known from South Africa or anywhere else in Africa."
The new PNAS study led by Villa also indicates big changes were occurring in hunting technology during the Later Stone Age at Border Cave, said Villa. They included a shift from spears hafted with stone points -- the main hunting weapon in the Middle Stone Age -- to the likely use of the bow and arrow, a technology that included very thin bone points that probably were tipped with poison, she said.
"The very thin bone points from the Later Stone Age at Border Cave are good evidence for bow and arrow use," said Villa. "The work by d'Errico and colleagues shows that the points are very similar in width and thickness to the bone points produced by San culture that occupied the region in prehistoric times, whose people were known to use bows and arrows with poison-tipped bone points as a way to bring down medium and large-sized herbivores."
Chemical analyses showed the poison used with such bone points was most likely ricinoleic acid, which can be derived from the seeds of castor oil plants and which has been identified as being used in South Africa at least 24,000 years ago. "Such bone points could have penetrated thick hides, but the lack of 'knock-down' power means the use of poison probably was a requirement for successful kills," said Villa.
The lump of beeswax from Border Cave also dating to about 40,000 years ago -- the oldest known beeswax used by humans ever discovered -- was wrapped in plant fibers that may have been similar to fibers used to make the strings for hunting bows, said Villa.
While stone tools continued to be manufactured in the Later Stone Age at Border Cave, stone spear points from the Middle Stone Age gave way to tiny, thin flakes known as microliths that were probably hafted on shafts, much like the bone points, with pitch made from the bark of a common type of coniferous tree found in the region.
While a 2011 study co-authored by Villa and Wil Roebroeks of Leiden University in the Netherlands showed that Neanderthals mastered the manufacture of pitch in Europe 200,000 years ago, it was not a particularly simple task since the process involved burning peeled bark in the absence of air, said Villa. The Later Stone Age inhabitants of South Africa probably dug holes into the ground and inserted bark peels, then lit them on fire and covered the holes tightly with stones. "This is the first time pitch-making is demonstrated in South Africa," said Villa.
The Upper Paleolithic Period in Europe that corresponds to the Later Stone Age in South Africa also spurred complex new technologies that helped humans survive and thrive in much different environments. Artifacts from the Upper Paleolithic included spear-throwers, bone needles with eyelets for sewing furs, bone fishing hooks, bone flutes and even ivory figurines carved from mammoth tusks.
Villa said that a fundamental rearrangement of human behavior that had its beginnings 50,000-60,000 years ago in Africa and spread to Europe -- an idea first proposed by Stanford University archaeologist Richard Klein -- appears quite plausible.
