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Descent of Man In this lecture, beginners can familiarize themselves with basic information and terms used to describe the evolution of humanity beginning with the origin of primates through the comings and goings of Genus Homo. |
Virus may have crossed species barrier
Posted: Saturday, March 29, 2003
By ANDRÉ PICARD
From Saturday's Globe and Mail
The deadly respiratory ailment SARS may have spread to humans from cattle, just like mad-cow disease.
Scientists say the infectious agent they have identified as the likely cause of severe acute respiratory syndrome is a previously unknown coronavirus, one that some researchers say looks remarkably like bovine coronavirus. In cattle, the common disease is known as "shipping fever."
Coronaviruses — which take their name from the prominent "crown" of spikes clearly visible by electron microscopy — occur in cattle, pigs, mice and humans.
The new pathogen may have crossed the species barrier and mutated.
"It's hard to be definitive at this point, but it can be hypothesized that it crossed the species barrier," Frank Plummer, scientific director at the National Microbiology Laboratory in Winnipeg, said in an interview yesterday.
He said he had examined the new coronavirus, which does not yet have a name, under an electron microscope and "it somewhat resembles several animal viruses. It's somewhere between a mouse corona, a bird corona and cow corona."
Dr. Plummer said that many new diseases have jumped from animals to humans in recent years, including HIV-AIDS, bovine spongiform encephalopathy [commonly known as mad-cow disease and in humans, Creutzfeldt-Jakob disease] and Ebola virus, often with deadly consequences. "As we change the way we interact with our environment, these things are going to occur, new diseases are going to emerge," he said.
While much of the attention of the scientific world has focused on the new coronavirus, Dr. Plummer said it is necessary to keep an open mind. In many of the samples analyzed, researchers have also found metapneumovirus, which comes from a family of viruses that usually cause respiratory ailments in children.
"At this point, we don't know if there are two separate epidemics, or if these two viruses somehow work together to cause SARS. There are still pieces of the puzzle missing."
Worldwide, there have been 1,485 SARS cases, including 54 deaths. In Canada, there have been 29 confirmed cases, including three deaths.
World Health Organization officials now say that the first known case of SARS occurred on Nov. 16, 2002, in Foshan, China. The city is located in Guangdong province, an agricultural area where there are large cattle farms. Guangdong is also a major supplier of food to Hong Kong, which has been hit hardest by SARS.
The Canadian outbreak, however, has its origins in a chance encounter in the elevator of the Metropole Hotel in Hong Kong on Feb. 21 of this year. There, a Toronto woman and a Vancouver man crossed paths with a professor from Guangdong who was infected with SARS.
Researchers now believe that professor was a "super-spreader," a modern-day Typhoid Mary who spread the disease readily to others. It is well-established that some people shed viruses much more readily than others, making them particularly infectious.
But viruses often lose their potency as they are passed on to others, and that may explain why the disease may be becoming less infectious and less deadly with each passing day.
After months of denial, China has acknowledged that the unusual pneumonia epidemic that started there last November was indeed SARS. It has just opened its doors to WHO investigators and it has agreed to start releasing daily statistics, like every other affected country.
Like a common cold, SARS is spread by droplets, and appears to be spread only by face-to-face contact. Virtually all the cases in Canada are among family members of those originally infected and health-care workers who treated them.
Containment measures, including quarantine of those affected and those who may have come in contact with SARS in Toronto, have been put into place to stop the spread of the disease.
http://www.theglobeandmail.com/servlet/story/RTGAM.20030329.uscie0329/BNStory
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Posted: Friday, March 28, 2003
28 March 2003, REX DALTON, www.nature.com
Palaeontologist claims geology set human relative apart.
A leading palaeontologist is questioning the heritage of a 3.5-million-year-old fossil skull hailed two years ago as a new human relative1. It's just one example, he suggests, of scientists being too quick to give us a bushy family tree.
The fossil hit the headlines in 2001 when Meave Leakey of National Museums of Kenya and colleagues described it as evidence of a new human-like lineage. They named their specimen Kenyanthropus platyops2 - literally, the 'Flat-faced Man of Kenya'.
Tim White of the University of California, Berkeley, now argues that K.platyops was more probably a Kenyan variant of one of the most famous human ancestors of all time - 'Lucy', discovered in Ethiopia in 1974. This fossil skeleton was formally named Australopithecus afarensis3.
Geology, not genes, gave the Flat-faced Man his distinctive looks, White reckons. Over time, he explains, fine-grained rock invaded tiny cracks in the skull and distorted its shape in an irregular way.
White has seen the Flat-faced Man, but has not conducted a full study. His suggestions are based mainly on the state of other fossils, especially some 30-million-year-old skulls of flat-headed pig relatives called oreodonts found in the early 1900s in the western United States. These were "flattened and narrowed by geological deformation, not natural selection", White says.
It is plausible that the same process has muddled the K. platyops story, says Elwyn Simons, who studies primate evolution at Duke University in Durham, North Carolina. Once again, he says, "the evidence may not support the description of a new genus".
Hominid specialist Bernard Wood of George Washington University in Washington DC agrees that geological processes altered the skull, but points out that Leakey's team knew that.
"What is at issue is whether that alteration materially affects if this is a new genus," he says - a question he feels unable to answer on current evidence. Nor does Wood think the case is made for the skull being Lucy's cousin.
These differences of opinion are the latest instalment of the long-running dispute over the diversity of human origins. White, Leakey and many of the world's leading hominid researchers will continue the debate next month at the annual meeting of the Paleoanthropology Society in Tempe, Arizona.
Rex Dalton is the West Coast Correspondent of the journal Nature
References
White, T. Early Hominids - Diversity or Distortion?. Science, 299, 1994 - 1997, (2003).|Homepage|
Leakey, M. G.. et al. New hominin genus from eastern Africa shows diverse middle Pliocene lineages. Nature, 410, 433, (2001).|Article|
Johanson, D. C. & Taieb, M. Plio-Pleistocene hominid discoveries in Hadar, Ethiopia. Nature, 260, 293 - 297, (2003).
© Nature News Service / Macmillan Magazines Ltd 2003
http://www.nature.com/nsu/030324/030324-10.html
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Chimpanzees With Little Or No Human Contact Found Posted: Friday, March 14, 2003
Source: Washington University In St. Louis
Chimpanzees With Little Or No Human Contact Found In Remote African Rainforest
It's been called "The Last Place on Earth" by National Geographic magazine, and Time describes it as the "Last Eden."
The Goualougo Triangle, nestled between two rivers in a Central African rain forest, is so remote that primate researchers who traveled 34 miles, mostly by foot, from the nearest village through dense forests and swampland to get there, have discovered a rare find: chimpanzees that have had very little or no contact at all with humans. The chimpanzees' behavior when first coming in contact with the researchers was a telltale sign of lack of human exposure -- the chimpanzees didn't run and hide.
Unlike chimpanzees in the zoo that seem to appreciate being the center of human attention, chimpanzees in the wild need to be habituated to the presence of humans, a process that can take several years. Dave Morgan, a field researcher with the Wildlife Conservation Society, Republic of Congo, and Crickette Sanz, a doctoral candidate in anthropology in Arts & Sciences at Washington University in St. Louis, report their study of "Naive Encounters With Chimpanzees in the Goualougo Triangle" in the April 2003 issue of the International Journal of Primatology.
During two field seasons in the Goualougo Triangle (February-December 1999 and June 2000-June 2001), Morgan and Sanz encountered chimpanzees on 218 different occasions, totaling 365 hours of direct observation. Their goal, as with other researchers at various field sites in Africa, was to directly observe the full repertoire of chimpanzee behavior, which includes eating meat, sharing food, grooming, mating and using tools, such as large pounding sticks to break open bee hives and leaf sponges to gather water.
During Morgan and Sanz's first five minutes observing individual chimpanzees at their field site, curiosity was the most common response the researchers recorded from 84 percent of the chimpanzees. The curious responses from the chimpanzees included staring at the human observers, crouching and moving closer to get a better view of them, slapping tree trunks or throwing branches down to elicit a response, and making inquisitive vocalizations.
"Such an overwhelmingly curious response to the arrival of researchers had never been reported from another chimpanzee study site," says Sanz. "Researchers have occasionally described encounters with apes who showed curious behaviors toward them. However, these encounters were rare and usually consisted of only a few individuals."
She says that chimpanzees at these other study sites most often fled from human observers during their initial contacts. Those researchers only had glimpses of individual chimpanzees as they rapidly departed.
Researchers have dedicated years at other field sites to habituating wild chimpanzees to human presence so that the chimpanzees regard the humans in their midst as neutral elements not to be feared. Morgan and Sanz often times were accepted at first meeting.
"Behaviors such as tool use and relaxed social interactions were only seen after years of patient habituation efforts," Morgan says of the other field studies, including Jane Goodall's site in the Gombe Stream National Park in East Africa. "Yet these behaviors were sometimes observed during our initial contacts with chimpanzees in the Goualougo Triangle.
"And many of our initial contacts lasted for more than two hours -- some up to seven hours -- and ended only when we chose to leave the chimpanzees to continue our surveys. Often times when we were leaving the chimpanzees, they would follow us through the forest canopy."
Often the chimpanzees continued to exhibit behaviors indicating their naivete toward humans after their initial curious responses. Morgan and Sanz define "naive" contacts as those in which the chimpanzees in a group showed interest in their observers throughout an entire encounter, other chimpanzees joined the group being observed, and they stayed for a relatively prolonged time, with the average encounter lasting 136 minutes. These "naive" contacts accounted for 69 percent of all chimpanzee encounters.
Other types of encounters occurred, Sanz notes, but much less frequently. Of the 218 encounters, during 12 percent of them the chimpanzees showed signs of nervousness, including hiding behind vegetation or climbing higher in the canopy; 11 percent departed; and eight percent ignored the observers.
"The high frequency of curious responses to our arrival and the naive contacts suggest that the chimpanzees had had little or no contact with humans," says Sanz. "They certainly had not formed negative associations between human presence and potential threats such as poaching, hunting and habitat destruction.
"During our research presence in the Goualougo Triangle, we've never encountered any other humans or even their traces, such as villages, campsites or paths," adds Sanz. "Because of the low human density in northern Congo and the remote location of the Goualougo Triangle, it is unlikely that these chimpanzees had ever encountered humans."
The study site's history substantiates this conclusion, says Morgan. People residing in Bomassa village, the closest village at 34 miles away, claim that they had not visited the Goualougo Triangle until initial surveys were conducted in 1993 by Michael Fay, a conservationist with the New-York based Wildlife Conservation Society (WCS). At the time, Fay, who received his doctorate in anthropology from Washington University in 1997, was part of a WCS team documenting the importance of the Goualougo Triangle to conservation and science. The 100-square-mile Goualougo Triangle is on the southern end of the Nouabale-Ndoki National Park. When the park was created in 1993, the Goualougo Triangle was left out because it was a part of a logging concession.
After discovering this naive chimpanzee population and their trust in humans -- as well as having had naivecontacts with other primate species like gorillas and monkeys that would be vulnerable to poachers and logging -- Morgan and Sanz felt an obligation to ensure their long-term protection. Nave encounters with the chimpanzees put the Goualougo Triangle at the top of the WCS' list of priority conservation projects, says Morgan. The chimpanzees' unique behavior helped persuade Congolese government officials and the local logging company, which had legal rights to the forest rich in mahogany and other valuable hardwoods, to preserve the pristine habitat.
In July 2001, representatives of the WCS, Congolese government and the logging company announced during a news conference that the Goualougo Triangle was to be annexed to the park and its intact ecosystem and undisturbed animal populations would be protected forever.
Goodall visits site "Dave and Crickette's work on this chimpanzee population is simply amazing," says renowned primatologist Robert W. Sussman, Ph.D., a professor of anthropology at Washington University and Sanz and Fay's doctoral advisor. "There is no doubt in my mind that this research will lead to a much better understanding of chimpanzee ecology and behavior, and will set the stage for data collection for years to come. I also believe that this research also may lead to better models of the evolution of human evolution because these chimpanzees are so free from human interference."
Goodall, considered the world's foremost authority on chimpanzees, also found Morgan and Sanz's discovery of a naïve chimpanzee population of such great interest that she visited the site last summer. In nearly 45 years of observing chimpanzees' behavior in their environment and working to gain their trust, Goodall's visit to Goualougo Triangle was the first at another study site other than her own in the forests of the Gombe National Park. Goodall was curious to see the naive chimpanzees that she had heard showed no fear of humans as well as interested in observing how these chimpanzees differed from those living at Gombe. Within the last few years, Goodall and other researchers have been comparing chimpanzee behaviors such as tool use and social traditions that are passed on from one individual to another through social learning.
The study of these "chimpanzee cultures" was limited to sites in East and West Africa, Sanz notes, because of political instability and logistical difficulties of setting up long-term field sites in Central Africa.
"Prior to the Goualougo Chimpanzee Project," Morgan says, "there were no sites where researchers could conduct direct observations of the behavior and ecology of the central subspecies of chimpanzee residing in the largest tracts of undisturbed forest remaining in equatorial Africa."
As a result of her visit to the Goualougo Triangle -- which National Geographicmagazine covered and will feature in its April 2003 issue -- Goodall has extended her conservation efforts into Central Africa. The Jane Goodall Institute recently launched a fund-raising "Campaign to Save the Rainforest of the Congo Basin." After her visit to the Goualougo Triangle, Goodall wrote to the National Geographic Society: "This study is of the utmost importance -- it is the first such work to be undertaken in a rainforest that has not been exploited by humans, where the chimpanzees, initially, had never seen human beings. Such places are becoming increasingly rare, and the information that has already come out of the research is both fascinating and important."
"It was such an honor to have Jane Goodall in our camp," Sanz says. "Our field site is going on four years and her site has been active for that many decades! But as we enter our fourth year in the Goualougo Triangle, we have accomplished a lot within a relatively short research presence, including collecting detailed behavioral data, and beginning to describe the social structure of several communities within the study area.
"Although we will continue to census individual chimpanzees throughout the area," Sanz continues, "we hope to habituate only a few communities in the core of the study area. The other communities will be left to live their lives free from human contact"
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Oldest human footprints found Posted: Wednesday, March 12, 2003
By Dr David Whitehouse
http://news.bbc.co.uk/1/hi/sci/tech/2844287.stm
The oldest human footprints have been found in volcanic ash in Italy.
They were made by individuals scrambling down the flanks of an active volcano about 350,000 years ago.
Italian scientists, who identified three separate fossilised trackways, say the people that made them walked on two feet using their hands only to steady themselves on a difficult descent.
"They're the oldest footprints to be found of the genus Homo, the group that we belong to," the researchers told the BBC.
Commentators say the prints were probably made by Homo heidelbergensis, a forerunner of Neanderthals, that dominated Europe at this time.
'A shocking experience'
Paolo Mietto and colleagues from the University of Padua studied the trackways, known to locals as "devil's trails", and say they are particularly detailed.
The prints were found in the western margin of the Roccamonfina volcanic complex in southern Italy, in a pyroclastic flow dated between 385,000 and 325,000 years ago.
"We found three sets of footprints. One set came down in a zig-zag, while another showed that the person didn't run but walked normally," Dr Mietto told BBC News Online.
Occasional handprints are also visible, suggesting that the hands were used for steadying the individual during the steep descent, but otherwise each person walked upright.
On one of the trackways, the footprints make two sharp turns, presumably made in order to also negotiate the descent more easily.
"Finding the footprints was a shocking experience - an astounding experience because I wasn't expecting to find something like that. It was astounding because the footprints were so well preserved," said Dr Mietto.
Commenting on the discovery, Professor Clive Gamble, director of the Centre for Palaeolithic Archaeology at Southampton University, UK, told BBC News Online: "By 385,000 years ago, hominids are hunting and making really quite elaborate stone tools. But we still don't have much evidence of campsites. These were very well adapted and successful hominids."
Bipedal ancestors
The earliest hominid footprints of any kind are roughly 3.75 million years old. They are the famous Laetoli footsteps in Tanzania, discovered in 1973 by Mary Leakey.
They were made by the human ancestor known as Australopithecus afarensis. These footprints demonstrated unequivocally that our distant relatives were bipedal.
Dr Mietto said: "[The Italian footprints] are the oldest footprints to be found of the genus Homo; not as old as those found in Tanzania - but the genus Homo. The footprints in question have one unique aspect: the ones found up to now have been on flat ground and this is on a slope."
The team that found the Homo footprints do not want to debate who exactly made them. "It's outside our competence [to say whether they're our direct ancestors]," they say. "We prefer to say they're pre-Neanderthals."
The footprints - 20 centimetres in length - also suggest that the ancient travellers were diminutive in stature, with heights of less than 1.5 metres.
According to Professor Gamble, this "is interesting because the bone evidence of heidelbergensis is of a big, strapping lad 1.8 metres tall and weighing 100 kg.
"Sexual dimorphism could be an interesting factor - whether there are big differences between males and females, which you don't get with the Neanderthals that came later."
The research is published in the journal Nature.
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