By Nizamuddin Siddiqui
THE BUGTI HILLS of Balochistan - which have already given us Baluchitherium, the largest land mammal ever discovered, and Bugtilemur, the oldest fossilized lemur - have now turned the theory on its head that deals with the origin of primates, the group of creatures to which human beings belong. The widely accepted "Out of Africa" theory has it that primates originated on the African continent and it was there that the first human beings arose. However, work carried out by a group of French and Pakistani palaeontologists has shown that primates lived in South Asia some 30 million years ago. Previously it was thought that at that point in time the region was devoid of stem anthropoid families, owing to "drastic climatic deterioration."
The revelation came in the shape of a stunning discovery of three anthropoids - named Bugtipithecus inexpectans, Phileosimias kamali and Phileosimias brahuiorum. The creatures were small and similar to modern lemurs.
The discovery of three new species dating back to Oligocene (the period between 30 and 25 million years from now) has been accorded due recognition by the Proceedings of the National Academy of Sciences of the United States of America (PNAS), which is published by the National Academy of Sciences (of the US). The prestigious publication’s early edition, released on June 3, breaks the story with a paper - entitled "Anthropoid primates from the Oligocene of Pakistan (Bugti Hills): Data on early anthropoid evolution and biogeography" - which has been written, among others, by Laurent Marivaux and Pierre-Olivier Antoine of the Institute of Evolutionary Science, Montpellier II University, France, and S. Rafiqul Hassan Baqri of the Pakistan History of Natural History, Islamabad.
Many well-known news organizations too have hailed the discovery as an important breakthrough. Prominent among these are The Guardian, Discovery News and Australian Broadcasting Corporation.
In its section captioned "Discussion and Conclusions", the aforesaid research paper says: "Until recently, the Oligocene in southern Asia remained undocumented palaeontologically. The discovery of a diverse primate fauna in early Oligocene coastal deposits from Pakistan. has revealed an extensive radiation of primates in South Asia, whereas primate communities otherwise disappeared across the Holarctic continents at that time. .
"Assuming this clade to be the Anthropoidea clade, from the present evidence, eosimiids and amphipithecids (and by extension Phileosimias and Bugtipithecus, respectively) are stem anthropoids, and as such, support the hypothesis that Asia was the ancestral homeland of the Anthropoidea clade."
The lead author of the paper, Dr Laurent Marivaux, told Sci-tech World that the discovery was unexpected. In response to one of the questions sent to him via email he wrote: "The discovery of anthropoid primates from the Oligocene (about 30 million years old) was somewhat surprising and very exciting! It was generally hypothesized that the Eocene Asian stem anthropoid families. may have left no descendent in Asia after the drastic climatic deterioration characterizing the late Eocene-early Oligocene interval, which was seemingly lethal for primate communities elsewhere across the Holarctic continents. So, you can understand our surprise in discovering an important primate community in South Asia at that time."
The French palaeontologist claimed that the discovery made at Paali Naala in Bugti Hills of the species that belonged to the group of "our oldest cousins", substantiated the "Out of Asia" theory. He, however, added that the discovery pertained to a period that came millions of years prior to the appearance of early man. Nevertheless, it involved early primates - the group from which the human beings later arose. Admittedly, therefore, the discovery didn’t relate to early man directly. But it surely concerned his ancestors.
"We must keep in mind that our discovery from the Oligocene of Pakistan is far from the human origin. The evolutionary history of humans is much more recent and our discovery has no direct implications on that account. The fossils of the human lineage are so far exclusively from Africa.
"The human lineage belongs to the anthropoid tree, but it represents one of the last and recent branches of this tree. Our discovery concerns the early branches of the anthropoid tree. The evolutionary history of these old anthropoid lineages represents the beginnings of the evolutionary history of humans," he explained.
About the newly discovered creatures, Dr Marivaux said: "(T)hese new fossil species lived in forests, they were probably nocturnal and they probably ate insects and fruits as their modern counterparts, which have similar size and exhibit a similar dental morphological pattern.
"Small primates are confined mostly to tropical or subtropical forests and are highly sensitive to environmental changes. You can easily imagine the palaeoenvironmental conditions in which these small-bodies primates evolved: seemingly a tropical rainforest with warm and humid conditions."
Meanwhile, according to the paper published in PNAS, the genus name used by the palaeontologists honours the Bugti tribe. One of the newly found species - Phileosimias kamali - has been so named to acknowledge the help a Pakistani journalist extended in organizing expeditions to the fossil-rich area, while the name Phileosimias Brahuiorum honours all people who speak Brahui, the second language of Balochistan.
The following are some excerpts from the research paper, which further describe the newly discovered creatures.
Bugtipithecus inexpectans
"Diagnosis: Small-bodied amphipithecid, similar in size to the modern mouse lemur Mirza coquereli. Body-mass estimate of 350g is based on M area (from all primate least-squares regression equation). For hypodigm, description and metrics, see supporting information on the PNAS website."
Phileosimias kamali
"Diagnosis: Differs from the Phileosimias brahuiorum in being slightly larger, in showing more triangular and distally waisted upper molars. Body-mass estimate of 250g based on M area."
Phileosimias brahuiorum
"Diagnosis: Differs from Phileosimias kamali in having upper molars with more rectangular and transverse outline, better development of buccal and lingual cingula. ."
The writer heads the Sci-tech World team
Troubles stop research work
THE FRENCH team led by Dr Jean-Loup Welcomme, which has made startling discoveries in the shape of Bugtipithecus and Baluchitherium, planned to carry out further research in Balochistan earlier this year, but due to unfavourable political climate decided against mounting an expedition.
According to Dr Laurent Marivaux, the work will resume as soon as the situation improves. "We had planned to work in the Bugti Hills in February-March 2005. But the political situation forced us to cancel the mission," he told Sci-tech World.
"The mission is postponed to next spring or next spring (2006)." He added that Bugti Hills were nothing but a treasure trove for palaeontologists. "This area is famous for having produced the richest tertiary faunas to be found in Asia thus far.
"Even if the conditions of fieldwork are difficult. the fossils are extremely interesting and all are new to science. We are delighted and privileged to work in such an area."
Dr Marivaux pointed out that the palaeontological record of South Asia was incomplete because very few scientists had worked in the region. It was important, therefore, that research work in Balochistan was resumed as soon as possible.
- Nizamuddin Siddiqui
http://www.dawn.com/weekly/science/science3.htm
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