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Human and Primate
Evolution
My primary interests in the study of primate evolution are in the
discovery of the history of primate lineages and the illumination of the
lifestyles of extinct primate species, as revealed by the integration of
paleoenvironmental and paleontological data. This area of research is
broad, and comprises basic research in and integration of data from
systematic biology, functional and comparative anatomy, and
paleoenvironmental reconstruction.
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Evolution of Old
World Monkeys
The Old World monkeys (Superfamily Cercopithecoidea) comprise one of the
geographical widespread and diverse lineages of primates that has ever
existed. Although their evolutionary history dates back to the early
Miocene, evidence of Old World monkeys becomes common in the fossil
record only in the latest Miocene and Pliocene. The fossil record of the
group in Africa is particularly rich and well-dated. My research has
concentrated on illumination of the evolutionary history of the
Theropithecus lineage. My research on the evolution of the snub-nosed
monkeys of East Asia has led me to have a strong interest in the
evolution of the colobine monkeys, especially in the significance of
ruminant digestion in that group.
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Evolution of Bipedalism in
the Human Lineage
The evolution of habitual bipedal posture and locomotion is considered
the key innovation which distinguishes the human lineage. Despite its
importance, our knowledge of the processes leading to the emergence of
habitual bipedalism remain remain unclear, largely because the behaviors
that provided the impetus for this momentous change were not preserved in
the fossil record. My research on the evolution of human bipedalism and
its ramifications has been done mostly in collaboration with George
Chaplin. The premise of our research has been that the behaviors leading
to the regular adoption of bipedal postures in pre-humans must have
conferred considerable reproductive success to individuals engaging in
those behaviors. Behaviors that were common (e.g., feeding, resting,
sleeping) are not necessarily important in terms their impact on
reproductive success. For this reason, our research has emphasized the
importance of bipedal displays and appeasement postures in the evolution
of habitual bipedalism in human ancestors. These behaviors are important,
especially in our closest African ape relatives, in determining the
outcomes of agonistic encounters and of disputes over mating access in
females.
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Evolution of Human Skin
Coloration
Research on the evolution of skin color in humans was avoided by
scientists for many years. Skin color is worthy of scientific
investigation, however, because it is the product of over five million
years of evolution in the human lineage, it the most obvious
characteristic in which people vary in their appearance, and it is of
great social importance. My research on the evolution of human skin and
skin color, done mostly in collaboration with George Chaplin, has
demonstrated that skin color is the product of natural selection acting
to regulate levels of melanin pigment in the skin relative to levels of
ultraviolet radiation (UVR) in the environment. Melanin is a natural
sunscreen that prevents the breakdown of certain essential biomolecules
(in particular, the B vitamin folate, and DNA), while permitting enough
UVR to enter the skin to promote the production of essential vitamin D.
In October 2006, Nina Jablonski's new book, Skin: Its Natural
History, will be released by the University of California Press. For
more information, see their website at http://www.ucpress.edu/books/pages/10283.html
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Evolution of
Environments and Mammalian Faunas of East Asia
The existence of paleoenvironmental information derived from
geological, geochemical, and paleobotanical data from Tertiary and
Quaternary sites in eastern Asia permits paleontologists great
opportunities to reconstruct the history of faunas in relation to the
history of environmental change. When faced with environmental changes,
animals can migrate, adapt to changing conditions or go extinct. We find
evidence of all three scenarios in the history of primates in East Asia
in the last two million years. One of the projects in which I am
currently involved is a paleontological survey of the large vertebrates
of the remote and isolated Gaoligong Mountains in western Yunnan Province
in China. This effort is part of a major biodiversity survey of the
region funded by the National Science Foundation and spearheaded by
scientists from the California Academy of Sciences.
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RESEARCH NEWS
Panda Bones in a Chinese Sinkhole
In November 2005, as part of the Academy's Gaoligong Shan
Biodiversity Project, Nina Jablonski led a team of investigators on
explorations of fossil-bearing karst cave and sinkhole sites in western
Yunnan Province. The team worked three sites, one of which was the deep
sinkhole at Jiangdongshan. This natural well yielded a rich cache of
bones, including the remains of the giant panda, rhinoceros, and other
large mammals -- all animals, which had accidently fallen into the hole
over the last few hundreds of years.
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First Fossil Chimpanzee
On September 1, 2005, a description of the first chimpanzees to be
recognized in the fossil record was published in Nature, in a
co-authored paper by Sally McBrearty (University of Connecticut) and Nina
Jablonski. The fossils, from the Kapthurin Formation in Kenya, show that
representatives of chimpanzee (Pan) were present in the East
African Rift Valley during the Middle Pleistocene, where they were
contemporary with an extinct species of Homo. Habitats suitable
for both hominins and chimpanzees were clearly present there during this
period, and the Rift Valley did not present an impenetrable barrier to
chimpanzee occupation. Read the abstract of the Nature paper at: http://www.nature.com/nature/journal/v437/n7055/abs/nature04008.html |
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