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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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