the past. Although agriculture may have aris- en there over 6500 years ago, highland New Guinea societies are still relatively egalitarian and characterized by “big men,” whose influ- ence is largely persuasive and consensual. The evidence for early agriculture from high- land New Guinea signifies the potential di- versity of prehistoric trajectories after the inception of agriculture and challenges uni- linear, often teleological, interpretations of human prehistory.
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T.P.D. directed the multidisciplinary research and conducted the archaeological, pedological, and sedimentological investigations. S.G.H. undertook pollen and charcoal particle identifications and counts. C.L. undertook phytolith identifications and counts, with an emphasis on Musa spp. R.F., J.F. and
T. undertook starch grain analysis of stone tool residues. N.P. undertook insect identifications.
W. undertook diatom identifications and counts.
The authors are indebted to J. Golson for his generous assistance and encouragement during ev- ery stage of the work documented here and for unfettered access to the site archive for the 1970s investigations. J. Golson, G. Hope, M. Spriggs, S. Blau, and anonymous reviewers are thanked for their comments on a draft manuscript. T.P.D. ac- knowledges scholarships and a fieldwork grant from the Australian National University (ANU) and grants from the Australia-Pacific Science Founda- tion (awarded to J. Golson in 1998 and 1999) and the Pacific Islands Development Program (1999). S.G.H. completed this work while on an Australian Research Council QEII Fellowship. C.L. acknowledg- es a scholarship from Southern Cross University and grants from the Pacific Biological Foundation (2002) and Australian Museum. The Centre for Archaeological Research at ANU, Australian Nucle- ar Science and Technology Organisation, and Re- search School of Earth Sciences, ANU (courtesy of J. Chappell) provided radiometric age determina- tions. Thanks are due to K. Dancey, R. Patat, and A. and C. Rohn for their assistance with the graphics. Current studies were made possible with the per- mission and assistance of the Papua New Guinea National Museum and Art Gallery, National Re- search Institute, Western Highlands Provincial Government, and the Kawelka at Kuk.
Supporting Online Material www.sciencemag.org/cgi/content/full/1085255/DC1 Tables S1 to S3 References
2 April 2003; accepted 16 May 2003 Published online 19 June 2003; 10.1126/science.1085255 Include this information when citing this paper.
A Young White Dwarf Companion to Pulsar B1620-26: Evidence for Early Planet Formation
Steinn Sigurdsson,1* Harvey B. Richer,2 BradM. Hansen, IngridH. Stairs, 2 Stephen E. Thorsett4
The pulsar B1620-26 has two companions, one of stellar mass and one of planetary mass. We detected the stellar companion with the use of Hubble Space Telescope observations. The color and magnitude of the stellar com- panion indicate that it is an undermassive white dwarf (0.34 0.04 solar mass) of age 480 106 140 106 years. This places a constraint on the recent history of this triple system and supports a scenario in which the current configuration arose through a dynamical exchange interaction in the cluster core. This implies that planets may be relatively common in low-metallicity globular clusters and that planet formation is more widespread and has hap-
pened earlier than previously believe
Messier 4 (M4 equals NGC 6121 and GC 1620264) is a medium mass [105 solar mass (MJ)] globular cluster and the one clos- est to the Sun. It has a moderately dense (0 3 104 MJ pc3) core. The metal content of the cluster is 5% that of the Sun, with little variation in composition or age
between different member stars. The cluster has a substantial population of white dwarfs (stellar remnants which have exhausted their nuclear fuel), recently detected in deep Hubble Space Telescope (HST) observations (1, 2), that have been used to determine an age for the cluster of 12.7 109 0.35
109 years. Furthermore, M4 contains the bi- nary radio pulsar PSR B162026 (3, 4), a recycled millisecond pulsar with a P 11 ms rotation period and a companion in a low ec- centricity (e 0.025) orbit with an orbital period of 191 days. For an assumed pulsar mass of 1.35 MJ, radio timing observations constrain t h e c o m p a n i o n m a s s t o b e M c 0 . 2 8 M J / ( s i i), where i is the unknown inclination of the binary orbital plane to the line of sight (5, 6). The pulsar also possesses an anomalously large second time derivative of the rotational period n
¨ (P) (7, 8), seven orders of magnitude larger than
that expected from the intrinsic pulsar spin- down and of the wrong sign. When discovered, the pulsar had a characteristic spin-down time
1525 Davey Laboratory, Department of Astronomy, Pennsylvania State University, University Park, PA 16802, USA. 2Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1, Canada. 3Department of Physics and Astronomy and Institute of Geology and Planetary Physics, University of Cali- fornia at Los Angeles, Math-Sciences 8971, Los Ange- les, CA 90095–1562, USA. 4Department of Astrono- my and Astrophysics, University of California, Santa Cruz, CA 95064, USA.
*To whom correspondence should be addressed. E- mail: firstname.lastname@example.org
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