Stephen Blair Hedges

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Stephen Blair Hedges
Stephen Hedges.jpg

Stephen Blair Hedges (known as S. Blair Hedges) is Laura H. Carnell Professor of Science and director of the Center for Biodiversity at Temple University where he researches the tree of life and leads conservation efforts in Haiti and elsewhere. He co-founded Haiti National Trust.


Hedges has a Bachelor of Science undergraduate degree from George Mason University, and a Masters and Ph.D. in Zoology from the University of Maryland.[1] Before he joined Temple University in 2014, he was a professor at Penn State.[1][2] He is also a founding member of the NASA Astrobiology Center. He has published over 277 peer-reviewed works including 8 books and monographs.[3] He was elected as a fellow of the American Association for the Advancement of Science in 2009 for "revealing connections between biological evolution and Earth history in diverse groups of organisms",[4] and was awarded the 2011 Penn State Faculty Scholar Medal for Outstanding Achievement in the Life and Health Sciences.[5]


Hedges has studied the relationships and timing of major groups in the tree of life using genomic data.[1] This research has led to a number of discoveries including an early origin for the orders of placental mammals and modern birds,[6][7] estimates of when prokaryotes and eukaryotes first colonized land and its relevance for the planet,[8][9] and the phylogenetic relationships of reptiles and insectivorous mammals.[10][11][12][13] He has coined the word timetree for a phylogenetic tree scaled to time, co-founded the TimeTree database for exploring the time-scale of the tree of life, and co-edited the book Timetree of Life.[14] Hedges and his team produced a spiral tree of life in 2015 to visualize the relationships over time of 50,000 species, and discovered that diversification and speciation are both relatively constant through time and among groups.[15]

Hedges also has a field program in the Caribbean where he has studied the evolution and biogeography of amphibians and reptiles with genetic data and maintained a database of information on these species, CaribHerp. He discovered many new species in his work and has so far named 124 species of reptiles, amphibians, and butterflies. He also described three of the smallest species of reptiles and amphibians, including the Monte Iberia dwarf frog (Eleutherodactylus iberia)[16], Jaragua gecko (Sphaerodactylus ariasae), and the Barbados threadsnake (Tetracheilostoma carlae). Eleven articles in the New York Times have described his research [17]


Work by Hedges and his team in Haiti has defined hot spots of biodiversity leading to the establishment of three national parks in Haiti. He also initiated a captive breeding program to conserve ten endangered species of frog at the Philadelphia Zoo.[18] Together with Haitian CEO Philippe Bayard, he founded Haiti National Trust, an environmental protection NGO.

Personal life[edit]

Hedges is interested in Renaissance art, which led him to conduct several scientific studies of early artwork, including the development of a method for dating old prints[19] and a study on the historical biogeography of beetles based on the holes they bored in old books.[20]


  1. ^ a b c "Hedges Lab - Evolutionary Biology". Retrieved 2017-04-20.
  2. ^ "Meet CST'S New Faculty Members". College of Science and Technology, Temple University. 2014. Retrieved March 20, 2015.
  3. ^ "Blair Hedges awarded Faculty Scholar Medal". Department of Biology, Penn State. March 17, 2011. Retrieved March 20, 2015.
  4. ^ "AAAS Members Elected as Fellows". AAAS. December 18, 2009. Retrieved March 20, 2015.
  5. ^ "Blair Hedges awarded Faculty Scholar Medal — Penn State University Department of Biology". Retrieved 2017-04-20.
  6. ^ Hedges, S. B.; Parker, P. H.; Sibley, C. G.; Kumar, S. (1996-05-16). "Continental breakup and the ordinal diversification of birds and mammals". Nature. 381 (6579): 226–229. Bibcode:1996Natur.381..226H. doi:10.1038/381226a0. ISSN 0028-0836. PMID 8622763.
  7. ^ Kumar, S.; Hedges, S. B. (1998-04-30). "A molecular timescale for vertebrate evolution". Nature. 392 (6679): 917–920. Bibcode:1998Natur.392..917K. doi:10.1038/31927. ISSN 0028-0836. PMID 9582070.
  8. ^ Battistuzzi, Fabia U.; Hedges, S. Blair (2009-02-01). "A major clade of prokaryotes with ancient adaptations to life on land". Molecular Biology and Evolution. 26 (2): 335–343. doi:10.1093/molbev/msn247. ISSN 1537-1719. PMID 18988685.
  9. ^ Heckman, D. S.; Geiser, D. M.; Eidell, B. R.; Stauffer, R. L.; Kardos, N. L.; Hedges, S. B. (2001-08-10). "Molecular evidence for the early colonization of land by fungi and plants". Science. 293 (5532): 1129–1133. doi:10.1126/science.1061457. ISSN 0036-8075. PMID 11498589.
  10. ^ Hedges, S. B.; Poling, L. L. (1999-02-12). "A molecular phylogeny of reptiles". Science. 283 (5404): 998–1001. Bibcode:1999Sci...283..998B. doi:10.1126/science.283.5404.998. ISSN 0036-8075. PMID 9974396.
  11. ^ Vidal, Nicolas; Hedges, S. Blair (2005-10-01). "The phylogeny of squamate reptiles (lizards, snakes, and amphisbaenians) inferred from nine nuclear protein-coding genes". Comptes Rendus Biologies. 328 (10–11): 1000–1008. doi:10.1016/j.crvi.2005.10.001. ISSN 1631-0691. PMID 16286089.
  12. ^ Stanhope, Michael J.; Waddell, Victor G.; Madsen, Ole; de Jong, Wilfried; Hedges, S. Blair; Cleven, Gregory C.; Kao, Diana; Springer, Mark S. (1998-08-18). "Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals". Proceedings of the National Academy of Sciences of the United States of America. 95 (17): 9967–9972. Bibcode:1998PNAS...95.9967S. doi:10.1073/pnas.95.17.9967. ISSN 0027-8424. PMC 21445. PMID 9707584.
  13. ^ Fry, Bryan G.; Vidal, Nicolas; Norman, Janette A.; Vonk, Freek J.; Scheib, Holger; Ramjan, S. F. Ryan; Kuruppu, Sanjaya; Fung, Kim; Hedges, S. Blair (2006-02-02). "Early evolution of the venom system in lizards and snakes". Nature. 439 (7076): 584–588. Bibcode:2006Natur.439..584F. doi:10.1038/nature04328. ISSN 1476-4687. PMID 16292255.
  14. ^ Blair., Hedges, S.; 1967-, Kumar, Sudhir (2009-01-01). The timetree of life. Oxford University Press. ISBN 978-0199535033. OCLC 268792961.
  15. ^ Hedges, S. Blair; Marin, Julie; Suleski, Michael; Paymer, Madeline; Kumar, Sudhir (2017-04-20). "Tree of Life Reveals Clock-Like Speciation and Diversification". Molecular Biology and Evolution. 32 (4): 835–845. arXiv:1412.4312. doi:10.1093/molbev/msv037. ISSN 0737-4038. PMC 4379413. PMID 25739733.
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  18. ^ Mihelich, Peggy (January 4, 2012). "Blair Hedges is saving Haiti's endangered frogs". AAAS MemberCentral. Retrieved March 20, 2015.
  19. ^ O'Connell, Frank (July 25, 2006). "SCIENCE ILLUSTRATED; Old, but Just How Old? Making Early Prints Give Up Their Secrets". New York Times. Retrieved October 3, 2016.
  20. ^ Bhanoo, Sindya (November 26, 2012). "In Art Prints, Clues to Beetles in Europe". New York Times. Retrieved October 3, 2016.

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