Remember the hilarious 1966 film ‘One Million Years B.C.’ (http://www.imdb.com/title/tt0060782/) featuring Raquel Welch in a bear skin and her co-star John Richardson? They are portrayed having to fend off dinosaurs. Hilarious because dinosaurs became extinct 66 million years ago, whilst modern humans (‘homo sapiens’) only appeared around 200,000 years ago. So the discrepancy was a mere 65 million years! But how do we know these things?
Ann Gibbons (http://www.anngibbons.com/bio/bio.shtml) tells the story of human origins by relating the search for the earliest human. Until 17 July 1959, the conventional wisdom placed human origins in Asia. Then Mary Leakey discovered Zinjanthropus boisei, a link between Africa’s much older Australopithecans and us. In so doing she securely demonstrated the African origins of humankind. However, Potassium-argon dating came along and ‘Zinj’ suddenly became 1.75 million years old. Then mitochondrial DNA demonstrated that separation of chimps and hominids occurred somewhere between five and seven million years ago. Human palaeontologists suddenly had a lot of time to account for. Today, ‘Zinj’ is seen as an aside, a late offshoot Australopithecine not even in the direct human lineage.
Until recently, there just weren’t many three million year old hominid (https://en.wikipedia.org/wiki/Hominidae) fossils. In the early 1960s a shoebox contained the finds. Then, Donald Johnson, working in Ethiopia, found spectacular 3.1 million year old hominid remains, Meave Leakey pushed the date back to 4.1 million years, and Tim White and Gen Suwa pushed it back to 4.4 million years. Then in 1995, bones started appearing from some really odd locations, notably around Lake Chad in central Africa, and dates of five, six and even seven million years started being mentioned. The main focus of Gibbons’ book is this most recent, post-1995, period in the search for the first human. To get there she reviews the early history of the subject between the 1891 discovery of Java man and Michel Brunet’s discovery of a 3.5 million year old fossil he called ‘Abel’ in central Africa. Then it’s on to modern researchers. There is Tim White of the Middle Awash (Ethiopia) Research Group and a professor at the University of California, Berkeley. There is the Frenchman, Michel Brunet, a professor at the University of Poitiers who has heart trouble and works under impossibly difficult conditions where his tents are frequently buried in wind blown sand. There is the now retired Meave Leakey, wife of the famed Richard Leakey. There is Michael Pickford, the British born geologist who is exploring Kenya’s Tugen Hills with his French partner, Brigitte Senut.
Currently, scientists think the diagnostic human characteristic is bipedalism, and the chief contender for the first hominid seems to be Brunet’s six-to-seven million year old Sahelanthropus tchadensis from Toros-Menalla, Chad. Agreement is not universal, however. Bipedalism could be the telling characteristic, but ecologically, there’s no telling what characteristic our first human ancestors thought made mating with chimp ancestors so unattractive. It could have been the colour of their fur. With hominids this old there aren’t enough matching parts left to permit much comparison between individuals. Neither is Brunet’s Sahelanthropus tchadensis likely to be the last word on the subject. New data will emerge, new tools will analyze those data, and new theories will help explain them. In the end, however, we’ll probably never know the specific animals who took the first tentative steps away from the African bush to begin the long journey to modern day Lanark.
This is a book you would expect from an award winning science writer of uncommon skill. The bibliography is meticulous. The map, the time lines of fossil finds and of human evolution, and the glossary are all expertly presented, as are the brief biographies of the main characters.
This is a superlative effort, a book for anyone interested in human origins, or the history and practice of science. Check if this ‘must read’ book on human origins is in stock at your local library by consulting the online catalogue at https://www.sllclibrary.co.uk/cgi-bin/spydus.exe/MSGTRN/OPAC/BSEARCH
336 pages in Bantam Doubleday
First published 2006
ISBN 978-0385512268
Ann Gibbons