Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [94]
The feuds of this period are covered in detail by Virginia Morell, Roger Lewin, Jon Kalb, and Delta Willis. Alan Walker writes about the discovery of Turkana Boy in The Wisdom of the Bones (1996).
CHAPTER 12
Elisabeth Vrba, a graduate in zoology and statistics from the University of Cape Town, decided in 1968 to spice up her life as a high-school teacher in Pretoria by applying for voluntary work at the Transvaal Museum. The director, Bob Brain, an expert on South African cave fossils, gave her a pile of rocks containing antelope fossils to clean and sort. From such humble beginnings, Vrba developed an expertise on antelope species that led her to challenge standard assumptions about their evolutionary history.
Hitherto, biologists had measured evolutionary ‘success’ in terms of the number of species that a particular animal had produced. Hence, wildebeest, which had split into some forty different species during the previous 6 million years, were regarded as more ‘successful’ than impala, which had produced only one or two species. A study that Vrba conducted in Kruger National Park revealed a different perspective. Vrba noted that not only were impala there far more numerous than all the wildebeest and other antelopes combined but that their lifestyles were different. As generalists, impalas thrived in a variety of habitats, ranging from savannah to woodland, consumed most kinds of vegetation, and saw little need to migrate. Wildebeest, by contrast, were specialists, preferring to graze in dry, open savannah and willing to migrate long distances in search of a suitable niche. Specialists, she concluded, were more affected by environmental change and thus more prone to evolutionary pressures than generalists.
Vrba’s 1980 paper ‘Evolution, Species and Fossils’ gained international attention. As deputy director of the Transvaal Museum, she also became drawn into hominid studies, observing that dramatic episodes of evolutionary change in antelope history—such as occurred 2.5 million years ago—appeared to coincide with crucial events in hominid history. The common cause, she concluded, was climate change. ‘We palaeontologists saw evidence long before the climatologists found it of massive climatic change 2.5 million years ago by looking in the fossil record’.
CHAPTER 13
In The First Human (2006), Ann Gibbons follows the exploits of four teams of scientists as they raced to discover the earliest ancestor: Tim White and members of the Middle Awash Research Group in Ethiopia; Meave Leakey’s team at Kanapoi in Kenya; Michel Brunet’s Mission Paléoanthropologique Franco-Tchadienne; and Martin Pickford and Brigitte Senut, co-leaders of the Kenya Paleontology Expedition. Among Meave Leakey’s team was her daughter, Louise, a skilled palaeontologist from the third generation of Leakeys to take to the field.
In 1999, an Ethiopian expedition leader, Zeresenay Alemseged, exploring the Dikika area adjacent to Hadar, discovered the earliest and most complete afarensis juvenile yet found. He spent five years separating bones from a block of sandstone ‘grain by grain’. He named the juvenile ‘Selam’, meaning ‘peace’.
CHAPTER 14
In 1999, the fossil sites of Sterkfontein, Swartkrans, Kromdraai and the surrounding area—popularly known as ‘the Cradle of Humankind’—were declared a World Heritage Site. About 40 percent of the world’s human ancestor fossils have been found there. Opening a visitor centre in 2005, President Thabo Mbeki remarked: ‘I would ask you to be very still. If we are very still, we will hear, if we really listen, these rocks and stones speaking to us today. They are the voices of our distant ancestors, who still lie buried in them’. A collection of essays entitled Origins (2006),