Choosing One's Relatives
A New Human: The Startling Discovery and Strange Story of the "Hobbits" of Flores, Indonesia. Mike Morwood and Penny van Oosterzee. xiv + 256 pp. Smithsonian Books, 2007. $25.95.
The discovery of a new hominin species in human ancestry is always exciting, never more so than when it is completely unexpected. And certainly no one anticipated that the fossil remains of such a species would be found in 2003 in Liang Bua, a limestone cave on the Indonesian island of Flores. But that year a team of archaeologists, anthropologists and geologists from Australia and Indonesia working at Liang Bua uncovered the bones of a tiny woman, whom they eventually concluded was a hominin of a new species, Homo floresiensis. That bold claim has ignited considerable controversy among paleo-anthropologists.
Now one of the members of the team that found the specimen, Mike Morwood, has written a book titled A New Human, with science writer Penny van Oosterzee as coauthor. Their fascinating account of how the large-scale, multidisciplinary excavation was set up and run shows just how such an investigation should be conducted. They cover everything: the preliminary groundwork to find out who has to be approached to get permissions, with all the politics and administrative matters that are an unavoidable adjunct to such forms of scientific inquiry; the actual business of excavation and the dating of the deposit; and finally, the process of publishing a description of the fossils and their context. Anyone thinking of undertaking such a project would do well to consult this book.
Two years of excavation at Liang Bua turned up not just the early human skull the team had been hoping to find but nearly the whole skeleton that went with it. The discoveries were so significant that they generated massive media attention. What is it about the Flores woman (nicknamed "Hobbit") that is so important?
First of all, she lived relatively recently—only 18,000 years ago. Other fossils found subsequently show that similar beings lived on Flores up to 95,000 years ago.
Second, there is controversy over how she should be classified. She has been assigned to a new species of the genus Homo, but at 380 cubic centimeters, her brain would have been only about one-third as large as that of a modern human. Brain size is usually considered one of the defining attributes of humans, and prior to the discovery of the Flores woman, the smallest skull to have been classified as belonging to the genus Homo indicated a brain size of 500 cubic centimeters. The choice then was either to change the criteria for Homo to include a brain size as small as Hobbit’s or to exclude her from the genus. Not surprisingly, there was some disagreement among team members over which of these options to choose, and the article they submitted to Nature initially put her in a separate genus. But the scientists who refereed the article encouraged them to assign her to Homo, and ultimately they did so.
Third, although the Flores woman was only about one meter in height, she was clearly bipedal, walking upright on two legs. Her limb proportions differ from those of modern humans: She had short legs, relatively long arms, and uniquely long feet puzzling to scientists.
Finally, the circumstances of her discovery—that she was found on an island where there is evidence of dwarfing of associated animals such as the proboscidean Stegodon—are significant. They suggest that many of her attributes, particularly her small stature and shortened but very robust legs, may have been the product of island dwarfism—the phenomenon of animals isolated on remote islands evolving to have body sizes much smaller than those of their recent ancestors. (There is also an inverse form of the process, in which small animals breeding in isolation become larger.)
All this evidence provides the basis for rich scientific discussion, and there has indeed been extensive debate. Along with it has come the predictable outcry against the unexpected.
Scientific method rests on acquiring and organizing information about the natural world and making it available to others. This depends on asking relevant questions, using appropriate methods to find the answers, publishing the results in scholarly journals and making the material studied available for independent testing. As described in A New Human, the research on the Flores woman carried out by the team who found her has followed this procedure to the letter. Their findings have inspired an impressive amount of critical but informed discussion, with many possible alternative interpretations being aired.
Unfortunately, because other people wanted to get in on the act, departures from the scientific method occurred after the Nature article was published. Most notably, Teuku Jacob, an Indonesian anthropologist who was not a member of the team, precipitously removed the skull, lower jaw and femur of the Flores woman, along with another lower jaw found at Liang Bua, from the lab where they were being kept. He then restricted access to the specimens and dismissed them as the remains of modern humans with the pathological condition known as microcephaly. According to Morwood and Oosterzee, Jacob essentially hijacked the remains, claiming falsely that Morwood had agreed to their transfer. The authors also complain that when Jacob finally returned the fossils, the bones had been mishandled and irreparably damaged.
Whatever* the process by which Jacob arrived at his conclusion, it remains the case that if his hypothesis were to be proved correct, the Flores hominins would not have any evolutionary significance. On the other hand, history tells us that similarly negative reactions have greeted other unexpected hominin fossils, such as the first Neandertals found in the 19th century and the first australopithecine in the early 20th century.
This well-written, entertaining book is both scholarly and accessible to the general public. Morwood and Oosterzee make the case that the Flores hominins occupy a unique position in human evolution. The authors counter some but not all of the evidence for microcephaly. Chapter 3 contains an interesting but short account of the faunal movements across Indonesia during the Pleistocene, especially with reference to the Wallace Line along the eastern edge of the Asian continental shelf, to the west of which are found Asiatic species, and to the east, mostly Australian ones. Oceanic barriers and climate change had an immediate impact on those movements. Morwood and Oosterzee subscribe to the belief that in the past, cooler periods coincided with reduced precipitation; however, present-day climatologists are predicting that in tropical environments, drier climates and loss of rain forest will be associated with global warming, not cooling. Which view is correct? The authors also rely on the now-outdated savanna hypothesis, which posited that early hominins evolved when the replacement of African forests by savanna grasslands made upright walking advantageous. In fact, evidence is increasing that early hominins evolved and lived for quite some time in woodland environments.
Scientists working in Asia have a natural tendency to assign greater importance to their fossils than to those found in Africa (as Eugène Dubois notoriously did with his 1891 discovery of Pithecanthropus erectus in Java). So it is unsurprising that Morwood and Oosterzee devote chapter 6 to showing that the genus Homo may have originated in Asia, rather than Africa as is generally believed. They claim that Homo ergaster in Africa had no known ancestry, and they assert that populations of hominins emigrating from Africa to Indonesia around 1.8 million years ago encountered "other" hominins already resident in eastern Europe and the Middle East. However, no information is provided (because none is yet available) as to the origin of these "other" hominins. And the evolutionary pedigree of ergaster is, in fact, well documented in the African fossil record, as indeed is acknowledged later in this book.
The Flores discovery, although it throws no light on this particular issue, opens up many new lines of inquiry as to the nature of human evolution. I am sure it will not be the last surprise to come in the ambitious project of investigating our origins.
* Editor's Note: This word replaces text in the printed review that left an impression unintended by the reviewer and the editors.