The Five Million Year Odyssey
Princeton University, $29.95
Archaeologist Peter Bellwood’s academic odyssey has spanned from England to teaching posts halfway around the world, first in New Zealand and then Australia. For more than 50 years, he has studied how humans colonized islands from Southeast Asia to Polynesia.
So it’s only fitting that his new book, a plain English summary of what’s known and what isn’t about the evolution of humans and our ancestors, emphasizes movement. In The Five Million Year OdysseyBellwood examines a parade of species in the human evolutionary family – he refers to them collectively as hominins, while others (including Scientific News) use the term hominids (SN: 09/15/21) – and tracks their migrations across land and sea. It gathers evidence indicating that moving hominids continually changed the direction of biological and cultural evolution.
Throughout her tour, Bellwood presents her own take on contested topics. But when the available evidence leaves a debate unresolved, he says so. Consider the first hominids. Species at least 4.4 million years old or older whose hominid status is controversial, such as Ardipithecus ramidus, get a brief mention. Bellwood makes no verdict on whether these finds are from ancient hominids or ancient apes. Rather, it focuses on African australopithecines, a collection of erect but partly ape-like species thought to have included populations that evolved into members of our own genus. Homo, about 2.5 to 3 million years ago. Bellwood insists that the manufacture of stone tools by the last Australopithecines, the first Homo groups or both contributed to the evolution of larger brains in our ancestors.
The action picks up when homo erectus became the first known hominid to leave Africa, around 2 million years ago. Questions remain, writes Bellwood, about the number of such migrations and whether this human species reached distant islands such as Flores in Indonesia, possibly giving rise to small hominids called hobbits, or Homo floresiensis (SN: 03/30/16). What is clear is that H. erectus groups traveled across mainland Asia and at least as far as the Indonesian island of Java.
Intercontinental migration flourished after Homo sapiens originated about 300,000 years ago in Africa. Sincerely Bellwood H. sapiens, Neanderthals and Denisovans as separate species that interbred in parts of Asia and Europe. It suggests that Neanderthals died out around 40,000 years ago as they mated with members of more H. sapiens populations, leaving a genetic legacy in people today. But it does not address an opposing argument that different Homo populations at this time, including Neanderthals, were too closely related to have been separate species and that it was intermittent mating among these mobile groups that drove the evolution of present-day humans (SN: 05/06/21).
Bellwood pays considerable attention to the rise of food production and domestication in Europe and Asia after about 9,000 years. He relies on an argument, taken from his 2004 book Early farmers, that the expanding populations of the early cultivators migrated to new lands in such numbers that they spread with them large linguistic families. For example, farmers in what is now Turkey spread Indo-European languages across much of Europe around 8,000 years ago, Bellwood claims.
He rejects a recent alternative proposal, based on ancient DNA evidence, that horse herders of the Yamnaya culture from Central Asia brought their Indo-European traditions and languages to Europe around 5,000 years ago (SN: 11/15/17). Too few Yamnaya have immigrated to impose a new language on European communities, says Bellwood. Likewise, he argues, ancient Eurasian conquerors, from Alexander the Great to Roman emperors, could not get speakers of regional languages to adopt new languages spoken by their outnumbered military masters.
Bellwood completes his evolutionary odyssey with a reconstruction of how early agricultural populations developed across East Asia and beyond, to Australia, a chain of Pacific islands, and the Americas. Around 4,000 to 750 years ago, for example, sea farmers spread the Austronesian languages from southern China and Taiwan to Madagascar in the west and Polynesia in the east. Exactly how they accomplished this remarkable feat remains a puzzle.
Unfortunately, Bellwood does not weigh in on a recent archaeological argument that ancient societies were more flexible and complex than long thought (SN: 09/11/21). On the positive side, its evolutionary odyssey is moving at a steady pace and, like our ancestors, covers a lot of ground.
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