by Clive Gamble
It’s a difficult question. Why did earliest man leave Africa and migrate to new areas. Mostly, animals evolve suited to their environment and they don’t stray far. They may have several areas they frequent, but they return to each, not leave them entirely.We had already accommodated ourselves to ravel more than 12 kilometers for raw materials, which is less than modern hunter-gatherers, but more than other primates.
For modern man to leave Africa, an environ for which he was quintessentially suited with his lack of hair and omnivorous appetite, and go to areas that were colder and populated with unfamiliar foods was a leap. there are a few postulates that make sense:
- A shift toward meat eating. The animals available in Africa were familiar with the crafty humans, so might be adept at avoiding us or preying on us. Migrating to areas that had no knowledge of our thinking ways and our Acheulian tools might explain how humans managed to survive outside of Africa,
- They were following herds of animal north. Vrba also has shown that some six species of African bovids, a relatively large number for any period, dispersed to Eurasia during the Middle Pliocene (man dispersed in the Plio-Pleistocene first and several times after that. Modern man left over 100,000 years ago, during the Pleistocene). The dispersal of large bovids is especially interesting because their shift from the forest to the open resembles that hypothesized for the hominids. Moreover, since open-country bovids could have been hunted or scavenged by Homo, the two groups may have emerged and dispersed together.
- A biographic event in which a new niche for large carnivores induced hominids, along with the lion, leopard, wolf and hyena, to exploit a new abundance of grazing animals in Eurasia
- Wanderlust–a need to know what lay beyond that hill or river or tall savanna grass.
- A need for change
- We had become equipped for long-distance travel with our long rangy human-like body. This equipped us for long distance travel, such as the steady migration beyond Africa.
- The larger body size of each successive Homo species required:
- Greater home range
- More food requirements
- Lower population density
- Increased strength and speed, that made them more predator resistant and avoidant, gave them increased longevity with allowed increased reproductive span
- Marge body size allowed more flexibility with temperatures, able to adapt to a greater temperature range—maybe why they could leave Africa for colder climates
- Larger size made them less susceptible to predators—too big to be appealing to the typical predator that traveled alone
Gamble explores this migration in Timewalkers: the Prehistory of Global Colonization. He discusses not only the logistics of mankind’s ability to do what no other species ever did, but why we would. Why go to climates too cold to survive without fur, forcing us to invent clothing? Why go to the edge of land abutting not just a lake, but full-blown oceans (like what lay between Indonesia and Australia) when we didn’t know how to sail? We didn’t just follow one path out of Africa, but exploded throughout the world, crossing oceans, seas, lakes, deserts, mountains, valleys–whatever was in our way, in an effort to get to the horizon. Along the way, we developed civilization, religion, culture, the ability to specialize in our jobs and generalize in our survival.
Gamble covers these interesting questions with clarity and humor (at times). Some quotes I like from the book:
- I will show how prehistory contributes new knowledge about ourselves through the study of a shared past
- An alternative, as Stephen J. Gould and Elizabeth Vrba have argued, is to acknowledge that not all features are currently adaptive. They are instead the source for future change.
- But more important is the active role of climate for shaping our society
- subsequent improvements in genetic mapping of these sister species (of man) have shown that chimps and humans are considerably closer to each other than either is to the gorilla.
- since behavior rather than taxonomy is my main interest, I need an account of the fossil record which takes notice of space and time in the distribution of the earliest timewalkers. This will allow for investigation of how behavior developed and the contexts which selected for its change.
- A great deal has been written about the advances this large brained hominid is supposed to represent… For a long time technology (stone tool use) did not lead to any appreciable extension of range.
- due to a set of evolutionary opportunities…all timewalkers (what Gamble calls man’s migration from Africa) have the necessary elements, such as big feet, which make them fit for, rather than fitted to, expansion
- the body is an excellent medium for communication. It commands respect through size and condition and relates to the optimum use of resources. The foraging success of individuals as fusion of the group’s members occurred will be all too apparent.
A bit of background on Dr. Clive Gamble from his staff page at Royal Holloway University of London:
… He is Professor of Geography at Royal Holloway, University of London and a member of the Centre for Quaternary Research and an archaeologist with a particular interest in our earliest origins and the evolution of human society. He has undertaken research in many parts of the world to answer the question; when and why did we become the only human species to achieve a global distribution? The answer combines quaternary science, and its insights into changing climates and resources, with an understanding from archaeological evidence of how our social lives developed over the past two million years. Clive has written three books exploring these questions.