Where and when did our species evolve in Africa? What role did the foods our ancestor ate and cooking play in our evolution? Did the discovery of seafood play a significant, perhaps defining role? How did climate variations and geographical barriers influence where and how we evolved? Was the periodic isolation of the northern and southern tips of Africa a key driver in our cultural evolution?
How did it happen that we ended up here, with over 7 billion of us straining the planet to its sustainable limits? Human Origins provides a comprehensive chronological narrative of the major evolutionary events leading up to where we find ourselves today. The book comprises 10 chapters spanning 384 richly-illustrated pages written in a style and language that are easily accessible without ‘dumbing down’ the science behind our latest understanding of how we evolved.
The story starts with the Big Bang and the beginning of time as we know it. Although our species arrived only recently – in a blink of an eye relative to deep time, our evolutionary roots run deep as revealed in our shared, common ancestry with all life on Earth. So much about us can be traced back through eons of geological time, linking us to the diverse life forms with which we now share the planet.
Our initial breakaway from other apes is marked by when our ancestors came down from the forest trees to move over open ground on two legs as forest canopies gave way to savanna grasslands under prevailing cooler and drier climates. The major shift from bipedal apes to our earliest human (Homo) ancestors is argued to reflect the impact of highly variable climate associated with the waxing and waning of large ice sheets. Our ancestors were compelled to make stone tools, eat a greater variety of foods, take control of fire and adapt novel cooperative social behaviours to survive an increasingly unsettled world.
Human Origins focuses on the last million years and the latest evidence from fossil bones and stone tool artefacts, ancient DNA and past climates and landscapes. The integrated evidence reveals the timing, the places and possibly the reasons for past events leading to our evolution. Place matters because where we evolved, how easily we could move about and the resources available all played a role in defining who we are. Highly variable climates drove a continuous positive feedback loop in which changes in habitat forced changes in diet and tools leading to bigger brains better able to adapt to change. Many of the details remain unknown and proposed scenarios of the past remain highly contentious, but speculative scenarios allow for a piecing together of our understanding of where, when and why we evolved.
Questioning our Human Origins
Compton, John S. “Pleistocene sea-level fluctuations and human evolution on the southern coastal plain of South Africa.” Quaternary Science Reviews 30.5 (2011): 506-527.
Human Origins presents new perspectives on many aspects of our evolution:
- The evolution of our species in Africa and our relatives in Eurasia was complex and strongly influenced by the repeated expansion and contraction of populations divided by climatic and physical barriers.
- Climate variations over the tens of thousands of years associated with glacial to interglacial climate swings were particularly important at accelerating our evolution by allowing small, isolated groups to diverge significantly from larger populations who upon mixing interbred to form hybrids.
- Scavenging meat from lion kills, exploiting highly diverse aquatic foods from wetlands and the control of fire to cook foods were all major steps in accessing high-calorie foods to fuel the evolution of a big brain in our lineage.
- Rather than East Africa, our species, Homo sapiens, may have originated in the southern coastal region of South Africa as groups isolated and under pressure, and adopted a seafood diet – the ideal brain food, for the first time.
- The first appearance of symbolic artefacts at the periodically isolated far northern and southern tips of Africa indicates that these areas may have served as the initial engine rooms of our cultural evolution.
- When and by what route did our species first successfully leave Africa? Who did they encounter and interbreed with in their expansion into Eurasia? Why did we end up the only member of our human lineage left standing?
- What impacts did our expansion throughout the world have on continents such as Australasia and the Americas, which had never seen the likes of us before? Just how early on did our activities start to adversely affect the planet?
- How did farming give rise to the earliest civilisations and the accelerated development of the highly cooperative human superorganism?
- How did the Industrial Revolution propel us to where we find ourselves today? And what are possible scenarios for our immediate and more distant future? Will we continue to thrive or will we end up, along with our clever, big brains the extinct, evolutionary dead end of our lineage?
Ours is a deep, complex, incomplete and highly contentious history, but one that can enlighten us as to who we are and where we might be headed.