Animal evolution involves genetic change, and this is how modern humans evolved from their ancestors. These modern humans appeared around 20,000 years ago, and, according to recent research subsequent changes owe more to cultural transmission than any biological changes.
Modern Humans
Homo sapiens sapiens (the subspecies usually known as ‘Modern Man’) probably originated in Africa around 200,000 years ago. Biologically they were the same as any humans alive today, and the earliest used stone tools much as their ancestors had.
Stone Ages of Man
Humans, and pre-humans, have made and used stone tools for 99% of human history.
- At first the tools were little more than handy cobbles with sharp edges made by banging two stones together, and the sharp flakes of stone that were created in the process
- Later the stones (usually flint) were shaped much more carefully, producing ‘Hand Axes’ or ‘Bifaces’.
- In the final stages of the palaeolithic (the Upper Palaeolithic, or the Late Stone Age) much more complex stone tools were created.
- Eventually (in the Neolithic) the stone tools associated with agricultural people were finely polished.
Length of Each Period in the Stone Age
- The first two stages lasted for an incredible length of time (around 2 million years), and it has always been thought that the changes reflect the evolution of the various species involved. All these animals spent most of their time in small groups, and life was short.
- The last two stages began around 90,000 years ago and ended when people began using metals. During these (much shorter) periods people seem to have been living in larger groups, culminating in settled agricultural villages.
Skull remains show that the new species (Homo sapiens) had a larger brain size than most predecessors, and the fact that this species went on to develop new technologies at an ever-increasing rate used to be attributed to a steady increase in intelligence. But there have always been problems with this idea, for example:
- The New Stone Age began in Africa around 90,000 years ago and then died out 25,000 years later, only to re-appear about 40,000 years before present. This would imply that the species became more intelligent, then lost intelligence for thousands of years, then re-gained its mental abilities.
- People in different parts of the world developed new technologies at different times – indeed in historical times some were still in the Stone Age while others were industrial. How is this possible if they were all equally intelligent?
A team at University College London has just put forward a new theory to explain why people in different parts of the world might have developed their technologies at different rates. Broadly this theory suggests that the size and age-structure of the population was the most important factor – a lot of people having a lot of ideas, and some people lasting long enough to pass on these ideas to the next generation. This would explain the accelerating effects of literacy, printing, and more recently the internet – indeed, in one sense, the whole human population in now one community, and new ideas can be spread widely and archived indefinitely!
Zoologists have long considered humans a special case where their recent evolution is concerned, recognising that changes in the way they behave owe more to their cultures than their genetic makeup. This new theory uses evidence to show that they are correct.
Reference: University College London study – ‘high population density triggers cultural explosions’.
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