B6.4 How do humans develop more complex behavior?
The evolution of a larger brain gave early humans a better chance of survival – early humans could use tools, coordinate hunting and formulate plans about what might happen in the future. Having a larger brain meant that early humans were more likely to survive and reproduce – passing on the genes for producing a larger brain.
Mammals have a complex brain that contains billions of neurons – this enables them to learn from experience, including how to respond to different situations e.g. social behaviour.
In mammals, neuron pathways are formed in the brain during development – the way in which the animal interacts with its environment determines what pathways are formed. It is the huge variety of pathways available that makes it possible for the animal to adapt to new situations.
Learning is the result of experience where:
- Certain pathways in the brain become more likely to transmit impulses than others
- New neuron pathways form and other neurons pathways are lost
At birth, in humans the cerebral cortex has approximately 2500 synapses per neuron. By the time an infant is two or three years old – the number of synapses is approximately 15 000 synapses per neuron.
Each time an individual has a new experience a different pathway between neurons is stimulated – every time the experience is repeated the pathway is strengthened however if the pathways are not being used regularly they are eventually deleted.
If neural pathways are not used then they are deleted – there is evidence to suggest that because of this, if a new skill (e.g. learning a new language) has not been learned by a particular stage in development an animal or child might not be able to learn it in the same way as normal.
Feral children are children who have been isolated from society in some way so they do not go through the normal development process.
Memory is the ability to store and retrieve information
Verbal memory can be divided into long-term memory and short-term memory:
Short-term memory is capable of storing limited amount of information for a limited amount of time – for about 30 seconds
Long-term memory may last the whole of your life – there is no limit to how much information you can store in your long-term memory.
Humans are more to likely to remember information if:
- There is repetition of the information, especially over an extended period of time
- There is a pattern to it
- There is a strong stimulus associated with it – such as colour, light, smell or sound)
There are a variety of models to explain how memory works – including the multistore memory model – this model can be used to help explain some steps involved in long-term and short-term memory.
However, models will always be limited as they are not the real brain and memory, only a representation of how we think it works.