The evolution of hormones and the nervous system
During evolution, humans developed certain characteristics that gave them a better chance of survival. Multicellular organisms need ways for their cells to communicate, and there are a number of different means by which the body achieves this.
Humans did not evolve from apes such as gorillas and chimps. Instead, humans and apes share a common ancestor that lived millions of years ago. This common ancestor diverged over time to form many different species of hominid, only one of which survived to become modern humans. All the rest of the hominids, including early humans, became extinctextinct: Species of organism that is no longer living.
During the evolution of human beings, many features gave individuals advantages that offered them a better chance of survival, including:
It has taken scientists a long time to try to discover how humans evolved. Scientists do this by producing an explanation and then looking for data to support their theory or prediction. Sometimes the data agrees with and supports the prediction. This increases the scientist’s confidence that the prediction is correct.
Sometimes the data disagrees and does not support the theory. This can prove that either the prediction or the observation used to produce the data is wrong. An example of this is the discovery of a new gene that affects the evolution of brain size. Scientists think it first appeared about 40,000 years ago. It has been so successful that 70% of humans now carry this gene. Scientists think that the gene increases brain size and this may improve intelligence. Scientists are now examining this gene. Many predictions and theories about how the gene works will be made, but it will only be when much more data and evidence has been collected that we will know which of these theories is correct.
In your examination you may be given additional information about human evolution that you have not seen before. You will need to be able to identify valid conclusions from the data provided and say which supports a prediction and which does not.
Observations and data that support a theory still do not prove that the prediction is correct. For example, a theory that states that storks deliver human babies could be supported by the fact that populations of storks are often found near areas with higher human birth rates. This data supports the theory but does not prove it.
Observations and data that do not support a theory decrease the scientist’s confidence that the theory is correct.