Prof Campbell: Current archaeological and fossil evidence suggests that Neanderthals evolved separately from us. We are not their descendants. In fact, the evidence is that homo sapiens were responsible for the demise of the Neanderthals, who we quite sophisticated.
Question 30
I have a five year old daughter who has been asking how we got here for a few months. I have been trying to explain simplified evolution. Can you direct me to any information aimed at a five year old?
Prof Campbell: What a lovely opportunity, to try to explain such a difficult concept to a five year old. The key to grasping evolution is to understand its two principle components – the process and the mechanism, or, to a five year old, the what and the how!
Life began as tiny single units about 3,800 million years ago. As time went on some joined together, some started to make oxygen using the energy of sunlight. These 'evolved' into all the plants we see today. Then some found out how to make shells, and then bones. This led to the dinosaurs. Then some started to make milk, and mammals were born, leading to the appearance of humans. This is the 'what', the process of evolution, and was first written down in scientific terms by Charles Darwin's grandfather, Erasmus, one of the great geniuses of the 18th century.
It was Charles Darwin and Alfred Russel Wallace who discovered the 'how'. Look at the class of your five year old. Some children will be taller than others, some thinner, with different eye and hair colour, different abilities to do sums, or to paint pictures. This is the variation with a population. Imagine that in the only shop available in your village the shopkeeper cannot speak your language. When you want to buy something you have to draw it. So only those who can draw and paint well will survive to pass on their DNA to their children. This the how – natural selection in action. In this case the best painters will pass on their painting genes, and in 1000 years time everyone will be a Monet or a Rembrandt!
Question 31
Why do we not see a species in nature which is remarkably close to human? There is such a huge gulf between us and chimpanzees (albeit the genetic structure remarkably almost identical), our closest cousins. Why is there no race which is say very identical to humans in terms of conscience language or indeed culture? Surely evolution could have produced at least one species of the kind which competed with humans in some respect. But all we see in nature is just mutated mechanical machines.
Prof Campbell: It is a fascinating fact that our DNA is just 2% different from that of a chimpanzee. Small changes or differences in DNA can lead to big changes in shape or behaviour. Modern molecular biology is now trying to find out how this works.
Question 32
At the origins of life from the stage of the first single-celled bacteria how would such organisms have nourished and sustained themselves without any other life to feed off and without having evolved the ability to photosynthesise?
Prof Campbell: The first single celled life was bacteria. Bacteria metabolise chemicals found in the surrounding fluid. They don't actually eat other bacteria, though some can kill others and metabolise the degradation products. To divide, bacteria need sources of carbon, oxygen, hydrogen, nitrogen, chloride, sulphur and minerals like sodium and potassium. These would have all been found in the primeval soup. Some bacteria today can divide every 20 minutes or so. In the early times of evolution it could have taken a month, a year or even longer for a primitive bacterium to accumulate enough nutrients to divide.
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