Back
Home
6.1 analyse the possible effects on human evolution of the following factors: increased population mobility modern medicine genetic engineering
analyse the possible effects on human evolution of the following
- increased population mobility
- modern medicine
- genetic engineering
Increased population mobility
- As human culture developed, humans became better at changing their environment. This led to an increase in population. Greater population resulted in greater pressure on the available resources and this led to increased migration.
- At the same time changing climatic conditions moved prey species and in response hominins followed their prey. Humans were in Africa and Eurasia 50 000 years ago. They entered Australia at least 50 000 years ago using boats and land bridges formed by the lowered sea levels as a result of the Ice Ages. Humans entered America across the Bering land bridge and then moved into South America. These isolated groups developed minor changes according to their environment, for example, people in cold climates tended to be shorter and stockier than people in hot climates who tended to be tall and thin. The short people maintained their body heat better and tall thin people were more likely to lose body heat and remain cool.
- With increasing technology better transport developed allowing faster transport between different human groups. The effect of this is that geographic barriers no longer exist as air travel means that no group is isolated from other groups. This allows gene flow between groups that would have previously been isolated and this should lead to breakdown in the concept of race. In fact genetic testing has shown that there is more variation within groups than there are differences between different ‘races’.
Modern medicine
- This is the result of the growing understanding of how the human body works and the diseases that affect it. Some examples of modern medicine are vaccinations, antiseptics, antibiotics, pre-natal diagnosis, in-vitro fertilisation and birth control. The effect of all of these is reduced mortality and increased life span. Childbirth is no longer responsible for the death of many women. Children survive because of vaccination programs.
- This changes the possible gene pool as fewer people are dying and are no longer selected by the environment. Diseases that once acted as selecting agents are not as relevant. Genetic defects can be passed on to the next generation because many sufferers live long enough to reproduce while before they would have died at an earlier age. These genes therefore stay in the gene pool and are not eliminated.
- Birth control is reducing the number of offspring from individuals so no longer are the ‘fittest’ organisms the ones that produce the most offspring.
Genetic engineering
- This is the manipulation of living organisms especially the manipulation of genes. This has had an effect in two ways. Firstly in the increase of agricultural production, supplying cheap food for more people and secondly through the changes to human survival rates. Modern agriculture produces high yields from crops and domestic animals. Examples of genetic engineering in agriculture include crops such as Round up ready cotton (herbicide resistant), cloning of crops such as carrots and Bt engineered crops that produce natural pesticides. The production of genetically modified crops (GM) has lead to arguments about whether these crops should be labelled.
- The changes to human survival rates have come through the control of genetic diseases. Genetic diseases such as haemophilia and phenylketonuria can now be controlled leading to a change in the frequency of these genes in the population. Genetic engineering can have vast effects on future evolution of humans. This ranges from an increase in food supplies from agricultural techniques through to direct interaction into the human genome.