For a great many years evolution was conceived as being driven externally by environmental pressures and internally by mutations in DNA. Mutations in the DNA created genetic diversity and when there were changes in the environment, those animals with the mutated DNA were sudden in a more favorable position.

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Few of the changes in the handling and presenting of animals would be possible had great progress not come in veterinary care.

ECONOMIST: From zoo cage to modern ark

They also found changes in the mix of cells within the animals' immune system itself.

ECONOMIST: Social status and health

Human survival has been based on unrivaled adaptation to the environment, but plants and animals will and are inevitably succumbing to subtle changes in the climate.

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Weightlessness not only sees animals use their muscles less, but causes changes in the chemical reactions within the muscle cells, explained Nathaniel Szewczyk from the University of Nottingham, who is the lead author on the new study in the journal of the Royal Society Interface.

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Post-mortem examination often reveals subtle, but nonetheless fatal, flaws in the heart muscle or kidneys of these animals the sorts of changes that are hard to predict and therefore almost impossible to prevent.

ECONOMIST: Cloning around