Survival of the Smallest

Evolution is generally thought of as a very slow process in comparison to human life spans. Consequently we, as humans, make no difference to the evolution of life on earth. However, from a purely biological perspective this is far from true. Approximately 95% of the terrestrial world is now actively managed for the benefit of the human species and as a result the new epicentre of evolution is mankind and man-made environments.

These new environments consist of our crops, our waste, and us, with human pathogens sitting at the very top of the food chain. Over 50% of all species on earth are now parasites and for a growing number of these parasites we humans represent the ultimate gourmet experience. In other words, as we expand environments and numbers, the evolutionary possibilities for microbes also grow. Hence new pathogens like HIV emerge.

We are already seeing weeds evolve to mimic the chemical properties of agricultural crops so as to avoid man-made pesticides. Similarly, insect pests are developing resistence to avoid new pesticides. The most immediate issue arising from such developments is antibiotic resistance, whereby parasites evolve in ever more virulent forms to resist our best efforts to kill them. So what then does the future hold? One scenario is that we will take a whole host of new pests and pathogens into the future with us and, ultimately, it will be the smallest species that survive simply because big species like humans will be unable to evolve fast enough to cope. In other words, from an evolutionary point of view, the future belongs to pathogens, pests and their invited guests.

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