Have you ever thought of the future of our planet a million years from now? A million years from now, who can say whether humans will still roam the earth? …whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” Charles Darwin: The Origin of Species (1859).
When life is viewed through evolution-tinted glasses, much of it makes sense. The process of natural selection that involves the generation of variation in phenotypes as a result of random mutations, the greater success of some phenotypes over others and the heritability of these successful phenotypes could lead to what Darwin called descent with modification. To this must be added the process of random genetic drift as well as physical constraints of form relative to function given the available materials. The patterns of life are governed by such evolutionary processes.
What is the advantage of viewing life through evolution- tinted glasses? With this perspective, we can understand, for example, why lean Africans from the Rift Valley usually win marathons, and why athletes with the physiognomy of Usain Bolt usually dominate sprint events. This harks back to the evolution of slow twitch and fast twitch muscle fibres which facilitate endurance running for long periods of times or the burst of energy required in sprints.
Better oxygen capacity in the muscles of marathoners may have also been an ancestral “adaptation to the hypoxic high altitudes of the Rift Valley, or to the endurance required to keep pace with and hunt down prey using primitive weapons. This is the result of natural selection.
However, what about unnatural selection? What if, with our technology, we are able to engineer uber-athletes, just as scientists have engineered ‘Schwarzenegger mice’ by introducing suitable genes into normal mice? The threat of genetic doping in sports looms large and would be devastating in a world freshly recovering from the doping scandal of the alleged ‘Superman’ Lance Armstrong. His was an unnatural phenotype that won many races.
Through the perspective of comparative biology and evolution, we may be able to discern the natural limits of human endurance or speed. However, humans have crossed speed barriers by “legitimately” using aids that they have copied from nature or engineered with their own creativity. For example, swimsuits designed on the basis of shark skin have been credited with contributing to record-breaking Olympic performances. Here, humans have extended their own natural phenotype by copying and adopting that of sharks and have thus enhanced their performance.
Shark skin has been under natural selection for millions of years and has evolved to reduce drag and to increase the hydrodynamic efficiency of a shark in water, making it a most successful predator. Besides the beautiful view through these evolutionary lenses, what else can such a perspective provide? In today’s world, we have the technology to make organisms to order, i.e. we can insert genes into organisms and generate transgenic forms.
This has been a boon for many products, e.g. we have inserted the insulin gene into bacteria which now produce insulin for us under laboratory conditions. This is useful as long as we can control the products of our unnatural selection. When we insert genes into crops to control pests, as has been done with the gene for a toxin from Bacillus thuringiensis (Bt) that is toxic to many insects, what do we see through an evolutionary perspective?
We see that the insects, which are also under natural selection to detoxify poisons, quickly acquire resistance to Bt toxin. This necessitates the engineering of new transgenic plants in which new toxins are introduced, via new combinations of alien genes. One can easily imagine a scenario wherein monocultures of transgenic plants, which have been planted over large areas after uprooting the natural diversity of traditional crop cultivars, have to be replaced by the next generation of newer transgenics, and so on, endlessly.
In the meanwhile, evolution in the insects has progressed at a much faster pace, rendering them the winners in the transgenic race. In this process, humans have lost their natural diversity of crops and the wild relatives of crop plants. This would have served both as reservoirs of newer genes for future experiments, as well as a vast gene pool from which natural selection could act to reward better insect-resistant varieties.
The evolutionary perspective makes one realize that it is more powerful and wiser to preserve the natural variation that has survived battles against enemies over millennia than to eliminate most of it on the promise of technological prowess. What then of the future? With evolution tinted glasses and the lessons from Earth’s history, we know that ‘life’ is resilient, but life as we know it today is not. Individuals and species have won contests, but many have also lost them. Species have gone extinct, only to be remembered in the genes they may have shared with others more successful than them. A million years from now, who can say whether humans will still roam the Earth?
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Source
- Scientific American Magazine, Renee M. Borges
