The bulk of medical and other technological developments which protect us from our environment have come in just the past century. So in the developed world today, what is there left for natural selection to act on? But although in the developed world today, almost everyone lives long enough to pass on their genes, many of us choose not to. Some people have three children, and some people have none, so natural selection may be working in a different way. The realisation that people in the developed world are in effect choosing to prevent their genes from surviving beyond them has led evolutionary biologist Stephen Stearns to look at evolution in the current generations in a radical way.
A long-term medical study of a small town in Massachusetts, called Framingham, allowed him to look at the medical history of thousands of women going back to the middle of the 20th Century, and to calculate how the people that are having children differ from the population as a whole.
It has left him in no doubt that people - at least in Framingham - are still evolving and in a surprising direction. This was not just a case of people eating more and there was no evidence to suggest the trend of people putting on weight and losing height would continue indefinitely. In any case, the changes were very small and very slow, similar to those at work in Darwin's evolutionary studies. Interestingly, Stearns believes that rather than sheltering us from natural selection, the changes that we've made to the world may actually be driving our evolution.
Technology may have limited the impact of evolutionary forces such as predation and disease, but that does not mean humans have stopped evolving. Far from it, in a world of globalisation, rapidly advancing medical and genetic science and the increasing power of individuals to determine their own life choices, more powerful forces may come into play. The direction of our future evolution is likely to be driven as much by us as by nature. London, England: John Murray, Gillespie, J.
Population Genetics: A Concise Guide , 2nd ed. Haldane, J. A mathematical theory of natural and artificial selection, Part I. Transactions of the Cambridge Philosophical Society 23 , 19—41 Hedrick, P. Genetics of Populations, 3rd ed. The Hardy-Weinberg Principle. Evolution Introduction. Life History Evolution. Mutations Are the Raw Materials of Evolution.
Speciation: The Origin of New Species. Avian Egg Coloration and Visual Ecology. The Ecology of Avian Brood Parasitism.
The Maintenance of Species Diversity. Neutral Theory of Species Diversity. Population Genomics. Semelparity and Iteroparity. Geographic Mosaics of Coevolution. Comparative Genomics. Cybertaxonomy and Ecology. Ecological Opportunity: Trigger of Adaptive Radiation. Evidence for Meat-Eating by Early Humans. Resource Partitioning and Why It Matters. The Evolution of Aging. Citation: Andrews, C. Nature Education Knowledge 3 10 In natural populations, the mechanisms of evolution do not act in isolation.
This is crucially important to conservation geneticists, who grapple with the implications of these evolutionary processes as they design reserves and model the population dynamics of threatened species in fragmented habitats.
Aa Aa Aa. Figure 1: Allele-frequency change under directional selection favoring a a dominant advantageous allele and b a recessive advantageous allele. References and Recommended Reading Carroll, S. Futuyma, D. Evolutionary Biology , 3rd ed. Sunderland, MA: Sinauer Associates, Wright, S. Evolution: Selected Papers. Share Cancel. Revoke Cancel. Keywords Keywords for this Article.
Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. His novel Crabs on the Island tells the story of two engineers conducting an experiment in cybernetics on a deserted island. Soon the island is overrun with baby robot crabs. But the crabs begin to mutate. Some are larger than others, and ruthlessly cannibalize the smaller robots for spare parts to build even larger robots.
How would such an experiment end? Catastrophically, of course, as is consistent with the genre, with robot crabs spreading exponentially across the entire island. Science fiction can be terribly pessimistic, but that pessimism is unfounded. Other factors are at play. Resources are limited. Eventually, even the crabs on the island run out of materials with which to make new robots.
But we must also be cautious with our optimism. We rely on the age-old processes of natural selection to keep reproducing robot crabs in check; something will evolve to eat them.
But what if these were intelligent organisms, plotting a way to find new resources, discovering new ways to improve themselves, their evolutionary fitness, and their ability to learn from each other and from previous generations? Could such an army of replicating artificial intelligences be possible? If so, could they be stopped? How realistic is it that alien planets may be inhabited by artificial creatures so advanced that they can bypass natural selection itself?
And if that is possible, why has such a creature never evolved naturally? Battles fought million years before today helped fuel a blast that brought humans and most animals into existence. The great Cambrian Explosion was a period of unprecedented one-upmanship. Beastly claws crushed through thin skin, and soft-bodied creatures evolved shells It has probably not escaped your attention that the kind of intelligent transmission of experience from one generation to the next—together with the ability to know when to use that information—is not unlike what we see in human society in the cultural transmission of ideas from generation to generation.
Cultural transmission of experiences is a process with spookily Lamarckian characteristics. We do indeed inherit a tendency to certain cultural ideas from our parents and from society, but we can mold them to our best advantage, alter them, or even discard them. You might be brought up by parents who are wonderful musicians, but you decide that you never even want to touch a kazoo.
Cultural ideas that are used are reinforced, those that are neglected waste away. It is precisely this ability to improve and to prune ideas that has caused human civilization to advance at such breakneck speed.
And if this kind of cultural transmission does occur on another planet, you can be sure that evolution will be swift and effective—just as ours continues to be. Let us do a brief thought experiment. Imagine that you are a member of a highly advanced alien civilization, intent on spreading your legacy throughout the galaxy.
But instead of dropping off a biological molecule, you might be such an advanced alien that you seed this planet with intelligent artificial creatures, specially designed robots that have the capacity to bypass natural selection.
They are programmed to have the foresight that nature is lacking. Their robotic gazelle descendants would know that longer legs are better and would re-engineer their own design to give them longer legs.
Similarly, robotic lions would reprogram their own software to enable them to sneak up on prey more stealthily.
What would be the end result of such a scenario? Would there still be predators and prey?
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