This is an interesting point, which takes the evolution debate further.
Some evolutionists believe that we ARE evolving morally and intellectually, by cultural changes. However, in biological sense of changes in the gene pool it's impossible to say. This is very true, as it is impossible to observe human evolution in action. But saying it isn't happening is an increasingly difficult posistion to defend scientifically. Many people would rather have believe that evolution stopped about 50,000 years ago. Yet recent findings have shown that this isn't so. In fact, there is every reason to believe it's happening right now.
An experiment was carried out in the University of Chicago last year (Bruce Lahn). It found that brain development occured in recent history and swept quickly through the population. This was shown in two genes. The first one was a variant of a gene called microcephallin, which occured some 14,000 - 60, 000 years ago and is now carried by 70% of people. The other a variant of the APSM gene, is about 500 - 14,000 years old and is carried by about a quarter of the Earth's population. No one knows the functions of these genes, but it could be a good start.
It all raises questions, even of they are uncomfertable. Is natural selection still a driving force in humans, given that our survival is often less dependent on genes than technology? How can a genome change attributes we value, such as intelligence? What will our species look like 1000 years from now? This may be confusing, controversial even, but it's something that we cannot ignore.
In a sense, evolution is simply the change over time in a species' gene pool - all the genes in all the individuals alive at one time.
This means that all species are evolving, even those that reproduce by cloning (asexual reproduction), because DNA undoubtably changes over time through random mutation, and because some individuals of a species will have more offspring than others.1. A gradual process in which something changes into a different and usually more complex or better form. See Synonyms at development.
2.
1. The process of developing.
2. Gradual development.
3. Biology.
1. Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.
2. The historical development of a related group of organisms; phylogeny.
4. A movement that is part of a set of ordered movements.
5. Mathematics. The extraction of a root of a quantity.
(This is more complicating for me to explain, as this part of evolution IS complicating, so please forgive me for my ramblings! ¬_¬)
Imagine a boat bobbing on the sea. This represents all the genes present in the human population at the moment. When the boat is left on it's own devices, the boat wonders aimlessly. This is "genetic drift", where a species is changing randomly without any driving force from its environment. If the boat has sails it heads of with seeming purpose, when the wind blows. This is like natural selection, in which an external force influences the direction taken by the gene boat. This is the driving force for adaption to change in environmental conditions. For sexual selection, the force is put forth by other members of the species preferring to mate with individuals who possess desirable characteristics, which then become more prevalent. If the boat has a tiller and someone at the wheel to steer it, this could be similar to artifical selection. Which is similar to dog breeding say. The gene boat even encompasses artifical selection by genetic engineering. However, to what extent is evolution of our species being shaped by these elements?
Some experts argue that natural selection is diminishing in importance, and as it does, genetic drift comes to the fore. But even if they are correct, the aimlessness of drift makes it of limited interest. With natural selection however, it is clear that the human genome is not immune from mutations, some of which can be an advantage. But are there any selection processes at work?
Some believe, that in the developed world, survival no longer depends on genes. 500 years ago, a British baby was less likely to make it reproductive age (50% chance), than of now where 99% of British babies do make it to adolesence. Measuring reproductive success is difficult (as we need to take in account the development of science), but compared to Britain in the Middle Ages, survival and reproduction rates have led to a decrease in the opportunity for natural selection to act today.
Yet we know that genes can make a difference to survival and reproduction. One obvious example is genes to confer resistance to emerging diseases. Small pox is a good example, as in the Middle Ages, some people were immune to the disease which was rife at that time. Some parts of Africa have shown frequencies of one gene that offers some protection against HIV-1. There are others too, if not puzzling. One form of the dopamine receptor gene DRD4 has become more common over the past few thousand years. The variant is associated with ADHD.
Therefore, natural selection IS still at work, and it wouldn't come as a suprise to find more examples. These days, we live in an era of rapid technology progress, and hence a fast changing environment. Technological change has driven natural selection into the past. The invention of diary herding, for example, selected for a gene that gives adults the ability to digest milk sugars. Yet, some believe that technological change doesn't necessarily drive natural selection. Once culture emerged, it provided more non-genetic means to adapt to change. Though it is true in many ways, it does not mean that evolution has stopped. Technology and medicine, by enabling almost everyone to have kids might be causing "reverse evolution" by preventing unfit genes from being purged from the gene pool. It could be causing gradual deterioration of many functions, especially disease defences, due to artifical selection.
Culture itself could be driving natural selection. There is positive feedback between our culture and our genes that led to the rapid evolution of the most characteristic human attribute, the mind. No doubt our minds have shaped our environment, which have led to evolutionary changes to the way we think, and it is continuing. In the modern world, nobody can do everything, so the real advantage today is doing something not many others can do well.
But what about sexual selection? High rates of outbreeding, migration and cross-ethnic mating are recombining our genes at unprecendented rates. What is more, our gene boat is acquiring new mutations faster than ever. This is probably due to assortative mating. This is based on intelligence, personality, mental health, physical health and attractivness.
I think we are evolving at a swift pace. It's hard to say were we will go from here, but who knows....maybe we will be more symmetrical, in a 100 years time ¬_¬
