When Mutants mingle with Mutants

22. January 2008

The term "evolution" trepans into thinking of times long gone: Prehistoric men, stone age and primitive life. Doesn't the modern human stand at the end of this development? To the contrary says an international team of researchers which quantifies the scope of genetic changes. The human evolution proceeds faster than ever.

From the very first protozoic creature all the way to men, evolution determined our being human today. While about 10,000 years ago a few million people diffused all over the globe, today more than 6.5 billion modern men inhabit the planet. Even biologists up to now assumed that evolution of men happens at a rather leisurely pace over the past millenniums.

Per definitionem, evolution is a process: The biological evolution is to be apprehended as development of the phylogeny and subject to evolution factors such as mutation, recombination and selection.

Faster and faster into the future

Today our genes mutate a hundred times faster that in stone age times. Henry Harpending, professor of anthropology at the University of Utah, and his colleagues calculated that. Their study, published in the Proceedings of the National Academy of Sciences, shows that preliminary theories of a rather slow human differentiation are not correct. Thus we not only change faster and faster but also diverge – despite globalization. Underlying the research results is the analysis of data of the international HapMap-Project. The project catalogs genetic features of men from different origins for the past five years. The major target of HapMap is the identification of genes associated with diseases.

Mutation of seven percent of the genes is young

In the center of attention are researches regarding changes of single base pairs of the DNA – the single-nucleotide-polymorphism (SNP). Those make individual genetic differences visible. The researchers put nearly 4 million of such SNPs of 270 people from Asia, Africa and Europe under the microscope and established about 1,800 genes which have changed just recently. This corresponds to about seven percent of the human genotype. Highly decisive for the rapid changes of the genes are the environmental conditions men have to face. Climate, germs and nutrition are responsible for genetically optimal adjusted men further passing on the necessary genes and for those to prevail.

You are what you eat

Incisive feature of a genetic change in our days is the inherited lactose intolerance respectively -tolerance. The enzyme lactase is responsible for lactose digestion. We Europeans usually build it, different from for example population groups in the Far East or Africa. The gene for production of the enzyme relevant for digestion loses its function after the infant period if milk is not on their regular menu. As a consequence of sedentariness and development of agriculture in Northern Europe and the thus resulting pressure of selection, people here developed the lactase gene ensuring them to be able to digest milk even as an adult.

Another example of genetic diverging of population groups is the development of resistances against infectious diseases such as malaria and cholera. For example in malarian regions you will find a conspicuously high accumulation of sickle cell anemia – itself a genetic disease but at the same time in its heterozygous variation the perfect protection from malaria. In some regions of Africa, up to one third of the population is affected of this variation which protects them from a potential pandemic. In other regions of the world you will hardly find the sickle cell allele at all.

Man as a mutant

According to the scientists, environmental conditions and increase of population groups are responsible for the faster and faster development of genetic changes. People will continue to change and analogous to the living conditions perhaps even faster than so far. Harpending and his colleagues believe that – in view of climate changes and newly developing diseases – according mutations are surmisable within a short time. Survival and the rapid increase of mankind could lead to the realization: The human being is a mutant – in the past, today and always will be.

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