Genomic DNA is constantly mutating as the result of constant flow of DNA damaging agents that are produced in our bodies as well as in the environment. These agents include free radicals, mutagenic chemicals, ionizing radiation, microwaves and UV light. DNA mutations that occur in the reproductive cells of parents may be transmitted to their children and future generations and become a permanent (hereditary) mutation. Hereditary mutations are the main source of genetic diversity, and evolution. There is no a single person in the world that has no genetic mutations. Most of the mutations are silent as they do not affect the function of corresponding proteins. Some mutations cause production of proteins that do not function properly. In that case, the mutation may cause a disease. Currently there is no cure for the hereditary diseases, but it is now possible to identify them and in some cases treat symptoms.

It would seem that all of us should suffer from numerous hereditary diseases, however the vast majority of the world population does not have these diseases because each cell has powerful machinery specialized in finding and repairing the mutations. There are additional lines of defense against harmful mutations. For example, every human gene in the genome is represented by two copies of the so-called alleles, one from the father, the other from the mother. Usually defective alleles are recessive that means they do not manifest themselves as they are dominated and neutralized by healthy alleles. The disease manifests itself only if the child inherits both alleles with the same defect. There are more than a thousand of such systemic diseases with autosomal recessive type of inheritance found so far. The most famous of them is cystic fibricationosis and amaurotic idiocy.

Technological progress dramatically reduced natural selection in the developed countries and causes rapid accumulation of harmful disease-related mutations in the population. A new rapid DNA test that is able to identify dangerous mutations is now at the stage of clinical trials. DNA tests of parents-to-be allow them to make educated decisions as far as continuing or terminating pregnancy, having their own children or adopting. Biotechnology methods of the future will allow modification and improvement of human genome through in vitro manipulation of human embryonic stem cells that will hopefully improve health of rapidly degrading human population.

Even though Charles Darvin titled his famous book ‘The Origin of Species’, he considered the mechanism of new species’ origin a great mystery. Even now, one of the greatest mysteries of biology is how two groups of animals become genetically incompatible. It is possible to imagine that two groups of animals become separated in space and lose the ability to breed with each other for a long time, gradually adapt to different environmental factors until they lose physical ability to mate even living at the same territory. Development of new species without physical isolation is much more difficult to explain because of free exchange of genetic information between individuals. Even more difficult to comprehend is the fact that changing only one gene may be sufficient to create new biological species.

A gene called Prdm6 was found long time ago as a gene involved in recombination, the process of crossing chromosomes and exchanging DNA regions between paternal and maternal chromosomes in the gonads. The process takes place only during maturation of reproductive cells – spermatozoids and oocytes. The DNA shuffling is the reason why each organism is unique. So far, DNA recombination was not associated with the creation of new species. Scientists found that the protein Prdm6 has several so-called Zn-fingers that are encoded by short DNA repeats called satellite DNA. As satellite DNA is located in hot-spots of DNA recombination, it is frequently mutated and repaired. As the result, Prdm6 protein gets more or less repeats of its Zn-fingers. It appears that the chromosomes that have different variants of the gene cannot properly pair and exchange genetic information during gametogenesis. All animal species have homologous Prdm6 genes. Certain lines of laboratory mice that express different variants of Prdm6 protein cannot produce fertile offspring. Scientists found that different populations of humans also produce Prdm6 proteins with different number of Zn-fingers. It is conceivable that people with certain variants of Prdm6 proteins may not produce fertile children and may develop into a new human species. This process will require selective pressure, either natural or artificial, and many years to develop true new Homo species.

In order to say a word or a sentence, human brain must first receive either external trigger (such as a sound, taste, smell or visual signal that is recognized by our five organs of sense) or internal trigger such as a thought. Human brain can generate a thought based on its own sensory experiences of the past. Then the brain generates an emotion, then an idea, then it selects certain words that are relevant to the idea, and, finally, the mind arranges the words into a sequence that follows the rules of grammar. After this process is complete, the brain sends nerve impulses to the muscles of tongue, lips and larynx that set in motion a sound producing mechanism that converts thoughts into speech. Pronunciation of tongue-twisters requires especially good coordination of all these systems. The complexity of the process suggests that multiple genes affect the process of speech formation.

British scientists became interested in what genes are responsible for the speech formation and have made quite an interesting discovery. The researchers noticed that the gene Foxp2, which is located on the seventh human chromosome, is mutated in several members of one family. Protein FOXP2 encoded by Foxp2 gene is a transcription factor that controls the activity of other genes. One of the deficiencies associated with this mutation was impaired speech related to inability to control the movements of the tongue and lips. In addition, these people were not able to understand and apply certain rules of grammar. This gene has a direct impact not only on physical aspects of speech such as movements of the lips, tongue and larynx but also it affects brain ability to learn and apply grammar rules. Several years ago, it was demonstrated that mutation of this gene in birds also disrupted their singing ability. These birds could not learn songs from the adult birds.

To elucidate its function, the researchers created a similar mutation in mice. The expectations of scientists have been confirmed. The mutation foxp2 gene in mice affected not only the development of vocal organs at embryonic stages but also affected the synaptic plasticity of the adult mice. Scientists went further and substituted endogenous mouse gene foxp2 with human homologous gene Foxp2. The resulting mice produced sounds that are not typical for mice. What is still unclear to the researches is what language they spoke…