Thursday, 12 February, marked the 206th anniversary of the birth of Charles Darwin, one of the most influential scientists of our time who has certainly not gone out of fashion. In his famous theory, Darwin established that all species of living things are descended from common ancestors, like branches of a tree that all come from one another and trace back to a common trunk.

According to his theory, evolution takes place through a process of descent with modification, or natural selection, where new species occupy new ecological spaces, as when amphibious fish begin to colonise the land, and in this process of struggling for existence and searching for new habitats, natural selection works in a similar way to artificial selection in animal breeding.

Darwin published his theory of evolution in On the Origin of Species (1859) and within a decade academic community and much of the general public had accepted natural selection as the explanatory mechanism for evolution. However, other authors favoured alternative explanations and it was not until the emergence of the modern evolutionary synthesis between 1930 and 1950 that a broad consensus established that genetic mutations, natural selection and the passage of time constitute the basic mechanism of evolution. Today the evidence in favour of evolution is growing, although the mechanisms by which it takes place need to be studied in more depth.

Darwin's early interest in nature led him to neglect his medical programs of study at Edinburgh University and focus on marine invertebrates research . His later programs of study at Christ's College, Cambridge University, fuelled his passion for the natural sciences. And his five-year voyage aboard the HMS Beagle and the publication of his journal of the voyage made him a household name.

Intrigued by the geographical distribution of wildlife and the fossils he collected on the voyage, Darwin began a series of detailed investigations that would lead him in 1838 to conceive his theory of descent with modification (natural selection). However, as his geological work took precedence and his ideas needed to be matured, it would take him another 20 years to publish his landmark work. The final straw came when, while drafting his theory, Darwin received a essay from Wallace describing the same idea. The two immediately published their theories together. Subsequent reprints of On the Origin of Species routinely warn readers that the book in their hands belongs to the exclusive and select group of books that have changed our perception of the world.

Evolution remains the organising principle of all biological discipline . Yet it also remains a point of reflection and controversy, because of its close relationship to one of the greatest mysteries of the universe: the origin of man and his place in the world. Darwin sensed the conflict, and in the preface to the sixth edition of his book he wrote a text that is rarely translated into Spanish: "Therefore, to conclude, let no man, carried away by a frail presumption of sobriety or a misunderstood moderation, think or maintain, that man can go too far in his search or study either of the book of the Word of God, or the book of the works of God; divinity or Philosophy; but rather, let men strive without end both to progress and to be proficient in both fields".

The evolution of the human being from other species is not, as has often been presented, an alternative to the creation of the human being by God, but both thesis give an account of the same reality from different points of view; just as every human being is not only a product of biology but is primarily and primarily the fruit of parental love.