By Constanza Wulschner Montes
It is always advisable to clearly perceive our ignorance.
Charles Darwin
The origin of man and his evolution has been a controversial topic and studied for many years. The desire to understand our origin and our development throughout the history of life on Earth has been one of the greatest unknowns for science and biology.
Spoiler alert: We do not come from the monkey! (Figure 1)
Figure 1.- Wrong representation of the human evolution
When we talk about evolution, it is necessary to go back to the 1800s and mention the well-known name “Charles Darwin”. According to legend, in 1831, a young Darwin embarked on an adventure aboard the Beagle as a naturalist (although he had not studied anything related to the natural sciences until that moment), visiting, among other places, the Galapagos archipelago in Ecuador. In this place, Darwin observed different species of birds and their morphological changes generated by specialized diets, which inspired him to establish the well-known adaptive theory that suggests that the diversity of life on Earth and its changes over time is product of an organic process of descent with modification (evolution) and the mechanism is natural selection (Darwin, C. 1859). The reality is that specifying the evolutionary theory was not easy, nor was it as simple as it is proposed to us, Darwin, in addition to his morphological observation in birds and turtles, analyzed hundreds of fossil records and compared the fossil anatomy with the current anatomy of the specimens that he observed, this is called comparative anatomy (G, Cuvier et al. 1795) based on the investigations of Georges Cuvier. All these previous investigations were giving rise to the study of the evolution of the human being, we can often find the image of the evolution represented by a monkey, then a series of missing links until reaching a hominid and later a human, however, Darwin, from the beginning, established that evolution was not a linear process, that is, he did not affirm that we descended directly from the monkey, but that we had a common ancestor that over time and through adaptations, we were separated into several species. The monkey is the product of the evolutionary history of one of those species separated from the common ancestor and the human from another (Figure 2). Evolution process is random (Ayala, F. 1979), it is based on trial and error driven by natural selection and later, adaptation. But how did we come to these conclusions nowadays? To understand it, it is necessary to know the history of evolution.
Figure 2.- Human evolution tree
The book The Origin of the Species was published until 1859, it was refuted for years by clergymen and other researchers attached to the creationist idea and it was not until 1940 that its evolutionary and adaptive theory was accepted when it was successfully integrated with genetics. The ideas of evolution revealed how little was known about genes and heredity. It took almost a century to find the affinities between the theory of evolution and genetics.
In 1871, Darwin published his book The Descent of Man, and Selection in Relation to Sex, which shows how the higher faculties of the human, such as intelligence, could have evolved through natural selection in ancestors of simian appearance.
In 1882 Darwin died, however, the theory of evolution is mostly accepted by the population, except for the concept that humanity descended from apes.
In the 1930s and 1940s, general biologists, population genetic biologists, paleontologists, and field naturalists agreed on a "modern synthesis" of reinvigorated Darwinism. Evolution is beginning to be seen as acting through natural selection and other random mechanisms; with which new species are generated through the gradual accumulation of mutations in isolated populations.
In 1953, Francis Crick and James Watson published the work of the English Rosalind Franklin, thus stealing the credit for the discovery of the double helix structure of DNA, solving the mystery of how genetic information is passed from one generation to the next.
In the 1970s, a series of fossil discoveries, made by the Johansson paleontologists, in the Great Rift Valley in East Africa, found part of the skeleton of a 3.2-million-year-old hominid in Ethiopia. The skeleton, named Lucy (Figure 3), helped define a new species, Australopithecus afarensis, which was placed at the base of the human lineage.
Figure 3.- Digital reconstruction of the Australopithecus afarensis named Lucy.
In 1977 Cal Woese redefined the tree of life by classifying organisms by their genetics, rather than their physical similarities; he showed that life is made up of three domains (Archea, Eubacteria, and Eukaria).
Evolutionary theory remained static for some years until 2003, when the sequence of the human genome was completed. The close similarity between the genomes of man and the chimpanzee underscores their descent from a common ancestor, just as Darwin predicted before the explosion of genetic knowledge.
Today, evolutionary biologists and geneticists continue to seek to extend Darwin's initial ideas, incorporating new genetic, paleontological, embryonic, and behavioral data. Variation between species is considered, in part, the result of mechanisms that control how genes are switched on and off during the development of an organism.
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