Life on Earth is believed to have arisen roughly 4 billion years ago. Although how our world went from an arid piece of stone to the beautiful blue planet is still a hot point of discussion amongst evolution biologists, it has been established and agreed that it all started wet.From this ancient time, billions of life forms have slowly developed to give rise to the 5 to 100 million species of organisms currently sharing the Earth. One of this species is indeed the Homo sapiens, aka Humans. The process of evolution has not, however, stopped when we, master minds, or so we think, appeared. Instead, evolution is slowly but surely happening at every nanosecond.
What this whole evolutionary theory of life famously described by Darwin means in practical terms is that every organism that has lived, lives, or will live in our planet share a genetic code.Being cut from the same cloth as every parasite, bacteria, animal, plant, or fungi means that it is possible to construct a genealogic tree of the living Earth. Phylogenetics is the research area that studies these long-term relationships between organisms.
No matter how different or close two organisms are, it is always possible to quantify its divergence and to predict its common ancestor, or in other words, when and what triggered the separation of that common “father” into two (or more) different “children”.
The Tree of Life shows us the phylogeny of organisms or the progress of change through time.
Phylogenetic analyses are also useful to assess smaller degrees of differences, such as those seen between strains of the same bacterial species, virus, or parasite species, and to characterize the evolutionary pressure being put in a specific gene or set of genes in order to achieve the fittest phenotype. So, just like two close species diverge in time in order to achieve maximal reproductive fitness, two distant species may also converge if that suits their reproductive interests better. Similarly, pressures may be such that a given gene is maintained unaltered due to its vital importance for the organism’s survival, even when all other closely related genes are changing fast.
Phylogenetics is an immensely vast area that requires constant updating due to the fast discovery of novel genes, novel strains, and novel species. Nonetheless, all that effort is rewarded, as phylogenetic analyses are crucial to the identification of important genes, be it drug resistance genes, virulence, or host-adaptation genes. Albeit we, scientists, have made great progress in the past 150 years, we are still light-years behind of understanding the magnificent machinery called Earth.