Q. What is an evolutionary tree? Is there a precise evolutionary tree known by science that explains the emergence and origin of every type of living being?
Evolutionary tree is the schematic and pictorial representation of evolutionary relations among species of living beings in which the trunk (or a preceding branch) represents common ascendants of species and groups of living beings that are distributed along its branches according to hypothesis on their origin. For instance, today it is admitted that birds and mammals are two distinct branches of the same preceding reptile branch.
Biology cannot guarantee a definite evolutionary tree (phylogeny) on the species of living beings that live or have lived in our planet. There are many knowledge gaps and many data to be discovered to be filled. One of the mainly promising methods to study phylogeny is the comparison of DNA molecules from different groups of living beings researching similarities and differences in nucleotide sequences that may indicate less or more relatedness among species.