Classification of organisms changes as more knowledge emerges.Scientists can now study biological molecules such as DNA and proteins like haemoglobin to establish relationships between organisms.Phylogenetic classification is based on evolutionary relationships between organisms and their ancestors.Scientists establish theoretical, extinct common ancestors by comparing the DNA of different species.Homologous characteristics have similar genetic origins e.g. the wing of the bird and the arm of a human.
In the past, artificial classification grouped organisms according to observable characteristics such as colour, size, number of legs, leaf shape.These analogous characteristics have the same function but do not have same evolutionary origins.An example of this is fins in sharks and whales or wings in birds and butterflies.
In the past, artificial classification grouped organisms according to observable characteristics such as colour, size, number of legs, leaf shape.These analogous characteristics have the same function but do not have same evolutionary origins.An example of this is fins in sharks and whales or wings in birds and butterflies.