The family tree
The process of evolution produces a pattern of relationships between species. As lineages
evolve and split and modifications are inherited, their evolutionary paths diverge. This produces
a branching pattern of evolutionary relationships.
By studying inherited species' characteristics and other historical evidence, we can
reconstruct evolutionary relationships and represent them on a "family tree," called
a phylogeny. The phylogeny you see
below represents the basic relationships that tie all life on Earth together.
The three domains
This tree, like all phylogenetic trees, is a hypothesis about the relationships among organisms. It illustrates the idea
that all of life is related and can be divided into three major
clades, often referred to as the
three domains: Archaea, Bacteria, and Eukaryota. We can zoom in on particular branches of the
tree to explore the phylogeny of particular lineages, such as Animalia (outlined in red). And
then we can zoom in even further to examine some of the major lineages within Vertebrata. Just
click the button below.
The tree is supported by many lines of evidence, but it is probably not flawless. Scientists
constantly reevaluate hypotheses and compare them to new evidence. As scientists gather even more
data, they may revise these particular hypotheses, rearranging some of the branches on the tree. For
example, evidence discovered in the last 50 years suggests that birds are dinosaurs, which required
adjustment to several "vertebrate twigs."