Although an infant's color vision is not as sensitive as an adult's, it is generally believed that babies have good color vision by five months of age. Most babies start crawling at about 8 months old, which helps further develop eye-hand-foot-body coordination.
A language tree, or family tree with languages substituted for real family members, has the form of a node-link diagram of a logical tree structure. Such a diagram contains branch points, or nodes, from which the daughter languages descend by different links.
Tree model of historical linguistics. The proto-languages stand at the branch points, or nodes: 15, 6, 20 and 7. The leaf languages, or end points, are 2, 5, 9 and 31. The root language is 15. By convention, the Proto-languages are named Proto-5-9, Proto-2-5-9 and Proto-31, or Common 5-9, etc.The overall Ursprache has a proto name reflecting the ordinary name of the entire family, such as Germanic, Italic, etc. The links between nodes indicate descent or genetic descent.All the languages in the tree are related. Nodes 6 and 20 are the daughters of 15, their parent.he overall Ursprache has a proto name reflecting the ordinary name of the entire family, such as Germanic, Italic, etc. The links between nodes indicate descent or genetic descent. All the languages in the tree are related. Nodes 6 and 20 are the daughters of 15, their parent.