The four sentences (labelled $1,2,3,4)$ below, when properly sequenced would yield a coherent paragraph. Decide on the proper sequencing of the order of the sentences and key in the sequence of the four numbers as your answer:
- Complex computational of the $\text{CNS}$ are organized according to a “nested” hierarchic criterion; the organization is not permanent and can change dynamically from moment to moment as they carry out a computational task.
- Echolocation in bats exemplifies adaptation produced by natural selection; a function not produced by natural selection for its current use is exaptation --feathers might have originally arisen in the context of selection for insulation.
- From a structural standpoint, consistent with exaptation, the living organism is organized as a complex of “Russian Matryoshka Dolls” – smaller structures are contained within larger ones in multiple layers.
- The exaptation concept, and the Russian-doll organization concept of living beings deduced from studies on evolution of the various apparatuses in mammals, can be applied for the most complex human organ: the central nervous system $\text{(CNS)}$.