I11 t.his article, the spectral ailalysis of cat,egorical time series is applied t,o t,he st.udy of DNA sequences. By ineails of t,lle st,udy of the spectral eilvelope for a ho~nologous DNA seglneilt from five different, pri1nat.e species, some global crit,eria are proposed to measure their similarity: and some iilforinat,ion concerning t,heir evolut,ioilary origin is obt,ained.