This evidence for a common ancestor clinches the argument for human/ape evolution that follows from shared functionless sequences. Although the most numerous documented examples of such sequences shared between different species happen to link humans and apes (see for example Hamdi et al, J Mol Biol 284:861, 1999), this simply reflects the fact that the DNA of humans has been studied more intensively than DNA from any other higher species, while considerable homologous chimpanzee sequence is also known. It is obvious, however, that the identical logic could be used to link other species on different branches of the evolutionary tree, and such examples have been reported, e.g. SINEs clarifying relationships between rodent species (Furano J Biol Chem. 270: 25301, 1995; Verneau et al, PNAS 95: 11284, 1998) or linking horses to rhinoceros (Gallagher et al, Mamm Genome:140, 1999) or establishing the phylogenetic affiliations of tarsiers (Schmitz et al., Genetics 157:777, 2001) or pecoran ruminants (Nijman et al J Mol evol 54:9, 2002). Species as disparate as humans and mice have been linked by examples of the ancient SINE family known as MIRs (Mammalian-wide Interspersed Repeats; see Smit and Riggs, Nucleic Acids Research 23:98, 1995; Jurka et al, Nucleic Acids Research 23:170, 1995) that were found embedded at the homologous location in the human and murine myoglobin and N-myc genes (Donehower, Nucleic Acids Research 17:699, 1989; note that at the time of this description the conserved sequence was not recognized as a SINE). Additionally, ancient LINE insertions link humans to cow, as mentioned above (similar LINE inserts lying upstream of the intestinal alkaline phosphatase genes in both species), as well as to rat (similar LINE insertions in the first intron of the alpha2 subunit of the sodium-potassium ATPase genes; Smit et al, J Mol Biol 246:401, 1995) and to mouse (e.g. LINE insertions in the mnd2 region of chromosome 2p13 [Jang et al, Genome Res 9:51, 1998] and near the CD4 gene at human chromosome 12p13 [Ansari-Lari et al Genome Res 8:29, 1998]). With additional sequence comparisons of long homologous stretches of human and mouse DNA anticipated from the Human Genome Project and Mouse Genome Project, additional LINE sequences shared between these species will likely be discovered.
Am I correct in reading that humans share “junk” DNA with chimps and other primates and with mice and cows?
Would it also be correct to assume that humans share a much greater amount of junk DNA similarities with chimps than with mice?
Do the similarities in junk DNA increase as the relationship between closeness of species increases?
You just can’t get some guys to shut up, can you?
What percentage of junk DNA do humans share with
What percentage of our DNA is junk DNA? Is the percentage of DNA that is junK DNA the same for all species?
this thread for a partial answer to your question.
I have to say that I’m somewhat suspicious of the term “junk” DNA. I don’t think we know enough about it to call it “junk”. If you removed all the junk DNA from an organism’s chromosomes, would it survive? If no, it’s not “junk”.