So, I understand why Peer would like to find a physical signal that can be used to identify the boundaries of “kinds” but as Peter and others have pointed out. This is no easy task. Peer seems to be looking for patterns and hopes that by looking at enough animals (and plants?) that eventually patterns will emerge. Sort of like, some microbiologists taxonomists have used cut-off values for %DNA similarity of certain genes to assign species and genera in a arbitrary fashion. That sounds possible but even if these is some pattern how do we know the pattern should be attributed to “kind” boundaries and not some other aspect of the nature of organisms. More importantly if one looks for patterns across many diverse “kinds” one seems to be required to assume that the amount of different in miRNAs or whatever else is some consistent value across kinds. What if each kind has its own different degree of internal variation. One might be in danger of calling foxes and wolves as the same kind which in fact they are different kinds according to God who made them with a different amount of variation than pands and polar bears. Also consider that if there is “degradation of genomes” and that creates variation or new miRNAs or even sorts out miRNAs as different rates in different lineages then the pattern approach is also doomed to failure. Joel