Darwinian Evolutionary Theory encompasses such tenants as natural selection, survival of the fittest, and environmental adaptation. Simply put, those members of a species who were best equipped to survive whatever environment they faced did so while those less well equipped perished. The survivors then passed on the genetics of whatever adaptation they had been blessed with and the entire species evolved and thrived.
Nature is full of examples.
The bigger, stronger, and faster gazelles avoided becoming cheetah food while the slower ones did not. They passed along their added speed to the next generation. Longer necked giraffes could better reach the tender leaves of certain trees so could survive where those with shorter necks could not. This adaptation was likewise passed along. Snow leopards blessed with a winter white coat avoided predators, while those that didn’t were easy targets. Soon all snow leopards carried that genetic advantage.
These are the basic tenets of evolutionary change.
We see this in medicine on daily basis. Bacteria are constantly adapting to survive the antibiotics that are used against them. Those bacteria who can avoid death by penicillin are free to procreate and pass on this resistance to the next generation. The very deadly infection known as methicillin-resistant staph aureus (MRSA) is an example of this. Staph aureus is a nasty little dude. Infections of the skin, the lungs, and particularly the cardiac valves by these bacteria often prove deadly. Methicillin is a form of penicillin originally designed to attack these very organisms but with time they developed resistance to all penicillins, including Methicillin. This is one of the reasons antibiotics should be taken until completion of the prescription but unfortunately many people feel better after two or three days and stop whatever antibiotic they were prescribed. This allows those bacterial organisms, which might ultimately have been killed, to survive and adapt to the presence of the antibiotic. This is passed on from generation to generation and nasty little bugs like MRSA are created.
So what does all this have to do with religious rites?
It seems that every year the Zoque of Southern Mexico gather at a particular cave known as Cueva del Azufre for an annual ritual. The cave is inhabited by molly fish. A portion of the ritual is to impregnate the water of the cave with the mashed root of the Barbasco plant. This root contains a powerful anesthetic that stuns the fish so that they can then be used in the religious ritual.
A recent study by Mark Tobler of Texas A&M University showed that over time the fish in this cave have become more resistant to the anesthetic toxin. They have adapted to the traditions and religious practices of the Zoque. Not consciously of course, but from the fishes’ point of view the drug is an environmental stress that has resulted in some change in the biochemistry of the species so that they can survive in this altered environment. This adaptation has been passed from generation to generation.
The irony of a religious rite promoting evolutionary change is thick to say the least.