Random mutation and sexual selection alone never seemed to me probabilistically sufficient to account for the origin of species as Darwin claimed. The way I understood Darwinism, it would mean that every random mutation on the way to a big mutation that could serve a competitive advantage would in itself have to be selected for and dominate a species at every step of the way so that subsequent mutations could build on them else subsequent mutations would randomly occur in organism not necessarily possessed of the original mutational building block. That just didn’t make mathematical sense to me in explaining the evolution of any trait that required more than a single genetic mutation. I figured there had to be some feedback mechanism at work that we haven’t discovered yet.
I investigated a little bit, found a book about something called developmental plasticity and tried to slog through it, but it didn’t seem really to explain the mechanism. (Though it did acknowledge the mathematical problem with Darwinism, I was gratified to discover 🙂 ) Still, I figured there was something to it–or something like it–that had to be at work. I hadn’t thought about it too much more though, until today….
I saw an article claiming that a mother’s smoking caused changes in the DNA of her unborn child. I had to call BS on that. No way. As a mother of a child with Down syndrome, I spent a lot of time trying to figure out if environmental factors could cause birth defects or genetic abnormalities and only a small number of things actually do–and smoking was not one of them. What the article explained halfway through, though, was that smoking didn’t actually change the baby’s DNA, but influenced what genes were turned on and which were turned off. Now that I could believe (tempered by my healthy suspicion of agenda-based science, of course).
I had figured that a mathematically possible adaptation of Darwin’s theory might be that random mutations occur all the time and accumulate without changing the species, but as the changes offer benefits appropriate to a changing environment, they could be turned on. The big question remained, of course, how the organism can make the connection between the environment and the beneficial mutations–it betokens some kind of subcellular intelligence that I, for one, can’t get my mind around.
The smoking mom article called this type of genetic on-off switching “epigenetics,” so I googled “epigenetics & Darwinism” and found 7,080 articles—many of which added Lamarck‘s name to the mix. Apparently, Lamarck was run out of town on a rail for proposing an evolutionary theory that presupposed a feedback mechanism from parental behavior to offspring attributes. He is getting some props now, though, for seeming to anticipate epigenetics, albeit too little too late.
I am obviously not a scientist (and obviously am a nerd), but I love questioning the scientific theories that underpin the most basic assumptions of our lives, and I love even more finding the fissures in them that might lead to passageways toward deeper truths. I am eager to see how this line of science develops–and to continue questioning assumptions!
Skull of Homo erectus throws story of human evolution into disarray
A haul of fossils found in Georgia suggests that half a dozen species of early human ancestor were actually all Homo erectus