Mrs. Love’s Note:I asked one of my favorite science teachers/doctors/bloggers I follow for a little clarification, because I knew that this information wasn’t completely on target. I knew we aren’t “fish” people. We are life forms. We share traits, like bones, guts, and eyeballs. I am using this as a metaphor, which I’m sure you all know. The metaphor is we share a sociological and biological imperative, a need to tell a story. At some point, humans stood up, looked around, and said, “I want to talk about this! Better invent language! I need to write this down! Better invent pigments for the cave walls! I need to read a letter from Aunt Mudpie, better learn to read! (She has a recipe for grilled mastodon that is to die for!)
Here’s what he had to say:
A couple of thoughts on your evolution post.
Humans and fish and reptiles all have common ancestors–just about everything alive does depending how far back you go–but no species around today evolved from any other species around today. Humans did not go through a “reptile” stage–we go back to a common ancestor.
The ontogeny illustration is lovely, and you’ll occasionally find it in textbooks, but it does injustice to the real appearance of embryos/fetuses at their respective stages. Ontogeny sort of recapitulates phylogeny, but not nearly as closely as would be fun to believe.
“Phylogeny” is a great word–it comes from “phylon” which means tribe, race, or clan; “geny”, of course, goes back to the same roots as genesis, and means birth or origin. So phylogeny is looking at the origins of our tribe!
Also: It is a lovely illustration, isn’t it? We animals/birds are all thrown together in an antiquated chart like some sort of indigo rainbow spectrum of life-light, albeit scientifically erroneous.
This is a stretch, I know, but perhaps early mankind felt more connected to the critters, creepers, and caterwaulers of the earth and sea, and that’s why animal spirits played an important role in spirituality, mythology, and fables.
Now, on to our originally scheduled post, already in progress:
If carbon-based organisms keep some genetic memory, some imprint, of our collective consciousness, is that why we keep telling the same stories?
Ontogeny is the development of an individual organism; in other words, from its embryonic “egg” form to its mature, developed state. Phylogeny is the scientific discipline that studies the evolutionary history of a group of organisms. In other words, ontogeny would study how you went from an embryo to who you are now; phylogeny would study the entire human race’s path. (I think that’s what it means. Perhaps one of my science friends can help me out with this one!)
The Connection between Ontogeny and Phylogeny
The evolution of the human brain over millions of years and its development over the course of one lifetime are inextricably linked. In fact, the best way to get an overview of the stages through which our brain passed in the course of evolution is to look at those through which it passes as an individual develops.
|The phrase “ontogeny recapitulates phylogeny” was coined by Ernst Haeckel in 1866 and for many decades was accepted as natural law. Haeckel meant it in the strict sense: that an organism, in the course of its development, goes through all the stages of those forms of life from which it has evolved.Modern biology now rejects this dogmatic perspective. Though recognizing that human beings evolved from fish and reptiles, biologists cannot discern in our development any stages that correspond precisely to those of a fish or a reptile.That said, species that share the same branch of the evolutionary tree clearly also go through the same early stages of individual development, though they diverge subsequently. One good example here is the basic skeletal structure of all vertebrates, which is one of the anatomical structures that is laid down earliest in the process of embryogenesis. In fact, the most precise way to describe this whole phenomenon might be to say that related organisms start with a common general embryonic form and then eventually diverge into distinct adult morphologies as they complete their development.
To understand the link between phylogeny and ontogeny (in other words, between the evolution of a species and the development of an individual), one must understand that a species can evolve from a series of small mutations in the development program encoded in its individuals’ genes. The earlier that these mutations occur in an embryo’s development, the more likely they are to be lethal, because of the fundamental changes that they will involve. That is why we tend to see more mutations in the later stages of development, and why various species show similarities in their early embryonic stages. But sometimes a mutation in the program at an early stage of development will still leave the embryo viable, resulting in a differentiation of these early stages that erases any strict correspondence with the phylogeny of this species. That is why a strict interpretation of Haeckel’s law of recapitulation does not withstand close empirical scrutiny.
Great conversation Friday afternoon, tying in with our World History studies. Consider early mankind. If you want to put a face on it, think about Lucy. With more time on her hands, perhaps she communicates a story to her young. They in turn, tell a story, too. They ask questions. They think of answers. They think outside of themselves. They begin to reflect on the meaning of their own existence. They use the spark, the light, the inner awareness (call it what you will) to look to the skies and ask, “Why am I here?”
How are we answering that question today? We’re still asking it. We’re still fighting over it. We’re still debating it. And sometimes it even involves blood, sweat, and tears. We want to know. We ate the fruit. We got fire. We created big rock clocks. And though we increase our data/technology construct, processing more information in the last five minutes than we did in the last five hundred years (I’m guessing), we still tell stories.
Is that what keeps us moving forward, or stuck in a rut? Or, is just a way to stay human?
That’s my story, and I’m sticking to it.