A FINGER, A TOOTH AND A TOE

A finger, a tooth and a toe change everything.

http://www.edge.org/conversation/rethinking-out-of-africa

This url will bring up both the video and the text of a talk by Christopher Stringer, a paleoanthropologist, who is himself a good example of a cultured and evolved man, which is to say that he is clear-headed, generous, willing to reconsider new facts, and persistent. I recommend the video.

He has been an advocate of the idea that all modern humans evolved from a population in Africa which was over millenia driven by weather events to both migrate and evolve. Now there is genomic evidence first that Neanderthals interbred with modern humans enough that we all have a little Neanderthal in us, and also that the mitochondrial DNA of a fossil finger of a little girl that was found in a Siberian cave indicates a whole new branch of humanity called Denisova. The finger is confirmed by a tooth and a toe found in SE Asia, which also supplies nuclear DNA (the main cell code) confirmation. The genomic map shows these people in Australia and New Guinea as well as a few other places. Evidently they were once all over eastern Asia. Many more fossils are expected.

Now it appears that the original hominids who left Africa separated into at least three large evolving mainstreams, some of which ended and some of which merged back into the people of today. The whole story gets more complex all the time. I will say, with no grounds whatsoever, that aboriginals in Australia and the people of New Guinea have always seemed eerily and qualitatively “different” somehow. Dare I say more “Zen”? I’m anxious to hear what contribution the Denisovans made to the genomes of Native Americans, some of which (not all) seem to have that same vibe.

One hardly knows whether to be more curious about the mtDNA (mitochondrial DNA, the little bracelet of “power” code in the intracellular blobs that convert glucose into energy) or the main nuclear DNA. I sometimes wonder whether the diabetes plague is related to the mtDNA and whether we are doing something that hurts those little power paks. There are swarms of them in each body cell, but a proportion of them can die or fray as we age. Maybe CAUSE aging. Too many missing would cause death, I suppose. Stringer is confident that even without more fossil finds, a thorough review of the fossils we have, using the new techniques, will reveal a great deal.

When he began his doctoral thesis, he set out across Europe with a set of calipers and rulers, going from one collection of fossils to another so he could carefully measure certain forms and bony spans considered characteristic of different stages of human development. A half-day per skull on average. It took years. Then more years to record his findings on punch cards, which was the way many computers worked in those days. Today that work could be done in a matter of weeks by scanning and using computer programs. BUT, he cautions, it was quite different to hold those skulls in his hands. No computer could give you that experience. It is human.

So here we are with our lives in our hands, stranded between what we thought we knew about the past (now rolling over into revision), speculating about what might happen in the future, where our evolution will carry us next, given that we are now meddling in our environment so massively as well as directly tweaking our genome, epigenome, hemocycling, and things in us that we barely know exist. Can we evolve fast enough to handle industrrial chemical contamination? A new climate? Beyond that we realize that evolution has gotten into our culture -- those memes instead of genes -- equally uncontrollable and contagious, moving across the continents into each other’s lives.

The just previous new paleoanthropology species proposed was homo florensiensis, a small microcephalic creature with big feet which was dubbed the “Hobbit” because it looked so much like that fictional species. The developing consensus is that they were dwarfed by the restriction of resources because they were trapped on an island, something like the current below-standard growth of North Koreans due to governmentally enforced starvation. The alternative is that the fossil people were suffering from some sort of pathology, but there are enough of them over a time period to challenge that idea. In time that species simply died out, almost certainly in a massive volcanic eruption 17,000 years ago.

What truly IS being challenged is the idea of species. There are enough living people walking around with Neanderthal or Denisova genes to make it clear that there must have been sex between these species -- but the definition of species is evolved sets of creatures who are separated enough that they cannot interbreed. The double helix unzips, one side of it goes to the other partner, and in that other partner’s ovum it zips to that new and different zipper strip. If there’s a bad fit, the code doesn’t work and no viable baby is produced. If there’s a possible fit, just a little wonky, you might get a mule. You can cross breed a zebra and a horse, or a lion and a tiger, but they don’t occur in nature because part of the process is the sexual memes: the timing, the place, the conditions, the come-on. If a zebra comes into heat in May and a horse comes into heat in June, it may only be a few outliers of each group who overlap enough to be in the proper state for zipping. If all the lions live on the grasslands and all the tigers live in jungle, they never meet. What not-interbreeding may say about species is simply that they don’t patronize the same bars, so to speak. We already know from YouTube that primates are a kind of animal that never gives up hope of fucking something new. Sod the consequences.

I keep thinking about the time-line. The homo erectus line left Africa 60,000 years ago. The long withdrawing roar of the glaciers melting back was 10,000 years ago, presumably the beginning of agriculture. By Old Testament times, the written records were having to provide a justification for moving from hunting/herding to agriculture and for building cities. By New Testament times anti-war ideas were seeping over from India, or so some think. So was Jesus simply a man with more than the usual percentage of Denisovian genes? On one side of the zipper it’s a silly question. On the other side, what sort of really rockin’ sci-fi story could a person get out of it?

But the kind of sci-fi stories that always worry me are the ones about outliers who are destroyed because they are different, stigmatized, non-conformist. There are quite a few of these worrisome stories because so many people who are interested in speculations are outliers themselves. Roiling times seem to create the danger out of for fear of their new memes. On the other hand, we’re in need of more evolution.