Stephen Bové - Art, Technology, Right Action

Sunday, December 19, 2004

Grist for Evolution's Mill

Kinsey, Wasps, Giant Eagles & Speciation

The film Kinsey.

Kinsey was a botanist...with a passion for demonstrating variety within a given species...he collected over 1 Million specimens of a single species of wasp and noted, "they're all different."

He also was a pioneer in the scientific study of human sexual behavior and variation:

Recent findings in evolutionary science indicate that the primary (not only) font of speciation may simply be meiotic/sexual variation.

Meiosis is the process where sex cells are produced with a randomly generated "genetic payload" (haploid gametes/spores) comprised of half of each parent's genome. The resolution in this process is at the "gene" scale.

Sexual combination (fertilization) is what happens when a sperm and egg mesh the two parental genomes into a single genome.

Both of these processes induce variation - statistically, a single human, with 46 chromosomes, can form 6,388,608 different gametes during metaphase I of meiosis alone.

Human science hasn;t yet worked out the subtle nature of the meiotic process, so random may not be may only be "approaching random", or better yet, "directed random."

Evolution may be the result of normal genomic expression. Evolution may not require "mutation" in the deleterious sense of the word.

Check out this article on the Great New Zealand Eagle and the new genetic evidence that it evolved from a local small eagle:

"The results showed that the New Zealand giant was in fact related to one of the world's smallest eagles – the Little Eagle from Australia and New Guinea, which typically weighs under two pounds. Even more striking was how closely related genetically the two species were. We estimate that their common ancestor lived less than a million years ago. It means that an eagle arrived in New Zealand and increased in weight by 10 to 15 times over this period, which is very fast in evolutionary terms. Such rapid size change is unprecedented in birds and animals," adds Bunce.

Read the whole article here.

When a species exists in an environment that does not change there is often No evolution. This is backed up by the theory/evidence of Punctuated Equilibrium first put forward by Anthony Aveni, Niles Eldredge, and most famously, Stephen Jay Gould. There are hundreds of examples in both the fossil record and the living world of species that retain their exact forms for MILLIONS of years - total stability over enormous amounts of so called DRIFT, and no so called evolution by mutation. The species is not changing because all the variation produced by meiotic/sexual probability is proving stays confined to a narrow band and no evolution takes place. There is probably lots of radiation-induced mutation, transcription error etc. over 1 million years, but a healthy genome manages this effortlessly. A genome that can't manage mutation becomes a diseased dead end.

It appears that mutations build up in the code for vestigial features and functions, but that doesn't impact an organism's chances for success, and the genomic operating system has complex (and little understood) mechanisms for ignoring (commenting out, suppressing the expression of) unneccary/dangerous parts of the code base.

The definition of species is notoriously hard to define. At some point, usually through geographic isolation and significant evolutionary pressure, different branches of a single species diverge so greatly in morphology and phenotype that their genomes become sexually incompatible. A wolf and a dog can still reproduce. Are a wolf and a dog the same species? Polar Bears and Grizzly bears can also reproduce. A wolf and a Bear cannot reproduce. Can Humans and Chimps breed? The truth may be shocking...and the answer is, no one knows. We need a better definition of species (for sexual and asexually reproducing organisms).

What about asexual reproduction. No meiosis. No fertilization. These organisms must be evolving by mutation, right? There are other forces at work in the asexual realm. Bacteria are not CLONES. Asexual reproduction induces variation (perhaps as much or more, statistically speaking, than meiosis/fertilization) into each and every offspring. A deep "probability cloud" of variation is created in any healthy and sufficiently large population of asexually reproducing creatures that enables rapid opportunistic evolution in the face of environmental stress. I would wager that understanding how this variation is created at a base-pair level of specificity would shine great light on the sexual-reproduction-meiosis problem.

If you and a single mate had 1 million children, no two of them would be alike. The variation you would see amongst your offspring would probably amaze you. Short, fat, athletic, wide, musical, mathematical, visually talented, mechanically oriented, tall, beautiful, downright ugly, diseased/deficient, hunters, gatherers, traders, maniacs, name it. If you picked the two or three children furthest apart in looks/features/traits, and those just happened to be your first, second and third chronologically born children, you would be astounded! Christie Brinkley and Elvis Presley (just to make a quick example) came from the most ordinary parents
(sorry mom and dad Brinkley/Presely) and Mozart's kids by his Musically gifted opera singer wife were NOT musical geniuses. I have two best friends who have 11+ brothers and sisters. The variation amongst the siblings is truly amazing. It's a living bell curve. The ends of the curve have kids you would never think are related to the center where the kids look/behave most like Mom and Dad. Unless your family and that of your spouse have been carefully controlling looks/traits for 20 or 30 generations (highly isolated populations are the closest we have to this today) , you can only guess what your kids will look/behave like. The more diverse your genetic background, the wider the divergence in your offspring will be. The power of normal meiotic/sexual variation is great, even in one mating pair! Statistically, all the variation in the human race on all the continents can be recreated from any four parents randomly chosen from anyplace on earth in less than 10,000 carefully controlled generations [[Update: this is being proven out by mitochondrial and Y chromasome DNA studies that link, in the case of the Y chromasome, all humans on earth today to a single male ancestor in south-west africa about 50,000 years ago. -- See ]]

Another interesting area for deep research: "Tribal Genomics": the expression of the genome can probably best be seen in it's fullest functional aspect when a whole tribal unit is studied (Craig Venter is onto this with his work sequencing whole marine biotas). Any group of 100 or 200 people who are closely related probably expresses a fully functional human "pack" or tribe genome...where the sum of the individual's talents equates to a formidable functioning human meta-unit -- it's the unit/tribe that gives Humans a seriously unfair advantage over all other lifeforms on Earth. At around 50,000 people, you see enough variation so that the ends of the bell curve show the absolute highs and lows (statistically) of human genomic expression. In a city of 50,000 people, say Florence in 1400, you will have a bunch of healthy Michaelangelos, Leonardos, Cosimo de Medicis, and other "geniuses" in every field/occupation at one end of the curve and the worst sort of diseased, nasty, unproductive laggarts imaginable at the other end. What is the genome of the Tribe trying to do? A) through communication and diversity of stregths, give the tribe a great advantage in a harsh world...hunting, gathering, child rearing...all easier in an intelligent tribe, and B) make sure that the sum total expression of the genome at any given time is capable of adapting, in the shortest possible period of time, to the widest range of environmental conditions.

Stasis should see the full flourishing and expression of the genome with no drift or evolution. Punctuation (the opening of new niches) should favor some fraction of the total genomic pool and provide opportunities for branching. The force of genomic variation through reproduction which is built into the the code of life itself, plus environmental variation & isolation over large periods of time seems to be the primary driver of speciation and evolution.