Emergencein elovution

Old bacteria never die; they just split in two. But cells in a multicellular organism have suicide programs. Genetically encoded self-deconstruction of cells is called apoptosis (the second ‘p’ is pronounced). In cell division, the molecules which copy the DNA work in opposite directions along the two strands of the DNA double helix. But the DNA gets unzipped in only one direction during the duplication process. So one of the copying molecules is likened, in the description of its work by Boyce Rensberger in his highly readable book Exploring the Realm of the Living Cell, to a short-legged man at a barn dance, continually dashing back to the newly unzipped part it has just danced away from. Also, like someone chewing along a corncob, these molecules need to grab on at both ends of the DNA section they are transcribing and so inevitably leave a last little bit uncopied. Nature's compromise is to stick a slew of throw away sections on the ends of the DNA helix of every chromosome. This strand of chromosomal DNA is called a telomere.

The number of divisions which a cell can undergo faithful to the original is limited. After this, cell division initiates senescence in which a cell, without protective telomere caps to chromosomes at the time of cell division exists, is altered. The senescent cell has missing, extra, or end-to-end fused chromosomes. In test tubes, cells stop doubling when they reach senescence. For example, skin cells (grown in test tubes) normally senesce after about 60 doublings. In the body, division of a senescent cell stops or continues through changing chromosomal states, with different patterns of gene activity, after each cell division until a limit is reached and after various lengths of time, which can be years, the cell dies. When it does, its DNA which would be dangerous material indeed if released unbidden into the body, is also destroyed (the more than a meter length of it unraveled) by enzymal activity. Senescence is not inevitable. In 1997, Woodring E. Write reported that the enzyme telomerase in a cell rebuilds the cell’s telomere after each cell division. Adult cells that retain or acquire the ability to produce this enzyme are thus immortal in the sense that for them senescence does not occur. Most cancers have this feature (10 percent of human cancer achieve immortality without it). In adult humans only the germ cells (which give rise to sperm and eggs) normally produce telomerase.

When a cell’s exit from the scene has been graceful, genetic theory insists that its genes benefit because replicas of its genes are in the other cells of the organism that its death somehow benefits.

Sex and programmed cell death (apoptosis) have an early association and division in the individual. The single-celled organism Paramecium identified by its comparative simplicity as one of the earliest sexual reproducers to have evolved, also evolved the programmed destruction of DNA used for cell maintenance but not of DNA set aside for reproduction. This theme of division of labor into somatic and germline DNA is a feature common to multicellular organisms. Why has this not been selected against in sentient creatures’ interest in their self? An extreme yielding to human hard wiring is neonaticide (normal in hunter gathering societies) when, what is akin to triaging, a mother (not without incurring emotional cost) kills her new born in dire times or when it is malformed. "Natural selection cannot push the buttons of behavior directly; it affects our behavior by endowing us with emotions that coax us toward adaptive choices" writes Steven Pinker.

Evolutionary biologists find no evidence that individuals sacrifice their interests to those of a group. Where this appears to be the case we have a "superorganism." But even in this, the selfish interests of an individual can coincide with those of the group and we have only the illusion of altruistic behavior. Dawkins’ early success was his book "The selfish gene." In this he adroitly showed how thoughtless competition between segments of chromosomal material can easily account for emergent physical niceties and group behaviors of sexual organisms. No matter how surprising these are, they are explainable if statistically they can be shown to increase the frequency of a gene in a gene pool. Here the individual is not important. The group of these momentary bearers of the selfish genes are behaving in a way that will improve the chances of increase of those genes in the population. For example, in herding animals, behaviors such as the giving of an alarm all at the approach of a predator, seem only to be for the good of the group until one observes that these alarm calls are given only when relatives are around or to direct attention away from the caller and towards the other (unrelated) fleeing members of the group. Among ants, bees and wasps genetic inheritance known as haplo-diploidy means that nonreproductive workers can actually reap higher fitness from rearing their sisters than from reproducing themselves. This does not mean that neo-Darwinists such as Dawkins are genetic determinists. Behavior of the individual and the group has a lot to do with the knocks of experience. For much evolution, statistical analysis of gene frequencies, and how these should fare, must err for equilibrium is rarely if ever achieved. Populations are found to be too small and their reproductive rate too slow in comparison to the rapid shifts in environmental conditions. Ecological studies would be easy were this not so and selfish genes are at the mercy of their bearers going extinct. Citing reasons such as these, Gould claims that neo-Darwinism fails in its ambitions. He considers how ensembles of genes fare but does not say as much; preferring to call them body plans laid down long ago. How evolution tinkers with the details of these (The Pander’s Thumb), is never ending source of supply for his marvelous essays.

Can such shamelessly selfish behavior be avoided by humans? According to Howard Bloom in his book The Lucifer Principle (1995) reproductively inefficient human behaviors such as suicide and celibacy could have some ancient basis in promoting one's immediate relatives, if by these actions the relatives are substantially better off. But it is doubtful whether people commit suicide or give up reproduction to promote a societal superorganism. So war and Crusades are aberrant indeed short of human society being an emergent "superorganism."

Our ability to speak our thoughts, our appreciation of art or skill for calculus are emergent capabilities of our brain (which was evolved to orchestrate immediate needs of survival and reproduction). Operating on different physiques nature endows differently. Do we doubt Jim Holt that better "reading maps (men) versus reading faces (women)" are not the legacy of the Pleistocene grasslands? Darwin’s reading was that men received the greater dowery. Helen Fisher in The Natural Talents of Women and How They Are Changing the World is anxious to read otherwise.

Whatever, and forever to confuse, emergence is more rapid than natural selection can coordinate. We find ourselves too irrational, victims to our emotions, too ready to believe in absurd animistic causes and too dumb when it comes to probability and statistics.

Also, what obedience do humans have to the prompting of their genes when Susan Golombok can report that parenting in families with a child conceived through donor insemination is measurably better than that observed in well-functioning families with a naturally conceived child; and, adoptive parents show child-rearing skills equal to those of parents of children conceived with medical help? If we can generalize from her study: for humans, genetic ties are less important for family functioning than is the overarching desire for (pets and) parenting. [go back]