Explaining the punctuation of equilibrium

| August 16, 2011 | 1 Reply

The April, 2010 edition of Discover Magazine profiles biologist Lynne Margulis, famous for her well accepted suggestion that eukaryotic bacteria did not evolve in linear fashion, solely as as a result  of natural selection. Rather,

mitochondria and plastids–vital structures within animal and plant cells–evolved from bacteria hundreds of millions of years ago, after bacterial cells started to collect and interactive communities and live symbiotically with one another. The resulting mergers yielded the compound cells known as eukaryotes, which in turn gave rise to all the rest-the protoctists, fungi, plants and animals, including humans.

There was a shocking idea at the time (1967), but, as described in this article by Dick Teresi, the more recent ideas of Margulis are even more controversial. The Discover Magazine article documents her arguments that symbiosis is “the central force behind the evolution of new species.” This position runs counter to the holding of modern conventional scientific wisdom, that new species arise through “gradual accumulation of random mutations, which are either favored or weeded out by natural selection.” Margulis holds that random mutation and natural selection play a minor role and that the big leaps in the evolutionary record “result from mergers between different kinds of organisms, what she calls symbiogenesis.”

The Discover article takes the form of an interview, in which the dominant theme is that “natural selection eliminates and maybe maintains, but it doesn’t create.” Margulis argues that the laws of genetics “show stasis, not change.” She was prompted by the fact that there is no record of major fossil change until 542 million years ago, yet all of a sudden we see the Cambrian explosion. Stephen Jay Gould coined this phrase, “punctuated equilibrium,” “to describe a discontinuity in the appearance of new species.” According to Margulis, her explanation of symbiogenesis explains these discontinuities and should thus be considered the primary mechanism for evolution.

Margulis carefully distinguishes her approach from arguments based on “intelligent design.” She holds that those who advocate for “intelligent design” have nothing meaningful to offer to the scientific conversation.

In the Discover article, Margulis points out that “all visible organisms are products of symbiogenesis, without exception. The bacteria are the unit. . . . Symbiogenesis recognizes that every visible life form is a combination or community of bacteria.” She gives examples of mitochondria and chloroplasts.

Margulis describes how bacteria could become part of the cell of another organism:

At some point an amoeba ate a bacterium but could not digest it. The bacterium produced oxygen or made vitamins, providing a survival advantage to both itself and the amoeba. Eventually the bacteria inside the amoeba became the mitochondria. The green dots you see in the cells of plants originated as cyanobacteria. This is been proven without a doubt . . . I believe in acquired genomes.

She argues that evolutionary biologists “are basically anthropocentric zoologists.”

They’re playing the game while missing four fifths of the cards. The five are bacteria, protoctists, fungi, animals, and plants, and they’re playing with just animals–a fifth of the deck.

How important are bacteria?

We couldn’t live without them. They maintain our ecological physiology. There are vitamins and bacteria that you could not live without. The movement of your gas and feces would never take place in the bacteria. There are hundreds of ways your body wouldn’t work without bacteria. Between your toes is a jungle; under your arms is a jungle. There are bacteria in your mouth, lots of spirochetes and other bacteria in your intestines.… Bacteria are our ancestors.

What else does Margulis have to say that is controversial? Quite a bit. She holds that HIV is not an infectious virus “or even an entity at all. There is no scientific paper that proves the HIV virus causes AIDS.” She also holds that penicillin does not kill syphilis. “If you really get syphilis, all you can do is live with the [oftentimes dormant] spirochetes. She argues that “consciousness is a property of all living cells. She holds that human beings are “mammalian weeds… Like many mammals, we overgrow our habitats and that leads to poverty, misery and wars.

I found this to be a well-written article about a thoughtful and provocative scientist.

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Category: Biology, Evolution, Human animals, nature

About the Author ()

Erich Vieth is an attorney focusing on consumer law litigation and appellate practice. He is also a working musician and a writer, having founded Dangerous Intersection in 2006. Erich lives in the Shaw Neighborhood of St. Louis, Missouri, where he lives half-time with his two extraordinary daughters.

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  1. Erich Vieth says:

    From Edge.org:

    Biologist Lynn Margulis died on November 22nd. She stood out from her colleagues in that she would have extended evolutionary studies nearly four billion years back in time. Her major work was in cell evolution, in which the great event was the appearance of the eukaryotic, or nucleated, cell — the cell upon which all larger life-forms are based. Nearly forty-five years ago, she argued for its symbiotic origin: that it arose by associations of different kinds of bacteria. Her ideas were generally either ignored or ridiculed when she first proposed them; symbiosis in cell evolution is now considered one of the great scientific breakthroughs.

    Here’s a quote from a Margulis interview:

    I work in evolutionary biology, but with cells and microorganisms. Richard Dawkins, John Maynard Smith, George Williams, Richard Lewontin, Niles Eldredge, and Stephen Jay Gould all come out of the zoological tradition, which suggests to me that, in the words of our colleague Simon Robson, they deal with a data set some three billion years out of date. Eldredge and Gould and their many colleagues tend to codify an incredible ignorance of where the real action is in evolution, as they limit the domain of interest to animals — including, of course, people. All very interesting, but animals are very tardy on the evolutionary scene, and they give us little real insight into the major sources of evolution’s creativity. It’s as if you wrote a four-volume tome supposedly on world history but beginning in the year 1800 at Fort Dearborn and the founding of Chicago. You might be entirely correct about the nineteenth-century transformation of Fort Dearborn into a thriving lakeside metropolis, but it would hardly be world history.

    . . .

    I’ve been critical of mathematical neo-Darwinism for years; it never made much sense to me. We were all told that random mutations — most of which are known to be deleterious — are the main cause of evolutionary change. I remember waking up one day with an epiphanous revelation: I am not a neo-Darwinist!

    . . .

    Although I greatly admire Darwin’s contributions and agree with most of his theoretical analysis and I am a Darwinist, I am not a neo-Darwinist. One of Darwin’s major insights is the recognition that all organisms are related by common ancestry. Today direct evidence for common ancestry — genetic, chemical, and otherwise — is overwhelming.

    . . .

    Neo-Darwinism is an attempt to reconcile Mendelian genetics, which says that organisms do not change with time, with Darwinism, which claims they do. It’s a rationalization that fuses two somewhat flawed traditions in a mathematical way, and that is the beginning of the end.

    . . .

    Even today most scientists still don’t take symbiosis seriously as an evolutionary mechanism. If they were to take symbiogenesis seriously, they’d have to change their behavior. The only way behavior changes in science is that certain people die and differently behaving people take their places.

    . . .

    While Gould and the others tend to believe that species only diverge from one another, I claim that — more important in generation of variation — species form new composite entities by fusion and merger. Symbiogenesis is an extremely important mechanism of evolution. Symbiogenesis analysis impacts on developmental biology, on taxonomy and systematics, and on cell biology; it hits some thirty subfields of biology, and even geology. Symbiogenesis has many implications, which is part of the reason it is controversial. Most people don’t like to hear that what they have been doing all these years is barking up the wrong tree. . .

    http://edge.org/conversation/lynn-margulis1938-2011

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