August 12, 2007 | David F. Coppedge

Immune System Appeared Early

“Social amebas” or slime molds have gotten praise recently as inventors of the immune system.  These amebas can band together in a “slug” that can move as a unit and generate stalks and spores.  Science Daily reported on research at Baylor College of Medicine that found “sentinel cells” in a colony of amebas that patrol the slug and engulf invading bacteria or toxins.  “Finding an immune system in the social amoeba (Dictyostelium discoideum) is not only surprising but it also may prove a clue as to what is necessary for an organism to become multicellular,” the lead researcher, Dr. Adam Kuspa, said.
    A Darwinian explanation was not long in coming.  The article continued,

One way to estimate the characteristics of the organism that went before those that were multicellular is to look for characteristics that are present in two, three or all four of these main groups, he said.
    “Those were likely present in the progenitor organism,” said Kuspa.  Because three of the four major groups of organisms have this pathway, “I argue that means that the progenitor of all multicellular organisms had this pathway.  Since that organism was not likely multicellular, it must have used it as some kind of signaling to respond to bacteria in the environment.”
    Looking at it from another point of view, “it’s possible that one of the properties of those (crown) organisms that allowed them to become multicellular was the ability to distinguish self from non-self — the hallmark of an immune system,” said Kuspa.  “The speculation is that a requirement of multicellularity is that you develop systems to recognize pathogens and other non-self cells from yourself.”

Kuspa did not describe how this might have come about by a blind process of random mutation and natural selection.  Astrobiology Magazine picked up on this story, adding this comment to its article, “We Are one” –

The evolution of multicellular organisms on Earth was an important step in the diversification of life on our planet.  Understanding these important moments in the history of life can help elucidate the mechanisms through which life develops and evolves, which in turn can help astrobiologists determine the potential for life’s development on distant worlds.

The original work was published in Science.1,2  Kuspa and his team only speculated about the evolutionary significance of their description of sentinel cells.  They said that this “first glimpse” of an immune-related signaling system might represent an “ancient function” in the common ancestor of plants and animals, but they did not explain how it arose; in fact, their discovery represents “another layer of complexity to the cellular cooperation observed in the social amoeba.”  They ended with more speculation about this as a function present in the hypothetical common ancestor: “If true, it would suggest that this system of pathogen recognition was advantageous to organisms before the evolution of multicellularity.”  Mitch Leslie said amen in his commentary: “the results suggest an early beginning for the specialized immune system now seen in multicellular organisms.”
    By contrast, another paper on the immune system in Science the prior week said nothing about evolution.3  Ira Mellman wrote that “immune cells often exhibit remarkable degrees of specialization and adaptation.”  The system “comprises a variety of cell types whose activities must be carefully regulated to act as a coherent unit for the purpose of host defense.”  Because of the “emerging complexity” of the field, he encouraged cell biologists and immunologists to get their heads together to try to understand how immunity works.

1Chen, Zhuchenko and Kuspa, “Immune-like Phagocyte Activity in the Social Amoeba,” Science, 3 August 2007: Vol. 317. no. 5838, pp. 678-681, DOI: 10.1126/science.1143991.
2Mitch Leslie, “A Slimy Start for Immunity?”, Science, 3 August 2007: Vol. 317. no. 5838, p. 584, DOI: 10.1126/science.317.5838.584.
3Ira Mellman, “Private Lives: Reflections and Challenges in Understanding the Cell Biology of the Immune System,” Science, 3 August 2007: Vol. 317. no. 5838, pp. 625-627, DOI: 10.1126/science.1142955.

As usual in evolutionary fables, the observation-to-assumption ratio is so low, the paper is indistinguishable from fiction.  They assume the millions of years, they assume a hypothetical progenitor, they assume neo-Darwinian mechanisms can invent an immune system, and they assume it can evolve into the highly-functional immune systems of higher animals and plants.  What’s the only observation?  that an organism observed today (not millions of years ago) has a clever way for ridding itself of harmful bacteria and toxins.  Those not infected by Darwin narcosis might think this to be evidence of design.
    “Don’t assume” is a security principle in almost every facet of life except evolutionary biology.  Don’t assume the power switch is off.  Don’t assume the gun is empty.  Don’t assume the items on the flight checklist have been checked.  Don’t assume Dad knows he’s supposed to pick up the kids.  Don’t assume the rock on the cliff will support your weight.
    Numerous Darwin Awards have been won by victims who assumed things.  The Darwinists who write in science journals, though, get away with their rampant assumptions because they never have to face the consequences.  We think it’s time for them to learn a little responsibility, or else kindly help humanity by removing themselves from the gene pool.

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Categories: Cell Biology

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