Your Throat Has Tasteful Antennae
Our airways are lined with cells that have beating oars called motile cilia. Like galley slaves on a Roman ship, they beat in coordinated waves, setting up currents that propel dust and foreign matter out toward the mouth. Scientists just found out another amazing capability of these motile cilia: they can “taste” toxic chemicals and send out an emergency response call when they can’t beat fast enough to sweep the airways clean.
The findings by Shah et al were reported in Science.1 In a Perspectives piece about the paper in the same issue,2 Kinnamon and Reynolds said that “human airway epithelial cells use elements of the bitter taste cellular signaling pathway to detect and eliminate potential noxious agents from the airways.” This was the first time motile cilia were found to be chemosensory. The non-motile primary cilia that stick out like antennae on many cells were known to have the ability to detect foreign molecules and react to them. Motile cilia now are found to have this ability. They can essentially “taste” noxious chemicals, just like the tongue can. They react by beating faster, trying to get the chemicals out. They have receptors that can also signal more responses such as coughing or sneezing. That’s how your body can quickly and automatically go into emergency reaction to dispel harmful chemicals.
Here’s a sample from Kinnamon and Reynolds to show just how complex this system is:
A similar signaling pathway is initiated by bitter compounds in taste cells and solitary chemosensory cells. Activated T2R receptors trigger the production of inositol 1,4,5-trisphosphate (IP3) and release of Ca2+ from internal stores. Ca2+ activates a nonselective cation channel, TrpM5, which depolarizes the cell and together with Ca2+ evokes the release of a transmitter that activates a target sensory neuron. In ciliated epithelial cells, bitter tastants signal through a similar pathway, but the functional outcome is an increased rate of ciliary beating.
Their article did not mention evolution. The original article mentioned it once, but only to refer to a paper that claimed that primary cilia and motile cilia are “evolutionarily related.”
1. Shah, Ben-Shahar, Moninger, Kline and Welsh, “Motile Cilia of Human Airway Epithelia Are Chemosensory,” Science, 28 August 2009: Vol. 325. no. 5944, pp. 1131-1134, DOI: 10.1126/science.1173869.
2. Sue C. Kinnamon and Susan D. Reynolds, “Cell Biology: Using Taste to Clear the Air(ways),” Science, 28 August 2009: Vol. 325. no. 5944, pp. 1081-1082, DOI: 10.1126/science.1179180.
Cilia are examples Michael Behe cited as irreducibly complex structures that defy evolution and show evidence of intelligent design. In the 11 years since his first book Darwin’s Black Box (1996) first called attention to the amazing properties of cilia, much more was discovered about them. Behe’s second book The Edge of Evolution (2007) discussed them in much more detail. They are just as complex as the flagellar motor – perhaps more. They are built by a complex system of molecular trucks that carry the building materials from base to tip. They use ATP to beat like oars. They coordinate their movements with neighboring cells. Now we find that they are also loaded with chemical taste sensors and connected into numerous signaling pathways. How are evolutionists going to explain all this? They can’t. They don’t. They just assume that natural selection can work any miracles required. Behe showed how this is contrary to evidence and common sense.
Speaking of Dr. Michael Behe, he witnessed some more Darwinian intolerance this past week. He was invited to appear on Bloggingheads with John McWhorter and received a very cordial welcome and good response by McWhorter, an evolutionist and agnostic, who was clearly fascinated with The Edge of Evolution and its implications. Shortly after the interview was posted, it was removed – but savvy I.D. investigators found it and posted it on Uncommon Descent. Watch the interview, then go to Behe’s blog page on Uncommon Descent where he explains what happened and why.