Natures wonders: navigating by using the magnetic field (Introduction)

by David Turell , Wednesday, January 17, 2024, 18:51 (100 days ago) @ David Turell

Many animals use the field by similar mechanisms:

https://evolutionnews.org/2024/01/in-bats-and-other-animals-evidence-of-common-design-i...

"One bat species, the soprano pipistrelle (Pipistrellus pygmaeus), migrates between northeast and southwest Europe. In this study researchers determined that the species calibrates their magnetic compass with the position of the sun at sunset. A compass based on the earth’s magnetic field is susceptible to various errors, including global drift over time and local anomalies. Therefore, a calibration mechanism improves its accuracy for traveling long distances.

"The bats do not just detect the direction of the magnetic field, but also the vertical inclination. Detecting the sun’s position is also not a simple mechanism. Research has found that bats can determine its location through the polarization pattern of sunlight. That enables the animal to determine the sun’s position even on cloudy days. This mechanism also involves a complex algorithm because the polarization pattern vectors change as the sun moves through the sky during the day.

"One bat species, the soprano pipistrelle (Pipistrellus pygmaeus), migrates between northeast and southwest Europe. In this study researchers determined that the species calibrates their magnetic compass with the position of the sun at sunset.1 A compass based on the earth’s magnetic field is susceptible to various errors, including global drift over time and local anomalies. Therefore, a calibration mechanism improves its accuracy for traveling long distances.

"The bats do not just detect the direction of the magnetic field, but also the vertical inclination. Detecting the sun’s position is also not a simple mechanism. Research has found that bats can determine its location through the polarization pattern of sunlight. That enables the animal to determine the sun’s position even on cloudy days. This mechanism also involves a complex algorithm because the polarization pattern vectors change as the sun moves through the sky during the day.

"The magnetic compass calibration demonstrated in bats is very similar to the behavior observed in some migratory songbirds, who have long been known to navigate using a magnetic compass. This was the case in an experiment with Savannah sparrows. The birds calibrate their magnetic compass by detecting the sun’s position using polarized light. What is different about the mechanism in the sparrows is that they calibrate their compass based on information decoded at both sunrise and sunset. This more complex method enables a more accurate calibration as the two measurements are averaged. A more accurate navigation path reduces the distance travelled, saving both time and energy for the animals.

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"Birds and bats are not conscious of these behaviors. Instead, they are programmed and involve neural networks and memory. There are physical organs that include mechanisms for detecting and encoding the magnetic field, and detection of the solar polarization pattern. An algorithm must perform the translation of the polarization pattern to the sun’s position, and an algorithm must compare the sensor data and calculate the required calibration. Finally, another algorithm must compute the corrected flight path based on the calibrated magnetic compass.

"The typical Darwinian explanation for common traits in species lacking a common ancestor is “convergent evolution.” Usually the specific mechanism invoked is developmental constraint. Paleontologist George McGhee explains, “The same forms have been produced by the repeated channeling of evolution along the same developmental trajectory…Natural selection has a limited repertoire of potential forms from which to choose, and convergent evolution is the result. (my bold)

"That explanation is inadequate for a number of reasons. The most obvious is that these behaviors do not involve forms that have developmental constraints. But the most significant problem in this instance is that these behaviors involve a number of complex physical and neural mechanisms and large numbers of genes. There is nothing deterministic that constrains all of these elements. A recent article here by Emily Reeves, “Convergent Evolution: An Argument that Comes at a Price,” explains other difficulties with the convergence explanation. The better explanation is common intelligent design. An intelligent agent, it seems, has chosen to design and optimize these complex mechanisms and applied them in unrelated animal species for purposes specific to those animals."
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Comment: The appearance of convergence in evolution has been used as a signal for a designer. 'Limited designs' can certainly mean a clever designer.