by David Catchpoole

Turtles at loggerheads with evolution

Biological compass detects magnetic intensity and angle to create “mental map”


Loggerhead turtles, thus termed because of their massive heads with large crushing jaws, certainly get around. Just as the aptly-named ‘Crush’ in the animated movie Finding Nemo famously rode “the EAC” (East Australian Current), so real loggerheads migrate not just from north to south along the east coast of Australia but also across the wide expanses of the Pacific and Atlantic oceans. For example, the journey that loggerhead turtles take from their nesting beaches in Japan to their feeding areas along the Californian coast and back is the longest migration known for a marine animal. The enormous range of loggerhead turtles encompasses all but the most frigid waters of the world’s oceans. How are loggerheads able to navigate across thousands of kilometres of open ocean, all the way back to the very beach where they hatched, to lay their eggs?

For over a decade now, it has been known that loggerheads, even as hatchlings, can use the earth’s magnetic field to help them tell north from south and steer themselves along the right latitude. How could such an amazing ability have arisen by evolution? As famous evolutionist J.B.S. Haldane noted in 1949, evolution could never produce “various mechanisms such as the wheel and magnet, which would be useless till fairly perfect”. To detect the earth’s magnetic field, loggerhead turtles must have some sort of magnetic sensor—thus, by Haldane’s criterion, proving evolution false.

Despite this, modern evolutionists have blithely continued to credit the loggerhead’s navigational capabilities to evolution, illogically disregarding the sophisticated design required for magnetic field sensing. And now recent findings have caught evolutionists by surprise, as it has been discovered that loggerheads’ positional and directional sense is way better than expected—explaining it without a Creator just got a whole lot harder.

Loggerhead longitude long-shot

Notwithstanding loggerhead turtles’ ability to use magnetic cues to determine latitude, it was widely believed that this wasn’t possible for longitude, because of how little the earth’s magnetic field varies in the east-west direction around the globe. (When you travel north or south away from the earth’s magnetic poles, their pull weakens substantially. In contrast, when travelling straight east or west, the intensity of the magnetic pull essentially doesn’t change—only the angle of the magnetic pull changes, and that only to a very slight degree.) As Princeton University evolutionary biologist James L. Gould put it in 2008, regarding turtles and other migratory animals’ uncanny ability to steer an accurate course: “A skeptic could reasonably believe that the latitudinal cue is magnetic, but that determining east-west position depends on magic.”

However, loggerheads have surprised evolutionists by demonstrating, “against reasonable expectation”, that the turtles can clearly determine longitude. The researchers took turtles that had just hatched in Florida but had never been in the sea and put them in a pool surrounded by computer-controlled magnetic coil systems. The magnetic coils were set to reproduce the geomagnetic characteristics of two points on the loggerheads’ trans-Atlantic migratory route at identical latitude—one in the western Atlantic, near Puerto Rico, and the other in the east, near the Cape Verde islands. Turtles in the ‘Puerto Rico’ tank swam northeast, just as loggerheads in the wild do when setting off on their migration, riding the currents that circle the Sargasso Sea and loop around the Atlantic. In the ‘Cape Verde’ pool however, the loggerhead hatchlings headed northwest, as if returning on the homeward leg of their circular migratory route.

So, loggerheads can detect both the intensity (field strength) and the inclination (angle) of the earth’s magnetic field to create “a mental map that covers all four points of the compass”. Actually, it’s more like a GPS than a mere direction-finding compass. As University of North Carolina researcher Nathan Putman pointed out, “a compass doesn’t really tell you where you are” whereas loggerheads’ mental magnetic map “gives them positional information”. I.e., “turtles determine longitudinal position by using pairings of intensity and inclination angle as an X, Y coordinate system.”

Putman adds that the findings might have a role to play in the development of human navigational technologies. “There may be situations where satellite might not be available, where this system of using two aspects of a magnetic field could be very useful,” he said.

In one sense, one can appreciate evolutionists’ surprise at the loggerheads’ “astounding migrational abilities” in relation to longitude. After all, it took human navigators hundreds of years to figure out how to determine longitude in their long-distance voyages—even with the impetus of huge prizes offered by Spain, France and then Britain. (Eventually, John Harrison (1693—1776) with his chronometers won the most money—£23,065, equivalent to over £3.3 million today.)

loggerhead turtles

Thus the ability to determine longitude, requiring such intense and directed human intelligence, would surely not be found in the “tiny brains” of loggerhead turtles—for surely such could not have arisen through evolutionary processes?

Indeed not — and therefore the fact that turtles have that capability points to its having originated from an intelligence surpassing that of humans, i.e. loggerheads have such features by design, not by evolution. In light of Romans 1:20 (those who deny the Creator are “without excuse”), one can see there’s a reason that turtles are at loggerheads with evolution. They were created to thwart evolutionary storytelling!

Want more? Read the fully referenced article at

Courtesy Creation Ministries International,

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