Unique Mammal Senses

The ability to sense the environment is vital to all living things, and is a key characteristic that separates life from non-life.  The senses are not limited to the five we learn as children – sight, hearing, touch, taste, and smell.  In the animal kingdom there are more.  Some of them repurpose existing organs; some detect other information from the world not detectable with the normal sense organs.  In mammals, two very different animals – bats and dolphins – have expanded our understanding of sensation.

Two papers in Science this week added to our understanding of echolocation in bats.  One paper explored how bats are able to separate target information from background clutter.  Bates, Simmons and Zorikov, writing in Science,¹ experimented with “big brown bats” and found that they “exploit harmonics to distinguish clutter echoes from target echoes, sacrificing delay acuity to suppress masking.”  That ability would be amazing enough for a stationary target, but bats do this while flying rapidly through complex aural surroundings.  One would think from the researchers’ description that they are sophisticated audio engineers: “The key to how the bat recognizes weaker FM2 from lowpass filtering is an interaction between the amplitude of an echo and the timing, or latency, of the neural responses it evokes—an effect called amplitude-latency trading.”

In the other paper in Science,² Simon, Holderied, Koch and von Helversen discovered a neat cooperation between a nectar-eating bat and its host plant.  Targeting of the plant is enhanced by a specialized leaf that reflects the bat’s echoes like a satellite dish.  Science Daily showed a picture of the flower with the sonar dish right over the flowers.  This host plant lives in low abundance in the tropics, so it relies on the bat’s wide foraging range and excellent spatial memory.  By providing the bat with an echolocating enhancer, the plant has a 50% higher chance of being found.  The bat gets its energy drink, and the flower benefits from the pollination that occurs.  The shape of the leaf, therefore, serves a similar purpose to an echolocating bat that beautiful colors in flowers serve for daytime pollinators.  “Because of their peculiar shape and presentation, we hypothesize that these special leaves evolved as echo beacons that attract pollinating bats,” the authors said.

M. Brock Fenton analyzed these two papers in the same issue of Science.³  Since echolocation was first discovered, he said, it has been a “gift that keeps on giving” as scientists learn more about it.  “The sophistication of bat echolocation is becoming increasingly apparent—they ‘design’ echolocation signals (by manipulating the frequency, intensity, and harmonics in their calls, for example) as well as their patterns of call production (such as call duration and time intervals between calls) in particular situations,” he said.  “Furthermore, the echolocation signal that one individual bat uses to collect information can simultaneously serve a communication function, allowing, for example, group members to remain in contact with one another.”  In addition, bats have to control their calls to outsmart rivals and to sneak up on prey that can hear the bats coming.

Fenton ascribed the phenomena to “evolutionary arms race” and to “coevolutionary relationships,” but did not describe how these abilities might have arisen by random mutations.  “At what point in their evolution did echolocation appear?  How often did echolocation evolve in bats?” he asked, indicating that fundamental questions remain for evolutionists.  Reviewing the history of how bat echolocation was discovered, first suggested by Spallanzani in 1794, then confirmed by Donald Griffin in 1944, he added, “Simon et al. and Bates et al. have demonstrated that echolocation is a gift in research that keeps on giving, whether the study organisms are bats, birds, shrews, toothed whales, or even people.”  He was referring to experiments on blind people that show their enhanced ability to locate objects by sound.

Dolphins and toothed whales are among the mammals with the sixth sense of echolocation, but now a seventh sense has been found in at least one species.  New Scientist reported that Guiana dolphins can sense electrical fields of their prey.  This species needs to forage in the murky coastal waters of its habitat and find prey at close range, where echolocation is less effective. Experiments by German scientists show that the sense organs are in pits corresponding to the whiskers of land mammals.  Live Science put it, “Through evolution, the dolphins have lost their whiskers, but kept the pores.”  Prime researcher Wolf Hanke from the University of Rostock also ascribed the ability to evolution.  Believing that electrical sensing also evolved in the duck-billed platypus and echidna, he reasoned that “it is relatively easy to evolve, to change mechanoreceptor organs into electroreceptors.” That opinion was not supported by any empirical evidence mentioned in the article.

1. Bates, Simmons and Zorikov, “Bats Use Echo Harmonic Structure to Distinguish Their Targets from Background Clutter,” Science, 29 July 2011: Vol. 333 no. 6042 pp. 627-630, DOI: 10.1126/science.1202065.

2. Simon, Holderied, Koch and von Helversen, “Floral Acoustics: Conspicuous Echoes of a Dish-Shaped Leaf Attract Bat Pollinators,” Science, 29 July 2011: Vol. 333 no. 6042 pp. 631-633, DOI: 10.1126/science.1204210.

3. M. Brock Fenton, “Ecology: The World Through a Bat’s Ear,” Science, 29 July 2011: Vol. 333 no. 6042 pp. 528-529, DOI: 10.1126/science.1209933

Such explanations ignore, even if it were possible to account for the reception of the information, the ability of the brain to interpret the signals and respond appropriately.  If a mutation suddenly gave your skin the ability to detect the hiss of distant quasars, would it cause you to become a cosmologist?  No; for one thing, unless the receptor were connected to nerves that traveled to an appropriate area of the brain, you would not even know about it.  For another, the hissing noise would be a defect that might distract you from getting married.  You would go extinct.  Even if you had offspring, the trait would be unlikely to become established in the population.  Signaling and functional response imply design.

The two main papers barely mentioned evolution, but the scientists and reporters who did committed the common fallacy among evolutionists of saying these animals “evolved” this or “developed” that, as if they held a committee and said, “Fellow bats, we would have better luck hunting if we would just invent the ability to echolocate.”  This is the folly of personification, and it misrepresents neo-Darwinism, the intent of which was to eliminate teleology from science.  A bat or dolphin can no more “evolve” echolocation or electrical sensing than a rock can decide to evolve an office building. 

If the Creator put into animals and plants the ability to adapt to changing environments, however, then the existence and subsequent enhancement of these innate abilities through microevolution make sense.  Read Randy Guliuzza’s ICR article “Natural Selection Is Not ‘Nature’s Design Process’’ where he describes such Darwinian explanations as cases of personification and circular reasoning.  If we force Darwinists to be faithful to their own theory, they would have to shut up, resulting in less fallacy and greater fascination at the design in living things.