Bat Designs Tainted by Batty Evolution Stories
When learning about well-designed flyers like bats, is it helpful to speculate about how Darwinian evolution invented the traits by chance?
Drink Up, Boys
In previous news, we learned how dogs drink using “acceleration-driven open pumping” (15 Dec 2015). There’s a method in that mad slurping: to lift water from the bowl, your dog employs some elegant engineering to “to deal with the physical challenge of crossing fluidic regimes.” Bats have a similar, but contrasting challenge: they need to lift nectar, which is more viscous than water, while hovering over a flower. Scientists at Massachusetts Institute of Technology decided to figure out how they do it. They noticed that tiny hairs on their tongues are efficient at lapping up nectar and preventing it from draining away down the tongue, explains Phys.org. They experimented with artificial hairs on surfaces to model the factors governing the efficiency of the process.
Bat used in the experiments. Credit: MIT
Now engineers at MIT have found that, for bats and other hairy-tongued nectar feeders, the key to drinking efficiently lies in a delicate balance between the spacing of hairs on the tongue, the thickness of the fluid, and the “speed of retraction,” or how fast an animal darts its tongue back to slurp up the nectar. When all three of these parameters are in balance, a good amount of nectar reaches the animal’s mouth instead of dribbling away.
Given this information about engineering design, and how optimal it is, does MIT help readers by relaying the following story? “Animals have evolved all manner of adaptations to get the nutrients they need.” It makes even less sense to say that when the animal had no choice in designing its tongue:
“They all lie close to the theoretical optimal,” Nasto says. “They have evolved to be good drinkers. And if you think about it, humans can use tools for drinking and other behaviors. But a lot of other animals have to have their tools built into their physiology.”
More Engineering Than First Heard
Another species of bat gained respect in recent experimental science. The Egyptian fruit bat, a heavier bat than the nectar-eating bat studied by MIT, lives in trees instead of caves. Because it emits simple tongue clicks instead of vocal squeaks, and because it has large eyes to see during daylight, scientists had thought its echolocation abilities were more primitive than those of microbats. Wrong; scientists at the University of Washington have found that its “echolocation may work like sophisticated surveillance sonar,” according to Phys.org. (Note: the [T] indicates a tontology.)
“Before people thought [T] that this bat was not really good at echolocation, and just made these simple clicks,” said lead author Wu-Jung Lee, a researcher at the UW’s Applied Physics Laboratory. “But this bat species is actually very special—it may be using a similar technique that engineers have perfected for sensing remotely.“
Using high-speed cameras and head modeling, the researchers found that the high-frequency clicks are off center from lower frequency clicks. This makes its echolocation more like that of dolphins which, as the Illustra film Living Waters shows, is highly sophisticated (see the Dolphin Echolocation segment). The trick bats use to gain more information from the echoes is similar to what sonar and radar engineers do.
Lee recognized the pattern as a common one in radar and sonar surveillance systems. Invented in the early 20th century and now used throughout civil and military applications, airplanes, ships and submarines emit pulses of radio waves in the air, or sound underwater, and then analyze the returning waves to detect objects or hazards. While a simple single-frequency sonar has a tradeoff between the angular coverage and image sharpness, a “frequency-scanning sonar” solves this problem by pointing different frequencies of sound at slightly different angles to get fine-grained acoustic images over a large area.
Lee wondered if the bats use the frequency-scanning technique. Using high-speed cameras and acoustical equipment in a “bat lab” at Johns Hopkins University, Lee confirmed that “different frequencies point in different directions—just as a frequency-scanning sonar would act.” But then she said something illogical:
“For me, what’s exciting is the idea that you almost have a convergence between a system that was evolved, and the effects are very similar to what we have invented as humans,” Lee said. “This is not the classic case where we learn from nature—we found out that the bat may be doing the same thing as a system we invented many years ago.”
Surely she knows that bats used frequency-scanning sonar long, long before humans thought of it. And again, how helpful is it to be told this was an “evolutionary solution” that “was evolved”? Did she get that information from her bat lab, or from BAD assumptions? The paper at PLoS Biology actually has little to say about evolution, other than futureware: “other genera of the same family may provide insights into the evolution of lingual echolocation.” It sppears that speculation about evolution was tacked onto the science after the facts were in.
Does Bat Freeloading Endorse Communism?
It may be rare to find the word ‘scrounge‘ in a scientific paper, but evolutionists at Tel Aviv University used it often to describe these same fruit bats. In their paper in Science Advances, the open-access journal of the AAAS, they think some bats are scroungy characters. To “scrounge” means to borrow without any intention of returning it. Egyptian fruit bats live in trees in colonies of tens of thousands of individuals or more, building relationships for over a decade. In their attempt to understand the social relationships of these bats, the evolutionists set out some fruit in bowls to see how the bats behaved. The majority were “producers” who hunted for fruit and flew back to the roost with it. A minority, however, were “scroungers” who stole it from the mouths of the producers. The scroungers tended to act more wary at the bowls, holding their heads higher, looking around, and not taking as much of the fruit. They also tended to scrounge from the same limited number of individuals. Female bats tended to work more on producing during lactation periods. That’s the extent of the empirical observations.
What’s the take-home message of this apparently persistent relationship of producers and scroungers? Does it provide useful information about the ‘evolution’ of sociality in other mammals—even in humans? First of all, the astute reader should notice drawbacks in the materials and methods. Putting out fruit in a bowl is a highly artificial situation. The scientists knew they could not easily observe the bats in their natural roosts, hidden as they are by dense foliage, so they studied artificial habitats with highly reduced populations. Nevertheless, they claim they observed more than 13,000 social interactions – enough, they believe, to draw generalizations about wild-type behavior:
What is known about scrounging outdoors? It is hard to observe the bats’ behavior within the thick foliage, but we have witnessed scrounging many times in the wild when a bat returns to its colony with a piece of fruit in its mouth and is approached by individuals trying to scrounge the food. We do not have data on persistent producer-scrounger ties outdoors. However, an inspection of 24 scrounging attempts on bats that returned from foraging with food in their mouth to a wild monitored colony revealed two scroungers that scrounged at least four times on different nights and four additional scroungers that scrounged at least twice on different nights (movie S1).
That’s a pretty small sample to describe millions of animals that have lived for thousands of years without the watching eyes of modern scientists. Even giving the researchers the benefit of the doubt, however, generalizations about the “evolution of sociality” from this experiment and the use of “game” theory to describe it go too far beyond the data. They cannot be sure that the same behaviors hold true in nature in the dark of night, at all seasons of the year, throughout the vast range of the bats. They also do not know what other factors enter the equation: relatedness, sex, communication, microbiota transfer, and factors not even thought of. The researchers acknowledge that many questions remain about not just bats, but Egyptian fruit bats.
Most importantly, such observations cannot in any way advise humans on economics or political science, because humans have the power to think, reason, and choose. No one should assume that this paper tells people that a society of scroungers produces a stable economy. The 20th century should already provide ample data to conclude that “From each according to his ability, to each according to his need” and other redistributionist strategies are unstable and eventually collapse, leaving incalculable suffering in their wake.
Humans are not bats. We observe bats, but we do not see them putting us in a ‘human lab’ at the Bat Institute of Technology. The differences are too profound to generalize about human behavior from observing bats. Beware the evolutionists who try to apply “the evolution of sociality” into political systems.
We have some similarities with the bat colony, though. There are many humans who take things without any intent of returning them. We see this most clearly among Darwinians. They scrounge theological premises, such as the laws of logic, parts of morality and rationality – things they could never produce on their own – then gulp it down, breaking it apart with Darwin acid, reassembling it, and extruding it out the terminus of their philosophical convolutions as Darwin Fudge. Biology teachers and secular reporters scrounge for this toxic substance and think they are doing their duty as recyclers. The founders of science were producers, not scroungy characters scrounging other people’s good fruits and making garbage out of it.
Real science shows these amazing mammals batting close to a thousand. That’s the message from the data.