Bats and Evolution
by Ron Lyttle

Have you ever gazed up into the sky on a warm summer's evening as darkness was enveloping the land, and seen flying creatures darting and swooping through the air?  Birds, you thought at first, but as you watched, there was a fluttering, twisting, dropping motion to their flight that wasn't right for birds.  Bats! you suddenly realized.  And you were either pleased at the chance to observe them in action, or a little frightened as myths of Dracula and vampires, coupled with concerns about rabies, came to mind.

Through the ages, bats have been the stuff of myths and legends, misunderstood and feared.  But what are bats, and where did they come from?

Bats are mammals.  They are covered with fur, give live birth, and nurse their pups with nipples located on the sides, under their wings.  But what makes them unique among mammals is the fact that not only are they perfectly designed for hanging upside-down, like the sloth, but they can also fly.  They are the only flying mammal.  Flying squirrels and flying lemurs can only glide; only bats actively fly.

Bats are not rodents, although many people think of them as mice with wings, and indeed, the members of the genus Myotis (including the common Little Brown Bat, Myotis lucifugus) are called mouse-eared bats.  But they only have one pup per year (a few have twins or up to four), and live twelve to thirty or more years, depending on the species.  Bats are so unique that they have been placed in their own order, Order Chiroptera, meaning "hand-wing".  As the name implies, their wing consists of an arm that ends in a wrist with a thumb and four separate fingers which are webbed with skin, and form the ribs of the wing.  By contrast, a bird's wing  possesses a greatly-reduced number of "finger" bones.  When bats aren't flying they fold their fingers back along their forearms out of the way.  While the thumbs of most insect-eating bats who catch their prey on the wing are small and weak, the big fruit-eating bats called flying foxes (because of their fox-like or dog-like face) have very long and strong thumbs with curved "thumbnails" like claws, which they use for climbing around in trees and gripping fruit.  Bat fingers have the same number of bones ours do, but they are proportionately much longer.  The last bone of the "middle" finger of the Rodrigues bat (Pteropus rodricencis), for example,  is actually folded behind the elbow when at rest.

Look at your fingers and forearm; try to fold your fingers down against your arm, and try to imagine your fingers extending past your elbow.  But don't forget to leave your thumb extending forward for gripping and climbing.  Then there is the webbing that connects all the fingers except the thumb, and extends all the way along the arm and body to the ankle, and in most species continues to envelop all or part of the tail.  When bats extend their fingers and arms, their wings are ready for flight.  By shaping their "hands" they control the shape of their wings.  Slow-motion photography (National Geographic Video) has actually shown insect bats scooping up insects in their wings and tail membranes, transferring them to their mouths in mid-flight.  Truly they are unique mammals.

The order is broken down into two sub-orders, Megachiroptera, the "big bats", and Microchiroptera, the "little bats".  All the insect bats are microbats;  the old-world fruit bats, the flying foxes, are megabats.  All the rest are in one or the other, mainly according to their size.  The system breaks down, however, since some micros, like the little Jamaican fruit bat (Artibeus jamaicencis), eat fruit, and one flying fox, the Queensland blossom bat (Syconycteris australis), weighs only half an ounce.

Since most bats eat insects, evolutionists have traditionally taught that bats evolved from primitive insectivores, as did shrews, moles, etc.  Fruit-eaters merely modified their diet due to ecological pressures.

Then in the early '80s J. D. Smith (Smith pp. 347-365) suggested that megabats and microbats evolved separately, because there are many physiological differences between the two other than just size.  Microbats have a complicated shoulder joint and a claw only on the thumb, for example, while megabats have a simple shoulder joint but a claw on both the thumb and first finger.  Micros use echo-location, while macros mainly rely on their keen eyesight.  Micro teeth are designed for prey, while mega teeth grind plant parts.  Megabats can live only in the tropics, needing a year-round food supply; many microbats have the ability to hibernate through cold winters.

In 1986 Dr. John Pettigrew further proposed that flying foxes most closely resemble primates (Pettigrew p. 1), and that along with flying lemurs who also have their own order but don't actually fly, they share a common ancestor with the primates.

He based his conclusions on research that showed that primates have unique neural pathways in the brain, having to do with vision, and that these pathways were so unique that it was thought that they distinguish primates from non-primates.  Dr. Pettigrew discovered that all flying foxes also have them, including the little blossom bat mentioned above, but that no microbats do.  As the flying lemurs also have these pathways, he proposed that they are really all primates, sharing a common ancestor, and that powered flight in bats evolved a second time, later in evolutionary history, only coincidentally resembling that of microbats.

Since then, however, other researchers have challenged his "two-origins" idea (Gibbons p. 34).  Studies with mitochondrial DNA have shown that all bats are closely related, and separate from primates.  Also, there is a muscle complex in the wings of all bats that is different from birds and all gliding mammals.

Rather than saying that all the similar adaptations necessary for powered flight evolved separately in the two groups of bats, the alternative explanation is that it is actually the similar neural pathways, associated with visual acuity, that arose independently in flying foxes, flying lemurs, and primates, as all rely on their vision to find food.  The microbats, in contrast, rely mostly on their hearing in echo-locating, and never developed these pathways.

In trying to understand the origins of bats, researchers can study living animals, but nobody was around millions of years ago to observe the formation of bats, so they have to rely on fossils to supply the evidence of what they propose.  What, then, is the evidence?  What do the fossils say?  In Bioscience, May 1992, we find this quote:
"Unfortunately, the fossils available only complicate matters.  They do not represent transitional morphology between quadrupedal (four-footed) animals and flying bats, and they represent animals nearly as specialized as their modern relatives"  (Thewessin p. 340).

And in Bats:  A Natural History, John Hill says almost the same thing:
 "...all fossil bats, even the oldest, are clearly fully-developed bats and so they shed little light on the transition from their terrestrial ancestor" (Hill p. 33).

The oldest known skeleton, supposedly 60 million years old (Wilson p. 79), is a fully-formed bat which apparently could echo-locate (UCMP Berkeley).

When you ask an evolutionist to show you the ancestor of a bat, he will, in all likelihood (as does the ZooBooks volume on "Bats"), show you a mythical creature with elongated limbs connected by stretched skin gliding from branch to branch like a modern flying squirrel.  It will have paws on all four limbs, and may be seen perching on a branch with skin folds hanging down (Wood and Rink, p. 6).  What the evolutionist will not show you is any kind of transition between paws used for standing and running, and hand-wings used for flying.  He won't show you because there is no fossil of such a creature, and he can't imagine what one would look like.  He also can't explain how "survival of the fittest" would produce it.  At some point elongating front toes would interfere with quadrupedal (four-footed) movement long before they could become the ribs of functional wings.  And why and how upside-down?  Birds perch very well right-side up.  How does "survival of the fittest" turn an animal upside down, with all the physiological changes necessary for maintaining that position?  Try swallowing while hanging upside-down.  And what happens to your blood after a while?  Yet bats eat, sleep, and mate upside down, and many also give birth in that position.

"Survival of the fittest" is half of the standard answer when evolutionists are asked about the mechanisms of evolution.  They will point to examples like Darwin's famous finches, or bacteria that become immune to antibiotics used against them.  But are these examples of evolution, or of selective breeding?  Is there any new information present?

In 1859 Charles Darwin published his Origin of Species, in which he presented his concept of the evolutionary development of species, based in part on his observations on the Galapagos Islands.  There he observed that while there were finches on all the islands, similar to finches on the mainland of South America, the birds on each island differed in bill shape (corresponding to different diet) and in coloration, both from each other and from the "parent" form on the mainland.  Similar differences were observed with species of tortoises and lizards found on the islands (Darwin p. vi).  Although he admitted that fossil evidence did not support his ideas (Darwin pp 272-3, 423), Darwin postulated that the same pressures that produced such variation in birds could also account for the larger differences between species, families, and orders, and that all must have evolved from a common ancestor by an accumulation of many small changes sometime in the distant past.  Most modern evolutionary thinking "evolved" from these early observations and thoughts.

Unfortunately, another famous set of observations was not published until 1866, seven years later.  That's when Gregor Mendel reported his observations and experiments with the color of pea flowers (World Book Encyclopedia vol. 9 p 202).  He had noted that peas in his garden had either red or white flowers, and discovered that by carefully controlling the source of pollination, he could produce peas with only white or only red flowers, or those with a mixture of the two, and that there was a regular and predictable pattern from one generation to the next.  I said "unfortunately" because before this the mechanism of heredity was not understood, and people thought that characteristics acquired by one animal or plant could be passed on to its offspring, and no one knew why a red-flowered pea plant could produce peas that would have either red or white flowers (World Book Encyclopedia, vol. 9 p. 208, vol. 13, p. 398).   Indeed, it was not until 1900 that the importance of Mendel's work was understood, and the concepts applied to other characteristics in both plants and animals, giving rise to the modern science of genetics.  Had Darwin known about genes and chromosomes and how they affect heredity, he might have realized that as Mendel could selectively produce all red-flowered peas or all white-flowered, so "natural selection" produced finches with different bill shapes and colorations.  The potential for different shapes and colors was present in the original population, and no real change or "mutation" had occurred.  What Darwin saw as different species may in fact have been no more than the extreme variation between a great Dane and a Chihuahua (both are dogs) or between a miniature horse and a Clydesdale (both are horses).  These extremes, while seemingly "obviously" different species altogether, are in fact genetically (if not mechanically) capable of interbreeding and producing viable offspring.

So it is with the bacteria.  In any "normal" population there are a few individuals who will survive drugs that will kill all the others.  When only these are left to reproduce you wind up with a new population of drug-resistant bacteria, but no mutation has occurred, contrary to popular literature (Wieland p.11).

In all these examples, there has been no gain in genetic material, no increase in information.  As peas that produce only red or only white flowers have lost the gene that codes for the other color, so the birds with short heavy beaks have lost the ability to produce long, slender ones, and the bacteria have lost potential that they once had.  If environmental circumstances change, they are now less adaptable, not more.  Evolution, on the other hand, requires a gain in information to produce new species.  Otherwise amoebas remain amoebas, fish remain fish, and bats came from other bats.

"Mutation" is the other half of the standard explanation for evolution.  It is assumed that over countless generations, mistakes occur in the genetic code, producing new characteristics, and that, given enough time and mistakes, a new species results.  But is this good science, or wishful thinking?

Every living thing, from the most simple virus to the most complex animal, contains in its cells very complex compounds called nucleic acid.  There are two forms, called ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) (World Book Encyclopedia vol. 14 pp. 602-603).  Viruses contain only one or the other, but cells contain both.  While RNA controls protein production, DNA is the main component in chromosomes, which provide the blueprint or pattern of heredity.  Every time a cell divides into two, the RNA in the cell body and the DNA in the nucleus must be exactly copied, with one copy going with each cell.  DNA is an incredibly complex molecule, resembling a long ladder that has been twisted into a spiral.  The sides of the ladder are made up of compounds called phosphates and sugars, while the "rungs" are composed of two of four possible bases in all the possible combinations.  The exact make-up and order of "rungs" varies from one kind of living thing to another.  Each DNA "ladder" has about 20,000 "rungs", and each chromosome contains many thousands of DNA molecules.  RNA has a similar structure, but the sugar is different, and one of the four bases is also different.

Since it is the chromosomal DNA (and in some cases RNA) that provides the blueprint for each cell and individual, if any of the thousands of rungs gets damaged, or if different combinations get substituted in the copy, that cell will be defective.  Contrary to popular belief, most changes in the DNA structure (mutations) at best weaken, and at worst kill the cell.  Only a very few are neutral, and beneficial changes are virtually non-existent (Sunderland pp 142-143).  To produce a healthy, fully-functional individual, each copy of DNA and RNA must be identical to the original, down to the last "rung".  "Weakened scales" in dinosaurs cannot logically and scientifically mutate into wondrously-complicated bird feathers, for example; far too much genetic information would need to be added to accomplish that, and mutations do not add information (Sunderland p 154).  In a few rare instances, there has been a mutation that allows a bacterium to avoid the effects of an antibiotic, but only because the mutation blocked a normal function of which the drug was designed to take advantage (Wieland p. 12); again, this represents a loss of information, not a gain.

Thus "survival of the fittest" and "mutations" cannot logically produce the fully-functional hand-wing found in even the oldest known bat fossils, no matter how much time is allowed, but Darwin did not understand that.  He blindly assumed just such a development, saying "Nor can I see any insuperable difficulty" (Darwin, p. 142) in getting from a gliding animal to a bat by many small steps, not understanding just how preposterous they are in the light of modern understanding of genetics and DNA.

A far simpler explanation is that bats, like cars and planes, are the product of very careful, intelligent design;  all the varied shapes and features equip different bats to function in different ecological niches.  All the anatomical details necessary to fly and to hang upside down have been thought of and "programmed" into the genetic code.  Bat feet are totally relaxed when they are hanging (Dr. Blair Csuti, personal communication, October 17,1998), requiring effort to let go; how did that "evolve"?  Bracken Cave, in south-central Texas, is home to some 20 million Mexican free-tail bats (McCracken pp 67-68).  Each bat has to recognize the echo of its own call in the middle of millions of other echoes to avoid collisions and find its way.  How did that ability develop through chance mutations?

The problem with accepting intelligent design is not that it is unscientific; as has already been discussed, it is evolution that is in fact unscientific in its suppositions.  No, the real problem is that if you accept intelligent design, then you have to have a designer.  Determining the nature and identity of that Designer gets into the realm of religion, and if there really is a Designer, then maybe the Bible is true when it talks about a God that claims to have created the universe and all that is in it, and maybe people have some accountability to that Creator.  To many people, scientists and lay people alike, that accountability is unacceptable, unthinkable.  There must therefore be an explanation that does not require a Creator (and they will go to great lengths, twist and ignore the facts, to come up with such an explanation).  That is the real problem with accepting design rather than chance evolution, regardless of what the facts seem to indicate.  In fact, several honest scientists insist that the facts do show evidence of intelligent design (see Dr. Michael Behe, Darwin's Black Box, and Dr. Michael Denton, Evolution:  A Theory in Crisis, just to name two with books; there are many more).

Astronomers are spending millions of dollars building and using huge radio-telescopes to search for non-random radio signals from outer space.  It is believed that a non-random, orderly sequence would be a sign of intelligence "out there", because it couldn't happen by chance stellar activity.  But when molecular biologists turn their microscopes to the study of DNA  molecules, the incredible non-random sequences they observe are seen as only chance accidents.  Does this make sense?  Is this scientific?

At the conclusion of his book, Evolution: A Theory in Crisis, Denton sums it up like this:

" one has ever observed the interconnecting continuum of functional forms [Darwin's many small steps] linking all known past and present species of life.  The concept of the continuity of nature has existed in the mind of man, never in the facts of nature.  In a very real sense, therefore, advocacy of the doctrine of continuity has always necessitated a retreat from pure empiricism, and contrary to what is widely assumed by evolutionary biologists today, it has always been the anti-evolutionists, not the evolutionists, in the scientific community who have stuck rigidly to the facts and adhered to a more strictly empirical approach"  (Denton pp.353-354).

Did bats just evolve, or were they intelligently designed?  Think about it.  Be honest.


Behe, Michael (1996).  Darwin's Black Box: the Biochemical Challenge to Evolution, The Free Press, New York, N.Y.
Darwin, Charles (1872, reprint 1963).  On The Origin of Species by Means of Natural Selection, 6th ed. (with new preface), The Heritage Press, New York, N.Y.
Denton, Michael (1986).  Evolution: A Theory in Crisis, Adler & Adler, Bethesda, Maryland.
Gibbons, Ann (1992).  Is "Flying Primate" Hypothesis Headed for a Crash Landing?  Science, Apr. 3, v. 256 n. 5053, p. 34.
Hill, John E., and James D. Smith (1984).  Bats:  A Natural History, University of Texas Press, Austin.
McCracken, Gary F., and Mary K. Gustin (1987).  Batmom's Daily Nightmare, Natural History, Oct., v. 96  n. 10, pp. 66-73.
National Geographic Society (1973).  Strange Creatures of the Night [Video].
Pettigrew, Dr. John D. (1986).  Are Flying Foxes Really Primates?  Bats, Jun. v. 3 n. 2, pp. 1-2.
Smith, J. D., and G. Madkour (1980).  Penial Morphology and the Question of Chiropteran Phylogeny, Proceedings of the 5th International Bat Research Conference, Texas Tech Press, pp. 347-365.
Sunderland, Luther D. (1988).  Darwin's Enigma, 4th Ed., Master Book Publishers, Santee, CA.
Thewissen, J. G. M., and S. K. Babcock (1992).  The Origin of Flight in Bats, BioScience, May, v. 42 n. 5, pp. 340-345.
UCMP Berkeley (1999).  Chiroptera:  Fossil Record.  [On-Line].  Available:  http://www.UCMP.Berkeley.EDU/mammal/eutheria/chirofr.html.
Wilson, Don E. (1997).  Bats in Question, Smithsonian Institute Press, Washington D. C.
Wood, Linda C. and Deane Rink (1994).  ZooBooks: "Bats". California: Wildlife Education Ltd.
World Book Encyclopedia (1999).  Heredity, v. 9 pp. 200-210.
World Book Encyclopedia (1999).  Mendel, Gregor Johann, v. 13 p. 398.
World Book Encyclopedia (1999).  Nucleic Acid, v. 14, pp. 602-603.

Ron Lyttle is a volunteer Animal Talker at the Oregon Zoo in Portland, specializing in bats from around the world.  In fact, he is usually referred to by his colleagues and tourists as:  Batman.  Ron is also an active member of DSA, Oregon's "Design Science Association" for the study of creation/evolution issues. 
"Bats and Evolution"

Main:  EN_Articles