- The Verge: Scientists raised These Fish to Walk on Land
Could a popular African air-breathing aquarium fish—the bichir—hold the key to mysteries underlying our presumably pre-terrestrial past? These fish aren’t lobe-finned like the ones evolutionists think evolved into terrestrial animals. Nevertheless, University of Ottawa evolutionary biomechanist Emily Standen and her McGill University colleague Hans Larsson decided to raise some bichirs out of water to see what would happen.
The bichir (or “dinosaur eel”) is a ray-finned1 fish that has both gills and lungs. Lungfish are lobe-finned fish with both gills and lungs. These fish pop their heads above the surface for air to supply or supplement their oxygen needs. Both gills and lungs appear very deep in the fossil record, so evolutionists debate which evolved first. This research focused on walking, however, not breathing.
Raised To Be Walkers
Like most fish, lungfish and bichirs move best by swimming. However, lungfish are able to pull themselves between pools on their front fins.2 And Standen says, “There’s anecdotal evidence that [bichirs] move on land from ephemeral pond to ephemeral pond, but they don’t do it voluntarily.”
Would a bichir raised on land learn to “walk” on its fins? Would it be a better “walker” than aquatic bichirs? Would constant “walking” model growing and shape the landlocked fish’s bones to allow it to move more efficiently? These are questions that Standen and colleagues sought to answer, and the answers, they report in Nature, are resoundingly affirmative.
After raising 111 juvenile Senegal bichirs (Polypterus senegalus) for eight months in 3 millimeters of water under a mister (like those in your grocer’s produce department), Standen reports, “Fish raised on land walk with a more effective gait. They plant their legs closer to the body’s midline, they lift their heads higher, and they slip less during that walking cycle.”
Dissection showed that as land-raised bichirs matured, in comparison to aquatic fish, “the bones in the pectoral girdle—the bones that support the fins—changed their shape. And their clavicles became elongated.” These morphological adjustments were predominantly those that permitted the fish to lift their heads higher.
“It’s an important change,” Standen explains, “because if you think of a terrestrial lifestyle, you actually need a neck on land because you’re stuck on this plane, and you need to have more head motion that’s independent from the body.”
Actually, the bichirs’ enhanced ability to lift their heads as they grew—owing to a slight lengthening, thinning, and flattening of two bones3—had nothing to do with seeing the wide world. In order to move its pectoral fins back and forth to “walk,” a bichir must lift its head and gill chamber up out of the way, and this motion is facilitated with the bone variation found in the land-raised bichirs. Their growing bones responded to the constant stresses of gravity, friction, and the posture constantly assumed by the fish in order to move,4 as indeed all bones of vertebrates do with use and load.
“It’s quite possible that larger changes would occur if we kept them on land for longer,” Standen says. “The big dream is to do this over several generations.” The team wonders if offspring of these fish would be good “walkers,” and they plan to find out. Environmentally induced epigenetic changes can sometimes be heritable, so they might. McGill University coauthor Hans Larsson says they want to see whether the characteristics are fixed and “see how far this plasticity goes, how consistent developmental changes are in the long run.”5
Adaptability or Evolvability?
Plasticity means the ability to make modifications in response to the environment. These juvenile bichirs demonstrated plasticity in their “walking” skills and in their bone morphology as they grew up. But can plasticity produce “fish-to-fox” evolutionary changes? Standen and colleagues believe the adaptive capacity of these bichirs helps solve the terrestrial mysteries of evolutionary history.6
But we beg to differ. They presume the small adjustments in bone shape and “walking” efficiency that they observed are a mechanism for producing the major anatomical changes needed for a whole new kind of animal—a terrestrial tetrapod—to evolve. The authors have leapt from the pool of observable adaptations into the land of imagination where the never-seen not only could have happened but is faithfully believed to have happened.
Bones are designed to adapt to stress.
Standen did not demonstrate that fins could develop into non-fins. Neither did her fish acquire bone shapes needed for walking or to begin growing any new kinds of bones. These landlubber fish developed some minor variations in bone shape that accommodated their growing bodies to the demands of moving without buoyant water to hold up their heads for them and allowed the greater range of motion their “walking” fins needed to move about on land.
By way of comparison, people whose lifestyle regularly places mechanical stress on particular bones may change bone density, size, shape, and cortical thickness. Bones are designed to adapt to stress.
Conditioned to use better biomechanics, the bichirs slipped less because they planted their fins closer together to push off. Yet none of these behavioral adjustments or bony accommodations to obligatory terrestriality produced behavior or anatomy abnormal for fish. These fish simply became a little better at doing what bichirs normally do. These fish did not show how an ancestral fish could rise, lift up its head, and walk out onto land and up the evolutionary ladder. They did not demonstrate how fish-to-land evolution could have happened.
Tales of Terrestrial Transition
Evolutionists believe that terrestrial tetrapods—land-based vertebrates—evolved from an ancestral fish (a stem tetrapod). Their best candidates for showing how vertebrates took their first landward steps are lobe-finned fish, since they at least have some bones in their fleshy fins. The fossil record contains a number of extinct lobe-finned fish—“dots” that evolutionists connect with transitional claims.
The myriad of changes necessary to transition from being a fish to a land animal would have been so numerous that it is hard for even evolutionists as imaginative as the incredible Mr. Limpet7 to know where to start. Did “stem tetrapods” first learn to breathe air? Or did they leap through air before discovering they needed lungs? Did they do lots of push ups and grow front legs first, or did back legs evolve first.
Standen and Larsson believe their bichirs will help solve these mysteries. “I used to look at fins and their motion, and I always thought it was so interesting and complex,” Standen says. “And then I thought, wow, how does that change from a fin to something that might work on land? That’s how this project started.”
Extrapolating backward to a presumed evolutionary past, Standen says, “It seems quite clear that environmentally induced changes may have facilitated their [extinct lobe-finned fishes’] transition to land. Selective pressures then acted on these changes, and they became fixed in the genome over very long periods of time.” Explaining why evolutionists think “fishapods” prospered on land, she says, “Fish that had the plasticity to allow them to move out onto land benefited by removing themselves from a very competitive environment into a new habitat of plants and insects supplying shelter and food resources, free of major predation or competition.”5
In evolutionary thinking, given enough time, anything can happen. The slight shape variations in the bones of these landlubber bichirs resemble the shapes of the corresponding bones in extinct lobe-finned fish fossils. Therefore, believing those lobe-finned fish evolved to walk on land, the evolutionary researchers claim these shapes were the evolutionary changes that tended towards terrestriality. Yet these are all fish bones in functioning fish. If anything, this experiment demonstrates the kind of variations in fish anatomy that might have helped extinct lobe-finned fish push off the bottom while maneuvering in shallow water.
Don’t Be Deceived
A Nature Video available online shows how Standen’s bichirs move.8 It includes animation that makes it appear that the bones of extinct lobe-finned fish were on the fast track to becoming the bones of walkers. The stirring narration sums up the evolutionary significance of Standen’s research:
When Standen examined the skeletons of her land-living bichirs, she found that their muscles and bones had changed as they adapted to walking. It appears that the bichirs’ anatomy is as plastic as their behavior. These changes looked strikingly similar to the kinds of changes scientists see in the fossil record as ancient species started making the transition to land. It might not look elegant, but don’t be deceived: After all, one small flappy step of our fishy ancestors may have led to the giant leaps of mankind.9
The “changes” scientists see between these ancient fossils, however, are just differences between fish. Evolutionary scientists presume those fossils were the transitional steps to land. To extrapolate from fish being better at doing what they are designed to do to claiming to know how stem tetrapods long ago took their first evolutionary excursions into becoming non-fish is quite a leap.
Standen expects “larger changes” might occur if the experiment lasted longer. Larger changes? Based on all previously known biology, any “larger changes” would still be insufficient to turn these fish into non-fish. Nothing in the experiment showed fish developing characteristics of non-fish. Nothing in the fossil record shows any fish acquiring the bone structure to walk on land. And nothing in observable biology has ever demonstrated any way that environmental pressure can induce one kind of animal to evolve into another. Experimental biology shows that animals vary but they do so just as Genesis chapter one indicates God designed them to do: they vary only while reproducing within their created kinds.
These researchers assume that ancestral fish made a terrestrial transition 400 million years ago in the unobservable past and think they only need to determine how. In fact, the existence of various lobe-finned fossils in Devonian rock layers does not demonstrate that fish-to-land evolution happened. Evolutionists simply connect the dots between fossils of fish and other animals to make the fossil record paint the picture to which they are already committed.Read more about fishy claims in some of the articles linked below, and don’t be deceived!
- Did Humans Evolve from a Fish out of Water?
- Review: Your Inner Fish
- Did Tiktaalik’s Pelvis Prepare Fish to Walk on Land?
- Lungfish Studied to Determine Transitional Evolution
- Did Paired Fins Foreshadow Paired Limbs in Terrestrial Animals?
- Tiktaalik and the Fishy Story of Walking Fish, Part 2
- Fish Fins Are Not Fingers That Failed
- Developments in Fish Said to Show How Limbs Evolved
- How Cavefish Went Blind, and Why It Matters
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