Can scientists “reverse evolution” in the laboratory? Can they rewind the evolution of birds from dinosaurs and see how it happened? Trying to replay the evolutionary movie in reverse has become a popular thing to do. The goal is to show that evolution really happened and to find out the steps it took. To do this, evolutionists have tinkered with the genes in chicken embryos to make them grow dinosaur-like tails. Others, more mechanically inclined, have tacked little plunger-like appendages onto chickens as tails to see if they could yield clues to the way their supposed theropod ancestors walked. Last year researchers claimed to backtrack evolution from bird beaks to dinosaur snouts when they turned off beak-building genes in chicken embryos. (Read “Rewinding Evolution from Bird Beak to Dinosaur Snout” to see why those scientists were mistaken when they thought they’d discovered a transitional form lost to the fossil record.)
Now evolutionary scientists are tapping out their evolutionary story with chicken drumsticks. A team led by João Botelho at the University of Chile has discovered why the needle-like bone in a chicken’s leg isn’t as large and long as the adjacent, grip-friendly bone in the drumstick—speaking from the point of view of fried chicken aficionados. They have discovered why a chicken’s lower leg develops with one sturdy bone beside a short, splintery one, instead of with two robust bones like the legs of dinosaurs, dogs, and humans. With that discovery they think they have rewound the dinosaur-to-bird evolutionary movie and unveiled one of its important secrets.
The Ankle Bone’s Connected to the Shinbone . . .
Below your knee you don’t have a chicken-like drumstick. You have two leg bones: the thicker shinbone (the tibia) and the thinner fibula. The knobs on the sides of your ankle are the lower ends of these bones. These paired bones are a great design, and the hind legs of dinosaurs and of most other tetrapods are similarly equipped. Though the fibula is much thinner than the tibia and supports comparatively little weight even among those of us who walk on two legs, it serves an important role in stabilizing the ankle and providing leverage for the muscles attached below the knee.
But a bird’s lower limbs are designed differently. A bird’s knee and the thighbone above it are hidden up inside the bird’s body. This hidden part of the bird’s leg helps prevent abdominal air sacs from collapsing and helps it breathe. (Learn more about this unique bird-breathing arrangement in “Lizard Breath Fails to Support Kinship with Birds.”) Because it walks with its hips and legs at different angles from biped humans and theropod dinosaurs, a bird doesn’t need the stability and leverage afforded by a full-length fibula and its attachments. The fibula on a chicken is very thin and so short it doesn’t even reach the ankle, leaving the bird to support its weight on its tibias.
Now why are we comparing the bird’s fibula to a dinosaur’s? Not surprisingly, it is because evolutionary scientists think birds evolved from dinosaurs. And to help prove it, they’ve gone to the laboratory and engineered a chicken embryo to grow a dinosaur-like lower leg. The drumsticks on these chickens—if they were allowed to mature and hatch—would be unrecognizable as a chicken leg, containing two sturdy bones instead of one and the splintery fibula like what we find hidden in the drumstick when we chow down on a bucket of “extra crispy.”
Embryonic Birds and Evolutionary Baby Steps
Because evolutionists believe the dinosaur ancestors of birds acquired their bird features in a series of small steps, “the experiments are focused on single traits, to test specific hypotheses,” says Alexander Vargas, in whose lab Botelho grew the malformed chickens. “Not only do we know a great deal about bird development, but also about the dinosaur-bird transition, which is well-documented by the fossil record,” he says. “This leads naturally to hypotheses on the evolution of development, that can be explored in the lab.”1
Not only do we know a great deal about bird development, but also about the dinosaur-bird transition, which is well-documented by the fossil record.
Well, we do know a lot about bird development, as eggs have been studied for years, their familiar embryological stages making them a staple in undergraduate biology laboratories. But we do not, from observable evidence, know anything about the “dinosaur-bird transition” since it has never been observed and even defies the observable biological fact that living things reproduce and vary only within their created kinds. The claim that this evolutionary transition is “well-documented by the fossil record” is a worldview-based claim, not a claim based on observable scientific evidence. The existence of many varieties of birds and many varieties of dinosaurs in layers in the fossil record does not demonstrate that one evolved into the other or anything about their origin, only that they existed and were catastrophically buried and fossilized.
But as Vargas says, we do know—from observations of embryos in eggs—a lot about bird development. Early on, bird embryos have a pair of robust long bones in the lower leg. As the embryo develops, the fibula loses its connection to the ankle and is outgrown in diameter and length by the adjacent tibia, leaving the fibula to be a shadow of its former self. Is the bird’s thin, pin-like fibula a ghostly reminder of its evolutionary history? Evolutionists believe so.
How Bones Grow
Bones grow longer by replacing cartilage with bone. In a developing embryo, this process typically produces long bones containing cartilaginous growth plates near the ends, where growth continues until a hormonal stop-signal is received. Length-wise growth is brought to a halt when a stop signal causes maturation of those growth plates. Once a growth plate receives the signal to mature, the cartilage in the growth plate is completely replaced by bone (ossified) and the long bone grows no longer. This is true whether the bone is in an unhatched bird or an adolescent boy reaching manhood.
The embryonic bird fibula develops as it does because it receives instructions to stop growing and to instead mature into a finalized adult sort of bone. Scientists have found that a genetic switch called Indian hedgehog is an important trigger that tells the fibula to do this. Indian hedgehog, produced by cartilage cells, is a signaling protein that tells bones in many different sorts of organisms to mature—to ossify and stop growing longer.
The production of Indian hedgehog is itself triggered by other signaling hormones, including those produced by nearby bones. The embryonic bird fibula, unlike the fibula in other embryonic terrestrial tetrapods, is initially pressed tightly against the heel bone (the calcaneus). This bone is thought to be the indirect source of the signal that triggers production of Indian hedgehog, setting the chicken’s fibula irrevocably on the path to its diminished state, after which the fibula loses its connection to the ankle.2
This discovery highlights the importance of our Creator’s coordinated and complex design for a bird’s leg as it develops in the embryo, but demonstrates nothing about how or why it came to be that way in an evolutionary past.
By inhibiting Indian hedgehog in chicken embryos, the Chilean team produced chicken embryos with long, fully formed fibulas reaching all the way to the ankle. This embryonic anatomy, the researchers noted, resembles the anatomical arrangement in a biped dinosaur. (Of course it also resembles the anatomy of our lower legs and that of many animals, but the point of the study is to connect the evolutionary dots between dinosaurs and birds, not to compare and contrast the common designs of birds and anything else.)
Furthermore, the normal embryonic pattern of fibula development is important to proper development of the tibia, the bone that must fully support a bird’s weight. (It is not uncommon for one embryonic structure to influence the growth of another.) Without the slim, short fibula beside it, a bird tibia does not grow normally. In fact, regardless of species or a bird’s adult leg proportions, most of the growth of the embryonic bird tibia happens after the fibula stops growing.3 This discovery highlights the importance of our Creator’s coordinated and complex design for a bird’s leg as it develops in the embryo, but demonstrates nothing about how or why it came to be that way in an evolutionary past.
Connecting the Fossil Dots
But what about Botelho’s assertion that his findings are corroborated by the fossil record?
The fossil record contains many varieties of birds, with many extinct and modern types coexisting. Most extinct toothed birds, like modern birds, had thin, tapering fibulas that didn’t reach their ankles. In fact, Archaeopteryx—which many evolutionists now claim isn’t in the lineage of modern birds at all—is the only known one that didn’t.4 The relative proportions of tibia-fibula length varied greatly among extinct toothed birds, some fibulas being nearly as long as the tibias and some much shorter.5 Since some had longer fibulas than others and many with short, modern-like fibulas apparently coexisted, Botelho’s team believes the bird fibula first evolved to lose its connection to the ankle and later got shorter in many birds through convergent evolution.6
Because evolutionists assume that extinct toothed birds represent a transitional phase connecting ancient dinosaurs and modern birds, they believe the fibula lost the ankle connection when a theropod dinosaur was evolving into a bird and then evolved its shortness many times over millions of years. Of course, what the fossil record reveals is simply that the needle-like fibulas of toothed birds varied a lot and generally were proportionately longer than those of modern birds. The fossil record reveals nothing about the ancestry of birds from dinosaurian ancestors.
Evolutionists assign ancient dates to Mesozoic toothed birds based on unverifiable assumptions and their need to build in enough time to allow the biologically impossible—molecules-to-man evolution—to become plausible. (Read more about these age-old fallacies in “Doesn’t the Order of Fossils in the Rock Record Favor Long Ages?”) When seen through the lens of biblical history instead of evolutionary presuppositions, however, those extinct toothed birds are understood as simply birds that were rapidly buried as a result of the global Flood, varieties of the representative bird kinds that were preserved on the Ark with Noah but that subsequently became extinct. That their leg design resembled modern birds except for the relative proportions of the bones’ lengths, like their other anatomic distinctions, is a testimony to variations in bird design, not to their evolutionary development from dinosaurs.
The similar designs shared by many living things—such as arms and legs in a body plan that contains four limbs—are built according to the blueprints in many similar genes. During embryonic development, genetic switches typically control how and when these genes are turned on and off. Differences in these control mechanisms are one major way that our common Designer, the Creator God, has produced many different kinds of anatomical results, each designed from the beginning to vary and reproduce only within its kind. These developmental events in an embryo are observable in a laboratory. And by tinkering with these genetic switches, scientists can determine the function of those switches and the genes they control. That’s what this group of scientists has done. They have not however observed evolution, not even in reverse.
Experimental biology here reveals similarities of design during embryonic development but cannot substantiate evolutionary claims about common ancestry.
The genetic information, both in the genes to produce the various leg bones and the genetic switches to control how and when those genes are expressed, is already in each kind of organism. It is that information—working in a developing embryo—that makes a bird a bird and a dinosaur a dinosaur. The same sort of development in other embryos makes a dog a dog and a lizard a lizard. Experimental biology here reveals similarities of design during embryonic development but cannot substantiate evolutionary claims about common ancestry. The fact that there is some shared information that can be switched on or off to produce different anatomical results is not evidence of common ancestry, but rather of a Common Designer, the Creator God, whose eyewitness account of life’s history is preserved in the Bible.
- Did Dinosaurs Turn into Birds?
- Jurassic Spark?
- Recapitulation Repackaged and Re-Applied
- Do Tacked-on Chicken Tails Tell How T-rex Walked?
- The Big Bang of Bird Evolution?
- What If Dinosaurs Really Had Feathers?
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