Giraffe Genome Too Distinct for Evolution
The giraffe genome is now published. Does it show evolution from an ancestor in the time allowed?
Giraffe evolution stories go way back to Erasmus Darwin, Charlie’s grandfather. Lamarck wove tales about how constant stretching gave them their long necks. Charles Darwin advanced the hypothesis of natural selection, but later admitted elements of Lamarckism in his own theory of evolution. Skeptics point out that baby giraffes and females would starve while the males reached the scarce upper leaves. There’s also much more to explain than the neck: modifications to metabolism, the heart, the brain, the legs and much more must be explained.
The poor giraffe has been in a tug-of-war between advocates and opponents of evolution; a poor fossil record shows one extinct relative (Samotherium) with a neck one meter long, but that animal is not thought to be in the lineage of modern giraffes. The okapi looks a bit more like a zebra, and lacks the long neck. Evolutionists cannot point to a clear gradual lineage among living or fossil representatives. To passengers on safari vans, or to visitors at the zoo, giraffes look as unique as they did to Lamarck.
Now we have the giraffe’s and okapi’s genes to look at, published for all this week in the open-access journal, Nature Communications. What story do they tell? We know that Darwinians will claim victory, because all evidence is evolutionary evidence, in their thinking. Nature‘s celebration was predictable: “Genome reveals why giraffes have long necks,” Bethany Augliere writes as her headline. “Scientists spot mutations that could explain how giraffes became the world’s tallest living mammals.” Genetic mutations are, of course, the neo-Darwinians’ supply store for evolutionary change, the raw material natural selection can draw from.
One problem is, there are too many of them. Another problem is that the time for 70 dramatic mutations is too short: just 11.5 million years, in their estimation. A third problem is that humans don’t have long necks. Are you, as lead author Douglas Cavener [Penn State] seems to say, a potential giraffe?
The scientists found about 70 genes in the giraffe genome that showed adaptations not seen in other mammals. Two-thirds of these genes code for proteins linked with regulating different aspects of development and physiology, particularly in the skeletal and cardiovascular systems. Four of them, for instance, are ‘homeobox’ genes associated with development of the spine and legs.
“All of these genes in the giraffe — we have them ourselves. What made giraffes unique is just to tinker with them a bit and alter them in subtle ways,” Cavener says.
One might suppose, by simple observation at the zoo, that there is more to the difference between the human on one side of the fence and the giraffe on the other side than a little bit of subtle genetic tinkering. Don’t think too hard about it, because it’s joke time. Not everyone is taking the evolutionary story seriously, at least yet.
Some of the specific genes identified are involved in regulating both skeletal and cardiovascular development. This could mean that mutations in a small number of genes are driving the giraffe’s adaptations, such as a long neck and a turbocharged cardiovascular system, in parallel, says Cavener.
This study identifies genes associated with the giraffe’s adaptations, but does not prove their role in the animal’s evolution. Cavener and co-author Morris Agaba — a molecular geneticist at the Nelson Mandela African Institute for Science and Technology in Arusha, Tanzania — plan to test this connection by introducing the spine- and leg-related mutations in mice using gene-editing techniques. “The ultimate would be to make a long-necked mouse,” Cavener jokes.
University press departments tend to be overly celebratory about their own, but Penn State’s press release only suggests that Cavener’s team found “clues” (not answers) to giraffe evolution. And they are, surprisingly, only the “first clues”. Here’s what evolutionists are up against:
“The evolutionary changes required to build the giraffe’s imposing structure and to equip it with the necessary modifications for its high-speed sprinting [up to 37 miles per hour] and powerful cardiovascular functions have remained a source of scientific mystery since the 1800s, when Charles Darwin first puzzled over the giraffe’s evolutionary origins,” said Cavener, a professor of biology and the Verne M. Willaman Dean of the Eberly College of Science at Penn State. The giraffe’s heart, for example, must pump blood two meters straight up in order to provide an ample blood supply to its brain. This feat is possible because the giraffe’s heart has evolved to have an unusually large left ventricle, and the species also has blood pressure that is twice as high as other mammals.
Look at the picture of an okapi in the article. Its neck is short. There are stripes on its legs, like a zebra’s. The coloration is different. The face and ears bear a slight resemblance, but this “closest living relative” is surely a long way from a giraffe.
Is Darwinian evolution the only explanation? One would predict there would be genetic differences in any account, whether or not they came about by a mutation-selection process. Cavener recognizes the speed that neo-Darwinism would have to act. “Okapi’s gene sequences are very similar to the giraffe’s because the okapi and giraffe diverged from a common ancestor only 11-to-12 million years ago – relatively recently on an evolution timescale,” he says.
The rest of the press release points to specific genes for this or that trait, but merely assumes they “evolved” in the giraffe. The paper claims positive selection has occurred in some genes, but that only means that genes related to functional differences are also different. That’s to be expected in a design explanation. Mutations to a couple of genes, the paper points out, cause defects or death. No one watched the mutations produce the phenotypic changes from a short-necked ancestor to the giraffe, especially in a coordinated way. Creationists have ridiculed evolutionary explanations on that point. What good is a longer neck if the giraffe’s brain explodes every time it takes a drink because evolution didn’t fix the blood flow yet? What good is a speedy gallop if the giraffe passes out when it sees the predator coming and lifts its head too fast? Dr. Job Martin had fun with these kinds of questions in his DVD, “Incredible Creatures that Defy Evolution.” They’re not just funny. They demand answers.
New Scientist doesn’t provide any additional explanation than the other articles, but does quote a geneticist from the San Diego Zoo, who says, “It reveals the complexity of the evolutionary process that resulted in the modern giraffe.” And we learn that “Cavener has not yet proven that the genes he has identified are actually responsible for the giraffe’s body form.”
So how much is known today that was not known before? Apparently, not much.
Evolutionary stories only work at a simplistic, childhood level. Yes, the pre-giraffe keeps stretching its neck, and over time, it finally reaches the leaves of the tree. When those leaves are gone, the ones with longer necks can reach higher, winning the competition. Take a few million unobserved years, and presto! the giraffe is born. Such stories crumble under thoughtful questions.
If evolution were a law of nature that explains the giraffe, then all animals should have long necks. Giraffes live side-by-side with zebras, wildebeest and other grazing animals. “Ah!” the evolutionist interjects, “but their specific diet is the acacia tree. The short-necked giraffes died out, unable to reach the leaves that got progressively higher.” OK, then. Wouldn’t it have been far more economical for evolution to teach pre-giraffes how to eat other plants? All the other mammals live in the same environment eating grass and shrubs. If the environment drives selection, it should work the same way in them all. Just eat some grass, giraffe, for crying out loud! Or go migrate to a better habitat!
We’ve seen similar breakdowns in evolutionary stories for other animals. Zebras evolved stripes to hide from predators, we’re told, until you realize that other prey don’t have stripes, and the stripes aren’t really visible when the predators hunt, anyway. So they evolved to deter flies then. Same problems; other mammals living alongside didn’t get the stripes option but are doing just fine. The storytelling goes on (2/06/15; see list of questions from 12/22/03).
Maybe the Creator made such diverse animals, each well-adapted for its niche, just to make evolutionists frustrated.
Note: Lee Spetner has a different take on the giraffe genome announcement in Evolution News & Views. Our coverage was written independently of his. He has a modified evolutionary explanation, but agrees the changes had to be nonrandom and had to happen quickly.