Fish Still Considered a Transitional Form of Evolution

Tiktaalik tries again.

Despite substantial differences between the fossilized fish Tiktaalik and terrestrial tetrapods, many evolutionists insist the fish was a transitional form. Biologists Neil Shubin and Igor Schneider have swapped genes which regulate limb and fin development between living fish and mice. They conclude that their success demonstrates Tiktaalik evolved genes for legs 400 million years ago.

Believing the lobe-finned Tiktaalik became extinct 400 million years before its descendents crawled across the land on all fours, many evolutionists maintain its fins were antecedents to legs. However, the fleshy fins of Tiktaalik do not attach to the bony pelvis and so could not support weight for walking.

Furthermore, the bones in the fins of these fossil fish do not resemble digits. In Nature, evolutionist fish experts Ahlberg and Clack pointed out that “although these small distal bones bear some resemblance to tetrapod digits in terms of their function and range of movement, they are still very much components of a fin. There remains a large morphological gap between them and digits. . . . If the digits evolved from these distal bones, the process must have involved considerable developmental rearranging.”1

The current research seeks to get around the obvious problems with the fishy identity of Tiktaalik by experimenting with the regulatory genes of various animals to see if they are interchangeable. They exchanged genes which control limb and fin development between chickens, mice, frogs, zebrafish, and skate. In the mice, fish regulators were able to switch on limb development. And in fish, mice regulators were able to turn on fin development. The team concluded that a common ancestor from Tiktaalik’s time evolved the needed genes for limb development and passed them down through the ages.

“These sequences function in these organisms despite 400 million years of separation,” Schneider said. “The homologies that are perhaps not evident by morphology—just comparing a hand and a fin—can be traced back to the genome, where you find that the regulatory regions that control the making of those structures are actually present and shared between these organisms.”

Since all kinds of organisms and all genetic chemistry were designed by the same God, we should not find this compatibility surprising.

The experiment involved genes (like Hox genes), which are master switches controlling development of certain features. Such genes control other genes. Some gene regulators work across species lines, but that does not prove evolution happened. Since all kinds of organisms and all genetic chemistry were designed by the same God, we should not find this compatibility surprising.

Furthermore, genetic experiments on living fish cannot tell us anything conclusive about the genomes of extinct fish. The “Darwin fish” still doesn’t have a leg to stand on, physically, homologically, or genetically.

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  1. David Menton, “Tiktaalik and the Fishy Story of Walking Fish, Part 2,” Answers in Genesis, May 23, 2007,


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