From Fins Into Hands: Scientists Discover a Deep Evolutionary Link

Aug 19, 2016

By Carl Zimmer

To help his readers fathom evolution, Charles Darwin asked them to consider their own hands.

“What can be more curious,” he asked, “than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative positions?”

Darwin had a straightforward explanation: People, moles, horses, porpoises and bats all shared a common ancestor that grew limbs with digits. Its descendants evolved different kinds of limbs adapted for different tasks. But they never lost the anatomical similarities that revealed their kinship.

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5 comments on “From Fins Into Hands: Scientists Discover a Deep Evolutionary Link

  • Dr. Shubin got a similar surprise when he saw the results of a parallel experiment run by Andrew R. Gehrke, a graduate student. Mr. Gehrke engineered zebrafish so that he could follow individual cells during the development of embryos.

    In Mr. Gehrke’s altered fish, cells that switched on the Hox genes started to glow. They kept glowing throughout development, until they reached their final location in the fish’s body.

    Mr. Gehrke observed that a cluster of cells started making the Hox proteins early in the development of fish fins. When the fins were fully developed, Mr. Gehrke found that the fin rays were glowing. In a similar experiment on mice, the digits and wrist bones lit up.

    Using Crispr to manipulate genes and combining this with implanted luminescent features has enabled this research to address key issues in the evolution of fins and wrist bones, in these studies of comparative embryology.

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  • Dr Shubin’s TV series “Your Inner Fish” explores this in an entertaining and educational form, accessible even to at least one 10-year-old of my acquaintance. I recommend it to anyone whatever their level of awareness of biology.

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