Think of the cost of shoes

This is the most extreme case of polydactyly I’ve seen — a child in China born with 31 fingers and toes.


They’re hoping to carry out a surgical correction, which can cause new problems…but in this case it’s necessary, because apparently the child’s thumbs have been transformed into other digits, or failed to form, so all they’ve got is 15 fingers. Opposable thumbs are generally useful.

Oh, and look at those big toes — triphalangeal digits? Developmentally fascinating, personally tragic.


  1. says

    Even the lacking thumbs can be fixed. I met a woman once who was born without thumbs, they had to be recreated from the index fingers. The result was simply astonishing, it took me a while to notice the lacking digit.

  2. says

    I wonder why this seems so much more common in cats than humans? Or do more people have extra toes than I realize? Our kitty is polydactyl and while it makes her extra cute, it is potentially harmful to her if I don’t keep her nails clipped since it impedes her ability to shed them properly.

  3. chris61 says


    Most people with extra digits have them surgically removed. Plus since you aren’t the only one to find polydactylous cats cute I expect they may be encouraged to reproduce more than their non-polydactylous relatives.

  4. says

    My son has syndactilia in both hands, a family trait from his father’s family. While he was in hospital to have this corrected, the girl in the next bed had 10 fingers, no thumbs. The surgeons moved and reconstructed two of the fingers to give her thumbs, successfully. Both kids were about 3 years old at the time.

  5. magistramarla says

    We also have a much-loved polydactyl cat. He has seven claws on each front foot and six on the back. He looks like he has thumbs, and he makes good use of them.
    Our daughter brought him home when she found him in a box with a note that read “Nobody wants this damned deformed cat”.
    We think that he’s just perfect, and he thinks so, too.
    Most of my children and grandchildren have second and third toes that are connected to the first “knuckle”. My youngest granddaughter’s toes are connected to the second “knuckle”. The pediatrician has told my daughter that this might need to be corrected surgically if it affects her walking. Is there a name for this?

  6. says

    magistramarla #9;

    Is there a name for this?


    (from Greek συν- meaning “together” and δακτυλος meaning “finger”) is a condition where in two or more digits are fused together.

    From Wikipedia.

  7. anchor says

    PZ: it looks like many if not most of those visible digits are or may be expressions of bone structure we can’t see. An X-ray would show what’s going on, but I’m wondering where the developmental aberration kicks in with the digits as opposed to the limbs that apparently have not suffered this repetition?

  8. ledasmom says

    It’s my understanding that when extra digits happen in people, they are generally removed as early as possible. In cats, they’re left unless they cause a problem. Our big orange cat has double thumbs in front; because of the way they split, he can’t retract the claws on any of his thumbs, and can start sticking to the carpet unless they’re kept short. The thumbs on one side are connected pretty firmly to each other, but on the other side you can wiggle them relative to each other. He sometimes stands with the thumbs on one side on top of the thumbs on the other.
    We recently had a cat where I work who had twenty-four toes. Seven each on the front, five on the back. Huge feet. And we had a kitten recently who was five and six on the front, six and five on the back.
    For those of you who don’t have cats, five in the front and four in the back is the more usual toe complement.

  9. says

    @ #6: Isn’t that awesome? Building a thumb! That is pretty darn impressive surgery, and from the case I saw the result is pretty much perfect.

  10. parrothead says

    Is it strange of me to first think of environments where feet like those would prove to be advantageous? Imagine those feet appearing on an ancestor in a dry, sandy environment for example where they’d act similar to snowshoes.

  11. briquet says

    I highly recommend “The Mutants” by Armand Leroi for stories about this and many, many other atypical humans. Life is amazingly diverse even within a species, and I find it incredible how many individuals thrived and even founded family lines with “problems” I thought would have been likely to be fatal today, let alone hundreds of years ago.

    @parrothead: I know you didn’t say or imply this, but I think it’s worth mentioning that adaptive or not this isn’t the sort of mutation that provides fuel evolution. It is generally the small changes in gene expression switches that drive changes, not the major ones. The major ones are dramatic illustrations of where we can end up but not how we would get there.

  12. chris61 says

    @12 anchor

    I’m wondering where the developmental aberration kicks in with the digits as opposed to the limbs that apparently have not suffered this repetition?

    It has to do with how limbs develop. They start as small swellings referred to as limb buds that protrude out from the torso. As the buds grow the cells will differentiate to form the various elements of the upper arm, lower arm, hand and digits, with the digits developing last. The process is orchestrated by interactions between the cells within the limb bud, the cells on the surface and the cells in the body adjacent to the bud. These cells secrete proteins that signal to each other and induce the expression of different sets of genes in different regions of the bud. Either mutations or teratogens (such as thalidomide) can interfere in such a way that some parts of the limb may develop relatively normally while others don’t.