• Question: Without pose able thumbs how much would we have developed , would we even have survived?

    Asked by the josh to Chris, Josh, Rebecca, Rob, Susan on 19 Jun 2015.
    • Photo: Rebecca Dewey

      Rebecca Dewey answered on 19 Jun 2015:

      Without opposable thumbs we simply would not be able to pick anything up or grasp anything. Most primates have opposable thumbs, so it was definitely beneficial (if not necessary) quite early on in evolution. Quite a lot of other animals have an opposable digit (even if not quite a thumb), for example a dog can use its dewclaw or opposable claw to grip on to something but not to grasp or pick things up. I think it would have been very detrimental to humans to not be able to pick things up!

    • Photo: Susan Cartwright

      Susan Cartwright answered on 19 Jun 2015:

      Opposable thumbs, that is thumbs that can touch the other fingers, are essential for manual dexterity. I find it hard to imagine that we could have developed tool use and technology without them. However, nearly all primates do have opposable thumbs, so it’s extremely hard to imagine how anything remotely resembling us could have evolved without them.

      It is actually just possible that an animal which did not have an opposable thumb could develop an effective substitute. The giant panda, for example, appears to have a thumb – it can grasp bamboo shoots. But this is not a thumb: the panda’s fifth digit is part of the paw structure it inherited from its more normal, carnivorous, bear ancestors, and too specialised to be changed. Instead, one of the panda’s wrist bones has extended to form something that acts as a thumb. So an animal which did not have an opposable thumb, but developed a way of life in which dexterity was an important adaptation, might be able to evolve something that would work.

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