Baby humans are premature, fetal apes

My dad calls the first few months of a baby's life "the necessary larval stage". I've heard other people refer to it as "the fourth trimester". Basically, newborn human babies are pretty useless, as far as baby animals go. This is especially true in comparison to baby apes, who come out of the womb at a much higher level of development. Scientific American has an excerpt from an upcoming book by Chip Walter that talks about this fact and its connection to two key moments in human evolution — the development of bigger brains (and thus, bigger heads) and walking upright (which has the side effect of creating a narrower birth canal).


  1. I call it “potted plant” stage.

    Some of the people I work with are studying how movement develops in children.  Humans are the only animal that take so long after they are born to learn to actually function and move about.

    1. Though it’s time well spent. Lots of animals are very, very old at one particular physical activity, but I have yet to see one that’s as mind-boggling versatile as a human. Plus, we usually live far longer than the other apes.

      1. Could you imagine, though, chasing a slimy newborn that just hits the ground running?! lol!!!

      2. Still, we’re odd. Even mammals are odd. Most other predatory animals get born and get on with killing the shit out of whatever shares a space with them from day one. And even among mamals we’re odd. Most prey animals (hooved or otherwise) get born ready to run. Few hours after birth they’re already mastering the art of running away. Humans need like half a decade to get to a halways decent sprint, but it’s pretty useless until the legs are longer and the speed is greater.

  2. Both of my kids, when they were newborns, completely ignored me when I said to them “Get a job… or at least forage or something, would it kill you to hang onto me rater than the other way round?” 

    This has not changed much either! Yet my wife behaves as though cross and will strike me when I recommend she go on all fours, and drink/smoke a bit to produce more useful offspring!

    1. And we’ve created a species of infant wolves to hang around us, too.  There’s something about prolonged immaturity that is deeply connected to what it means to be human.

          1. Have you seen Michael Clarke Duncan in Planet of the Apes? Once you go silverback, you… no, that doesn’t work….. Once you go sagittal crest, you’ll have no time for all the rest.

        1.  Don’t forget, the big silverback who could rip your arms off with ease probably has a smaller penis than the most scrawny-dicked adult human male you’re likely to meet; humans are the most hung of all the primates, if you consider that an asset.
          “Hung like a gorilla” is not a compliment.

  3. From the article: chimps and apes help pull themselves out of the birth canal.  I think I can comfortably speak for my wife in saying that she is likely happy that didn’t happen at least.


      1.  That could be why we evolved away from it.  Freaky screaming bloody creatures clawing their way out of the pelvis and then climbing up onto mom might not be conducive to her being interested in repeating the process.

        1. Better than clawing their way out of the chest, knocking the silverware off the table and scaring the cat.

    1. In a pinch…um…I think she’d probably be willing to exchange that for the screaming and the occasional splitting and bleeding.

  4. Anyone think we’d have been better off if we’d descended from marsupials? 

    1. Anthropomorphic Thylacines:

      Dude Thylacine: Hey baby, you’re unhingable jaw is so hot.
      Lady Thylacine: I think you’re gross.
      Dude Thylacine: *quietly retracts scrotum into pelvic pouch*

    2.  I just had my second and there are certainly times in the last two months I wished I was a marsupial.  Little tiny fetus crawls out into a pouch and automatically nurses and grows essentially outside your body?  Sign me up.

  5. So if we continue to evolve larger and more powerful brains, will the gestation time keep getting shorter, or have we hit a biological brain-size ceiling?

    1. Only if larger brains increase reproductive fitness. Since people reproduce just fine regardless of brain size, I’m thinking we’ve likely hit the limit.

  6. Not news. The term for this is “neoteny”, and scientists have been very aware of it for a very long time. Steven Jay Gould mentioned it in several of his essays, including a nice examination of how Mickey Mouse evolved over time to become increasingly neotenic (and hence “cuter”).

    SciAm really has fallen badly from what it once was. They dumbed it down in order to go after a larger audience … and in the process they lost those of us who read it because it gave us real leading-edge science. (Can you imagine today’s SciAm doing something like the Amateur Scientist column, which included some pretty dangerous experiments because the readership could be assumed to understand the hazards?)

    1. The article is not announcing the discovery of neoteny. It’s very interesting, you might enjoy it.

      1. The original post makes it sound like nothing new. If there’s more to it than that, great, but this isn’t a blurb that makes me want to go out of my way to follow up on it.

        Your milage will vary.

  7. We are all ape fetuses. That’s the only way this makes sense. Human life span is the last third of development stretched out to preserve some physical features such as brain to body ratio.

    1. Though we miss out the immortal protector stage, not having enough thallium in our soil.

  8. “As for you, Man […] You will look like an embryo till they bury you, but all
    the others will be embryos before your might. Eternally undeveloped,
    you will always remain potential in Our image, able to see some of Our
    sorrows and to feel some of Our joys. We are partly sorry for you, Man,
    but partly hopeful. Run along then, and do your best.”– T H White, “The Once and Future King”

  9. My my my…

      Last Tuesday my wife gave birth to a 23 week premature fetus… It is astounding how simian my new daughter Eris is. 
      From muscle structure to being completely covered in fine whit hair she looked exactly like a baby chimpanzee with a button nose.  My wife who has a MA in Nursing and I are enjoying watching the evolution unfold on a near daily basis.

    Stats:  Eris Elayne was born because of uterine constriction Last Tuesday at 8:30 AM via Cesarian section.  She weighted 1 pound even and was 11 inches in length.  Being the “Always one exception” premature child needed only a C-pap for her first day, perfect skin, no cranial bleeds and her eyes still fused.

    This entire experience so for has been amazing and outside the birth NO DRAMA.

    1. Congratulations!
      Amazing how much premature baby care medicine has improved.  A friend of mine was a 25-week baby about 45 years ago, and at the time she was really at the limit of viability.  She needed hearing aids and wore thick glasses, which might have been related to the premature birth, but otherwise did fine.

      1.  The Doctors involved with her case are amazed.  Statistically considering her size and weight she was given a very low chance of surviving but she has surprised them on a daily basis.  She never needed a Vent let alone a Jet-Vent and only a C-pap for her first day.  Yesterday she lifted and then turned her head, I’ve met many full term newborns that couldn’t do that.  She’s strong like bull.

    2.  Congratulations and best of luck.  You’ve given her a beautiful name and it sounds like she is determined to grow into it. 

  10. I was under the impression that humans and our bipedal ancestors have wider pelvic girdles than our knuckle-walking ancestors, not narrower, and that this wider pelvis actually preceded and in some sense enabled our bigger brains.

  11. At least we’re not like marsupials. Kangaroo joeys are born when they’re jelly-bean-sized fetuses and then they have to crawl to the pouch, grab a nipple and stay in the pouch and grow. Could you imagine walking around with a fetus attached to your boob, just hanging off and slowly growing? Ouch! 

  12. I still remember the line from MC Frontalot song “This Old Man: “…Lets chew on that infant. Infants are useless…

    I never laughed so hard.

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