The inner reptile

Last week’s episode of “Your Inner Fish” was great! Really cool animations of embryos and long-extinct creatures, some excellent science, a fair bit of “filler” – taking up valuable minutes of show time (which could have been filled instead with MORE SCIENCE!) with landscapes and human drama, but overall an awesome show for anyone interested in human ancestry or living things generally.

I’d forgotten that we have Tiktaalik – or a creature much like it – to thank for more than our ability to do a pushup (and thus move around on land): it’s also our first ancestor (yet discovered in the fossil record) to have a neck.

So episode two will be on right about now in the U.S. It’s apparently going to be about your “inner reptile”. A topic that is very dear to me: I discovered my inner reptile some years before I properly discovered the fish (some years after the worm, and many years after the ape).

Let’s go back to Tiktaalik for a minute. A fish with lungs, a neck, and fins with the strength and structure to do a pushup and support the weight of the body outside the water. Basically, it’s a fish that’s starting to move like a reptile.

In the “Evolutionary movement patterns” video above, filmed some years back, I wanted to show some of the patterns of movement inherent in the spinal column which we have in common with all other vertebrate species. By practicing the simplest possible lateral movements of individual vertebrae and allowing the rest of the body to soften, the lateral undulation of the whole spine gradually begins to manifest. Then, this spinal undulation connects through the ribcage and pelvis to the limbs, generating coordinated movements of the arms and legs. The undulation of the spine is the key driver of fish locomotion through the water. With the development of limbs strong enough to hold the bodyweight outside the water, the same undulation is the driver of reptile locomotion on four legs.

Reptiles walk with what’s called a “sprawled” gait. Their legs stick out to the sides of the body so their center of gravity stays low and stable making it difficult for them to tip over, and also keeping their softer and more vulnerable bellies protected.

Locomotor Organization in Land Vertebrates (from A – The early tetrapod Eryops. At a very early point in the emergence onto land, fins became five fingered digits and the spine demonstrated its five regions. B, C, D – Walking in amphibians and some reptiles involves body undulation as in a fish, with the limbs far out to the side. In the evolution of mammals, the limbs shift to a new position below the body.

Humans also use the sprawled gait and side-to-side undulation of the torso. Before and as we learn to crawl, most of us spend a lot of time like this:

All of us go through what I think of as a “froggy” period in our development. Our bodies are squat, and the arms and legs seem to be reflexively drawn back into the body.

And then eventually we learn to “creep” and to “crawl”:

Any student of human movement can get a lot of insight by studying babies. “Developmental movements” are a goldmine, by studying them we learn not just the many ways in which babies (ie humans) move, we also start to learn how babies (humans) learn to move. In the documentary above, from 30 seconds in we get to see several little people crawling on hands and knees. They use the sprawling gait, or what might be called a semi-sprawl. Arms and legs are held wide so they’re nice and stable, and then they use the side-to-side spinal undulation to move the body forward in what’s called the “cross-crawl” or contralateral pattern which, as we’ll see later, is also the foundation of walking. The basic mechanics of this (and how they relate to those of the salamander and the monitor lizard) are shown at about 2:00. It’s a really cool documentary, 2 parts, a total of about 20 minutes. Recommended watching, here are the contents of part 1:

00:50 definition of creeping
01:26 Eadweard Muybridge (1839-1904)
02:05 diagonal or cross-pattern creeping pattern (lizard)
02:24 salamander-like creeping-pattern
03:57 creeping only with the hands
04:09 dragging the knees under the stomach
04:28 side-leg creeping or crab crawl
05:01 creeping backwards
05:29 creeping on elbows and knees
05:50 definition of crawling
06:01 marine-, army, or military crawl
06:33 feet pushing
07:09 one arm crawling
07:22 crawling with simultaneous arm movements
07:51 push-up crawling (caterpillar crawl)
09:11 crawling on your back

Where can we go with this? What does this movement have to offer us, once we’ve learned to walk? Well, the original baby crawl is used in the army, for sneaking.

It’s an amazing movement, training many of the fundamentals: cross-body connection, connecting upper and lower, making the spine into an arch, getting power from the ground, through the hips and the armpits.

It can be taken even further, into the actual lizard crawl:

It’s tempting to think that the movement pattern Ido’s doing in that video has no relevance to normal life as an adult human. As an exercise (or, better, an exploration), it’s quite incredible, challenging strength and mobility, coordination and balance, power and softness. But these body positions show up in other interesting places:

Screen Shot 2015-09-05 at 10.39.34 am

There are so many patterns in our anatomy and our behaviour which originated with our fishy and reptilian ancestors, and which we still display today, but I’ll leave it there. Our four limbs, fingers and toes, the quadrupedal locomotor patterns which eventually led to walking on two legs, and our ability to climb.


The inner fish

– Our arms, legs, necks and lungs were bequeathed to us by a fish that lumbered onto land some 375 million years ago.

I just found out that one of my favourite books has been made into a new TV show. “Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body”, by Neil Shubin, is something like the book of my dreams, exploring the origins of various features of human anatomy as they are found in the fossil record and the genomes of different species.

This is exciting stuff for those of us interested in “ancestral” anything. I can’t wait to watch the show, and I’d recommend the book to pretty much anyone that can read. They’re basically describing the intellectual side of my ancestral movement work: study the anatomy of the human being, examine any one part, find the same part in other creatures living today, find it in the fossil record, trace the fossil record back to find the earliest appearance of that body part, getting a feel for all of the creatures in which this body part is found or has ever existed, their behaviours, environments, etc. We can take that a (crucial) step further by learning to feel and move that body part, differentiating it from the parts next to it, and differentiating each of its component parts from each other, and exploring what is revealed about this part’s contributions to our various whole-body movement patterns in different environments.

So the first step can be things like these:

Body part: the spine. Mission: differentiate each vertebral segment from the ones above and below, using simple movements. What it reveals: firstly, that most of the spine has been ignored and thus forgotten, but that as the spine is rediscovered and segments more clearly differentiated we begin to see undulations – wave-like movements inherent in the structure of the spine itself, which contribute to basic movement patterns like crawling, squatting, jumping and galloping. We feel for ourselves that all of the possible movements of our spines, we share with all of the creatures on our planet that have spines. We also discover a whole range of “postures” – essentially gestures performed with our torsos, rather than hands – associated with the different combinations of possible positions of the spinal segments, which often quite accurately communicate information about our emotional states (to others, but also to our own brains). This is a concept a lot of people may be familiar with. Amy Cuddy’s classic TED talk gets into this:

There’s another guy called John A. Appleton who does some very, very interesting (and powerful) work he calls “Posture Release Imagery“, a lot of which involves the different possible relationships between the dorsal and ventral surfaces of the body.

And there’s the Center for Nonverbal Studies:

Again, this is ancient stuff. So ancient it boggles the mind. By working with it physically, unlocking the movements of each of the individual spinal segments, we become able to gesture with them. We also come to feel a particular truth: that we have a segmented body structure – or even better, that we are a segmented body structure, and that we share this particular pattern of morphology with just about every animal alive today.

Picture 6

The image above is from “Your Inner Fish”, showing the Hox genes, responsible for the growth of the different body segments from head to tail, in humans, and in fruit flies.

A good chunk of the book is about the discovery of a fish called Tiktaalik, a “fish with a wrist”, a “fish, that could do a pushup”.

This is the oldest fossil creature found with the bones of the forelimb arranged in the same way as the human arm: one long bone, two long bones, lots of bones. in the forelimbs of all the tetrapods – including humans, we have the humerus, radius and ulna, and then the carpal or wrist bones:


In Tiktaalik, we have this:

The idea is that this particular structure (one bone, two bones, lots of bones) is effective at supporting weight, something that fins had never had to do previously, but which allowed this fish to start doing things in shallow water which others couldn’t.

So, some 375 million year old fish could do a pushup, and had wrists built like ours, and oh that’s right – we’re descended from those fish.

I hope we’ve established that the central tube from mouth to anus, the segmented structure of the vertebral column, and their basic movement patterns of peristalsis, undulation, and orienting behind the mouth, are all things we have inherited from our fishy and wormy great-great-great-great-great grandparents.



Could any of the movement patterns of ancient Tiktaalik still be present in our bodies today?


It’s something that we’ve all spent a lot of time doing, whether we remember it or not. It’s something we all had to do to get to where we are today. Some of us still enjoy crawling on our bellies, so we do it all the time, as do plenty of people who practice Yoga asanas or Pilates, or even people who like to lie on their tummy in the sun reading a book. The Center for Nonverbal Studies (one of my favourite websites) call this posture the “highstand display” when it’s used in a social context.

 – “Sea origin. It is likely that paleocircuits for “standing tall” developed in sea creatures before animals set foot on land. Fossil evidence is lacking, but in living fishes, such as gobies, status and rank vary in proportion to physical body size. The very big dominate the merely large, who in turn dominate the small. Gobies and other piscines, however, may appear “bigger” through an array of nonverbal illusions. To loom larger, a goby stiffens and raises its fins, lifts its head, puffs out its throat, and flares its gill covers…In land animals, forelimb extension lifts the body’s front end to more vertically imposing heights. Doing a pushup makes living iguanas and lizards, e.g., look “bigger” than they appear with their bellies lowered to the ground... Mammals push up in aggressive stiff-walk postures. Bulls, e.g., take several stiff-steps to loom “large” before galloping ahead at full charge. Bears, coyotes, and wolves strut with a stiff-legged gait to carry their bodies higher off the groundPrimates show dominance by straightening their legs and widening their arms...An aggressive chimpanzee rises to a bipedal stance, widens its bristling arms, and swaggers from side to side.”[from]

Hopefully I’ll be able to find and watch episode one of “Your Inner Fish” this week. They’ve already released the preview for episode two, showing next Wednesday, which will be on “Your Inner Reptile”. In the meantime, I’m going to remember Tiktaalik every time I do a pushup.