Everything changes. Looking around in nature, this seems like an obvious thing to say. But we weren't always so sure. As an example, many scientists were once pretty certain that we (people) were created as we are, and remained unchanged ever since. The idea of chimpanzees changing over time to create less and less furry humans seemed crazy.
But most scientists now hold evolution as a pretty solid theory. If it's in nature, it changes. The more recent debate has been around how. Is it a slow progression over time, almost imperceptible unless you look across millions of years? Or are long periods of business-as-usual occasionally interrupted with abrupt change? What does this have to do with yoga? Well, yoga changes too. It evolves. And just like the "punctuated equilibrium" model of evolution, it appears yoga has evolved in substantial leaps from time to time. While we may often hear talk of preserving the ancient traditions of yoga "untouched" -- the real history might not uncover itself quite in this light.
A Brief History of Yoga
The Beginning. About 5,000 years ago, yoga was invented. We think this happened in the Indus Valley, on a sunny Tuesday afternoon. We know this because we've uncovered stone carvings that show people sitting in meditative-looking positions. It's worth noting that this is well before Hinduism came into being. Also of interest, ancient Egyptian images from over 5,000 years ago show some pretty good tree-poses, among other things. Concluding things about ancient times can get a little wobbly, especially without context.
Vedic Period. Between 3,500 and 2,500 years ago the Vedas were written, which formed the basis for Hinduism. Yogis at this time were often solitary types, living in forests. Their interests aimed at enduring physical hardship by sharpening their minds.
Pre-Classical Yoga. About 2,500 years ago, the Upanishads were written. The Bhagavad Gita is left as the oldest known yoga scripture, dating to 500 BCE. Yoga practice seems to soften a bit, becoming more meditative and less reclusive.
Classical. Patanjali's Yoga Sutras form the defining text here, outlining the Eightfold Path of yoga: what to do and not do, how to relate with ourselves and others, how to sit, breathe, withdraw, focus, concentrate, meditate, and of course, enlighten. It's worth noting there is only a single mention of physical activity here, as preparation for proper sitting.
Today. Now we have Iyengar, Ashtanga, Kundalini, Strala (where I spend my time)... many choices! Yoga likely came to the US in the 1800's, but its popularity really emerged in the 1960's. Along with LSD and trips to India. Yoga now is substantially more active. It's also apparently more fun to watch, as there is some talk of adding it as an Olympic sport.
History in Context
We know from the fossil record that dinosaurs disappeared about 65 million years ago. If we want to know how, we have to dig a little left and right for context, which is often where we find the most interesting parts of the story. It's the same with yoga history. Here, the context gives us a constant that has it all make sense. In fact, the one constant for yoga, throughout all its changes over all this time: it has always made sense right where it is. The practices of yoga that left a lasting mark in the record all made sense as the right creation for people in their own time and place.
Five thousand years ago in the Indus Valley, we were all farming. People worked pretty hard on their feet, and moved around quite a lot. Whether we call those stone carvings yoga or not, it makes sense that people needed to sit down and rest. Sitting and getting quiet has a way of uncovering some interesting things for all of us. This may have lead to increasingly long walks in the woods, and some effort to test just how far we can go inside.
Moving along to 2,500 years ago: this was about when we came in from the fields and started living in cities. When we live so close to each other, pretty simply, we make each other sick! Respiratory infections abound. It makes sense for breathing techniques to find their way into yoga practice now. Once again, sitting and breathing gives way to more interesting discoveries and texts about how capable we are. We have all kinds of powers just waiting to be explored.
Life is a little different today. Many of us are sitting at desks for many hours every day. Then we sit in cars. At home we're sitting in front of another computer, or maybe the TV. So we have plenty of sitting in our lives. Also, we have high-tech food - in the convenient size of a hockey puck -- that gives as much energy as the woolly mammoth eaten by an entire cave family. So what do we need today from our yoga? We probably need to get up, reconnect with our bodies, and move! Unsurprisingly, the styles of yoga that are popular today are more physical, and circle around this need.