It's difficult to say if the most groundbreaking discoveries are already behind us or that they are still ahead of us. I'd say the latter is more likely. We are still relatively primitive in lots of stuff like what we use as energy for example. There are so many things left to discover that we probably can not even imagine yet. And history shows us time and time again that what we think we know turns out to not be true at all.
I disagree here. I would agree that there's loads more to learn than we already know, and that there will be developments that will fundamentally alter our way of life, but if the knowledge discovered is as groundbreaking as the discoveries we've made so far I strongly doubt,....
We originated from a situation where the only way to communicate was with sounds, and all every day was simply struggling to feed ourselves and any encounter with a predator or disease could prove fatal. We had no understanding of the nature of the world, not just the planet at large, but no understanding of why it rained, why there are seasons, why some things are good to eat and other bad, or where the animals around us came from.
Since than we've learned so much, and yes, we've often been wrong, the earth isn't flat, isn't created by a god, there are more than 4 atoms, the sun is quite big and the universe really large, but by know we actually do have a very functional understanding of everything around us. The gaps in our knowledge are in the details or in the things further away than we could ever reach or smaller than we can ever see.
We know we are on a planet, we can calculate and predict the movement of it and all other objects in our universe, we can communicate through time and space, we understand toxins, diseases and nutrients, we understand spacetime itself and we can go anywhere on our planet and back quickly and safely. We have easy lives without any real worries.
Arguably the only changes that can impact our lives more than they already have from our beginnings are either the start of intergalactic live, or complete virtualization. And we already know and understand more about those things than we did about getting to the point we are know.
My guess is that the next major step(or stop?) in human development is the development of artificial being that has an intellect superior to our own.
