Anatomically modern humans have lived on the planet for hundreds of thousands of years. For most of our time on the planet, we've actually coexisted with Neanderthals (a closely related human species). When I say 'coexisted', we actually got quite cozy with them; around 1-3 percent of our DNA is of Neanderthal origin. It's only within the last ten-thousands years that humans have become urbanised and reliant on agriculture instead of hunting and gathering. The 'Agricultural Revolution' happened at different times in different parts of the world. Today, very few humans still live hunter-gatherer lifestyles (for example, remote tribespeople of the Amazonian rainforest).
We're really not far evolved from paleolithic humans, although there have been significant evolutionary developments as a result of the Agricultural Revolution. For example, lactose tolerance evolved with the domestication of cows, and blue eyes are a recent development. Bonus interesting fact: paleolithic humans had bigger brains and were taller than modern humans. This is probably due to a tougher lifestyle and the resulting evolutionary pressure (only the strongest passed on their DNA). In addition, paleolithic humans needed to have a broad range of skills to survive, so they had bigger brains. With agriculture came worse diets, more regular famines, but also urbanisation and role specialisation, so brains and bodies shrunk.
We're essentially very similar to our paleolithic ancestors, who hunted in the open and slept in caves. This is why I think it is vital for our well-being that we get outside and stay physically active - it's what we've evolved to do. Now I'm not suggesting we return to a caveman existence. The modern world has a lot going for it. Vaccinations are really great, and so is Western medicine generally. Televisions are brilliant, and we don't have to risk our lives every time we want some meat for dinner. A paleolithic human's life expectancy was somewhere between 30 and 45 years, and child mortality was terrible. However, we should be acutely aware of our evolutionary heritage.
So what can we do to satisfy our inner cavemen? Here are three simple things related to health and fitness.
Get outside. Being out in the cold doesn't give you a cold (it's staying inside, breathing in other people's viruses that does), and your body is far more resilient than you think. You're not going to lose your fingers to frostbite going for a walk in -1 degrees. You're also not going to melt in the rain. Get some sun on your skin (although of course apply sunscreen in the summer), get mud on your hands and feel the wind in your hair, just like 99% of the homosapiens who have lived on our planet.
Move. We have evolved to move, not sit in front of a computer for hours on end. This movement wouldn't have been anywhere near as glamorous as people like to make out. Paleolithic humans were not built like bodybuilders, and they were not constantly sprinting around with elk over their shoulders, despite what social media personalities like to tell us. Paleolithic humans would have been active for long periods of time at a low to moderate level, with lots of variety to their exercise (lots of walking, a bit of jogging, clambering across uneven surfaces, throwing spears occasionally, gathering wood, chopping down trees, collecting water from streams, creating tools out of flint etc.). If you want to know what paleolithic humans looked like (and what you would look like if you lived a hunter-gatherer lifestyle), take a look at this photo of Aboriginal Australians from the early 1900s.
Avoid processed food. Modern food is easily available, hyper palatable, nutrient dense and calorie dense. This is quite the opposite to the food we've evolved to eat, so it's not surprise that so many of us are overweight. Even fruit and vegetables have been cultivated over the last few thousands years, and as such are nothing like what our ancestors would have eaten (try scoffing a crab apple). Don't demonise modern food, just exercise moderation and self-discipline. Focus on managing the quantity of food consumed, and increase the quality. Quality food isn't processed, like fruit and vegetables, nuts and seeds, grains, and meat and fish.