Archaeological evidence reveals that humans 10,000 years ago who lived a hunter-forager lifestyle consumed approximately 135 grams of prebiotic fiber every single day. If you’re thinking that this sounds like an abnormally high number compared to current standards (that’s a lot of fiber bars!), you’re spot on. In fact, we’re lucky to get even 10 percent of that amount of healthy prebiotic fiber in our diets—most Americans eat only 10 to 15 grams of total fiber per day. Our ancestors also had far more diverse microbiomes than humans living a "modern" lifestyle today, and they lived free from many of the diseases we face. However, without probiotic supplements and grocery stores stocked with the latest probiotic-infused drinks and foods, how were they still able to maintain a rich diversity of microbes in their guts?
Many researchers think the answers lie in how much prebiotic fiber prehistoric humans had access to as they foraged for food—fiber that nourished and fueled their friendly flora and helped them stay healthy in the face of many challenges. For example, Aborigines in Australia ate nearly 300 different varieties of fruit, 150 types of tubers and roots, and countless seeds, nuts, and vegetables!
Even modern-day hunter-gatherers—like the Hadza in Tanzania, who have been in the area for thousands of years and still live a very traditional pre-agriculture lifestyle—harbor much "richer" microbiomes (nearly double the biodiversity) than people living in the West, due to their extensive foraging. In contrast, we live in a society rife with processed foods devoid of the fiber and nutrition our microbes desperately need. And the truth is, even if we were to commit ourselves to eating as much prebiotic fiber as possible, it’d be very difficult to get even close to the 100 daily grams our ancestors consumed.