Scientists and archeologists have been able, with the assistance of modern genetic research and technology, to identify that the entire human race today derives from about 600 breeding individuals at the southern tip of Africa about 115,000-90,000 years ago. These humans prospered because of their diversity of diet, while all other forms of the humanoids became extinct, like the Neandertals whose diets were dependant upon a single food source.
Some have believed that when homo sapiens migrated to Europe they simply interbred with the Neandertals and that is why the Neandertals disappeared. However recent genetic testing proves that never happened - we have absolutely no Neandertal DNA mixed in with our own DNA (but we do have a common ancestor that both species derived from). Rather, the Neandertals were solely dependant upon meat for their diets - pure carnivores - a source that dwindled during the last ice age causing Neandertals to starve to extinction.
Meanwhile, we homo sapiens had developed a diverse diet that included both hunted and foraged meat, as well as foraged vegetables, fruit, and grains - the four food groups we nutritionally require today. (This clearly invalidates the Paleo Diet that many follow today, which is comprised primarily of meat.) Archaeological evidence also points to the fact that the meat our earliest ancestors survived on was wild goats and other small game. (Art historians and archaeologists have proven that the cave paintings of bison and other large animals were religious in nature, not the scenes of hunting as previously believed.) The game we hunted was far safer for us to hunt, and we developed lighter spears that could be thrown greater distances, allowing us to hunt from a safer distance - i.e. less of our population died from hunting accidents thus keeping our population up.
We survived because the longest ice age of that era of human history demanded species to be able to adjust and change their diets as climates changed and food sources were impacted. The Neandertals, dependant upon large game, began to have difficulty obtaining food as large game populations dwindled due to the glaciers that pushed so far south into Europe. Other humanoid species, as well as other homo sapien groups in Africa, who were primarily or solely dependant upon carnivorous diets, probably also starved to extinction as Africa became almost entirely a desert climate due to the extreme ice age. The significantly higher caloric needs, due to larger body masses, were also a factor in other humanoid extinctions - the Neandertals' caloric needs were about 5,000 kcal/day: now that's a lot of meat!
Even our own group of homo sapiens nearly became extinct, but because our foundational group of about 600 individuals down at the southern tip of Africa had developed leaner bodies (lower daily caloric needs) and a diversity of diet, they were able to weather the bottle neck to become the only group of humanoids to survive. Then, after the end of the ice age, they flourished and spread across the entire planet and grew their population to the current 7 billion people alive today. All because we had the diversity of diet to survive that long ice age.
So what did that group of 600 homo sapiens eat? That foundational group of humans, because they were coastal, learned to collect and cook clams and other coastal sources of meat - much leaner and safer than hunting large game. The most incredible part of that feat: they had to have had the intellectual capacity to understand the phases of the moon so as to know when the lowest tide would occur, exposing the clams and oysters, allowing them to safely collect the shell fish they depended upon for a large part of their protein needs. Yet, this regular monthly supply of shell fish was obviously not enough to survive on alone, so they developed diversified diets that included hunting small game, and foraging berries, vegetables, and wild grains. As the generations passed and their bodies became nutritionally dependant upon this diverse diet it also allowed them the flexibility to find food through cycling seasons and climate changes, a skill the other species had lacked and had thus led to their extinction whilst we survived and flourished.
The lesson we learn form this is that if we as humans are going to continue to survive, as our ancestors did, in the face of climate change and shifts in food resources, we must maintain a diversity in our diets, allowing us to nutritionally adapt to those changes in food sources: meaning a diet that is spherical and moderate!
Two final interesting facts: 1) Today our brains use 25% of the calories that we consume each day, even though our brain is less than 2% of our entire body mass! That's one energy hungry muscle! Its no wonder we're the smartest species to ever live. 2) It is because we all descend from such a small group of only 600 individuals that humans today have such similar DNA. We all have 98% the exact same DNA as each other - it is only 2% the creates our individuality. Other species have a much greater percentage of variations in the DNA between individuals.
For more information on this subject, check out the 3 part series from Nova titled "Becoming Human" (available on iTunes).
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