Revisiting Human Evolution: Part 2

In Part 1 I went over how reproduction is at the heart of evolution in order to clear up any misconceptions about what evolution means for the modern lifestyle. Now I'd like to turn to an equally important and foundational topic that will further what evolution means for our bodies.

The Human Timeline

A lot of dates get thrown around about our hunter-gatherer past. I want to tackle this topic strategically, so I'll start with the most conservative interpretation first. This is from Geoff Bond's Deadly Harvest:

We have our humanlike beginnings with East African Homo erectus over 1,000,000 years ago. Out of that population, Homo sapiens arose and existed for 190,000 years before leaving Africa about 60,000 years ago. This period, from over 1,000,000 years ago to 60,000 years ago is critical—it is our formative era. It is the time when the African environment forged the bodies that we possess today...

Geologists have a convenient, often-used epoch for this approximate time period—the Pleistocene, which runs from 1,600,000 years ago to 10,000 years ago. However, I want to conclude the formative era earlier, at about 60,000 years ago. Since our ancestors spent this time entirely in Africa, I will call this critical formative era the “African Pleistocene.”

Now, you might be thinking that this time period ignores a huge chunk of significant history, but I want to highlight the importance of this message. This was a long time that a relatively small number of humans -- all of them -- evolved in a relatively small corner of the world. Many conditions were relatively stable throughout this million-year period compared to what happened to our species after the African Pleistocene, 60,000 years ago, when we left Africa and spread slowly throughout the rest of the world. The takeaway: our species is a tropical one whose homeland was a small pocket of Africa in what is now Kenya, Tanzania, and Ethiopia. Bond's "formative era" is the most indisputable core of human history that cannot be nit-picked or challenged. This is why it's worth noting before moving on to a more moderate, but still significant, timeline.

The Cambridge Encyclopedia of Human Evolution dates humans according to the genus Homo, starting with Homo habilis. This is the 2.4 million year number that you've probably heard. Homo habilis had a slightly different physique more adapted to tree climbing, due to its tree-dwelling ancestor, Australopithecines. The takeaway: habilis used stone tools, foraged plants, and scavenged animal foods. That's right, we ate paleo two and a half million years ago.

Now lets talk about the time period after the African Pleistocene, 60,000 to 10,000 years ago. This was the time when our species left Africa and spread over the world, entered new geographies and climates, and saw some degree of differentiation, what we now call 'race'. While there was a great deal of differentiation in terms of adaptation to climate/environment, many important things stayed the same, but I'd like to highlight two: our hunter-gatherer diets and the physical movements necessary for survival. Thus, throughout all of human history in the Paleolithic we ate specific types of foods and performed specific types of natural movements all the way up to the agricultural revolution (the Neolithic).

So hopefully now you can recognize a million-year core of indisputably formative human history, but also the preceding million and a half years and how that's relevant, and finally the tumultuous 50,000 years before the agricultural revolution and how that doesn't contradict diet or exercise either.