Having provided a basic introduction to the Paleo Diet last week, this week we’re going to delve into the background and science of the Paleo Diet a bit more, exploring why many people believe that humans have not evolved to eat a lot of the foods that are in the modern western diet, including agricultural produce and refined sugars.
Who were our ancestors?
Archaeologists generally consider human development to have started when we began walking on two legs, embracing bipedalism. Bipedalism freed up the hands and the altered gravitational pull changed the system of blood flow around the head, cooling the brain and allowing it to cope better with the open savannah heat, which also enabled it to expand. The anthropology department at the University of Texas at Austin have put together a lesson about bipedalism and the anatomical adaptations resulting from this, which is fascinating reading.
Bipedalism starts to appear in the archaeological record with the Australopithecus genus (a predecessor to Homo) 4.4m years ago, although that isn’t to say that our ancestors didn’t start to appear even earlier, that’s just the earliest evidence we’ve found so far. Over the next few million years we slowly adapted and changed. The most recent variation, us, is Homo sapiens and we arrived on the scene approximately 100,000 years ago.
When did agriculture appear and what’s the problem anyway?
The first evidence of agriculture appears only 10,000 – 12,000 years ago in the form of einkorn wheat. However, a recent study comparing skeletal data has shown that health showed a marked decline at a similar time to agriculture becoming widely adopted across Europe. In particular, there were marked increases in bone infections, tooth decay and vitamin deficiencies.
This study provides support for earlier anthropological research into tribes where a hunter-gatherer lifestyle is still followed and where healthier traits can be observed, such as a lack of tooth decay (despite there being no toothbrushes and fluoride toothpaste available) and better longevity.
So that’s agriculture but what about milk?
There is evidence that some blood lines have evolved to handle lactose a little better than others, but as Loren Cordain said during an interview with Super Human Radio (show number 341), have you ever seen someone milk a wild animal?
Several people advocate that a truly paleo diet should be entirely lactose free. This isn’t something I’ve done as much reading on but I have continued to include plain live culture yoghurt (without any added sugar) and cheese in my diet.
The probiotics in the yoghurt are invaluable and I believe that we would have eaten the contents of an animal’s stomach after killing it. If the animal was young this could include fermented milk. Wolves eat the gut and its contents today when they make a kill and I understand that this is one of the first parts that they eat from a fresh kill, though wolves are documented as not eating the contents of the stomachs of herbivores. However humans, being omnivores like hyenas, would be more likely to consume the contents of the stomach as well.
Surely we’ve evolved in the last 10,000 years?
Not really. After all, most of the different species of our ancestors were around for at least 300,000 years (often up to a million years) before they evolved enough for us to be able to see any difference in the archaeological record.
Donald Johanson and Blake Edgar, authors of “From Lucy to Language”
How do we know what they were eating back then?
Depending on the climate of an area, certain items are preserved in the soil and can be seen in samples when these are analysed under a microscope. This could include seeds, pollen, bones, shells and mineral deposits. Depending on the pattern created by the deposits (e.g. in quantity around a carbonised area may indicate meal remains round a fire) it is possible to draw conclusions about what may have been eaten.
We will never know for certain, but we are able to see when foods only start to appear much later on and can draw conclusions for these foods.
A word of caution though. We should take care not to avoid foods just because we can’t find evidence for them. Some foods or methods of hunting for foods just don’t leave any evidence due to either extreme dry heat or very moist soil, most notably fibres used for netting fish often do not preserve well. Absence can only be interpreted to mean the food wasn’t eaten if we can see evidence that it has preserved in later years.
Is this the way ahead?
I certainly think so. As I said last week, I’ve seen great improvements since I switched my diet over and I would recommend this food-selection mindset to anyone. But as with all things, you have to keep your mind open to the ever-increasing pool of research and incorporate this into your thinking. I will let you all know how the latest research is colouring my own thinking and diet choices.
Do you already eat following the paleo diet, or are you considering it? If you’ve had any experiences of it, whether good or bad I’d be interested to hear from you.
Related posts:
Introducing the Paleolithic Diet (Part 2) | Paleo Diet | if you do the paleo diet you need supplementing // Oct 3, 2009 at 02:06
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