How did farming drive natural selection?
This is a fascinating question.
As farming took off, humans had more offspring at a faster rate. In natural selection terms, this means that more natural mutations to the human genome occurred. These mutations undergo natural selection and essentially change the human DNA profile over time.
For example, if a mutation for energy storage via insulin occurred in a population, it would be selected out for survival because simply these people would survive the long winter better than their friends who did not store fat well.
Interestingly, these DNA mutations were known to have occurred in many different paleolithic populations separated by vast distances.
Lets look at Malaria and sickle cell disease. Malaria is a mosquito borne parasitic protozoal illness that affects the liver and red blood cells. The illness is characterized by fever and many serious complications including encephalitis and death. Some humans developed mutations that allowed their red blood cells to change shape and become sickled. This shape change prevented the protozoa from gaining access to the red blood cell effectively preventing malarial disease.
This mutation naturally kept these humans alive during major malarial scourges in Africa. The down side is the mismatch disease. If you have one copy of the sickle cell gene, you are protected from malaria and have no disease. If you get two copies, you are protected from malaria, but also develop sickle cell disease. In natural selection terms, the majority of the farmers would be happy to survive free of malaria with the knowledge that a few relatives may develop sickle cell disease and die. Survival of the fittest.
Fast forward to 2013. Many people of African heritage live in malaria free areas like the United States where suffering from sickle cell disease makes little evolutionary sense.
When we think of our genes, think in terms of the past and what the benefit of the gene once was. I think this piece today really illustrates the path to understanding the human body.
There may be a lot more to the Paleo diet and more primitive diets than modern physicians wish to believe. There is one thing that I am certain of. Our DNA is surely telling us that Flour AND Refined Sugar are not inline with our evolution and is causing dysevolution.
I am going to continue to lay out the case for massive reductions in these types of standard American foods that are not inline with our DNA.
Read The Story of the Human Body by Lieberman for the entire unabridged version. I highly recommend it. At least from page 158 on.
Dr. M
