3
An Evolutionary Perspective on Human Diet and Lifestyle
“The greatest tragedy of life is that it must be lived forwards and can only be understood backwards.”
― Kierkegaard
If we are to consider our current eating habits without examining human history from the beginnings of mankind, we are doing great injustice to the subject. It is like looking for a solution for a problem without using the vast information we have collected throughout our lifetime. We would certainly not find the best solution for our problems under such circumstances. This is what fuelled my research into human evolution from the beginnings of mankind. I wanted to find real answers and not blindly accept the often biased information available. I wanted to combine information from all of the sciences to get the whole and true picture for our best health and dietary choices.
So let’s take a look at human evolution. Human evolution is a process that occurred over millions of years leading up to the appearance of modern humans. Evolution is a process by which organisms change over time as a result of changes in heritable genes (DNA), or in physical or behavioral traits.
So where did we come from? There are two popular answers to this. One is the scientific evolutionary theory preferred by scientists, and the other is the religious belief shared by religious people. I see that both theories can coexist quite well, however, that is a subject best left for another book. This book is based on scientific facts, therefore I will examine the existing scientific evidence of our evolution and how we can use this knowledge to improve the quality of our lives as well as that of our planet, and the quality of life of our fellow creatures who share this planet with us.
A Very Short Timeline Summary of Human Evolution
375 million years ago the earth began to assume recognizable forms. The earth's climate was warm and more humid at this time and remained so for the next 360 million years. It is at this time that the link between land animals and fish was determined. Scientists show that all animals who are walking on four and two feet come from a specific fish known as Tiktaalik roseae. This fish is believed to have been the first to have made the transition from the sea to the land. Tiktaalik roseae had similar limb bones to land animals, although on a different scale and in a different shape.
It is believed that reptiles have evolved from this ancestor, who later branched off into two groups 256 million years ago; one group remained reptiles or became birds, and the other group became mammals.
The earth then suffered from a mass extinction event which eliminated over 90-95% of marine animals. Land animals were not as seriously affected, but life on land took 30 million years to completely recover. (66)
From the second group that branched off to become mammals, another group diverged 85 million years ago to become primates.
Then the earth suffered another major extinction event which eradicated about half of all animal species, including all of the dinosaur reptiles, but excluded their descendants, the birds. (67, 68) It is at this time that mammals become the dominant species on earth.
Finally, 15 million years ago, the great apes evolved from their ancestors, the lesser apes, to form the homininae lineage which eventually led to modern humans. (69, 70)
Around 10 million years ago, the Earth's climate entered a cooler and drier phase and stayed that way until about 15,000 years ago. This further led to the transition to bipedalism, the transition from walking on four legs to walking on two feet.
Early Humans Separate from the Apes Six Million Years Ago
Looking at our family tree in the picture in Chapter 2 we can see that the emergence of modern humans (Homo sapiens), evolved from a distinct species of great apes of the homininae lineage 8 million years ago, which included 2 species of chimpanzees (Pan), 2 species of gorillas (Gorilla), 1 human species (Homo), and 2 species of orangutans (Pongo). (71) Molecular evidence suggests that apes split off from the lineage that eventually led to modern humans sometime between 8 and 6 million years ago.
The earliest fossils that have been argued to belong to the human lineage, hominins, after the split from the apes belong to an extinct species Sahelanthropus tchadensis, which dates back to 6 million years ago. (72, 73) The fossil skull shows that its brain size was only 320 cm³