Avoiding the Wet and Cold May Be Key to Walking on Two Legs

Do You Owe Your Upright Posture to Snowbound Ancestors?

Do you accept the theory of evolution as to how man became the dominant species on the planet? Some old theories about human development by researchers may still have relevance today, such as in how human beings came to walk upright in the first place. Evolutionary theory generally proposes that environmental triggers are to some degree responsible for changes in animal physiology, from a need to find new food sources (giraffes searching for untouched vegetation higher in trees through favoring individuals with longer necks for instance), to the necessity of escaping predators and so on.

In the mid 1950s a zoologist at the University of Virginia in the US proposed that he had found a compelling reason for why human beings walk upright today. He attributed this to his research on chimpanzees. Largely, the idea revolved around the stimulus of cold periods in Earth’s climate, perhaps previous ice ages tens of thousands of years ago also factoring into the development. Dr. Sydney Britton’s theory was that a particularly cold and wet climate would be uncomfortable, and perhaps unmanageable for warm blooded species like apes that walked on all fours and maintained a posture close to the ground.

Dr. Britton kept several chimpanzees in his home, and one in particular that he named Bonga was the subject of his theory on the evolution of walking upright. He stranded Bonga on a cold, wet island and observed the chimp’s behavior. While chimps can walk upright if they so choose, they normally avoid the posture as its difficult for them to maintain. Bonga however maintained an upright posture as the ape moved about on the island to avoid the wet and cold ground.

The zoologist theorized from this that a continuous requirement to walk upright in a colder climate would stimulate the development of other parts of a primitive human being’s anatomy. Namely, he believed that adrenal glands would have to work harder to maintain such a posture, which are responsible for producing steroids in the body to aid muscle activity, and hormones like epinephrine, which works to increase heart rate, metabolism and blood pressure.

Sustained walking upright would therefore increase the level of blood flow to the brain, which over time might actually result in the development of larger brains. Walking upright it would seem, would gradually increase intelligence level, making ape-like creatures who could sustain the posture more intelligent than those who could not.

It’s an interesting idea, though it would be difficult to verify if its correct or not. Unless we could travel back to the last ice age that occurred on Earth and observe primitive man, (which took place at least 11,000 years ago). If we want to observe the behavior of chimps around the world in the next ice age, we’ll have to wait an estimated 50,000 years or more. That is, of course, if there are any chimps left on Earth by that time. The BBC (British Broadcasting Corporation) estimates that there are only about 200,000 chimps left in the wild, versus over a million that existed 20 years ago.