Thursday, April 15, 2004

Artifacts of Evolution

I’ve got a few hypotheses about human evolution. The underlining hypothesis is that humans developed our large brain and self-awareness before evolution was completely done with the development our body plan. These are based on nothing more than observation, conjecture, and being a human myself. They were developed after considering lapses in the modern human body. It would be interesting to see someone explore these hypotheses.

Question: Why do we have Wisdom Teeth?
Hypothesis: Evolution provided humans which just enough teeth to get our ancestors through about 30 years of life.
Explanation: Wisdom Teeth provide one extra late life set of teeth to replace adult teeth lost due to harsh living conditions and tooth decay. The modern human generally do not have a need for this extra set of teeth.
In prehistoric times, humans had life expectancies limited to 30 years or so. Without dental care, our teeth tend to deteriorate rapidly in our adult life. Evolution adjusted to this attrition by providing one extra group of teeth. Prehistoric man relied on this extra set of teeth late in their lives. Maybe around 25 or so?
Observations: Many animals either have teeth that last roughly as long as their lives. Many hunter animals lose or damage teeth frequently do due the harsh nature of hunting. These animals either have teeth that rejuvenate, or that get replaced. For example, cats and dogs have teeth that grow throughout their life. Sharks are constantly growing new teeth to replace teeth lost during the hunt.

Question: Why do we get leg cramps?
Hypothesis: Leg cramps are part of a diminishing instinct to grasp items with our feet. This instinct is from a time when the body plan of prehumans was designed for tree climbing.
Explanation: Although there are certain medical causes for leg cramps at specific times, there seems to be an underlining cause to leg cramps at other times which go beyond the medical explanations. It is possible that instinct, which causes leg cramping, is an artifact of evolution that hasn’t quite died out yet, even though it is no longer useful.
Observations: Leg cramps can be triggered by things such as: our foot being in a tight space; while swimming; during sex; etc. Some monkeys appear to instinctively grasp branches with their feet while they are in trees.

Future questions to be addressed:

Question: Why do we require so much water for our survival?

Question: Why does our jawbone grow throughout our life?

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