Human Evolution

today's ditty: Black Keys - Lonely Boy

Consider the genetic selection of 1000 years ago.  It was the year 1013. Most people lived and worked on farms. This was a hard life. The typical family size was maybe 5 to 8 kids?   It wasn't at all unusual for one or two of the children to succumb to pneumonia, the flu or to a physical accident before reaching adulthood. Major wars in which large percentages of populations (>10%) would be killed were a fact of life. If an individual was not strong, physically healthy, quick to adapt, sharp of mind and at times just plain lucky, then more likely than not he or she would meet with an early death and not pass on his or her genes. Evolution of the human gene pool at the time was definitely in accordance with "survival of the fittest".

Now consider the genetic selection in today's societies, specifically in the industrialized and advanced technology societies (countries such as France, England, America, Brazil, South Korea, Japan, Sweden, Switzerland, Australia). Even though the individuals in these societies may have a genetic make-up that does not make them particularly strong, physically healthy, quick to adapt and sharp of mind, they live plenty long enough to have children and to pass on their genes. This might be considered a bad state of affairs for the evolution of our species. Actually, though, it sets the stage for a gigantic leap in evolution that could be much more than what classical evolution would ever deliver.

With the low mortality rates associated with today's lifestyles, genetic variations that would otherwise be culled out by survival of the fittest are instead being retained and spread across successive generations. This results in increased genetic diversity in the human species.  The below charts (sources: Nature and human evolution 2) clearly show this increased genetic diversity.

Visualization of the distribution of potentially harmful genetic variation across protein-coding portions of the human genome. The top section represents variation that predates the human population explosion 10,000 years ago. The bottom represents variation that arose since then. Image: Fu et al./Nature

The hard data in these charts are the quantities (darker red indicates more) and the chromosomal locations, of potentially harmful gene variations in our genome that arose in one time period in human history versus another time period. Comparison of the two charts shows that many more variations arose in the most recent 10,000 years than in the 100,000+ year time period preceding that. The raw data indicate the rate of accumulation of genetic variations in the more recent time period to be greater than 5 times higher.

So, in other words, humans today are becoming more genetically diverse at a rate that is >5x faster than in the past!

This from the article human evolution 2:

One consequence of this is the accumulation in humanity of gene variants with potentially harmful effects. Akey’s group found that a full 86 percent of variants that look as though they might be deleterious are less than 10,000 years old, and many have only existed for the last millennium. 

“Humans today carry a much larger load of deleterious variants than our species carried just prior to its massive expansion just a couple hundred generations ago,” said population geneticist Alon Keinan of Cornell University, whose own work helped link rare variation patterns to the population boom. 

The inverse is also true. Present-day humanity also carries a much larger load of potentially positive variation, not to mention variation with no appreciable consequences at all. These variations, known to scientists as “cryptic,” that might actually be evolution’s hidden fuel: mutations that on their own have no significance can combine to produce unexpected, powerful effects. 

Indeed, the genetic seeds of exceptional traits, such as endurance or strength or innate intelligence, may now be circulating in humanity.

Think about this for a minute. This is like an experiment - the ultimate experiment. The human species is careening off into the future evolving at ever higher rates and in unknown directions!

Taboo Territory, Beware

Maybe we should be doing something to direct this evolution. To push it in a direction that might be beneficial to our descendents and that might enhance the chances of our species' survival. From right now to maybe 100 years from now, I think we have a good opportunity to do just this.

There are two things that create this opportunity:

• First, as noted above, in many advanced industrialized countries negative population growth is becoming the norm. There are many who feel this is not a good thing and would like to see at least a zero growth level maintained. So, in a number of regions in the world, there would be a desire for higher birth rates.

• Second, we now have the capability to read an individual's genome and are rapidly learning to decode it - in terms of the specific human traits it carries.

So, here is a way we might increase our population growth rates, and at the same time do something toward improving the genetic pool of the species::

1.   Generate a good sized list of non-controversial positive human traits.  Traits such as:

·        low susceptibility to cancer, diabetes, schizophrenia and other specific diseases;

·        high intelligence;

·        good mental stability and self control;

·        good reflexes and dexterity;

·        good eyesight, balance, hearing;

·        compassion and altruism.

2.  Decode the genomes of a bunch of volunteer subjects, evaluate and compare these genomes for the above traits and characteristics  Use the results to identify the "top 20%" genomes.

3.  Establish a private foundation that gives away lottery prizes of value of 10x annual median income. Give free lottery tickets to a top 20% individual whenever he or she parents a child.   

Or, you could just do it the old fashioned way.  When you run across nice young couples who are healthy who seem to have their act together, befriend them, help them out when they have kids and encourage them to have more.

More good stuff to read on the topic of evolution:
Cryptic Variation
Spacial Sorting