Thursday, October 09, 2008

Genetic Evidence for Polygyny in Early Human Life

Perhaps the Mormons are just acting on raw human instinct! In class, we have discussed the relationship between genetics and behavior. Several examples were used including the cuddling behavior of Montane vs. Paririe mole which concluded that the distribution of Vassopressin (the protein which effects whether a male stays with a female) receptors in the brain for each species differs. Professor Houlihan even mentioned the Casanova study in which some genetic differences were found between happily married men and men with problems in their relationships.

An article found in Scientific America highlighted a study whose findings supported a theory on a link between genetics and monogamy in humans. Research published in PLoS Genetics ( a genetics journal) on September 26, 2008 reports that genetic evidence suggests that polygyny (where a man is recognized to have more than one sexual partner or wife) was once the sexual/social norm for humans. Researchers showed that, on average, more genetic material is shared by the mother rather than the father. Researchers believe that these genetic findings correlates to the social behavior of men who end up fathering few to no children. The study examined DNA from six geographically different areas of the world. Although they believed that genetic variation in the two kinds of chromosomes should be equal, they found that there was more variation on the X chromosome. The paper explored the behavioral consequences that would correlate with these findings and they deduced that polygamy was the most likely form of behavior to explain their genetic findings.

David Barash, an evolutionary psychologist, from University of Washington in Seattle was quoted in saying that "Monogamy is a recently inspired cultural add-on [for the human species]. This idea may frighten many to think that whatever behavior is culturally accepted now is not "normal" or, as the article pointed out, to even think that this may be biological proof and support for promiscuity (however you define it). Despite all the controversy it is interesting to note this link between behavior and genetics and how not only behavior can inspire genetic research, but that one can describe possible behaviors from just looking at genetics.

For more information here is a link to the article and the published study

Posted by Maura Mulvey (10/09/08)

10 Comments:

At 11:44 AM, Blogger PWH said...

This comment has been removed by the author.

 
At 11:45 AM, Blogger PWH said...

It's always interesting to see how genetics plays a roll on our behavior. Prior to this class I always looked at things as either genetically based or environmental, but know I am aware that they work hand in hand. Especially, polygamy I would have never imagined that it had to do with genetics I always assumed that it was just based on culturally accepted values that were learned. As I previously mentioned, genetics and the environment work hand in hand, so do do you know which one plays more of a role in polygamy?

Chantal Gomes

 
At 11:50 AM, Anonymous Anonymous said...

Very interesting. So, if we are genetically inclined to be polygamous, why is that behavior so rare in humans?

 
At 11:50 AM, Anonymous Anonymous said...

Very interesting. So, if we are genetically inclined to be polygamous, why is that behavior so rare in humans?

Cecelia Hunt

 
At 11:59 AM, Anonymous Anonymous said...

It always interesitng to look at behaviors that seem to be learned or random and see their genetically driven. As a culture we want to think its all about making the decision, but if its ingrained in us thats a while differnt story.

Erica Damon

 
At 8:45 PM, Blogger PWH said...

Great post. Classic genetics vs. environment case. I think that if you look at polygamy through a scientific view, it would make complete sense for a man to have many wives or visa versa. It is instinctual for animals (including humans) to insure their survival and continuance of their genes. The only thing that prevents modern society from acting this way are the ideals that our culture (puritan based religious values) deems it unacceptable. I would imagine that early man Cro-Magnon, homo erectus, etc. would have acted upon this instinctual behavior. On the other side of this argument there is competition for the best suitable mate, it can be argued that it is also genetic (in humans and other species) to be monogamous, such as the prairie vole. Do you know if there are any genes/proteins that have been isolated that point to monogamy? If so, I guess I could answer my own theory by attaining some Cro-magnon DNA and identifying a protein that could indicate monogamy (such as the prairie vole). Sorry to babble. Thank you for your awesome post!

Posted by: Amanda Sceusa

 
At 11:11 PM, Anonymous Anonymous said...

I can totally understand that polygyny was "normal" in early human life. You don't live for long and so you need multiple partners to reproduce and spread your genes. But this is back when humans were not that different from animals. We, on the other hand, are restrained by the rules of society, and our goal of life is not solely to survive and reproduce anymore. I guess this is a case where "nurture" wins over "nature".

Hanbing Guo

 
At 11:50 PM, Anonymous Anonymous said...

Why is there more variation on the X chromosome compared to the Y chromosome? I was wondering what were the other behavioral consequences that correlated with their findings?

SUSAN DUONG

 
At 11:30 PM, Blogger Maura said...

Thank you everyone for your comments and questions! There were a lot of good ideas that contributed to the theory behind the research I posted on and its really nice to hear everyone's take on it. I will do my best to try to answer the questions presented. First, there is more variation on the X chromosome than the Y because the X chromosome is the chromosome that is contributed mostly by the females. If a lineage has the same father, the children will receive the same Y chromosome with the same potential mutations; essentially making their Y chromosomes the same. Since the X chromosome is the sex chromosome that the female contributes, with more female partners, there will be more variation/mutations built up on the X chromosome, in the lineage. Obviously, this is somewhat simplified, but hopefully it gets the point across.
There were a couple questions regarding why polygamy is rare and which one, genetics or the environment, plays more of a role in polygamy. I would say in our western modern world where our culture has been performed and practiced for quite some time now, that our environment has practiced us to perform monogamy. There are cultures throughout the world that do practice polygamy and their environment allows/encourages them to. It's really hard to say which is responsible, but I do believe that we are all genetically capable of polygamy, but unless it is practiced in our environment, the potential stays at rest.

There was a very interesting question that asked if there was a monogamy gene or protein that had been isolated and i did find an article on the new scientist website that previewed a study done in Sweeeden in which the vole cuddling protein, vassopressin, was investigated in humans. Researchers found that the variation in a section of the gene coding for vassopressin affected how men were in relationships. Men with two copies of the section of the gene, RS3 334, were more likely to be unmarried than males with one or no copy.
link to article: http://www.newscientist.com/article/dn14641-monogamy-gene-found-in-people.html?DCMP=ILC-tabViewArt&nsref=dn14641

Yikes! After reading all of this, genetics seems to have more of a link to behavior than I ever thought before. More research is, I'm sure, being done on these topics, but hopefully this has answered some of your questions. This blog post could go on forever! Thanks again!


Posted by Maura Mulvey 10/14/08

 
At 7:31 PM, Anonymous Anonymous said...

I often say it is human instinct to not be monogamous. We are basically animals, and animals are usually polygamous because they want to maximize their reproductive success and being with just one other mate is not the best way to do this, usually. I think this article is very interesting because it puts something we think about in everyday society into a scientific point of view.

-Julie Riley

 

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