Why do Chromosomes Come in Pairs??

The answer to the question seems obvious; how else would offspring get genetic contributions from both parents? This answer just raises another question; why is it important that offspring be constructed from the genetic contribution of two, usually unrelated parents? The accepted answer to this second question is that combining the genes of two unrelated parents promotes genetic diversity, which is recognized to be health and fitness enhancing both in the individual and the population.

The findings of the Human Genome Project make this answer a little more complex.

Decoding the entire genome of a few selected individuals would be an epic achievement. This is not, however, what the Genome Project attempted to do. The Project’s mission was to sequence the entire DNA strand, and to turn that knowledge over to geneticists who would tackle the immense task of understanding the codes recorded there. Much of the scientific interest in the DNA sequences documented by the project has focused on the segments known as genes, the sections whose functions we want to understand in order to tackle genetic disease. These sections work as analog codes for the construction of proteins and make up less than 5% of our DNA. I call them analog genes.

The focus on these codes raises an obvious question. We are each of us so different, unique in so many physical ways. Shouldn’t the genes that create us be equally different, equally unique? And if each of our DNA strands are unique, how would decoding your DNA help to understand mine?

The analog genome revealed by the project has turned out to be largely identical for all humans, at least in function. Given this deep similarity, decoding any individual’s analog genome opens a window into ALL human analog genes. Sequencing the analog genome however leaves much unanswered about those myriad physical differences, the unique features that allow us to recognize each other at a glance.

The genome project expected to find that the human genome contained at least twice as many analog genes as did those of relatives like chimpanzees. Assuming that we were far more complex than chimps they looked to find far more genes to create that complexity. What they found however was that we have the same rough number of genes as do chimps, or most animals…

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