Junk DNA might be the secret to our genome
YOU are a chimpanzee. Well, you’re almost a chimpanzee. In fact, your genome is 98.5 per cent identical to that of a chimpanzee’s. This means one of two things. Either someone should call the local wildlife authorities and have you placed in an animal enclosure, or genetics is a really weird and baffling branch of science. Fortunately for you, it’s the latter. And the more scientists learn about our genome, the more weird and baffling things become.
Prior to the human genome being mapped in 2001, it was estimated that our genome should contain in the vicinity of one hundred thousand genes (protein coding DNA), but the teams responsible for the mapping clocked the total at roughly thirty thousand genes.
And now geneticists have discovered that the total is closer to twenty thousand.
To put that in perspective, a microscopic worm consisting of just one thousand cells holds a gene count similar to our own.
Given the massive disparity between the complexity of an organism such as ourselves, and that of a microscopic worm, it begs the question as to how such a thing is possible.
Furthermore, given that our genome is so close to that of a chimp, why are we so biologically different, not just in our appearance, but in our relative cognitive abilities?
The answer may just lie in what Dr Francis Crick, codiscoverer of the double helix structure of DNA, labelled as ‘Junk DNA’ in 1970.
At the time, this junk DNA appeared to hold no apparent purpose as it was non- coding (meaning that it did not code proteins and thus did not hold information pertinent to our structure as an organism).
But considering that this junk comprises roughly 97 per cent of our genetic structure, scientists have long speculated that, far from being useless, this junk yard of random DNA might just hold the key to the question of why we are human, and why a giraffe is a giraffe.
This comes as no great surprise to evolutionary biologists, most of who have long maintained that one hundred thousand protein coding genes would prove to be so complex as to be fatal for an organism, simply because the chances of offspring suffering extensive and life threatening mutations would be excessively high.
The jury is out for the time being as there is still much work to be done, but it would seem that geneticists will be up to their elbows sifting through the DNA equivalent of a rubbish dump for the foreseeable future.
But as they say, ‘One man’s trash is another man’s treasure’.
They may be more right than they ever knew.
PRACTICALLY IDENTICAL: The human genome is 98.5 per cent identical to that of a chimpanzee’s.