Of Apes and Men
Where we discover that 99.9% of our genetic information is identical to that of our neighbour, and how computers have facilitated this discovery.
Recently, I was in the waiting room of my doctor’s cabinet, when it occurred to me how drastically the field of medicine had changed over the last decades. The mere fact that all living organisms on the planet shared the same way of storing information, the DNA, completely changed our view of life. But there was more to it: for the first time all organisms could be compared to each other in a computer in terms of the similarity of their DNA sequences. But how?
Imagine you have three different strings of DNA, such as a gene from an ape, a similar sequence from your body and one from mine. Or, to make the example clearer, let’s use three words (which are also strings), namely „APPLE“, „APFEL“ (the german word for apple) and the french version „POMME“. Now, how similar are these three words to each other? And which letter could correspond to which one?
There are different algorithms to solve this problem, but all of them have in common that they compare the letters inside the different words, and align them in a way to minimise the matching errors. For example, in the case above the words „APPLE“ and „APFEL“ have more common letters in similar positions then the words „APPLE“ and „POMME“. The two words thus match better to each other (even if some letters seem to have shifted their positions). Based on the best alignment an overall similarity score is then calculated. This score is obviously higher for similar words, and hints at a common origin.
In a very similar way, the field of bioinformatics arranges the „letters“ of our DNA (the so-called bases) from different people or animals to each other. This revealed for example that humans and chimpanzees are overall less than two percent different (so Darwin was right, we do have quite a close common ancestor with apes). However, two humans are even less different, only about 0.1%, but this makes each of us pretty unique!
To do such kind of comparisons we first need to have access to the genetic code of an organism. While at the beginning of the 21st century such a feat was nearly impossible, and costed in the order of hundreds of millions of US dollars for a full human genome, today you can sequence it for approximately 1000 US dollars. However, all these sequences, from genes to proteins, must also be saved on some big servers. And it is interesting to note here that one of the most used databases for biological sequences worldwide is hosted here in Switzerland, at the Swiss Institute of Bioinformatics in Lausanne.
This is just the beginning of the digital revolution in the field of medicine. And if one thinks of the effects that the digitization had on our daily lives so far, one can only start to imagine what impact it will have on the future of medicine on the long run. In the meantime, I’ll still wait for my doctor in his waiting room…
