Just a few months ago, I watched Stanley Kubrick’s 2001: A Space Odyssey for the first time. It’s a brilliant science fiction movie, from the late 60’s, about human evolution and its associated technological development. In the movie we see our species starting as cavemen, but rapidly evolving into sophisticated creatures who explore the universe in spaceships, hoping to find out where everything is coming from.
Given this incredible evolution of human species to what we are today, it can’t be a coincidence we are living on earth by chance, can it? Proteins could be randomly shuffled for billions of years before humans emerged on earth in all our glory. Since the chance of human existence by chance is so small, surely intelligent design must be the best explanation (Vul & Kanwisher, 2010)!
Although this rationale is very flattering for us as humans, it doesn’t follow the rules of logic. The rationale is an example of the logical fallacy known as the “non-independence”error. Unfortunately, this error is not restricted to the unscientific domain, but is common in science as well.
So, what is the non-independence error, that leads to the flattering, but logical erroneous conclusion? Essentially, the error of non-independence is a problem of selection bias. When we use statistics hypothesis testing on a data set, we assume that the selection of data does not influence the data analysis. When the selection does influence the analysis, this assumption is violated.
To relate this to the human evolution rationale: If we would assume that the protein combination that led to the emergence of human species was a sample from the population of all possible protein combinations in the universe, and if the emergence of humans was specified in advance by some higher power (sorry, evidence from the Bible doesn’t count, since the book is written 196.500 years later than the emergence of the first modern humans), only then human existence would have been a miracle indeed; our path must have been predestined by intelligent design!
However, our data selection process was different . Our protein combination did not originate from the population of all possible protein combinations, because it was the only protein combination we observed. We did not look into any reference protein combinations that could have confirmed or reject our rationale (maybe there intelligent life on a planet that we don’t know yet!) Therefore, our selection is biased and results will be guaranteed: it leads to the erroneous conclusion that chance cannot be the reason human live on earth.
Until now, we don’t have evidence for intelligent life somewhere else in the universe. But as Kubrick outlines in his space Odyssey, humans are explorative in nature and will continue their search for life elsewhere. Maybe one day we will find out we’re not so special, after all.