The old spider sense tells me that the New Scientist article cited above is probably not going to herald the dawning of a new age of brotherhood between apes and humans. The article provides a link to the webpage of Professor Morris Goodman, in which he informs us helpfully that “(t)he molecular genetic view, free of anthropocentric bias, places all the living apes (gibbons, orangutans, gorillas and chimpanzees) with humans in the same family and within that family barely separates chimpanzees from humans, the two as sister subgenera grouping together in the same genus.”
Which is all very well and good, but does it really make sense to use molecular genetic similarity as the defining criterion of taxonomic classification? Would doing so provide an understanding that is “free of anthropocentric bias?” My guess would be “No” and “No,” respectively.
First off, I note that Prof. Goodman is using a fairly restrictive definition of “genetic similarity” that only takes into account the protein-coding regions of DNA. The total difference between humans and chimps is still apparently 95%, as cited in this article (which the above feature links to). For his part, Goodman argues that the noncoding regions aren’t biologically significant. Far be it from me to second guess a Ph.D in Biochemistry, but this seems to contradict my admittedly limited understanding of the current school of thought in molecular biology, which is discovering that the noncoding regions may indeed be fairly important to the genome. Then too, even if two organisms have exactly the same genetic material, its expression can be influenced profoundly by its position within the chromosome. Biologists, please correct me if I am overstating my case here.
Secondly, while molecular biology can be used to determine the degree of relatedness between organisms with great precision, the point where lines are drawn to designate “genus” and “species” are still fairly arbitrary. What percentage of similarity defines a difference in genus? Let’s assume for the sake of argument that we set the bar at .7% of protein-coding DNA, which means that humans and chimps are in the same genus as per Prof. Goodman’s scheme. Why not 10%, or .1%? Isn’t any such percentage going to be a more or less arbitrary value for determining genera, absent other considerations?
Lastly, I would suggest that if the manifold differences between chimpanzees and humans are not sufficient to warrant a generic distinction, then taxonomy would be fairly bankrupt as a useful system of classification. I guess that the “99.4% similarity = chimps are human” interpretation will be bandied about fairly heavily for shock value in the future, but won’t add any profound insights to considerations of science or morality. They’re still chimps, after all.