Proponents of evolutionary theory assume that human beings as well as every other living creature evolved through natural selection. They theorize that humans evolved from an ape-like ancestor and cite various archeological examples of possible pre-homo sapiens in hopes of filling in the missing links leading up to today’s version of human. Evolutionary biologists, therefore, tend to look towards the past to find confirming evidence of what they presume to be true, humans evolved. Transhumanists, on the other hand, tend to look forward to a day when, though the assistance of technology, a new species of human will evolve. As Nick Bostrom, one of the major spokespersons for the transhumanism movement, writes, “After the publication of Darwin’s Origin of Species (1859), it became increasingly plausible to view the current version of humanity not as the endpoint of evolution but rather as an early phase” (“A History of Transhumanist Thought” Bostrom, Nick originally published in Journal of Evolution and Technology vol 14, issue 1, April 2005).

How would we know when we’ve hit the next step in human evolution? Nicholas Agar, a critic of the transhumanist’s ideas about radical enhancement, considers this in his recently published paper in the Journal of Evolution and Technology (Journal of Evolution and Technology Vol 21, Issue 2, November 2010) where he elaborates on some of the themes in his book, Humanity’s End. While the Journal of Evolution and Technology usually deals with the advantages of interfacing humanity with technology, Humanity’s End does not paint as optimistic of a picture as many within the transhumanist camp do. One interesting proposition that Agar makes is in regards to speciation:

I propose that radical enhancement creates reproductive barriers in much the same way as would altering members of Homo sapiens to be genetically, physiologically, and psychologically indistinguishable from typical members of Pan troglodytes. The term “posthuman” is not just for show: it indicates a significant difference between the radically enhanced and the unenhanced.

Agar assumes Ernst Myer’s definition of speciation as reproductive isolation. He believes enhanced human beings would be uninterested in the unenhanced because conversing or interacting with them would be on par to current human beings trying to discuss art with a monkey. This, therefore, will lead to reproductive isolation. While this is still in the realm of speculation, it does bring up several good questions about evolutionary theory: What does it look like when a branch in the tree of life forms along the human line? Is it even possible that enhancement will produce a new species of human? And what happens to us when we become yesterday’s news in evolutionary terms?
Scientists have studied plant and animal speciation to try to develop a general mechanism of speciation. Peter and Rosemary Grant, foremost experts on Darwin’s Finches, published a paper last fall (2010) on speciation among Galapagos finches in the Proceedings of the California Academy of Sciences (Proceedings of the California Academy of Sciences Series 4, Volume 61, Supplement II, No. 14). They have also published numerous books and articles regarding speciation, including an announcement in 2009 that a new species of finch may eventually emerge. Discovery Institute fellow Jonathan Wells addresses their 2009 paper here. Obviously, there is controversy surrounding the definition of a species and how it emerges. As the Grants point out in their 2009 paper, they still don’t know how many generations must pass for a finch with particular preferences to be considered reproductively isolated. Furthermore, they are unsure how long one must wait to see if true reproductive isolation has occurred, or if a particular finch integrates back into the original population.
For Agar’s scenario of a new species of human arising from preferences, this would most closely correlate to the idea of female finches preferring males with certain traits. However, this is a contested cause of speciation. Agar and many others in the transhumanist camp like to toss around the idea of enhancement causing a new species of human as if reproductive isolation is an easily discernable factor in labeling a new species. Furthermore, they presume that enhancement is man taking the reins in his evolutionary development, implying that the new species, the posthuman, will be evolutionary advanced. This does not make sense biologically for several reasons.
First, if speciation is reproductive isolation, or the “cessation of gene exchange” as specified in the Grants’ paper, then being biologically sterile is not the only cause of speciation, but environmental factors and cultural factors play a role. The paper asserts, “The exact mechanisms by which speciation occur is still an area of research, because the process of speciation can be different for different organisms.” As reported in Jonathan Wells’ article, this is a bit controversial. Based on the finch studies, preferences for a particular mating song can play a role in determining reproductive isolation. In other words, it’s not that the finches can’t mate; it’s that they won’t mate. The controversial part is whether we can really call this a truly novel species. The problem becomes more obvious if we try to apply this to human evolution. If preference is a factor for reproductive isolation, then there are new species of humans emerging every day. Whether it is the guy who prefers blonds to brunettes or a person’s preference for a particular race, can we really claim that rejecting a reproductively viable option because of a particular physical trait produces a new species of human? The definition of speciation is difficult enough among the likes of finches whose criteria maybe a song and a beak, but humans are particularly complex in their preferences. Based on Agar’s assertion, the enhanced are no different than the guy who prefers blonds.
The second problem has to do with how Agar and others are defining evolution. If a new species of human were to emerge, perhaps this could serve as an example of how a branch gradually forms in the tree of life. However, the development of a new species from enhanced humans seems more similar to breeding or engineering than to evolution. The transhumanist group’s motto is to take control of their evolution, but by the mere act of “taking control” it is no longer evolution; it is engineering. Evolutionary biologists define evolution as an “unguided process” which cannot be the case if humans are using technology to control their evolution.
Thirdly, there’s the human factor. What about those humans that don’t want to be enhanced? These people will likely die off more quickly than the enhanced, and so the fit (literally) will survive. The presumption is that the unenhanced are evolutionarily inferior to the enhanced. But what about the unenhanced killing off the enhanced with other types of technology, such as weapons? Rarely do evolutionary biologists consider technology as part of natural selection because, according to Neo-Darwinian theory, evolutionary progress occurs when mutations are coupled with natural selection. Speciation is a step in an eventual genetic line that will eventually be selected. Furthermore, many biologists wish to study organisms or ecosystems that are isolated from human activity so that they can study how these organisms evolved apart from human influence, as is the case with the Galapagos finches. The transhumanists, on the other hand, believe that human ingenuity, such as technology, is part of the evolutionary struggle.
While it may be a good plot for the next sci-fi movie, the idea that a new species of human will emerge because of enhancement is an unlikely scenario. It is more likely that the enhanced will think of themselves as too good for or better than the unenhanced, and the unenhanced will consider themselves unworthy to interact with the enhanced, which is more a matter of human nature than a matter of evolutionary advancement.