This was an interesting year for science. But rather than stretch for a list of the top ten accomplishments or discoveries I would like to focus in on three specific feats of technological achievement that, I think, have broad implications both for the future of science and how humanity views itself.
I begin with the discovery of hundreds of exoplanet candidates in our galaxy. This does not mean that astronomers have found hundreds of exoplanets (though, with 100 billion stars in the Milky Way, it’s safe to assume that there are at least billions of planets). Rather, using indirect measurements, astronomers have found what look to be planets. As better telescopes (well, spectrographs) come online, astronomers will be able to confirm whether these are in fact planets.
There was one other very interesting find when it comes to exoplanets. In September one team of researchers was able to identify the first exoplanet known to hold liquid water. However, this discovery was contested when a second team could not find the planet. Whether the planet does exist and does contain water will remain in question; however, there is no question that somewhere out there exist other planets that do contain liquid water. Astronomers are currently looking for planets that have “biomarkers,” or the correct elements and compounds that would allow for life. Carbon. Oxygen. Water. Methane. Carbon dioxide. As well as uranium, potassium, and thorium to allow for tectonic activity. It may very well be that life exists within our solar system (Europa, Titan, Io, and Enceladus are all candidates).
The larger point here is that, at this point, it is very hard to assume that we are alone. The probability that there is other life at least in our galaxy, never mind our universe, is at this point very high. There is a natural tendency to think that this life would resemble something from Earth, presumably much like our bacteria. But it is worth remembering that we really cannot conceive of something that is truly alien; just think about Hollywood’s best attempts and you will understand my point.
The second breakthrough came from Craig Venter’s lab, which created the first self-replicating synthetic genome. They did not create new life. Rather, they created a synthetic copy of the genome of one bacterial species. They then put that genome into a cell that did not contain DNA and belonged to a different species. The cell then began metabolic processes and replicating. My opinion is that this was a great technological achievement, considering how difficult it was to create that synthetic genome. However, the importance is, in my opinion, in the future potential of synthetic biology.
One line of research will be to expand our knowledge of biology by taking existing genomes and altering them by removing genes to see what happens to the cells. Biologists will potentially be able to determine the effect of these genes, as well as the effects of having a smaller genome.
However, there is a more significant implication. Once the aforementioned work is completed, something that will take decades at least, biologists will be in a position to begin attempting to design synthetic life. In effect, humans should one day be able to design living organisms on a computer and then bring these organisms to life. There is great potential here, both for energy generation and for medicine. However, I am getting far, far ahead of the field. This is a field of research that will play out over the rest of the century.
The third great accomplishment was the sequencing of two ancient hominid genomes: in April and again in December work was published on what are now being called Denisovans from Siberia and in May the compete sequence of a Neandertal from Europe was published. The fact that biologists were able to sequence these ancient genomes is amazing in its own right. However, for the general public the significant part was that both genomes reveal evidence that both species interbred with our own.
Some of you may remember the philosophical questions that were raised in the wake of the evidence that Neandertals and humans interbred; the same questions apply to the interbreeding with the Denisovans. In both cases, the genes from the other species are present in only some population groups, meaning not all humans have these genes. Some people have raised concerns about how we define “human.” However, I think such concerns are pointless.
There is a tendency to envision evolution as a straight path, from ancestral species to current species. In reality, the process is much messier. It makes perfect sense that these species would interbreed. Our definition of species is temporal; species change constantly. The discoveries of the interbreeding shed light on how poorly we are prepared to deal with thinking about how the natural world really works; our incessant need to categorize seems to break down. The question ‘are you more or less human if you have these genes?’ is pointless, yet we all want to ask it.
There is still much work to be done on fleshing out the human family tree; archaeologists have seven million years to work with since our divergence from chimpanzees. Much happened during that time and our understanding of what happened when and why is extremely incomplete.
There are, I think, deep philosophical questions raised by each of these discoveries, but I do not wish to get into them here. The one point I will make is that these discoveries have highlighted something all scientists were already aware of: our understanding of reality is still far from complete and science has much work to do. The next decade will probably be a great period of medical progress, but one cannot help but wonder what new fossils will be discovered, how many habitable exoplanets will be found, and what new fields of science will be founded.