Free Neanderthal Man by Svante Pbo

at Cold Spring Harbor, along with my mummies. Through Allan, I now acquired a sample from a similar find in Florida of 7,000-year-old brains. I extracted DNA and retrieved short fragments that appeared to be an unusual mtDNA sequence that existed in Asia but that had not previously been seen in Native Americans. Although I found the sequences twice in independent experiments, I had realized by now that contamination with modern DNA was a very common problem, particularly when ancient human remains were being studied. So I cautioned in the paper that “indisputable proof that the amplified human sequences reported here are of ancient origin must await more extended work.” {10}
    Nevertheless, this research seemed promising; perhaps I needed to learn more about human population genetics. When Ryk Ward, a theoretical population geneticist from New Zealand who worked in Salt Lake City, contacted Allan’s lab to learn about the PCR, I volunteered to work with him. This resulted in a monthly commute to Utah, where I taught people in Ryk’s lab how to do PCRs. Ryk, an excellent population geneticist, was also pleasantly eccentric, given to wearing shorts and knee socks even in cold weather and taking on projects and various administrative tasks without finishing them. This latter habit did not endear him to his university, but on the plus side he loved to discuss science and had an almost infinite patience for explaining complicated algorithms to people like me who sadly lacked formal mathematical training. Together we studied mtDNA variation in the Nuu-Chah-Nulth, a small First Nations group on Vancouver Island with whom Ryk had worked for many years. Amazingly, we found that the few thousand individuals in this group contained almost half the mtDNA variation that exists among native people throughout the North American continent. This finding suggested to me that the common belief that such tribal groups in the past were genetically homogeneous was a myth, and that instead humans may always have lived in groups that contained substantial amounts of genetic diversity.
    Back in Berkeley, it seemed that almost everything we tried worked. When Richard Thomas, a Canadian postdoc, came to learn PCR in the lab and needed a project, I suggested he take a turn working on Thylacinus cynocephalus, the marsupial wolf that had frustrated me during my sojourn in Zurich. The thylacine, native to Australia, Tasmania, and New Guinea, looked very much like a wolf but was a marsupial, like kangaroos and several other Australian animals. It was therefore a textbook example of  convergent evolution, the process whereby unrelated animals in similar environments and subject to similar pressures often evolve similar forms and behaviors. By sequencing small pieces of mtDNA from the marsupial wolf, we showed that it was closely related to other carnivorous marsupials in the region, such as the Tasmanian devil, but distant from South American marsupials, although some extinct marsupials there had been very wolf-like. This meant that wolf-like animals evolved not only twice but three times, once among placental mammals and twice among marsupials. Thus evolution was, in a sense, repeatable—an observation that had already been made, and would be made again, in studies of other groups of organisms. We wrote this up for Nature, and Allan graciously allowed me to be last author, the place occupied by the scientist who has led the work. {11} This was a first for me, and I knew that my situation in science was beginning to change. Until now, I had been someone who did the work at the lab bench, producing results by doing experiments myself the whole day and often much of the night; even when the ideas were my own I was often helped and inspired by discussions with a supervisor. Now I realized that this was beginning to change. I was not doing all experiments myself anymore. Gradually, I would have to be the one to lead and inspire others. While this prospect