By Chet Yarbrough
Neanderthal Man: In Search of Lost Genomes
“Neanderthal Man” offers more than most science dilettantes will want to know about human origins. To introduce the complexity of the story, this 46 minute YouTube introduction to Svante Pääbo’s Neanderthal theory is helpful.
Three fourths of the author’s book takes one into the science of genetics. The remainder is about science competition, the race for publication, and the personal experience of the author. Pääbo convinces one that desire-to-know, curiosity, and enthusiasm are the ingredients of break-through discoveries. Pääbo’s explanation of how he became involved in cracking the genetic code of an ancient descendant of humankind begins with his interest in Egyptian mummies. Pääbo is curious about the potential of being able to recover genetic material from a mummified body. His curiosity and enthusiasm is symptomatically expressed with late-hour science lab experiments after his regular work day. During the work day he is an intern in a University lab while pursuing a PhD.
In the early years of Pääbo’s career, he pursues his interest by securing mummy samples to test a hypothesis that genetic material cam be recovered after mummification. His research is marginally successful but flawed by inexperience. Despite the marginal success of his early experiments, curiosity and enthusiasm lead Pääbo to an obsessive interest in the science of genetics. As Pääbo’s education and life progresses, the idea of genetically mapping human remains leads to a search for “Neanderthal Man”.
What Pääbo finds when he enters the field of specimen genetic research is that results are often contaminated by modern mtDNA (mitochondrial DNA). In handling ancient body parts, geneticists would contaminate aged specimens with modern strands of mtDNA and presume the DNA sequence is from the original specimen. Specimen contamination and misinformation lead to claims that dinosaurs might be reproduced from discovered mtDNA samples. Pääbo creates a “clean room” to conduct his genetic research. With a “clean room”, Pääbo recognizes that specimens over a million years old are unlikely to have enough preserved organic material to provide accurate mtDNA sequencing. Pääbo notes that, even with specimens that are only thousands of years’ old only fragments of DNA, rather than complete DNA sequences, can be found.
Mapping of the Neanderthal genome is found to be difficult because genetic markers break down over time so that only fragments of DNA survive. Pääbo and a team of scientists and computer whizzes, using fundamental genetic science knowledge and computer programming, manage to recreate a complete genome sequence for Neanderthal species. The generally accepted conclusion of the discovery is that Neanderthals are a branch of the human race that originated in East Asia and Europe but died approximately 30,000 years ago. The origin of humankind is still believed to have occurred in Africa but a variant of that species multiplied and then died out in Europe.
The ramification of sequencing an ancient human genome is in seeing the physical evidence of inherited and/or extinct characteristics of humankind. An example, given by Pääbo, is the genetic marker for a penial bone (presumed to accelerate ejaculation) that exists in early human species but disappears in later generations. This penile bone exists today in gorillas and chimpanzees, but not in Homo sapiens.
A host of ethical issues are raised in the author’s story. If one can genetically map a Neanderthal genome, it becomes theoretically possible to resurrect an extinct species of humankind. Further, it becomes possible to patent a genomic map that could be sold to companies interested in ancestral history or modern human genetic manipulation. Though both issues are discussed by Pääbo’s team, the first is beyond their control and the second is denied when Pääbo chooses to publish the genome sequence without patent. (Pääbo notes that genetic’ companies like 23andMe offer a genetic test for the presence of Neanderthal markers—but, for an added fee.)
Pääbo is ironically pursued by the Max Planck Institute in Germany to fund his genetics research. The obvious irony is the super race ambition of German scientists during WWII. Though Pääbo is Swedish, he chooses to take the Max Planck Institute offer. Pääbo is successful. With the Institute’s funding, the Neanderthal mitochondrial DNA is sequenced in 1997.
“Neanderthal Man” is an interesting book but more suited for a geneticist than the general public. A dilettante may choose to pass.
Ape to Man: Evolution Documentary History Channel