I reviewed four new science books for The New York Times. They span millions of years, beginning with the birth of humanity and ending with a serious look at AI.
Over the last year, two separate groups of researchers have been trying to sequence the Neandertal genome using DNA from the same fossil. An independent team assessed both group's analyses and announced this week that there were worrying inconsistencies between the two sets of findings. It's possible that at least one of the samples has been contaminated by modern human DNA. PLoS Genetics, Science.
How do bacteria survive encased in ice for millions of years? Scientist used to believe the genetic material was essentially frozen in stasis. New studies suggest that in order to stay viable the bacteria must undergo continual DNA repair over the many long years of preservation. PNAS. If life is to be found on Mars or Europa, they suggest, the best place to look will be in ice.
In the Dry Valleys of the Transantarctic Mountains there are pockets of ice up to 8 million years old. Last week, scientists announced that they resuscitated microbes from this ice. If the microbes are as old as the ice, they were around long before humans split from the chimpanzee/bonobo line, approximately 6 million years ago. The scientists call their sample a "gene popsicle" and speculate that in periods of the Earth's history when ancient ice melted, microbes in samples like theirs might have been reincorporated into current populations--which might be something like dating your great- great- great- to-the-1000th grandmother. They also wonder if the preservation of microbes in icy comets may have seeded planets with genetic material as distant in space as well as time. PNAS, National Geographic.
The difference between the hulking heads of our Neanderthal cousins and our more graceful selves is merely a matter of chance, say scientists in the Journal of Human Evolution. The difference between our skulls and theirs probably results from genetic drift--meaning that our head shape was not selected by nature or in any sense 'intended' but only accidentally came to be. At least we got the nice skulls... the authors of the study say, "Neandertal and modern human crania may simply represent two outcomes from a vast space of random evolutionary possibilities." Anthropology.net, Science Direct/Journal of Human Evolution.
An almost perfectly preserved baby mammoth has been found in Siberia, and scientists are hailing the discovery as invaluable. Virtually everything about the little beast is intact, even it's eyes remain. I'm not sure how rare it is to unearth prehistoric eyes, or if it has even happened before. The extinct animal may be our best bet so far for harvesting ancient DNA and trying to resurrect long-dead species. Good pictures at BBC, Guardian. In other enormous animal news, on the other side of the world a rare giant squid has washed up on the coast of Tasmania. Its hood is 2 meters long, and its tentacles longer. Scientists are racing to the beach where it lies in order to harvest what samples they can. The squid's photo appears in The Age. The article makes a distinction which is wholly new for me: apparently "giant squid" are merely the smaller relatives of "colossal squid," which can be ten meters long.
Did Neandertals and humans interbreed? Every couple of years this question cycles through the press, generally instigated by a scientific article presenting new evidence either way. Erik Trinkaus, who compares the bones of ancient humans and Neandertals, is the best known for arguing that they did. Most recently, Spencer Wells of the Genographic Project, told Wired magazine there was no evidence in the human genome that Neandertals and their European human contemporaries produced any children.
Trinkaus in PNAS.
Since last year when researchers announced their goal of reconstructing the Neandertal genome, the story has been getting play from many angles in all sorts of publications. In the team's most recent announcement, covered pretty much everywhere by everyone, they explain that the kinds of mistakes they might make trying to read ancient DNA are restricted to a few types. Knowing this should help the scientists avoid them. Part of the solution involves using DNA from many Neandertal individuals.