A pack of Senegalese chimps -- but only the females and infants -- sometimes snap off branches, chew the ends into a point, and stab holes in trees where bush babies sleep, in the hopes of skewering the morsel prey. The journal Current Biology reports 22 spear bouts in the last two years. Although they're not good at it; just one of those 22 spearings resulted in a bush baby death. What's more interesting is that this patch of Senegal is a wooded savanna that mimics the habitat of human ancestors who needed to leave the trees and begin hunting-gathering on the ground. The study's lead author, Jill Pruetz of Iowa State University in Ames, says the report offer insights into Australopithecine, the protohuman hunters who lived more than 1.2 million years ago.
Unfortunately, John Shea, an anthropologist at Stony Brook University who was not involved in the study, says this is just a natural extension of "termite fishing," wherein chimps poke sticks into wood so that termite glom onto their tools, then eat them like shiskabobs. "This is just a rather long extension of that behavior, not true projectile use of spears," he says, adding, "Chimpanzees are analogs for, not examples of, early hominids."
But perhaps they are closer examples than we think. Using what the eloquent folks at Reuters were good enough to describe as "a well-known type of calculation that had not been previously applied to genetics" (The Hidden Markov model, a 1960s statistical analysis originally applied to speech recognition), scientists developed a "molecular clock" for primate evolution that dramatically tightens the moment chimps and humans split to different evolutionary paths.
"Assuming orangutan divergence 18 million years ago, speciation time of human and chimpanzee is consistently around 4 million years ago,â? these scientists wrote in PLoS Genetics. Conventional wisdom had put the human-chimp split anywhere from 5 to 7 million years ago. What they found directly contradicts some other recent research. They found evidence that it took only 400,000 years for humans to become a separate species from the common chimp-human ancestor.
All a bit too Pierre Boulle for my taste.