Wired for Culture: Origins of the Human Social Mind by Mark Pagel Read Free Book Online

of Homo habilis or “handy man,” a small but upright ape whose fossil was discovered by Mary and Louis Leakey in Tanzania in the early 1960s (a recently discovered fossil of a species possibly even older than H. habilis has been attributed to the Homo lineage and named Homo gautengenis ). Another lineage of upright apes, the Australopithecines, was alive at the same time. Its most famous member is “Lucy,” or Australopithecus afarensis , who lived perhaps 3.2 million years ago in and around modern-day Ethiopia. The Australopithecines had smaller brains and were more primitive than Homo , and they would later go extinct, possibly the first casualty of the newly evolving human lineage. Both of these lineages of upright apes— Homo and the Australopithecines—trace their ancestry back through even earlier species, and eventually back to a chimpanzeelike common ancestor that lived perhaps 6–8 million years ago.
    Homo habilis clearly bore the marks of its ancestry to the apes, but not long after its appearance, sometime around 1.8 to 2 million years ago, a species called Homo erectus appeared. It stood fully upright and might have reached a height of five and a half to six feet tall. If you were to meet one you would recognize it as different from us, but you would also see in it the first real indicators of what we would become. Gone were the small brains, short legs, and long arms of the Australopithecines and early Homo species, and in came the bigger brains, long legs, and shorter torsos of so-called humans. Around 800,000 years ago, possibly even earlier, some Homo erectus populations made their way out of Africa and inhabited parts of Eurasia. Other Homo erectus , known by some archaeologists as Homo ergaster , remained in Africa. It was these H. ergaster populations that by about 800,000 years ago had evolved into a species known as Homo antecessor , which in turn gave rise by 500,000 years ago to a species called Homo heidelbergensis .
    There might have been one or two other premodern or archaic humans around this time with names such as Homo helmei and Homo rhodesiensis , but there seems to be a growing view that they can all be included within H. heidelbergensis . It is difficult to be precise and opinions vary, but H. heidelbergensis seems to have spawned two new lineages. One of these lineages would eventually lead to the Neanderthals and a species whose identity was only just confirmed in 2010, and which is known by just a single tooth and a finger bone. Originally designated X-woman , this species is now being called Homo denisovan after the Denisova Cave of southern Siberia where the tooth and finger bone were found. Dating of the cave suggests these people were still living as recently as 30,000 years ago, meaning they overlapped with both Neanderthals and modern humans. Remarkably, it has been possible to extract ancient DNA from the tooth and finger bone, and this reveals the Denisovans to have been a sister species to the Neanderthals.
    The second lineage is the one that would eventually lead through one or more premodern archaic humans to us. Our species, so-called fully modern humans, finally emerged from their archaic Homo sapiens ancestors only around 160,000–200,000 years ago. This might have occurred in East Africa, as has long been believed, or possibly in southern Africa, as hinted at by modern genome studies. But wherever we arose, we are still a very young species by comparison to most, like one of those birth-of-a-star events beloved of astronomers. Given our recent appearance, it is not surprising that the first modern humans would have been almost indistinguishable from us today, and one of them brought up in modern society would not be out of place. They had large brains, possibly even somewhat larger than our own, and somewhat bigger bodies; but compared to Neanderthals they were lighter, less robustly built, had high foreheads, and lacked the protruding brow that characterizes that