Analyses of 2-million-year old hominid teeth reveal sex differences in lifestyle Way back in the day, females came from far away and males didn’t stray — not far, anyway. That’s the implication, with apologies to Dr. Seuss, of a new study of members of two ancient species in the human evolutionary family. Adult females in both hominid lineages often moved from the places where they were born to distant locations, presumably to find mates among unrelated males, say anthropologist Sandi Copeland of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and her colleagues. Most males in both hominid species spent their entire lives in a home region that covered no more than about 28 square kilometers, or about half the area of Manhattan, Copeland’s team proposes in the June 2 Nature. These ancient “home boys” might have occasionally gone further afield, exploiting resources along wooded areas atop bands of bedrock that extend about 30 kilometers in opposite directions from the South African cave sites where the fossils were found. It’s not clear how far females traveled to reach new groups, only that they did not grow up where they died. “We have the first direct glimpse of early hominids’ geographic movements,” Copeland says. “Ranging differences between males and females were surprising.” Her investigation measured a chemical marker of childhood diet in teeth from 19 hominids found in two caves about 1 kilometer apart. Specimens represented 11 Paranthropus robustus individuals that lived 1.8 million years ago and eight members of Australopithecus africanus dated at 2.2 million years old. Some researchers regard A. africanus as a direct ancestor of the Homo genus, which includes living people (SN: 5/7/11, p. 16). P. robustus belonged to a dead-end branch of hominid evolution. Copeland’s group measured levels of two forms of the element strontium in hominids’ tooth enamel and in plants and animals now living within 50 kilometers of the fossil sites. Strontium is a naturally occurring element in rocks and soils. Specific strontium signatures characterize different landscapes. Strontium signatures in A. africanus and P. robustus teeth, defined by their diet, developed by age nine, the scientists estimate. Collective strontium data for both hominid species indicate that eight of nine large-toothed individuals — presumably males — grew up in the area where they died, whereas at least five of 10 small-toothed individuals — thought to be females — grew up elsewhere. Since chimpanzee and gorilla females leave their birth groups upon reaching reproductive age, some researchers have long argued that early hominids did the same. Copeland’s team “came up with an innovative way to test this model, and in the process, developed the first direct evidence of early hominid social organization,” remarks anthropologist Peter Ungar of the University of Arkansas in Fayetteville. A. africanus and P. robustus probably consumed all sorts of savanna delicacies, including fruits, nuts, seeds and grasses, although questions remain about ancient hominids’ favored foods (SN: 6/4/11, p. 8). If male hominids foraged limited areas, it’s unclear how they avoided predators such as saber-toothed cats while competing for food with baboons and other animals, comments anthropologist Margaret Schoeninger of the University of California, San Diego.
Their offspring could hold on to momma on it's own. A Baby just meant added weight and no real extra care, she was not confined as a caretaker like "modern"(100KYA) human women were.
This is the first time I've ever seen that assertion about gorillas. Everything I have read about them says the exact opposite: the females remain in the harem while the males are forced out by the alpha male when they reach puberty. This results in intensive inbreeding. A primatologist once wrote that if a zoologist unfamiliar with gorillas were to examine two skulls from opposite ends of their range, he would insist that they absolutely have to be two different species. It's up to the boys to start their own clans by wooing a few females away from their great-grandfathers' incestuous harems without getting their butts kicked by a bigger, smarter guy who's been kicking adolescent butts for twenty years. There were a fair number of Paleolithic human communities for scholars to study until one or two hundred years ago. Based upon their observations some of them concluded that during summer in a good year, when there was a modest food surplus and no reason to fight over the rights to hunting and gathering ranges, rival tribes would declare a truce and hold a festival. One of the things that took place was (ritual or casual) exchange of young females between tribes. This "maintained the chlorine level in the gene pool" so that inbreeding would not cause genetic problems and weaken the species. This also plays to our species's almost unique instinctive taboo against incest. Most other species will happily mate with their siblings or other close relatives, but humans are loth to do it. When possible, humans are likely to make considerable effort to take a mate from outside their extended family. In fact most of us find members of the opposite sex who look quite different from us, and therefore cannot be closely related, to be "exotic" and especially attractive. This is why civilizations that juxtapose diverse ethnic groups eventually become "melting pots" despite the efforts of their conservative leaders to maintain "racial purity." This was noted in the 1970s, when children who had been raised communally in Israeli kibbutzes began reaching adulthood and very seldom married each other. Even though they were not blood relatives, they grew up regarding each other as siblings. There's a name for this, the Somebody-or-other Effect, after the (probably) Israeli scholar who first described it, but I haven't got my notes on this computer. In the Paleolithic Era, when humans were nomadic hunter-gatherers, women had to be able to travel with their children, so (it's been postulated) they avoided having more than one small child at a time. It was in the Neolithic Era, when the tribes settled down in permanent agricultural villages, that women could stay home tending the crops while the men were out minding the herds. This allowed women to care for multiple young children, and bound them to the home. Ironically, it was the quantum step in our social evolutiion of inventing the twin technologies of farming and animal husbandry which together comprised the Agricultural Revolution, that restricted the freedom of women.
I found this and it seemed prudent to post it here: "Kong: You've gone a bit quite, haven't you? Fay Wray: Oh, you know...I was just thinking... Kong: It's my tiny penis, isn't it? Fay Wray: What?! No! Of course not. (There's an embarrassed silence. Kong swats at a passing bi-plane.) Fay Wray: It's just that it IS quite little... Kong: It's not my fault! It's my social structure! Fay Wray: Of course it is. Your social structure is to blame. I understand. Kong: Listen, Fay. Gorilla males guard isolated harems of females. Any competition between males is limited by the fact that we really don't want to mess with each other. I mean, just look at us! We're terrifying. I could rip Robert Armstrong in two without breaking a sweat! You only need big reproductive organs when you've got a sperm competition going on. Fay Wray: You're right, of course. It all makes sense. Even so...Two Inches?!"
It rather seems logical to me that in a nomadic lifestyle, the females would be quite as capable of mobility as the males and might need to wander for a variety of reasons. Farming and animal husbandry would indeed change the activities of both the male and the female and and as these became established, other nomadic groups would likely interact and possibly decide to adopt similar practices, or join the already established societies. Increasing size of groups/societies would bring about ever new challenges to be resolved as we observe in the differences between 'city' folk and 'country' folk, even this much farther down the path. Just my reflections of this morning.....Please Register or Log in to view the hidden image!
It's common into recent times, in cultures far removed from the paleolithic (China, Finland), for the new bride to move into the groom's house - however distant. It's one of the standard setups, the other being the groom joining the bride's family (Scotland, some others I forget). The consequent conflict between brides, grooms, and inlaws, has been the basis for many stories, songs, etc. But the setup - which one leaves home - seems to be based on local economics and ecological constraints. There's no reason to suppose it to be a basic fact of human nature, even way back then.
