Contents Updated: Thursday, August 05, 1999
Humans have been producing metals since the start of the Bronze Age about 6000 years ago. Tests in the ice cores from Greenland show up the first surges of metallic production during the times of Periclean Greece about 500 BC and during Roman times. The Athenians produced a lot of silver and lead as a by-product which polluted the air and it shows in the Greenland ice. Romans produced about 80 million kg a year, more than at any time until the industrial revolution began in the 18th century. Lead levels in Greenland ice of the Roman period are four times the naturally occurring amount.
Professor Tim White of the University of California describes Australopithecus Ramidus as like a pigmy chimpanzee. Pigmy chimpanzees are possibly more closely related to us than ordinary chimps, sharing 98.4 percent of their DNA with us. Ramidus had teeth which suggested it ate fruit and pigmy chimps seem not to eat animals as ordinary chimps occasionally do. Pigmy chimps sometimes walk upright, females cradling the infant on their hips. The remains of Ramidus are not sufficient to say whether it walked upright or not.
Pigmy chimps are also like humans in having ventro-ventral sex, indulge in group sex and lesbian and homosexual sex. Young females trade sex for food and older males are happy to oblige with a meal. They seem not to war like ordinary chimps and their fondness for sex might be a reason. Pigmy adults play with their infants and give them monkeys as pets. The monkeys are terrified but the chimps seem not to deliberately ill-treat them though they always died through carelessness, being banged about by accident as the chimps pulled them through the trees. The dead monkeys were discarded without being eaten showing they were not held as a food item.
A female chimp in Mahale National Park, Tanzania, became lethargic, lost her appetite and developed diarrhoea. Shortly she began eating the shrub, Vernonia Amygdalina, which has a bitter fruit not normally eaten by chimps. The next day she was back to normal health. Africans use the plant for bowel upsets! Was the chimp using the plant as medicine?
A pregnant elephant in Tsavo Park in Kenya was tracked for about half her gestation period to find out about elephant diet. Normally she walked about 5 km a day browsing on the same plants but near the end of the observation period she walked 28 km for a particular tree she had not eaten before while being observed. Four days later she gave birth. Native women brew a tea from the leaves and bark of the same plant to induce labour!
Starlings are clever birds that do not want to build a new nest every year so re-use their old ones. The trouble is that old nests might be infested with bacteria and parasites that would harm them or their hatchlings. Observers noted that in March or April on returning to their nests, male starlings do a little structural work to their old nests to refurbish them. They sought out the fibrous roots of particular plants—wild carrot and fleabane being examples. As the name of the latter suggests, it is effective against bloodsuckers and the others are in varying degrees bactericidal.
The Navajo Indians relate how bears gave to them one insecticidal plant. The bears chew the plant, spitting out on to their fur and spreading it with their claws. It is found to contain many natural chemicals called coumarins with antibacterial and insecticidal properties.
Robin Dunbar of University College, London, speculates that language evolved so that we could gossip. It replaced the social grooming of primates like chimpanzees, being less time consuming and more effective for bonding. Humans can chat to several people at a time and simultaneously can do something useful. Animals like baboons spend about 20 percent of their time grooming when their band is as large as 50. The time spent limits the size of the band. There is not enough time to bond with all the individuals of a larger band. Humans achieve this through gossiping.
The forerunners of human beings lived in bands of about 150, suggesting that human bonding is three times as effective as is individual grooming in apes and monkeys. Studies have repeatedly shown that people tend to talk in groups of four—one to three! Furthermore, the greater degree of bonding acted as a selective pressure on the brain forcing it to be able to cope with more interactions and providing a basis for sexual selection. Those that could manipulate others better would have more mating success. Dunbar has found that apes and monkeys have a brain size in proportion to their average group size. Ours is that suitable for groups of about 150, a number which springs out in many studies of social group dynamics. Nomadic hunter-gatherers have groups about this big and so did Neolithic villages in Mesopotamia. In groups this small, peer pressure keeps people conforming. Larger groups begin to require policing. Modern large organisations have to subdivide into working units roughly this size, just as the Roman army did. Groups this size are of course working groups. To relate more intimately requires the tactile bonding of more primitive species.
Dr Geoffrey Miller of Sussex University concurs that the brain grew through sexual selection. When the genes for a preference for big brains link to the genes for big brains there is the potential for feedback leading to explosive evolution. The women used their brains and their talking to entertain men, thereby being able to get the fittest,—those who would stay with them longest to protect and bring up the slowly maturing human infants. Men of course wanted to be entertained. A study of 37 different human cultures showed that the preferred traits in a sexual partner were kindness and intelligence, meaning common sense rather than academic excellence. Today we might say streetwiseness. The partner has to be interesting. There is no single courtship strategy but creativity, unpredictability and novelty are preferred. Our big brain is a side effect of being charming!
In 1993, two Russian scientists reported finding the remains of mammoths on Wrangel Island off the north east of Siberia that were dated at only 4000 years old. They were alive when the Pharaohs were ruling in Egypt! The north and east of Siberia is still the home of the Evenks, the only people remaining who survive by hunting and reindeer herding. When the Russians first contacted them at the turn of the twentieth century, they were reported to have large amounts of ivory and well preserved mammoth skins. They described to Russian ethnographers the appearance and behaviour of mammoths and even told them their diet and how they hunted them! Even as late as 1922, the Evenks claimed they had seen a mammoth walking alone by the edge of the Arctic ocean. This is not impossible when it is considered how vast and poorly known Siberia was. A whole mountain range was found to have been wrongly mapped in the 50s.