Nature and Scientific American Human Evolution content

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Human evolution has been believed to be omni-directional

BUT, the sub-human species politicianus shows regressive tendencies

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The high-precision dating of materials from 40 archaeological sites, from Russia to Spain, reveals that the disappearance of Neanderthals from Europe took place around 40,000 years ago. Rather than a rapid replacement of European Neanderthals by anatomically modern humans, the study, published in Nature this week, supports a more complex picture characterized by a biological and cultural mosaic that lasted for several thousand years.

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Determining the spatial and temporal relationships between Neanderthals and early modern humans is critical to the understanding of the processes underlying, and reasons for, the disappearance of Neanderthals. However, technical challenges have hindered the reliable dating of the period, as samples older than about 50,000 years preserve too little carbon-14 for conventional radiocarbon dating to yield accurate results.

Tom Higham and colleagues used improved sample processing and accelerator-mass-spectrometry radiocarbon dating to analyse bone samples and items from the Mousterian and Châtelperronian stone-tool industries, which have been associated with Neanderthals, and Uluzzian artefacts, which may have been made by modern humans. The results suggest that the Neanderthal disappearance and the end of the Mousterian culture occurred between 41,000 and 39,000 years ago, across sites ranging from the Black Sea to the Atlantic Coast. The findings also reveal a temporal overlap between Neanderthals and modern humans of 2,600 to 5,400 years, allowing for cultural — and possibly genetic — exchanges between the two groups.

Scientific American: The Human Saga Special Issue

Humans have been evolving for more than seven million years, and we continue to change. This special Scientific American issue takes stock of the latest insights- past, present and future.

Welcome to the family:

· Tracing the evolutionary ancestors of Homo sapiens was once thought to be a relatively straightforward matter: Australopithecus begat Homo erectus, which begat Neanderthals, which begat us.

· Over the past 40 years, fossil finds from East Africa, among other things, have completely shattered that hypothesis.

· The latest evidence shows that several different hominin species shared the planet at different times. Figuring how they are all related-and which ones led directly to us-will keep paleontologists busy for decades to come.

Climate Shocks:

· Changes in climate are emerging as elements that shaped human evolution over millions of years, as scientists learn that such alteration coincided with the extinction of some of our ancestors and the success of others.

· Evidence from ancient soils in East Africa, deep-sea sediments and fossil teeth from our forerunners combines to reveal rapid swings between wet and dry environments, as well as two distinct periods when grasslands replaced more wooded areas.

· The emergence of our own genus, Homo, our varied diet, advances in stone tool technology and the very human trait of adaptability in the face of ongoing change may be tied to these episodes, according to one theory.

Powers of Monogamy:

· Monogamous coupling might have been the best move our ancestors ever made.

· Even in societies where polygamy is permitted, monogamy is by far the most common human mating arrangement. In this regard, we are unusual animals: fewer than 10 percent of mammals form exclusive sexual relationships.

· How humans got this way has been the subject of scientific debate for decades, and it still is an open question. We know that the first hominins, which emerged more than seven million years ago, might have been monogamous for good reason: it helped them evolve into the big brained world conquerors they are today.

The “IT” Factor

· Humans- it was once thought- differed from other animals by their use of tools and their overall superiority in a range of cognitive abilities. Close observation of the behavior of chimpanzees and other great apes has proved these ideas wrong.

· Chimpanzees score as highly as young children on tests of general reasoning abilities but lack many of the social skills that come naturally to their human cousins.

· Comparison of human and chimp psychology reveals that an essential source of the differences in humans may be the evolution of the ability to intuit what another person is thinking so that both can work toward a shared goal.

Still Evolving

· For 30,000 years our species has been changing remarkably quickly and we are not done yet. Straight, black hair, blue eyes and lactose tolerance are all examples of relatively recent traits.

· Such rapid evolution has been possible for several reasons, including the switch from hunting and gathering to agrarian-based societies, which permitted human populations to grow much larger than before. The more people reproduce within a population, the higher, the chance of new advantageous mutations.

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