Tibetans evolved to cope with UV

Study identifies seven new loci associated with high-altitude living

Tibetan populations have evolved at least nine specific genetic variants to help them survive the extreme conditions of the Tibetan Plateau. Living permanently at over 4,000 m above sea level, these populations have been coping for millennia with 40% less oxygen and 30% stronger UV radiation, as well as exposure and limited food.

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Neanderthal Art

Neanderthals were once portrayed as unintelligent, uncultured brutes, but that picture is beginning to change. They are increasingly being viewed now as intelligent, cooperative creatures who performed cultural rituals and traditions and who mourned their dead. A discovery published in PNAS this year indicates they may have even had art. Art is considered to be one of the highest expressions of complex, abstract thought, and for a long time it was believed to be uniquely human (uniquely Homo sapien, that is).

Researchers excavating a cave in Gibraltar found an engraving on the rock wall in undisturbed ground alongside Neanderthal tools. The engraving from Gorham’s cave, which looks suspiciously like a hashtag, was placed prominently on the wall suggesting it may have been a message to visitors or intruders. There is no direct evidence, however, that the design actually means anything, but it seems likely it was intended to be seen. Interestingly, the engraving appears at a junction in the cave, where the cave changes direction by 90 degrees. It’s hard not to speculate that the design might therefore be intended to share some spatial information, a “You are Here”, perhaps. Likewise, it may have signalled that the cave was occupied.

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What Else Makes Us Human?
Fire

Over the last few months I’ve been discussing the characteristics that make us human, and which of the classic ‘uniquely human’ traits, really are ours and ours alone. But one aspect of human behaviour which I have not discussed so far is our use of fire. No other animal has learned to harness and control fire as humans have.

A recent discovery of wood ash along with animal bones and stone tools in a cave in South Africa suggests that humans may have used fire as early as 1 million years ago. This is around 300,000 years earlier than previously thought, and may indicate that earlier hominid species such as Homo erectus were using fire. Other tentative support for fire use by early hominids such as H.erectus and A.robustus have been found in South Africa and Kenya, possibly as early as 1.5 million years ago. Further evidence from Northern Israel in the form of burnt flint tools and plant remains indicates that H. erectusmay have been controlling fire around 800,000 years ago.

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What Else Makes Us Human?
Drug Use in the Animal Kingdom

Whilst writing the series on “What Makes Us Human?”, I started thinking about less obvious, less traditional ideas of what traits are truly human, and human alone. One characteristic occurred to me that seemed obviously to be unique to humans: recreational drug use. It seemed implausible that animals in the wild were indulging in drug abuse purely for their own entertainment, and I wondered if this could give some perspective on what it means to be human. But, as it turns out, I was wrong.

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What Makes Us Human Part IV
Culture and Faith

What makes us human? Many of the characteristics commonly listed as ‘uniquely human’, are in fact, upon closer inspection, NOT. We are not alone in our use of tools, language or a notion of self. We are not unique in our bipedal stance, our opposable thumb or our intelligence. Our societies seem simple and crudely constructed when compared to those of a bee or a termite. Perhaps there is one thing left, however, that is truly human – art. Surely culture, art and religion are something only humans have constructed? And if that is the case, what is it about humans that led us and only us, to create such a rich array of art and ritual, which appears, in evolutionary terms, to be superfluous to our survival?

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What Makes Us Human Part III
Anatomical Adaptations

When we look at other primates, although the similarities are clear, there are also several stark contrasts. Most noticeable, is our gait – humans are the only truly bipedal (upright walking) primates. Bipedality appeared early in human evolution, and may have marked our divergence from Chimpanzees around 6 million years ago. Bipedality had a number of benefits, allowing us to adapt to a new habitat, and freeing up our hands for other tasks, but compromises also had to be made. Changes in the shape of our pelvis, which enabled us to walk upright, also made childbirth considerably more dangerous and complex. Nevertheless, bipedality is thought to have facilitated the marked advances in tool use and gestural communication that are hallmarks of the human condition.

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What Makes Us Human Part II
Intelligence and Language

One of the most distinctive characteristics of Homo sapiens is our exceptionally large brain, and enhanced cognitive capabilities. In fact, large brains, measured by the encephalisation quotient (EQ), are a characteristic of primates in general, and brain size and complexity has been increasing in the primate lineage for nearly 70 million years. However, this trend is particularly noticeable in the human lineage, and the last 3 million years of hominid evolution have seen the most pronounced increases in encephalisation, with a tripling in brain size. Such a rapid increase in size is extraordinary, especially for an organ so complex. Some areas of the brain have expanded disproportionately, such as the cerebral cortex, which has increased in size by 3 orders of magnitude since our divergence from Chimpanzees. The cerebral cortex accounts for around 85% of total brain volume in humans, and is responsible for complex mental functions.

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What Makes Us Human Part I
A Brief History

The earliest known hominid was Sahelanthropus tchadensis, represented only by relatively few fossilised skull fragments, he is so ancient it isn’t clear whether he could truly be considered human at all. Fossils found in Chad, dated to around 7 million years old, may have belonged to a direct human ancestor, or more likely to a neighbouring branch of the ape family tree. This uncertainty is common until around 4 million years ago; many species are known only by partial skeletons and the relationships between them are often unclear. The Australopithecines may be the first group of hominids that we can be said to understand to any extent.

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What Makes Us Human?

Understanding the evolution of Homo sapiens, and how humans came to be human, has been a fascination for people since Darwin’s time, but it has also proved to be one of the most controversial of the sciences. Humans and Chimpanzees diverged about 7 million years ago and during this time a great deal of anatomical and behavioural changes occurred which now distinguish us from our closest relatives. Despite this, we still share over 99% of our genetic make-up with Chimpanzees; only 1% of our genes truly make us human. What is the manifestation of this 1%? Some of these differences are very clear visually; we are taller and less hairy, with larger brains and an upright, two-legged stance. Other differences are slightly more subtle; we have language, we use tools, we have culture and art enabled by abstract thought, we have a concept of self… but as that list continues, it becomes increasingly difficult to determine whether Chimpanzees, or indeed other animals, also share these qualities. If Chimpanzees can be taught language, then this indicates they have a brain capable of understanding and learning language, and thus, surely they can in some sense be said to have language themselves? Other characteristics are even more difficult to pin down; how do you measure self-awareness? Although there is a long list of traits that most people would consider to be exclusively human, the situation is in fact far less clear cut than that.

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