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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Reasons Why Evolution is True Part X:
Convergent Evolution

When you design many objects that perform similar tasks, the logical strategy is to reuse the same design, perhaps with small modifications, for each object. There would be little point in coming up with a new design every time, right!? In nature, however, there are many species that do similar things but have arrived at their method through different designs. This is known as convergent evolution.

Intelligent design, and decent by modification, predict different patterns of similarities and differences between species. Evolutionary theory, which places all living things on a tree of relatedness, leads us to expect that species that are more closely related to each other should tend to be more similar. This is because they have both evolved from a recent ancestor. This ancestor has been ‘modified’ in various ways by natural selection to produce the two (or more) daughter species, but with a shared starting point for these modifications, we expect a fairly similar outcome. Traits that are shared between species due to shared ancestry are known as homologies. Homology has been the basis for determining relatedness between species (phylogeny) for hundreds of years. However, as early taxonomists noted, there are some occasions when species share traits despite the lack of a recent common ancestor. Often these species have reached a similar solution to a shared problem, despite being only very distantly related. This is known as convergence, and the more we look for it in nature, the more we find.

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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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Reasons Why Evolution is True Part IX:
DIY Evolution

Although some people may try to refute the theory of evolution, nobody can deny that natural selection occurs. We can demonstrate this quite easily within a single human lifetime, and humans have been inadvertently using natural selection to our own advantage for over 10,000 years. The processes I’m discussing, of course, are artificial selection and domestication.

When Darwin first began to think about evolution, one area of greatest interest to him was domesticated species, in particular the pigeon. The pigeon exists in around 300 of varieties, which have been selected for by pigeon fanciers for at least 5,000 years. The similarities between domestic pigeons and their wild counterparts are clear, however it seems that humans have, over many pigeon generations, been able to shape many aspects of their appearance including plumage colour and shape, body size, and beak shape. Other domesticated species such as dogs, cattle and even crop plants, have undergone significant changes in their appearance and internal anatomy since humans first began breeding them.

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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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How the Beetle Changed its Spots

There is a huge amount of variety in the colours and patterns exhibited by plants and animals. However, most of this variation is fixed at the individual level; only when comparing individuals do we see differences. The ability to change your colour during your lifetime is a trait possessed by only a few animals, which have converged on remarkably similar mechanisms. Colour changes that occur during an animal’s lifetime can occur slowly, with seasonal changes or age (morphological colour change). More dramatically, and more interestingly, some species also have the ability to change their colour or pattern very rapidly, in response to environmental or social conditions (physiological colour change).

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Eye Colour Genetics: A Window Into The Soul

In literature, television and film, the eyes are often imbued special meaning; the idea that you can tell something about a person, or what they are thinking or feeling, by gazing into their eyes. Eye colour is often considered a very straight-forward trait, with eyes being either brown, blue or green. But it is easily apparent that there is far more variation in human eye colour than that allows for, and that its inheritance is not always what one might expect. There are even some people out there who will try to convince you that your eye colour is controlled by diet. What really controls the appearance of our eyes? What are our eyes saying about us?

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Reasons Why Evolution is True Part VIII:
PreCambrian Rabbits

The fossil record is one of the most obvious pieces of evidence for evolution. Fossils have been known since human history began, and Aristotle first noted the similarity between fossils and living animals, leading him to conclude that fossils represented deceased creatures, a view supported by Leonardo da Vinci. By the 19th century, people were increasingly beginning to appreciate that some fossils represented extinct animals, and that their positioning in the rocks appeared to represent that passage of time. Now there is also ample evidence from molecular genetics and radiometric dating that the fossil record does represent the evolutionary history of life on Earth. Despite this, creationists still continue to argue otherwise. Some have suggested that the fossil record represents animals killed during one or more biblical floods, however this is incongruent with the evidence available.

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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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