Introducing Anthropology. Laura Pountney

Pääbo, mentioned above, having made incredible scientific breakthroughs in understanding Neanderthals, in 2010 went on to sequence DNA from a tiny fragment of finger bone discovered in the Denisova cave in the Altai mountains of Siberia. The results confirmed that he and his team had discovered an entirely new species, the Denisovans. Although there is only a handful of bones and teeth so far discovered from this species, it has been possible to learn that the Denisovans probably lived across much of Asia tens of thousands of years ago. David Gokhman and Liran Carmel, researchers based at the Hebrew University of Jerusalem, used DNA to reconstruct the appearance of Denisovans. From these studies, it emerged that Denisovans looked similar to the Neanderthals, but with wider heads and more protruding jaws. This information is very useful because it explains how they adapted to their environment and how the genetic traces found in modern humans may have helped this process. Genetic tests show that the Denisovans were close relatives of the Neanderthals and that our ancestors bred with them too, perhaps as recently as 15,000 years ago, which has left modern Melanesians and indigenous Australians with up to 6 per cent Denisovan DNA. Professor Chris Stringer, a human evolution researcher from the UK’s Natural History Museum, states that Neanderthals may have overlapped with Denisovans across Asia for more than 300,000 years.

       STOP & THINK

      How has recent genetic information challenged the idea that humans evolved separately?

       ACTIVITY

      What kind of evidence proves that Homo neanderthalensis were social beings with specific cultural practices?

      What are the implications of the recent findings that Homo neanderthalensis overlapped with Homo sapiens?

Climate change, human evolution and the Anthropocene

      Earlier hominins evolved and diversified in Africa, and the fact that they migrated into Asia and Europe (Homo erectus nearly 2 million years old have been found in Asia) shows that they managed to adapt successfully to diverse climatic conditions. One particularly important characteristic of humans is our ability to acclimatize to changes in the environment. The climate became more changeable around 6 million years ago. Some anthropologists argue that certain adaptations, such as upright walking or tool-making, coincided with periods of environmental change.

One example of this view is the Savannah hypothesis, which claims that many important human adaptations arose in Africa as the savannah, an area of grassland between the rainforest and the desert, expanded. According to this idea, upright walking proved to be an energy-efficient and beneficial way of moving across an open landscape. Furthermore, walking upright had the additional advantage of freeing the hands.

      Overall, evidence suggests that early hominins were able to adjust to changing environments in different parts of the world, giving them a huge advantage over other species. This adaptation included the ability to use resources from a vast variety of plants and animals and to employ many specialized tools. Human beings are social and also use communication skills to exchange resources and information to help them survive in a constantly changing world.

      In recent years, however, humans have become the dominant force in shaping the Earth’s climate and processes. The Anthropocene is a term that has been adopted by a range of disciplines to describe the time period in which human beings have had an overwhelming impact on planet Earth. It is these changes, which we have ourselves created, that are now presenting some of the biggest challenges to our survival.

      Anthropocene A new planetary era in which humans have become the dominant force in shaping the earth’s physical make-up and processes

       ACTIVITY

      Visit your local natural history museum and explore the evidence of early human life. Make a note of the main differences between early humans and humans today. Learn about the ways early human lives are researched.

Where did modern humans originate from?

      Despite the success and diversity of our ancestors, coupled with the fact that we still carry genetic information from our ancestors, only one hominin species survived: modern Homo sapiens. Not all scientists agree on the levels of contact or conflict that these early forms of humans had with each other, the extent of interbreeding that occurred, or the factors that influenced the evolution and extinction of other hominin species. However, from the recent discoveries described above, we know that early humans overlapped far more than originally thought. We do know that Homo sapiens evolved in Africa around 200,000 years ago and first migrated in small numbers into Asia, probably between 130,000 and 115,000 years ago, by travelling up the Nile to the Levant. However, the ancestors of all current humans migrated into Europe later, around 60,000 years ago, and it was not until much later still that modern humans populated other parts of the world. For instance, people probably first arrived in Australia within the past 50,000 years and in the Americas within the past 16,000 years or so. By 14,000 years ago, our species had spread to every continent except Antarctica. The beginnings of farming and complex societies occurred within the past 12,000 years. Understanding the success of our species remains a fundamental question for evolutionary anthropologists. This problem brings us back to the question of what differentiates us both from our closest living relatives, the apes, and from extinct hominins.

Similarities and differences between humans and nonhuman primates

      So what characteristics do humans still share with other primates, and which are unique? Evolutionary anthropologists attempt to answer this question by comparing genes, morphology, physiology, behaviour and cognition in Homo sapiens and other primates. This section considers some of the main similarities and differences between them.

      Humans and African apes share most of their DNA, but important functional differences have accumulated. Scientists have shown how humans continue to manifest striking similarities to the African apes both physically and genetically, especially to the chimpanzees and bonobos. For example, humans have forty-six chromosomes in their cells, while all the great apes have forty-eight. Research on mapping the entire genome of common chimpanzees was completed in 2005 and shows that 99 per cent of DNA sequences and 96 per cent of protein sequences of humans and chimpanzees are the same. This reflects the relatively recent split between the species since their last common ancestor 6 million years ago. However, it was discovered, unsurprisingly, that the genes that differ mostly control speech, smelling, hearing, digesting proteins and the likelihood of catching certain diseases, as well as the growth and efficiency of the brain, reflecting the fact that humans have been evolving separately for the past 6 million years.

       ACTIVITY

      Go to your local zoo or watch video clips of chimpanzees.

      What physical similarities are there between humans and chimpanzees?

      How do chimpanzees move?

      Make a list of the behaviours that are similar to those of humans and those that are different, thinking, for example, about language, tools, parenting, learning, ways of thinking and social relationships.

       All hominins and African apes lack external tails

      Humans and the African apes all lack external tails. Monkeys, on the other hand, do have tails, which are useful for gripping trees and objects. Tails disappeared from apes 15–20 million years ago. Apes shin up and down trees rather than walking along branches as monkeys do. The earliest hominins climbed trees and walked on the ground. Fossil evidence shows how early humans made a gradual transition from climbing trees to walking upright on a regular basis.

       All humans and African apes have opposable thumbs