Posts Tagged ‘humans’
Evolutionary biology is not a slow-moving science. Just last month a new species of hominid (Homo naledi) was unveiled at a news conference in South Africa. When did modern humans branch off as an independent species? What have been our most important adaptations? And, most importantly, what is the next evolutionary step for humanity? We reached out and spoke to five of the foremost experts on human evolution, who shared their expertise and predictions.
Anatomically modern Homo sapiens (us), are thought to have emerged as a distinct species around 200,000 years ago in Africa. While we often imagine one species of hominid handing the baton to the next in a neat, linear “evolution of man” progression, Homo sapiens lived simultaneously with several other hominid species—Homo neanderthalensis, Homo floresiensis, and the much older Homo erectus, whose geographic and temporal boundaries remain fuzzy. They also had sex with each other, as evidenced by the amount of Neanderthal DNA in our genetic material (about 2.5% – 3% on average).
In recent decades, Susan Oyama and her colleagues in the burgeoning field of developmental systems theory have rejected the determinism inherent in the nature/nurture debate, arguing that behavior cannot be reduced to distinct biological or environmental causes. In Evolution’s Eye Oyama elaborates on her pioneering work on developmental systems by spelling out that work’s implications for the fields of evolutionary theory, developmental and social psychology, feminism, and epistemology. Her approach profoundly alters our understanding of the biological processes of development and evolution and the interrelationships between them. While acknowledging that, in an uncertain world, it is easy to “blame it on the genes,” Oyama claims that the renewed trend toward genetic determinism colors the way we think about everything from human evolution to sexual orientation and personal responsibility. She presents instead a view that focuses on how a wide variety of developmental factors interact in the multileveled developmental systems that give rise to organisms. Shifting attention away from genes and the environment as causes for behavior, she convincingly shows the benefits that come from thinking about life processes in terms of developmental systems that produce, sustain, and change living beings over both developmental and evolutionary time. Providing a genuine alternative to genetic and environmental determinism, as well as to unsuccessful compromises with which others have tried to replace them, Evolution’s Eye will fascinate students and scholars who work in the fields of evolution, psychology, human biology, and philosophy of science. Feminists and others who seek a more complex view of human nature will find her work especially congenial.
The Ontogeny of Information is a critical intervention into the ongoing and perpetually troubling nature-nurture debates surrounding human development. This was a foundational text in what is now the substantial field of developmental systems theory. In this revised edition Susan Oyama argues compellingly that nature and nurture are not alternative influences on human development but, rather, developmental products and the developmental processes that produce them. Information, says Oyama, is thought to reside in molecules, cells, tissues, and the environment. When something wondrous occurs in the world, we tend to question whether the information guiding the transformation was pre-encoded in the organism or installed through experience or instruction. Oyama looks beyond this either-or question to focus on the history of such developments. She shows that what developmental “information” does depends on what is already in place and what alternatives are available. She terms this process “constructive interactionism,” whereby each combination of genes and environmental influences simultaneously interacts to produce a unique result. Ontogeny, then, is the result of dynamic and complex interactions in multileveled developmental systems. The Ontogeny of Information challenges specialists in the fields of developmental biology, philosophy of biology, psychology, and sociology, and even nonspecialists, to reexamine the existing nature-nurture dichotomy as it relates to the history and formation of organisms.
There is no question that our large brains have provided humans an extraordinary advantage in the world. Still, the human brain is an incredibly expensive organ, taking up only about 2 percent of the body’s mass yet using more than a fifth of the body’s energy, and until about 2 million years ago none of our ancestors had a brain larger than an ape’s when compared to body size. So what kicked off the push for a larger brain? One possibility is that increased smarts helped our ancestors make better tools. Another is that larger brains helped us interact better with each other. Perhaps radical changes in the environment also demanded that our ancestors deal with a shifting world.
The purpose of the present study was to determine the efficacy of investigating spatial cognitive abilities across two primate species using virtual reality. In this study, we presented four captive adult chimpanzees and 16 humans (12 children and 4 adults) with simulated environments of increasing complexity and size to compare species’ attention to visuo‐spatial features during navigation. The specific task required participants to attend to landmarks in navigating along routes in order to localize the goal site. Both species were found to discriminate effectively between positive and negative landmarks. Assessing path efficiency revealed that both species and all age groups used relatively efficient, distance reducing routes during navigation. Compared to the chimpanzees and adult humans however, younger children’s performance decreased as maze complexity and size increased. Surprisingly, in the most complex maze category the humans’ performance was less accurate compared to one female chimpanzee. These results suggest that the method of using virtual reality to test captive primates, and in particular, chimpanzees, affords significant cross‐species investigations of spatial cognitive and developmental comparisons.
While most of us live our lives according to the working week, we did not evolve to be bound by industrial schedules, nor did the food we eat. Despite this, we eat the products of industrialization and often suffer as a consequence. This book considers aspects of changing human nutrition from evolutionary and social perspectives. It considers what a ‘natural’ human diet might be, how it has been shaped across evolutionary time and how we have adapted to changing food availability. The transition from hunter-gatherer and the rise of agriculture through to the industrialisation and globalisation of diet are explored. Far from being adapted to a ‘Stone Age‘ diet, humans can consume a vast range of foodstuffs. However, being able to eat anything does not mean that we should eat everything, and therefore engagement with the evolutionary underpinnings of diet and factors influencing it are key to better public health practice.
The evolution of human intelligence refers to a set of theories that attempt to explain how human intelligence has evolved. These theories are closely tied to the evolution of the human brain and to the emergence of human language.
The timeline of human evolution spans approximately 7 million years, from the separation of the Pan genus until the emergence of behavioral modernity by 50,000 years ago. The first 3 million years of this timeline concern Sahelanthropus, the following 2 million concern Australopithecus and the final 2 million span the history of actual human species (the Paleolithic).
Many traits of human intelligence, such as empathy, theory of mind, mourning, ritual, and the use of symbols and tools, are already apparent in great apes although in lesser sophistication than in humans.
Read also: Evolution of the brain and intelligence
Paleoanthropologists from the University of Zurich have uncovered the intact skull of an early Homo individual in Dmanisi, Georgia. This find is forcing a change in perspective in the field of paleoanthropology: human species diversity two million years ago was much smaller than presumed thus far. However, diversity within the “Homo erectus,” the first global species of human, was as great as in humans today.
This shows the need for a change in perspective: the African fossils from around 1.8 million years ago likely represent representatives from one and the same species, best described as “Homo erectus.” This would suggest that “Homo erectus” evolved about 2 million years ago in Africa, and soon expanded through Eurasia — via places such as Dmanisi — as far as China and Java, where it is first documented from about 1.2 million years ago. Comparing diversity patterns in Africa, Eurasia and East Asia provides clues on the population biology of this first global human species.
This makes Homo erectus the first “global player” in human evolution.