Scientists also debate over how to identify and classify particular species of early humans, and about what factors influenced the evolution and extinction of each species. Early humans first migrated out of Africa into Asia probably between 2 million and 1. They entered Europe somewhat later, between 1. Species of modern humans populated many parts of the world much later. For instance, people first came to Australia probably within the past 60, years and to the Americas within the past 30, years or so.
The beginnings of agriculture and the rise of the first civilizations occurred within the past 12, years. Paleoanthropology is the scientific study of human evolution. Paleoanthropology is a subfield of anthropology, the study of human culture, society, and biology. The field involves an understanding of the similarities and differences between humans and other species in their genes, body form, physiology, and behavior.
Paleoanthropologists search for the roots of human physical traits and behavior. They seek to discover how evolution has shaped the potentials, tendencies, and limitations of all people. For many people, paleoanthropology is an exciting scientific field because it investigates the origin, over millions of years, of the universal and defining traits of our species. However, some people find the concept of human evolution troubling because it can seem not to fit with religious and other traditional beliefs about how people, other living things, and the world came to be.
Nevertheless, many people have come to reconcile their beliefs with the scientific evidence. Early human fossils and archeological remains offer the most important clues about this ancient past. These remains include bones, tools and any other evidence such as footprints, evidence of hearths, or butchery marks on animal bones left by earlier people. Usually, the remains were buried and preserved naturally. They are then found either on the surface exposed by rain, rivers, and wind erosion or by digging in the ground.
By studying fossilized bones, scientists learn about the physical appearance of earlier humans and how it changed. Bone size, shape, and markings left by muscles tell us how those predecessors moved around, held tools, and how the size of their brains changed over a long time. Archeological evidence refers to the things earlier people made and the places where scientists find them. By studying this type of evidence, archeologists can understand how early humans made and used tools and lived in their environments.
Owen Lovejoy, was the emergence of monogamy six million years ago. Until then, brutish alpha males who drove off rival suitors had the most sex. Monogamous females, however, favored males who were most adept at providing food and sticking around to help raise junior. Our ancestors began walking upright, according to Lovejoy, because it freed up their hands and allowed them to carry home more groceries. We Eat Cooked Meat : Big brains are hungry—gray matter requires 20 times more energy than muscle does.
They could never have evolved on a vegetarian diet, some researchers claim ; instead, our brains grew only once we started eating meat, a food source rich in protein and fat, around two to three million years ago. And according to anthropologist Richard Wrangham , once our ancestors invented cooking—a uniquely human behavior that makes food easier to digest—they wasted less energy chewing or pounding meat and so had even more energy available for their brains.
Eventually those brains grew large enough to make the conscious decision to become vegan. We Eat Cooked Carbs : Or maybe our bigger brains were made possible by carb-loading, according to a recent paper. Once our ancestors had invented cooking, tubers and other starchy plants became an excellent source of brain food, more readily available than meat. An enzyme in our saliva called amylase helps break down carbohydrates into the glucose the brain needs.
Evolutionary geneticist Mark G. Thomas of University College London notes that our DNA contains multiple copies of the gene for amylase, suggesting that it—and tubers—helped fuel the explosive growth of the human brain. We Walk on Two Feet : Did the crucial turning point in human evolution occur when our ancestors descended from the trees and started walking upright? As Africa became drier around three million years ago, the forests shrank and savannas came to dominate the landscape.
That favored primates who could stand up and see above the tall grasses to watch for predators, and who could travel more efficiently across the open landscape, where food and water sources were far apart. One problem for this hypothesis is the discovery of Ardipithecus ramidus, a hominid that lived 4.
We Adapt : Richard Potts , director of the Smithsonian's Human Origins Program, suggests that human evolution was influenced by multiple changes in climate rather than a single trend. The emergence of the Homo lineage nearly three million years ago, he says, coincided with drastic fluctuations between wet and dry climates. Natural selection favored primates that could cope with constant, unpredictable change, Potts argues: Adaptability itself is the defining characteristic of humans.
We Unite and Conquer : Anthropologist Curtis Marean offers a vision of human origins well suited to our globalized age: We are the ultimate invasive species. After tens of thousands of years confined to a single continent, our ancestors colonized the globe. How did they accomplish this feat? The key, Marean says, was a genetic predisposition to cooperate—born not from altruism but from conflict. Primate groups that cooperated gained a competitive edge over rival groups, and their genes survived.
Many of them have merit, but they share a bias: the idea that humanity can be defined by a single well-defined trait or group of traits and that a single stage in evolution was a crucial turning point on the inevitable road to Homo sapiens.
And no single trait they acquired was a turning point, because there was never anything inevitable about the outcome: the toolmaking, stone-throwing, meat-and-potato-eating, highly cooperative, adaptable—and oh-so-big-brained—killer ape that is us. There is only one way to find the answer, says Stephen Hawking Read more. Existence: Why is there a universe? Why is there something rather than nothing, asks Amanda Gefter Read more.
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