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1º ESO/WHERE AND WHEN DID HUMANS EVOLVE - Contenido educativo
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Like all other species on our planet, our species was produced by the process of biological
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evolution.
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But where and when did we evolve?
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And will we one day be able to direct our own evolution in the future?
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Scientists have contemplated these questions for centuries.
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Perhaps unsurprisingly, the co-discoverer of the theory of evolution, Charles Darwin,
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was first to formulate a testable hypothesis about where we evolved.
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All it took was a trip to the London Zoo.
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After spending some time observing chimpanzees and gorillas, he thought it likely that our
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species' common origin was African.
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Although this idea offended British royalty and proved academically controversial for
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well over a century, Darwin, of course, turned out to be right.
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You, me, and everyone else we know is technically African.
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Since Darwin's time, scientists have collected an overwhelming amount of evidence to support
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this claim.
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Some of the first convincing clues came from the discovery of ancient human-like fossils
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throughout East Africa.
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These fossils weren't quite African apes, and not quite what we would think of as modern
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human either.
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They were species with a mosaic of human and ape-like features.
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Who were they?
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Your great-great-great-great-great-grandparents.
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One of the most well-known of our ancestors is Australopithecus afarensis.
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We know so much about afarensis thanks to a well-preserved fossil of a partial skeleton
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named Lucy.
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They lived over 3 million years ago in what is today Ethiopia, and like all other hominids
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from this time period, their brain size was closer to that of modern day chimpanzees than
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it is to humans.
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But interestingly, we know from Lucy's lower body that she was habitually bipedal, meaning
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she walked on two legs.
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This was an important find for scientists because it suggested that our ancestors started
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to walk upright before we started to evolve larger brain size.
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Of course, this was not a straightforward transition.
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Recent finds of Australopithecus sedeba date to about 2 million years old and reveal a
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species that was exceptionally well adapted to walking bipedally, but also exceptionally
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well adapted to climbing trees and perhaps sleeping in them.
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Such discoveries reveal that our mode of locomotion today evolved gradually over a period of millions
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of years.
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As for our big brains, current evidence suggests that we started to see an explosion with the
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emergence of our genus Homo 2 million years ago. Perhaps as a result of this relatively
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rapid brain growth, our ancestor Homo erectus started spreading throughout Eurasia. They
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may have been the first human species to leave Africa and adapt to alien environments, but
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we have more than just the fossil evidence. You have the evidence of your African ancestry
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in your genes as well. When geneticists started comparing human DNA with ape DNA, the startling
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similarity between our strands was undeniable. Studies on the amino acid sequence of our
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DNA proved Darwin's initial hypothesis. Chimpanzees were our closest living relatives, followed
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closely by gorillas and then orangutans.
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But when did we start to leave Africa? Today humans are truly a global species, permanently
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inhabiting every continent on the planet. Here the fossil and genetic evidence prove
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slightly contradictory, but it is safe to say that there was some form of modern human
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migration onto the Arabian Peninsula around 100,000 years ago. It is likely that these
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migrations from Africa were only of small bands of modern humans. We also know that
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the first modern humans out of Africa travelled down the shorelines of Asia and may have island
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hopped to Australia by 45,000 years ago. Throughout this emergence we encountered, interbred
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with and outcompeted several other human species in Eurasia, which only exist today as a small
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percentage of the total modern human genome. What is even more interesting is that our
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evolution hasn't stopped. In fact, over the past 10,000 years humans have been changing
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in new ways due to the development of civilization.
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For most of our evolution we were hunters and gatherers, but over the past 10,000 years
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an increasing number of human groups domesticated animals and plants, then became sedentary,
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started building large scale structures, and congregating in ever denser urban centers.
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This led to certain biological changes, like varying levels of adaptation to the consumption
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of lactose, and resistance to communicable diseases.
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But the most significant change has come with cultural and technological evolution.
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With the development of civilization, a small fraction of humans could for the first time
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dedicate their time and energy to tasks unrelated to food production.
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As this trend continued, more and more people could dedicate themselves to science, art,
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engineering, music, sports, teaching, medicine, politics, and thousands of other possible
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vocations.
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In the modern world, accelerating cultural and technological evolution has led to the
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development of technology that could allow us to intelligently direct our own evolution.
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This could be done by directly engineering our own genomes, turning on and off different
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sections within it? We could also do this by gradually replacing our cellular structures
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with nano-engineered computers, designed to perform the same tasks our cells perform,
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only better? Either way, one thing is certain. The nature of our evolution will be considerably
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different from the natural selection process that created us. As futurist Peter Diamandis has said,
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it won't be natural selection, but intelligent direction that causes our future evolution.
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How does knowledge of human evolution influence your perceptions of life and our history?
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More importantly, what do you think is the future of human evolution?
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Let's talk about this together in the comments.
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As always, thanks for watching, and don't forget to subscribe.
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Advanced States.
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- Subido por:
- Alicia M.
- Licencia:
- Dominio público
- Visualizaciones:
- 585
- Fecha:
- 27 de septiembre de 2020 - 20:18
- Visibilidad:
- Público
- Centro:
- IES LA SENDA
- Duración:
- 05′ 27″
- Relación de aspecto:
- 1.78:1
- Resolución:
- 1920x1080 píxeles
- Tamaño:
- 115.63 MBytes