from page 18, make a presentation- video using power point, genially, powtoon about the origin of Human beings.
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The origin of modern humans has probably been the most debated issue in evolutionary biology over the last few decades.
Where did we come from?
“The exact origin of modern humans has long been a topic of debate.
Our evolutionary history is written into our genome?. The human genome looks the way it does because of all the genetic changes that have affected our ancestors. The exact origin of modern humans has long been a topic of debate.
KEY FACTModern humans originated in Africa within the past 200,000 years and evolved from their most likely recent common ancestor, Homo erectus.
Modern humans (Homo sapiens), the species? that we are, means ‘wise man’ in Latin. Our species is the only surviving species of the genus Homo but where we came from has been a topic of much debate. Modern humans originated in Africa within the past 200,000 years and evolved from their most likely recent common ancestor, Homo erectus, which means ‘upright man’ in Latin. Homo erectus is an extinct species of human that lived between 1.9 million and 135,000 years ago.
Historically, two key models have been put forward to explain the evolution? of Homo sapiens. These are the ‘out of Africa’ model and the ‘multi-regional’ model. The ‘out of Africa’ model is currently the most widely accepted model. It proposes that Homo sapiens evolved in Africa before migrating across the world.
On the other hand, the ‘multi-regional’ model proposes that the evolution of Homo sapiens took place in a number of places over a long period of time. The intermingling of the various populations eventually led to the single Homo sapiens species we see today.
“Current genomic evidence supports a single ‘out-of Africa’ migration of modern humans.
This is still very much an area of active research, however, current genomic evidence supports a single ‘out-of Africa’ migration of modern humans rather than the ‘multi-regional’ model. Although, studies of the genomes? of the extinct hominids Neanderthals and Denisovans suggest that there was some mixing of genomes (1-3 per cent) with humans in Europe and Asia. This interbreeding between two previously separated populations is called ‘admixture’ and results in a mixing of genes? between the populations.
Our genomes are a combination of DNA from both our mother and father. However, mitochondrial DNA (mtDNA) comes solely from our mother. This is because the female egg contains large amounts of mitochondrial DNA, whereas the male sperm contains just a tiny amount. The sperm use their small amount of mitochondria to power their race to their egg before fertilisation. Once a sperm merges with an egg, all the sperm mitochondria are destroyed.
KEY FACTYour mitochondrial DNA is almost exactly the same as your mother’s and her mother’s.
As a result, mitochondrial DNA is described as being matrilineal (only the mother’s side survives from generation to generation). So, your mitochondrial DNA is almost exactly the same as your mother’s and her mother’s. Mitochondrial DNA has been extensively used by evolutionary biologists, as it is easier to extract than DNA found in the nucleus? and there are many copies to work with.