WHICH COUNTRY DID THE FIRST HUMANS COME FROM

[THE FUGITIVE]

Homo sapiens evolved from their early hominid predecessors between 200,000 and 300,000 years ago and developed a capacity for language about 50,000 years ago.

Homo sapiens, the first modern humans, evolved from their early hominid predecessors between 200,000 and 300,000 years ago. They developed a capacity for language about 50,000 years ago.
The first modern humans began moving outside of Africa starting about 70,000-100,000 years ago.
Humans are the only known species to have successfully populated, adapted to, and significantly altered a wide variety of land regions across the world, resulting in profound historical and environmental impacts.
Where do we begin?
Before we tell the stories that make up world history, it is useful to ask: where do we begin? Where did our human stories start?
Homo sapiens is part of a group called hominids, which were the earliest humanlike creatures. Based on archaeological and anthropological evidence, we think that hominids diverged from other primates somewhere between 2.5 and 4 million years ago in eastern and southern Africa. Though there was a degree of diversity among the hominid family, they all shared the trait of bipedalism, or the ability to walk upright on two legs. 


Scientists have several theories about why early hominids evolved. One, the aridity hypothesis, suggests that early hominids were more suited to dry climates and evolved as the Africa’s dry savannah regions expanded.
According to the savannah hypothesis, early tree-dwelling hominids may have been pushed out of their homes as environmental changes caused the forest regions to shrink and the size of the savannah expand. These changes, according to the savannah hypothesis, may have caused them to adapt to living on the ground and walking upright instead of climbing.

Hominids continued to evolve and develop unique characteristics. Their brain capacities increased, and approximately 2.3 million years ago, a hominid known as Homo habilis began to make and use simple tools. By a million years ago, some hominid species, particularly Homo erectus, began to migrate out of Africa and into Eurasia, where they began to make other advances like controlling fire.


Picture of a Homo habilis skull on a blue background. Skull is missing two of its front teeth.
Homo habilis skull. Image courtesy Wikimedia commons.

Picture of a Homo erectus skull on a white background. The cranium is more shallow than that of a Homo sapiens skull.
Homo erectus skull. Image courtesy Wikimedia Commons.
Though there were once many kinds of hominids, only one remains: Homo sapiens. Extinction is a normal part of evolution, and scientists continue to theorize why other hominid species didn’t survive. We do have some clues as to why some species were less successful at surviving than others, such as an inability to cope with competition for food, changes in climate, and volcanic eruptions.

Migration and the Peopling of the Earth
How and why?
Between 70,000 and 100,000 years ago, Homo sapiens began migrating from the African continent and populating parts of Europe and Asia. For instance, they reached the Australian continent in canoes sometime between 35,000 and 65,000 years ago.
Scientists studying land masses and climate know that the Pleistocene Ice Age created a land bridge that connected Asia and North America (Alaska) over 13,000 years ago. A widely accepted migration theory is that people crossed this land bridge and eventually migrated into North and South America.


Map of the world showing the spread of Homo sapiens throughout the Earth over time. Homo sapiens are reflected with red arrows (shown populating the entire world over time), Neandertalere is reflected in yellow in what is Europe and the Middle East today, and "early human" is represented in green in Africa, South Asia, and Southeast Asia.
Spread of Homo sapiens. Image courtesy Wikimedia Commons.
How were our ancestors able to achieve this feat, and why did they make the decision to leave their homes? The development of language around 50,000 years ago allowed people to make plans, solve problems, and organize effectively. We can’t be sure of the exact reasons humans first migrated off of the African continent, but it was likely correlated with a depletion of resources (like food) in their regions and competition for those resources. Once humans were able to communicate these concerns and make plans, they could assess together whether the pressures in their current home outweighed the risk of leaving to find a new one.

Adaptation and effects on nature
When humans migrated from Africa to colder climates, they made clothing out of animal skins and constructed fires to keep themselves warm; often, they burned fires continuously through the winter. Sophisticated weapons, such as spears and bows and arrows, allowed them to kill large mammals efficiently. Along with changing climates, these hunting methods contributed to the extinction of giant land mammals such as mammoths, giant kangaroos, and mastodons. Fewer giant mammals, in turn, limited hunters’ available prey.
In addition to hunting animals and killing them out of self-defense, humans began to use the earth’s resources in new ways when they constructed semi-permanent settlements. Humans started shifting from nomadic lifestyles to fixed homes, using the natural resources there. Semi-permanent settlements would be the building-blocks of established communities and the development of agricultural practices.

What do you think?
Why do you think Homo sapiens is the only surviving human species?
What effects do you think the environment had on human evolution? What effects did human evolution have on the environment?
What skills were needed for human species to populate the Earth?

[mahrkpat]

Where did we come from?

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.

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.

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.

[mahrkpat]

‘Out of Africa’: what’s the evidence?

‘Mitochondrial Eve’

Genetic studies tend to support the ‘out of Africa’ model. The highest levels of genetic variation? in humans are found in Africa. In fact there is more genetic diversity in Africa compared with the rest of the world put together. In addition, the origin of modern DNA? in the mitochondria (the ‘powerhouses’ of our cells) has been tracked back to just one African woman who lived between 50,000 and 500,000 years ago â€" 'Mitochondrial Eve'.

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.

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.

However, Mitochondrial Eve wasn’t the first or only woman on Earth at that time. She was simply the point from which all modern generations of human appear to have grown. Evolutionary biologists think the most likely reason for this is that an evolutionary ‘bottleneck’ occurred during the time Eve was alive. This is when the majority of a species suddenly dies out, perhaps due to a sudden catastrophe, bringing it to the brink of extinction. If Mitochondrial Eve was one of the few women to survive then this could explain why her ‘matrilineal’ mitochondrial DNA ended up being passed along so many generations.

Similarly, DNA from the Y chromosome? is only passed on from fathers to sons and a evolutionary tree relating all present day male individuals also supports the ‘out of Africa’ model.

Mapping skulls

Further evidence for the ‘out of Africa’ model can be found in the size of human skulls. After studying the genetics and skull measurements of 53 human populations from around the world, scientists found that as you move further away from Africa, populations are less varied in their genetic makeup. This may be because human populations became smaller as they spread out from their original settlements in Africa and so genetic diversity within these populations was less. As a result the scientists stated that modern humans could not have emerged in different places, but instead had to have come from one region, Africa.

The oldest known remains of anatomically modern humans are the Omo I and Omo II skulls. These were found in 1967 in Omo National Park in south-western Ethiopia. The skulls have been dated to 195,000 years ago, highlighting how humans have evolved relatively recently.

[mahrkpat]

Moving out of Africa
Evidence shows that the first wave of humans to move out of Africa did not have too much success on their travels. At times it appears they were on the brink of extinction, dwindling to as few as 10,000.
The eruption of a super volcano, Mount Toba, in Sumatra 70,000 years ago may have led to a 'nuclear winter', followed by a 1,000-year ice age. This sort of event would have put immense pressure on humans. It may be that humans were only able to survive these extreme conditions through cooperating with each other. This may have led to the formation of close family groups or tribes and the development of some of the modern human behaviours we are familiar with today, such as cooperation.
Between 80,000 and 50,000 years ago another wave of humans migrated out of Africa. These humans are likely to have been ‘modern’ in terms of their appearance and behaviour. Due to their newly cooperative behaviour they were more successful at surviving and covered the whole world in a relatively short period of time. As they migrated they would have encountered earlier, primitive humans, eventually replacing them. Genetically, the six billion people of today’s world vary very little from these earlier Homo sapiens that ventured out of Africa.
A map showing human migration out of Africa. Image credit: Genome Research Limited
   
Admixture with extinct humans: what’s the evidence?

Are Neanderthals our cousins or ancestors?

Homo neanderthalis, or Neanderthals as they are more often known, are an extinct species of human that was widely distributed in ice-age Europe and Western Asia between 250,000 and 28,000 years ago. They were characterised as having a receding forehead and prominent brow ridges. In 1856 the first Neanderthal fossil was discovered in the Neander Valley near Düsseldorf in Germany. Since then, researchers have been striving to uncover the position of Homo neanderthalis in modern human evolution. Homo neanderthalis appeared in Europe about 250,000 years ago and spread into the Near East and Central Asia. They disappeared from the fossil record about 28,000 years ago.

“Have Neanderthal genes contributed to the modern human genome?

  Their disappearance has been put down to competition from modern humans, who expanded out of Africa at least 125,000 years ago (100,000-year-old remains of modern humans have been found in Israel), suggesting that there would have been a period of co-existence. Did the two species interbreed? Have Neanderthal genes therefore contributed to the modern human genome?
Initial studies of DNA from the mitochondria of Neanderthals showed that their mitochondrial DNA looks quite different to that of modern humans, suggesting that Homo neanderthalis and Homo sapiens did not interbreed.

[mahrkpat]

Sequencing the Neanderthal genome

In 2010, scientists from Germany and the USA sequenced the DNA of an entire Neanderthal genome. They also identified another archaic human group called 'Denisovan', named after the Siberian cave in which the fossil finger, from which the DNA was obtained, was discovered. In 2013 they obtained a more refined Neanderthal genome sequence from a 50,000-year-old Neanderthal toe bone, found in the same cave in southern Siberia.

    “The genome sequence suggested that early modern non-African humans interbred with their now extinct ancient human cousins.

DNA can survive in bone long after an animal dies. Over time the DNA from various microbes that encounter the skeleton will also invade the bone. As a result, the DNA can be contaminated with microbe DNA. Scientists therefore have to ensure that they sequence only the Neanderthal genome and get rid of any DNA material left behind by these microbes or resulting from contamination by modern humans who handle these bones. As with the human genome sequence, the Denisovan and Neanderthal genome sequences were made available online for free. The genome sequence suggested that early modern non-African humans interbred with their now extinct ancient human cousins as they journeyed along coastlines and over mountains.

Analysis of the Neanderthal genome revealed that the toe bone came from a woman as it had two X chromosomes. Further analysis showed that each pair of chromosomes was similar in sequence. This suggests that her parents were closely related, perhaps an uncle and a niece. Inbreeding is generally bad for the genetic fitness of a species as it reduces the variation in a population making it more susceptible to disease and illness. This reduced genetic variation could explain why Neanderthals became extinct.

When comparing human genomes to the Neanderthal genome, human genomes resemble each other more than any of them resemble the Neanderthal genome. Some Neanderthal DNA is similar to DNA from people of European and Asian origin but these similarities are not seen in African DNA. This suggests that modern humans evolved in Africa and then expanded out into Asia and Europe, where Neanderthals lived. A degree of interbreeding between Neanderthals and early Homo sapiens then occurred in these areas. A study carried out in 2012 estimated that this interbreeding probably took place about 37,000-85,000 years ago and it is estimated that the proportion of Neanderthal-derived DNA in people outside Africa is 1.5-2.1 per cent.

From the past, to the future

Nowadays, many of us carry a small fraction of DNA from our archaic Neanderthal and Denisovan ancestors. This shared DNA could have shaped our individual susceptibility to modern-day diseases or adaptation to new environments and climates. Scientists have found nine Neanderthal genes in living humans known to be associated with susceptibility to conditions such as type 2 diabetes, lupus and Crohn’s disease. It has also been shown that high-altitude adaptation in Tibetans may be a consequence of archaic Denisovan DNA sequence in a region of DNA associated with haemoglobin concentration at high altitudes. Additional research is being carried out to investigate these links further.

please note all info from my posts is from https://www.yourgenome.org/stories/evolution-of-modern-humans

[THE FUGITIVE]

FIRST Humans in Briton (wilkipedia)

Prehistoric Britain
From Wikipedia, the free encyclopedia
This article is about the prehistoric human occupation of Britain. For the geological history, see Geology of Great Britain.
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Several species of humans have intermittently occupied Britain for almost a million years. The Roman conquest of Britain in 43 AD is conventionally regarded as the end of Prehistoric Britain and the start of recorded history in the island, although some historical information is available from before then.

The earliest evidence of human occupation around 900,000 years ago is at Happisburgh on the Norfolk coast, with stone tools and footprints probably made by Homo antecessor. The oldest human fossils, around 500,000 years old, are of Homo heidelbergensis at Boxgrove in Sussex. Until this time Britain was permanently connected to the Continent by a chalk ridge between south-east England and north-east France called the Weald-Artois Anticline, but during the Anglian Glaciation around 425,000 years ago a megaflood broke through the ridge creating the English Channel, and after that Britain became an island when sea levels rose during interglacials. Fossils of very early Neanderthals dating to around 400,000 years ago have been found at Swanscombe in Kent, and of classic Neanderthals about 225,000 years old at Pontnewydd in North Wales. Britain was unoccupied by humans between 180,000 and 60,000 years ago, when Neanderthals returned. By 40,000 years ago they had become extinct and modern humans had reached Britain. But even their occupations were brief and intermittent due to a climate which swung between low temperatures with a tundra habitat and severe ice ages which made Britain uninhabitable for long periods. The last of these, the Younger Dryas, ended around 11,700 years ago, and since then Britain has been continuously occupied.

Britain and Ireland were then joined to the Continent, but rising sea levels cut the land bridge between Britain and Ireland by around 11,000 years ago. A large plain between Britain and Continental Europe, known as Doggerland, persisted much longer, probably until around 5600 BC.[1] By around 4000 BC, the island was populated by people with a Neolithic culture.[2] However, no written language of the pre-Roman inhabitants of Britain has survived; therefore, the history, culture and way of life of pre-Roman Britain are known mainly through archaeological finds. Although the main evidence for the period is archaeological, available genetic evidence is increasing, and views of British prehistory are evolving accordingly. Toponyms and the like constitute a small amount of linguistic evidence, from river and hill names, which is covered in the article about pre-Celtic Britain and the Celtic invasion.

The first significant written record of Britain and its inhabitants was made by the Greek navigator Pytheas, who explored the coastal region of Britain around 325 BC. However, there may be some additional information on Britain in the "Ora Maritima", a text which is now lost but which is incorporated in the writing of the later author Avienus. Archaeological evidence demonstrates that ancient Britons were involved in extensive maritime trade and cultural links with the rest of Europe from the Neolithic onwards, especially by exporting tin that was in abundant supply. Julius Caesar also wrote of Britain in about 50 BC after his two military expeditions to the island in 55 and 54 BC. The 54 invasion was probably an attempt to conquer at least the southeast of Britain but failed.[3]

Located at the fringes of Europe, Britain received European technological and cultural achievements much later than Southern Europe and the Mediterranean region did during prehistory. The story of ancient Britain is traditionally seen as one of successive waves of invasion from the continent, with each bringing different cultures and technologies. More recent archaeological theories have questioned this migrationist interpretation and argue for a more complex relationship between Britain and the Continent.[4] Many of the changes in British society demonstrated in the archaeological record are now suggested to be the effects of the native inhabitants adopting foreign customs rather than being subsumed by an invading population.[citation needed]