How long people exist

The estimate, however, does not depend on the number of deaths during any period of time. The oldest hominins are thought to have appeared as early as 7 million B. The earliest species of the Homo genus appeared around 2 million to 1. Current evidence supports modern Homo sapiens appearing around , B. Modern Homo sapiens originated in Africa, though the exact location has long been debated. Diverse groups are thought to have lived in different locations across Africa for the first two-thirds of human history.

Around B. Table 1 displays very rough figures representing averages of an estimate of ranges given by the United Nations and other sources. Slow population growth over the 8,year period—from an estimated 5 million in B. In all likelihood, human populations in different regions grew or declined in response to food availability, the variability of animal herds, periods of peace or hostility, and changing weather and climatic conditions.

Poston Jr. In any case, life was short. Life expectancy at birth probably averaged only about 10 years for most of human history. Average life expectancy in Iron Age France from B. Under these conditions, the birth rate would have to be about 80 live births per 1, people just for the species to survive. To put that in perspective, a high birth rate today is about 35 to 45 live births per 1, population, and it is observed in only some sub-Saharan African countries.

These short life expectancies mean that the human population had a hard time increasing. Other historians, however, set the figure twice as high, suggesting how imprecise population estimates of early historical periods can be. The average annual rate of growth was actually lower in this period than the rate suggested for B.

One reason for the unusually slower growth was the Black Death. This dreaded plague was not limited to 14th-century Europe but may have begun in western Asia in about C. Using genetic markers and an understanding of ancient geography, scientists have partially reconstructed how humans could have made the journey.

These people made it to India, then by 50, years ago, southeast Asia and Australia. A little after this time, another group began an inland journey across the Middle East and south-central Asia, positioning them to later go to Europe and Asia, the magazine added.

This proved important for North America, as about 20, years ago, some of these people crossed over to that continent using a land bridge created by glaciation. From there, colonies have been found in Asia dating as far back as 14, years ago.

The first human mission to space took place April 12, when Soviet cosmonaut Yuri Gagarin made a single orbit of Earth in his spacecraft, Vostok 1. Since then, our colonization efforts in space have focused mostly on space stations. The men died during re-entry June 29 due to spacecraft decompression, meaning no further flights went to that station.

There have been other space stations since. A notable example is Mir, which hosted several long-duration missions of a year or more — including the longest single spaceflight duration of any human to date, days, by Valeri Polyakov in The International Space Station launched its first piece Nov.

These humans walked upright on two legs, just like us. Around 90, years ago, these humans started making tools to catch fish. Then, around 12, years ago, humans began to grow food and change their surroundings in order to survive and eat. As food became more sustainable, and living became easier, humans began to produce more. As humans developed and grew, their bodies changed.

Their brains became bigger, which helped them to develop new tools, including language. They changed the world around them to better survive harsh and changeable weather.