Only 1,280 Breeding Humans Once Roamed Earth, Gene Study Shows

Only 1,280 Breeding Humans Once Roamed Earth, Gene Study Shows

In a near extinction event, humankind struggled to survive during a 100,000 year period during the early Pleistocene, according to researchers who used a computer model to discover a severe population bottleneck in our species’ ancient past.

The bottleneck occurred between 813,000 years ago and 930,000 years ago, and reduced an ancestral human species to less than 1,300 breeding individuals. The issue persisted for 117,000 years, and aligns with a chronological gap in the African and Eurasian human fossil records in that period. The team’s research on the bottleneck was published today in Science.

Population bottlenecks are events in which a species’ total population is severely reduced, which causes an overall reduction in genetic diversity across the species. The loss of genetic diversity can cause populations to become less healthy. Bioengineers can now synthesize genetic diversity in animal populations through cloning and gene editing.

 

 

Around 900,000 years ago, during the Middle Pleistocene epoch, Earth underwent several important geological, climatic, and evolutionary changes. Here are some key events and developments during that time:

1. Glacial-Interglacial Cycles: The Middle Pleistocene was characterized by a series of glacial and interglacial periods, where the climate alternated between colder and warmer conditions. These fluctuations were driven by changes in Earth's orbital parameters, including variations in the tilt of its axis and the shape of its orbit.

2. Ice Age Extent: During this time, large ice sheets covered significant portions of North America, Europe, and Asia. These ice sheets expanded and contracted over the course of glacial cycles, shaping the landscapes and influencing global sea levels.

3. Homo erectus: Human evolution was ongoing during the Middle Pleistocene. Homo erectus, an early human species, had already migrated out of Africa and was present in regions across Asia and Europe. They were adapted to a variety of environments and are known for their sophisticated use of tools and ability to control fire.

4. Megafauna: The Middle Pleistocene was a time of diverse megafauna (large animals). Species like mammoths, mastodons, giant sloths, and saber-toothed cats roamed various parts of the world. These animals had to adapt to the changing climatic conditions and the presence of early humans.

5. Environmental Changes: The shifting climate and the advance and retreat of ice sheets had a profound impact on ecosystems. As ice sheets expanded, they displaced habitats and caused significant changes in plant and animal distribution. This could have led to extinctions and the emergence of new species as organisms adapted to changing conditions.

6. Early Human Culture: Homo erectus populations during this time were developing more advanced tool-making techniques and potentially exhibiting early forms of social behavior. Evidence of controlled fire usage also suggests advancements in cooking and shelter, which likely provided an advantage in the harsh Pleistocene environment.

7. Sea Level Changes: The fluctuating ice sheets had a direct impact on global sea levels. During glacial periods, sea levels were lower due to the accumulation of water in ice sheets, exposing land bridges between continents and influencing the migration of species, including early humans.

8. Continental Drift: The Middle Pleistocene also saw ongoing movement of Earth's tectonic plates, shaping the positions of continents and oceans. This movement influenced ocean currents, climate patterns, and the distribution of terrestrial and marine life.

It's important to note that our understanding of the Middle Pleistocene is based on a combination of geological, paleontological, and archaeological evidence. The specifics of events and conditions during this time can vary depending on geographic location, as well as the availability and accuracy of the fossil and sedimentary record.