There's a Massive Hidden Factor in The Evolution of Humans Over 2 Million Years

The course of human evolution over the last 2 million years was shaped by habitation shifts linked to climate change, according to a new study.

Using an unprecedented supercomputer simulation of Earth's climate as it transitioned through climatic shifts over the course of the Pleistocene epoch, researchers found that changes in variables such as precipitation and temperature were linked with how a range of different hominin species, including Homo sapiens, settled or moved over

Even though different groups of archaic humans preferred different climates, their habitats all responded to climate shifts caused by Earth's axis wobble, tilt, and orbital eccentricity, says climate physicist Timmermann from Pusan National University in South Korea.

The results add weight to the argument that prehistoric episodes of climate change helped to spur evolutionary developments in the Homo genus, due to a lack of hard climatic data.

Terrestrial records of habitat information, such as that obtained from sedimentary outcrops and paleolake drill cores, are often limited in terms of the time frames of data available.

To sidestep the issue, Timmermann and his team modeled changes in environmental conditions across Earth over a period of 2 million years.

The simulation took over six months to crunch the numbers, making it the longest running comprehensive climate model simulation to date.

The data was compared to the documented presence of several hominin species in the fossil record.

The results show a complex story of how different hominin groups dispersed across Earth over time, but they also show that the dispersals were tied to factors such as temperature and food availability.

Timmermann says that climate played a fundamental role in the evolution of Homo.

We are who we are because we have been able to adapt to slow shifts in the past climate.

The researchers suggest that climate stress in southern Africa could have led to the rise of H. sapiens. The study argues that shifts in human adaptation can't be fully explained without a broader understanding of climate factors.

The full spatial and temporal complexity of the climate signal and the corresponding habitat suitability must be considered in order to understand hominin evolution.

It will fall to new investigations to verify such ideas, carefully scrutinizing fossil records to discover traces of paleoenvironmental information we haven't yet uncovered.

There is still much to learn about the evolutionary implications of the variability of the climate over the past 2 million years.

This study provides a starting point for testing a range of theories about how climate and habitat changed the distribution, dispersal and identification of hominin species.

Nature reported the findings.