article: A warming climate may have enabled the earliest humans to venture into Western Europe 1.4 million years ago, a new study suggests. Researchers believe that the spread of our distant human ancestors, the hominins, had been halted by colder and drier temperatures. But as conditions warmed, they were able to branch out from Africa into Spain, and ultimately spread across Europe. Spanish researchers say climate change impacted human migration. Until 1.4 million years ago it was too cold to inhabit southeast Spain. But then the climate warmed to 13°C (55°F) and became more humid. This enabled hominins (stock image shown) - our distant ancestors - to move to new regions . The research was led by Dr Jordi Agusti from the Catalan Institution for Research and Advanced Studies (ICREA). Published in the Journal of Human Evolution, the paper suggests climate change affected the amount of resources available. There have been various theories put forward over the years about the diet of our early ancestors, but a study from Oxford University published last year claimed to have finally settled the debate. An ancient human ancestor known as ‘Nutcracker Man’ lived mainly on a diet of tiger nuts, worms and grasshoppers, according to research. Scientists believe this diet explains why the ancient hominin relative, called Paranthropus boisei, which lived in East Africa between 2.4 and 1.4 million years ago, had such distinctively powerful jaws and large, flat molar teeth. The theory is based on analysis of the Barranco León site in the Guadix-Baza Basin in southeast Spain. Here, simple Oldowan tools have previously been found, linked to the earliest known hominins 1.4 million years ago, reported Popular Archaeology. But they were not able to migrate to this region until conditions improved. The researchers said that the early Pleistocene era (the era lasted from 2.59 million to 11,700 years ago) was characterised by colder and drier weather. This ‘possibly impeded the settlement of this region by the early hominin population from the southern Caucasus,’ the researchers wrote. But shortly afterwards, ‘when the climatic conditions were again favourable, a hominin presence is suddenly evidenced.’ The theory is based on analysis of the Barranco León site in the Guadix-Baza Basin in southeast Spain, shown by the grey marker on this map. Here, simple Oldowan tools have previously been found, linked to the earliest known hominins 1.4 million years ago . The Acheulean tool technology period - between 700,000 an 300,000 years ago - followed the more primitive Oldowan period. Tools at the time included large stone hand axes (stock image shown) made from flint and quartzite, used to scavenge from carcasses . It should be noted that the warming climate referred to here is on a vastly longer time scale than modern climate change. At the time 1.4 million years ago, though, temperatures warmed above 13°C (55°F) and humidity increased, allowing hominins to inhabit the region - scavenging carcasses in the region with the help of tools. ‘The data reported here clearly support the idea that the early hominin occupation of Europe was strongly constrained by climatic and environmental conditions, rather than by physiography or cultural factors,’ the researchers wrote.
highlights: Spanish researchers say climate change impacted human migration .
  Until 1.4 million years ago it was too cold to inhabit southeast Spain .
  But then the climate warmed to 13°C (55°F) and became more humid .
  This enabled hominins - our distant ancestors - to move to new regions .
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