The prehistoric inhabitants of the current US state of New Mexico had to fetch water deep underground during periods of drought.
American archaeologists write in
that ancient humans in lava caves melted ice with fires to collect the resulting water and take it with them to drink.
The landscape of southwestern New Mexico, specifically the El Malpais National Monument area, has been a bare stone expanse for centuries.
Yet people here managed to survive in periods of severe drought.
This was at least between 150 and 950.
Now archaeologists know why.
Researchers found charred material in lava caves of the region.
According to the scientists, this indicates that the then inhabitants of the region made fires and used them to melt ice and collect water.
This could then be used as drinking water and possibly also be used in religious matters.
Scientists also found a pot that was supposedly used to collect water.
Initially, scientists went into lava tunnels to collect ice to study the climate of former New Mexico.
When they found traces left by primeval humans, it was therefore a great surprise.
Caves are remnants of large lava flows
Lava caves are created when large lava flows solidify on the outside, creating a kind of cocoons with flowing, liquid lava in the middle.
When the flow of lava subsides and eventually solidifies completely, large stone corridors may remain.
In this case, a corridor at least 171 meters long and 14 meters deep was investigated.
In this cave an amount of ice was found that probably once completely filled the deepest part of the cave.
In "normal" years, ice that formed in the winter at the cave entrances melted, which the primeval inhabitants of New Mexico could easily reach.
In drier periods, the inhabitants could go deeper into the cave to get drinking water.