Left: Dirk Hoffmann and Alistair Pike sample calcite from a calcite crust on top of the red scalariform sign in La Pasiega.Right: Drawing of Panel 78 in La Pasiega by Breuil et al.(1913). The red scalariform (ladder) symbol has a minimum age of 64,000 years but it is unclear if the animals and other symbols were painted later. J. Zilhão (left) / Breuil et al. (1913)/Science Advances hide caption
Demonstrators support former Catalan President Carles Puigdemont in front of the regional parliament in Barcelona on Tuesday. Puigdemont, who fled to Belgium to avoid arrest for leading a secession bid, is facing possible charges of rebellion, sedition and misuse of public funds and faces arrest if he returns from Brussels. Alex Caparros/Getty Images hide caption
Catalan separatist leader Carles Puigdemont arrives at Copenhagen Airport in Denmark on Monday, Jan. 22, 2018. On the same day, his name was put forth to return as Catalonia's president. Scanpix Denmark/Reuters hide caption
Ousted Catalan President Carles Puigdemont speaks at a press conference in Belgium last month, after a snap election in Catalonia gave pro-independence factions a slim majority in the regional parliament. Emmanuel Dunand/AFP/Getty Images hide caption
Caga Tiós, Catalan Christmas logs stacked up at a market in Girona, Spain. Lindsay Patterson hide caption
A woman casts her ballot in the Catalan regional election at a Barcelona polling station on Thursday. Javier Soriano/AFP/Getty Images hide caption
Ousted Catalan leader Carles Puigdemont (center) is seen in Belgium last month, where he has been living in exile since October. On Tuesday, a Spanish judge withdrew the international warrant for Puigdemont's arrest. Emmanuel Dunand/AFP/Getty Images hide caption
Catalan members of the Spanish parliament speak to the press outside Estremera prison, outside of Madrid, on Monday. A judge from Spain's Supreme Court granted bail to six imprisoned former members of the Catalan government, while two other politicians and two activists will remain in jail. Pablo Blazquez Dominguez/Getty Images hide caption
Thousands of people rally outside the regional presidential palace in Barcelona, protesting the arrest of Catalan politicians and pushing for Catalonia's independence, which was formally annulled in court Wednesday. The crowd is awash in Catalan independence flags and signs reading "free political prisoners." Manu Fernandez/AP hide caption
Ousted Catalan leader Carles Puigdemont has turned himself in to police in Brussels, following an international warrant for his arrest over Catalonia's attempt to secede from Spain. Getty Images hide caption
A banner reading "Freedom to political prisoners" hangs from City Hall in Barcelona as a protester waves a Catalan pro-independence Estelada flag during a demonstration on Friday to protest the detention of Catalan officials. Josep Lago/AFP/Getty Images hide caption
Sacked Catalan President Carles Puigdemont arrives for a news conference in Brussels on Tuesday. Olivier Matthys/AP hide caption
Catalonia's deposed leader, Carles Puigdemont (center), speaks at a news conference in Brussels on Tuesday with other members of his dismissed government. Aurore Belot/AFP/Getty Images hide caption
Some people unfold a Spanish flag as another man waves a Catalan pro-independence flag in front of the Catalan government headquarters in Barcelona on Monday. Spain enters uncharted and potentially perilous territory today as Madrid moves to take over the running of Catalonia, in response to the region's parliament unilaterally declaring independence. Lluis Gene /AFP/Getty Images hide caption
Spanish Prime Minister Mariano Rajoy (center) is applauded after a speech in Madrid on Friday in which he appealed to the country's Senate to grant special authority to dissolve Catalonia's regional government. Paul White/AP hide caption
