Hard Numbers: Election violence in Mexico, Baby deficit in Korea, tactical nuke leak in Russia, A gigantic disappearance in the Pacific, Gaza's bleak milestone

2: Two mayoral candidates in the central Mexican farming town of Maravatío were shot dead within hours of each other earlier this week. One of the candidates was from President Andrés Manuel Lopez Obrador’s Morena party, the other from the opposition National Action Party. Maravatío is in Michoacán state, where cartel wars have raged recently, spotlighting broader concerns about narco-fueled political violence across the country ahead of nationwide elections in June.

29: A cache of 29 secret Russian military documents from a decade ago appears to lay out the Kremlin’s threshold for using tactical nuclear weapons. The slides, leaked to the Financial Times by Western spooks, say Moscow would use the weapons – which are far smaller and more targeted than the intercontinental ballistic missiles that target the US – if Russia suffered an otherwise unstoppable conventional incursion, or sustained significant damage to its submarine fleets, airfields, or command centers.

0.72: South Korea’s birth rate, the world’s lowest, dipped further in 2023, according to new data which show that the average South Korean woman will have just 0.72 babies. That was down from an already dismally infertile 0.76 in 2022, and it’s far below the “replacement” rate of 2.1 children per woman. Experts say the high costs of child-rearing – as well as gender pay gaps and difficulties of balancing career and motherhood – are causing the fertility collapse.

7,000: What could have caused 7,000 of the world’s largest creatures to disappear? Scientists think that unusually high sea temperatures in the North Pacific led to the starvation of that many Humpback whales in the decade or so after 2013, as the hotter waters reduced the prevalence of their main source of food - tiny phytoplankton. The big bump in humpback deaths put a dent in what had been several decades of remarkable recovery for a species driven to the brink of extinction by hunters in the 1970s.

30,000: Over 30,000 Palestinians have been killed amid the devastating Israel-Hamas war in Gaza that began on Oct. 7, health officials in the enclave said on Thursday. It's likely that the official death toll is an undercount, given the challenges of tracking deaths in a warzone and the fact that many bodies are still under rubble. The Gaza health ministry does not distinguish between civilians and combatants in its count, but Israel estimates it's killed roughly 10,000 Palestinian militants so far.