The ongoing quarrel about whether dogs or cats are smarter has divided pet lovers throughout history—and scientific research has provided fuel for the debate.

Some studies suggest biological differences in intelligence between cats and dogs. Research reveals that the cerebral cortex, the layer of the brain that controls functions such as problem-solving and decision-making, tends to have many more neurons in dogs than in cats. While dogs possess on average about 530 million neurons in the cortex, cats have only about 250 million— nearly half the amount found in dogs. Though this data might seem to suggest that dogs are twice as intelligent as cats, a direct correlation between larger brain size and increased intelligence has not been conclusively proven. Regardless, dogs’ higher neuron count is often viewed as a gauge of their superior intelligence.

Dogs tend to demonstrate strong social intelligence, drawing comparisons to the mental capabilities of human toddlers. Studies indicate that dogs display self-awareness and succeed at cooperative communication tasks.

However, research about dogs’ social intelligence should be taken with a grain of salt in the cats-versus-dogs debate. Though many view dogs as prime subjects for social cognition research, cats are rarely studied in behavioral labs. Scientists began studying cat behavior only toward the beginning of the 21st century, and little information on feline intelligence has emerged. Some research suggests strong social intelligence in both dogs and cats; in one study, when representatives of both species competed in a test to find hidden food, they achieved quite similar scores. However, the deficit of information about cats’ behavioral tendencies means that knowledge of feline social intelligence remains limited.

In fact, the comparison between dogs and cats itself may lack factual grounding. Since the two species have such different habits and roles, some scientists conclude that comparisons are illogical. Dogs and cats each evolved to succeed at the duties of their own species, meaning that their intelligence types may not be comparable.

Ultimately, whether cats or dogs are more intelligent remains inconclusive. Though some data point to dogs displaying greater levels of social intellect, more research is required to settle the debate between cat lovers and dog lovers.

Nostradamus was a 16th-century seer. He and his prophecies—revered by some, ridiculed by others—are still well known today, centuries after he lived, and continue to be the subject of debate.

Nostradamus was born in France in 1503. He first worked as a physician and began his medical practice in the 1530s, although he did so without a medical degree. He began making prophecies about 1547, and he published his prophecies in a book entitled Centuries (1555). He wrote his prophecies in quatrains: four lines of rhyming verse. The quatrains were grouped in hundreds; each set of 100 quatrains was called a century. Nostradamus gained notoriety during his lifetime when some of his predictions appeared to have come true. He was highly sought after and was even invited to the court of Catherine de’ Medici, then the queen consort of King Henry II of France, to create horoscopes for her children.

Nostradamus’s predictions tended to be about general types of events, like natural disasters and conflict-related events that tend to occur regularly as time goes on. Some people believe that his prophecies have predicted actual events, such as the death of Henry II, the French Revolution, the rise of Napoleon, the rise of Adolf Hitler, and the 9/11 attacks. Others maintain that because his prophecies tend to be about general types of events that occur frequently throughout history—and are written in a cryptic and vague manner—it’s possible to find one that seems to match almost any event that has occurred.