5. Blood types
Blood types provide clues to our evolutionary history, however, it’s not clear how or why they evolved in the way that they did. Scientists believe that the start of blood types evolving began some 20 million years ago in our ancestors, as well as other primates. Blood types differ in that they have varying abilities in being able to fight off infections, but no-one knows why different blood types evolved in the first place.
6. Dreaming
Despite us spending one-third of our entire lives asleep, scientists are at a loss to explain why we dream. What is known is that we dream in REM sleep and that our heart rate increases when we dream. A popular theory about dreaming suggests that it’s our brain’s way of sorting through the memories of the day, allowing it to decide which ones to keep and which ones to get rid of. There are some scientists, however, that believe dreaming is simply the consequence of our unconscious mind being untethered from our awakened state.
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