Some science guys wrapped up a long research project and published the results this week. Bluntly, the Neanderthals and humans quit mixing up and having physical liaisons....about 47k years ago. Then 17k years pass, and the Neanderthals are no more.
So you draw out the scenario Caveman Joe (our friend Neanderthal) comes across this light-skinned human gal named Wanda....who lives four mountains over. Naturally, Joe is hooked up with his cave gal Marge and typically stays on the straight and narrow path. But once Joe gazes into Wanda's eyes....he is smitten and just can't get over how cute Wanda looks....even though she's not carry an extra forty pounds, or robust like Marge, and able to drag down a deer.
For several years, Joe admires Wanda and they share quiet interludes by the big lake. Joe doesn't communicate much, but always brings over a freshly caught rabbit, or bag of apples. Wanda thinks that Joe is different from the regular human guys.....kinda heavily built, and very "manly". He doesn't do alot of talking, which Wanda prefers.
Eventually, Wanda hooks up with a permanent guy....Joe doesn't meet his weekend gal any longer, and the end to the Neanderthal passion occurs.
Over the next 17k years, the Neanderthal guys kinda find a closed off situation....a birth-rate declining within their tribe.....and the summer seasons are harder to adjust to because of all that body-fat Eventually, the Caveman Joe's die off.
What you have left....are humans and this hybrid deal of some small percentage of Neanderthal-Humans...and this group of hybrids are being weeded out with more interaction with the humans. You are left with this oddball question....why did Wanda drop Caveman Joe eventually? There has to be some magical moment when someone said something or did something....and ruined this perfect odd relationship.