Kate McKinney

Kate McKinney is a Homo sapiens and one of the six characters in Cavemen with lead billing; she is in an inter-special relation with Joel.

Kate is Leslie's daughter and lives in San Diego, California with her friend Thorne.

History
It is assumed that Kate grew up with both of her parents, who remain married and outwardly in a happy relationship at the time of the series. It is implied that she has a history of dating cavemen before Joel, including Maurice, and she tells Joel she gets into a lot of short-term relationships ("Her Embarrassed of Caveman"). Thorne has used the nickname "3-Month Kate" to refer to her ("Nick Sick"), in reference to her apparent habit of breaking up with all of her boyfriends after three months.

Character arc
Kate is (canonically) introduced in "Her Embarrassed of Caveman." She has been hiding her relationship with Joel from all of her friends and this angers Joel when his friends lead him to think she is ashamed to date a caveman; however, she is actually just waiting until she is sure about the relationship. Her relationship with Joel meets with difficulty when he fails to defend her when she is insulted by a pretty cavegirl waitress ("The Cavewoman"), and though they reconciled following this, Nick's treatment of her once again caused problems in their relationship, when Kate refused to visit Joel at his apartment. This led to Joel briefly moving in with Kate and Thorne; however, he missed his own apartment and friends and moved out again after Nick apologized to Kate and learned to treat her better ("Nick Jerk, Andy Work").

Following this, however, as she and Joel approached their "3 month anniversary", Kate began pulling away from Joel, needing to "think about stuff"; apparently something she has done in previous relationships. When she finally decided to speak to Joel, however, he broke up with her, unwilling to put up with her behavior any more ("Nick Sick"). Following the break-up, Kate is invited by Andy to a Longnight celebration at Joel's apartment. Though she worries that Joel will get the impression that she wants to get back together with him, she comes anyway, claiming it to be "for the food". However, when the Longnight celebrants pair up at the end of the night, she ends up sleeping with Joel, only making things more complicated ("Caveman Holiday"). However, she and Joel do try to stay friends, despite some troubles caused by having a mutual friend in Thorne who hears both of their perspectives on the relationship (and passes them on) ("Andy the Stand Up").

Kate also continued her friendships with Andy and Nick after her breakup with Joel, though their interactions were occasionally stilted. Feeling alienated by Rocky the cave kid, Andy tries to spend more time with her, but doesn't feel as close to Andy as he does to her ("Cave Kid"). When Maurice informs Nick that he is a "gatherer" rather than a "hunter", he becomes close with Kate, Thorne and Leslie after failing to prove to Heather that he is a hunter; when she beats him, Kate and the girls are the safety net that comes to his side when he needs it most ("Hunters & Gatherers").

Pilot
In the non-canon pilot, Joel and Kate (who live in Atlanta, Georgia) are already engaged. However, Joel is still trying to gain Kate's father Tripp's approval to marry his daughter. Despite Joel's concerns, Kate does not think her father's feelings will be an issue.