Because she is the type most likely to enthrall men -- as Clio says, and as confirmed by the gushing commentary about her from guys -- it's important to find at least one or two weak spots in her deception, lest you become blind-sided by her fickle ways.
I've decided on a very simple and broadly applicable method -- looking at her profile on Facebook or MySpace -- based on the ones I've known, including my close friend. All arts and humanities majors -- who are distinct from practicing artists -- fall into two polarized camps: those who identify with the refinement of the upper class, and those who admire the struggle and toughness of the lower class. They see humanity but are blind to people. This is why the world needs cold-hearted science guys.
To illustrate what I mean, Clio describes the Amazonian Alpha heartbreaker as a woman who in social situations is surrounded by men "who may anxiously ask her opinion about public affairs and actually listen to what she says about them." (I find this as cute as Clio must find my use of the phrase "reproductive strategy" in talking about human beings.) Now of course, most people -- even most upper-middle class people -- don't care at all about public affairs, and this is just a humble way for Clio to say, "I hang out with people who do -- so nyah." And so, while true, this doesn't help us to identify her in most contexts.
But for a brief moment in her discussion of the Eternal Ingenue, Clio submits to the dark side of abstract systemizing and gets right to it:
What makes an ordinary Ingenue into a femme fatale, one who goes through many men and breaks their hearts, is that this is a woman "in love with love"...
Pay attention, guys -- this is her Achilles' heel. Especially when younger, but even still when over 25 or 30, her brain is so awash in hormones that she won't be able to hide her love for being in love. Plainly what this means is that love is addictive for her, so that once she's habituated to the flavor of your love drug, she'll run off to find a guy whose novel taste will excite her like you used to 4 to 6 weeks ago.
Because most of the females who you'd be interested in have a presence in some social network, and because they reveal much more there than they would in person, it's worth looking over her profile before you get too invested in her. Look for quotations, status messages, picture captions, etc., that sound like these:
"Love as a drug." Pretty obvious to spot -- "I've found him, my new addiction." "The heart has its reasons that reason does not know about" -- a typical response that addicts give as to why they keep taking drugs, regardless of what Pascal intended. Etc.
"Live to the extreme." More common, since she'll only have a "love as a drug" message when currently infatuated. Normal people don't talk like that -- "live so hard it hurts," "life is too short for mediocre love," "live each day as though it were the last," and so on. With that mindset, you'd list the 100 things that you just have to do before your life ends, and rush through all of them. That's how she views relationships: they're a whirlwind tour through the 100 perfect guys that she just has to date before she dies -- or, more to the point, before she has kids.
The more frequently she puts out these messages, the more likely she is to be a heartbreaker. Plenty of people feel something like an addiction when they're in love, but to be so extreme about it, and especially to be so public and vocal about it, is what distinguishes an Ingenue femme fatale. If she were planning on being with one or two men for her whole life, she would feel addiction for the first month, and say so in her Facebook status messages. But after that, she would mellow out. Even if she doesn't specify a new name or a new "him," a frequent output of vague "I'm so in love" messages means that she's gone through several cycles of falling in and out of love, each outburst corresponding to a new guy.
Also, by broadcasting how passionately in love she is, she attracts and maintains a large stable of potential suitors. Guys dread the prospect of dating a cold fish, so they quickly pursue any "I'm so passionate" signals that girls give off. If her genes' plan were to fall madly in love with one or two men, she wouldn't seek to keep such a stable. She might rave about it to her friends, but an honest girly girl would be far too bashful to skip up and down all of Facebook singing at the top of her lungs about how madly in love she is.
Because her plan is to cycle through as many guys as possible before settling down, you can't hold on to her for very long, so don't bother. Should you find yourself involved with one, don't get emotionally attached to her -- she's using you as an emotional pump-and-dump, so why not use her as a physical pump-and-dump? A lot of guys will find this too tough, though, since her appearance and girly affectations are so adorable and disarming. If you don't think you could deal with that, just probe her at the outset to see if she's an Ingenue or an Ingenue heartbreaker.
Browsing her Facebook is a pretty good way. Finding some way to introduce one of those sayings about "life is too short for mediocre love" into the conversation is good too. Then gauge her reaction. If she mildly agrees, she's probably being polite and doesn't want to sound boring. If she remarks how stupid those sayings are, there's no chance she belongs to this type. But if her reaction is to emote about how omg, she like totally believes in that, i mean like why wouldn't you live each day like the last day of your life??!?! -- then watch out.